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long gamma-ray bursts (grbs) have been discussed as a potential tool to probe the cosmic star formation rate (sfr) for a long time. some studies found an enhancement in the grb rate relative to the galaxy-inferred sfr at high redshifts, which indicates that grbs may not be good tracers of star formation. however, in these studies, the grb rate measured at any redshift is an average over all galaxies at that epoch. a deep understanding of the connection between grb production and environment also needs to characterize the population of grb host galaxies directly. based on a complete sample of grb hosts, we constrain the stellar-mass function (smf) of grb hosts, and examine redshift evolution in the grb host population. our results confirm that a strong redshift evolution in energy (with an evolution index of $\delta ={2.47}_{-0.89}^{+0.73}$ ) or in density ( $\delta ={1.82}_{-0.59}^{+0.22}$ ) is needed in order to account for the observations. the grb host smf can be well described by the schechter function with a power-law index ξ ≈ -1.10 and a break mass mb,0 ≈ 4.9 × 1010 m ⊙, independent of the assumed evolutionary effects. this is the first formulation of the grb host smf. the observed discrepancy between the grb rate and the galaxy-inferred sfr may also be explained by an evolving smf. | the stellar-mass function of long gamma-ray burst host galaxies |
we studied the stability property of numerical cherenkov radiation in relativistic plasma flows employing particle-in-cell simulations. using the implicit finite-difference time-domain method to solve the maxwell equations, we found that nonphysical instability was greatly inhibited with a courant-friedrichs-lewy (cfl) number of 1.0. the present result contrasts with recently reported results (vay et al. 2011, j. comp. phys., 230, 5908; godfrey & vay 2013, j. comp. phys., 248, 33; xu et al. 2013, comput. phys. commun., 184, 2503) in which magical cfl numbers in the range 0.5-0.7 were obtained with explicit field solvers. in addition, we found employing higher-order shape functions and an optimal implicitness factor further suppressed long-wavelength modes of the instability. the findings allowed the examination of the long-term evolution of a relativistic collisionless shock without the generation of nonphysical wave excitations in the upstream. this achievement will allow us to investigate particle accelerations in relativistic shocks associated with, for example, gamma-ray bursts. | stability property of numerical cherenkov radiation and its application to relativistic shock simulations |
in this work, by using strong gravitational lensing (sgl) observations along with type ia supernovae (union2.1) and gamma-ray burst data (grbs), we propose a new method to study a possible redshift evolution of γ(z), the mass density power-law index of strong gravitational lensing systems. in this analysis, we assume the validity of cosmic distance duality relation and the flat universe. in order to explore the γ(z) behaviour, three different parametrizations are considered, namely: (p1) γ(zl) = γ0 + γ1zl; (p2) γ(zl) = γ0 + γ1zl/(1 + zl); and (p3) γ(zl) = γ0 + γ1ln (1 + zl), where zl corresponds to lens redshift. if γ0 = 2 and γ1 = 0, the singular isothermal sphere model is recovered. our method is performed on sgl sub-samples defined by different lens redshifts and velocity dispersions. for the former case, the results are in full agreement with each other, while a 1σ tension between the sub-samples with low (≤250 km s-1) and high (>250 km s-1) velocity dispersions was obtained on the (γ0-γ1) plane. by considering the complete sgl sample, we obtain γ0 ≈ 2 and γ1 ≈ 0 within 1σ c.l. for all γ(z) parametrizations. however, we find the following best-fitting values of γ1: -0.085; -0.16; and -0.12 for p1, p2 and p3 parametrizations, respectively, suggesting a mild evolution for γ(z). by repeating the analysis with type ia supernovae from joint light analysis compilation, grbs and sgl systems this mild evolution is reinforced. | constraints on a possible evolution of mass density power-law index in strong gravitational lensing from cosmological data |
in this work, using the gaussian process, we explore the potentiality of future gravitational wave (gw) measurements to probe cosmic opacity at high redshifts through comparing its opacity-free luminosity distance (ld) with the opacity-dependent one from the combination of type ia supernovae (snia) and gamma-ray bursts (grbs). the gw data, snia and grb data are simulated from the measurements of the future einstein telescope, the actual pantheon compilation and the latest observation of grbs compiled by amati et al, respectively. a nonparametric method is proposed to probe the spatial homogeneity of cosmic transparency at high redshift by comparing the ld reconstructed from the gw data with that reconstructed from the pantheon and grb data. in addition, the cosmic opacity is tested by using the parametrization for the optical depth, and the results show that the constraints on cosmic opacity are more stringent than the previous ones. it shows that the future gw measurements may be used as an important tool to probe the cosmic opacity in the high redshift region. | exploring the potentiality of standard sirens to probe cosmic opacity at high redshifts |
an extended framework of gravity, in which the first friedmann equation is satisfied up to some constant due to violation of gauge invariance, is tested against astrophysical data: supernovae type-ia, cosmic chronometers, and gamma-ray bursts. a generalized expression for the friedmann equation, including the possible vacuum contributions, is suggested, and two particular cosmological models with two independent parameters are considered within this framework and compared on the basis of the likelihood analysis. one of the models considered includes contribution of the residual vacuum fluctuations to the energy density and places the limit on the uv cutoff scale as $k_{max} = 12.43^{+0.9}_{-1.6} [m_p/\sqrt{2+n_{sc}}]$, where $n_{sc}$ is the number of minimally coupled scalar fields. model comparison using the akaike information criteria and bayesian evidence shows a preference for the conventional $\lambda$cdm over the extended models. a more general model with three parameters is considered within which an anti-correlated behavior between the dynamical vacuum fluctuations contribution and a negative cosmological constant was found. the result is an upper limit of $\omega_{\lambda} \lesssim -0.14$ at $95\%$ c.l., which is only mildly disfavored ($\ln\mathcal{b} = -1.8$) with respect to $\lambda$cdm. | reference level of the vacuum energy density of the universe and astrophysical data |
in this paper, we perform a cosmological model-independent test of the cosmic distance-duality relation (cddr) in terms of the ratio of angular diameter distance (add) d = dasl/d as from strong gravitational lensing (sgl) and the ratio of luminosity distance (ld) d∗ = d ll/d ls obtained from the joint of type ia supernovae (snia) union2.1 compilation and the latest gamma-ray bursts (grbs) data, where the superscripts s and l correspond to the redshifts zs and zl at the source and lens from sgl samples. the purpose of combining grb data with snia compilation is to test cddr in a wider redshift range. the ld associated with the redshifts of the observed add is obtained through two cosmological model-independent methods, namely, method a: binning the snia+grbs data, and method b: reconstructing the function of dl by combining the crossing statistic with the smoothing method. we find that cddr is compatible with the observations at 1σ confidence level for the power law model which is assumed to describe the mass distribution of lensing systems with method b in a wider redshift range. | testing the distance-duality relation from strong gravitational lensing, type ia supernovae and gamma-ray bursts data up to redshift z ∼ 3.6 |
the swift active galactic nucleus (agn) and cluster survey (sacs) uses 125 deg2 of swift x-ray telescope serendipitous fields with variable depths surrounding γ-ray bursts to provide a medium depth (4× {{10}-15} erg cm-2 s-1) and area survey filling the gap between deep, narrow chandra/xmm-newton surveys and wide, shallow rosat surveys. here, we present a catalog of 22,563 point sources and 442 extended sources and examine the number counts of the agn and galaxy cluster populations. sacs provides excellent constraints on the agn number counts at the bright end with negligible uncertainties due to cosmic variance, and these constraints are consistent with previous measurements. we use wide-field infrared survey explorer mid-infrared (mir) colors to classify the sources. for agns we can roughly separate the point sources into mir-red and mir-blue agns, finding roughly equal numbers of each type in the soft x-ray band (0.5-2 kev), but fewer mir-blue sources in the hard x-ray band (2-8 kev). the cluster number counts, with 5% uncertainties from cosmic variance, are also consistent with previous surveys but span a much larger continuous flux range. deep optical or ir follow-up observations of this cluster sample will significantly increase the number of higher-redshift (z\gt 0.5) x-ray-selected clusters. | the swift agn and cluster survey. i. number counts of agns and galaxy clusters |
high-redshift primordial galaxies have recently been found with evolved stellar populations and complex star-formation histories reaching back to 250 myr after the big bang. their intense bursts of star-formation appear to be interspersed with sustained periods of strong quenching, however the processes underlying this evolutionary behaviour remain unclear. unlike later epochs, galaxies in the early universe are not located in large associations like clusters. instead, they co-evolve with their developing circumgalactic halo as relatively isolated ecosystems. thus, the mechanisms that could bring about the downfall of their star-formation are presumably intrinsic, and feedback processes associated with their intense starburst episodes likely play an important role. cosmic rays are a viable agent to deliver this feedback, and could account for the star-formation histories inferred for these systems. the cosmic ray impact on galaxies may be investigated using the wealth of multi-wavelength data soon to be obtained with the armada of new and upcoming facilities. complementary approaches to probe their action across the electromagnetic spectrum can be arranged into a distance ladder of cosmic ray feedback signatures. with a clear understanding of how cosmic ray activity in primordial systems can be traced, it will be possible to extend this ladder to high redshifts and map-out the role played by cosmic rays in shaping galaxy evolution over cosmic time. | cosmic rays as a feedback agent in primordial galactic ecosystems |
cosmic transients, such as gamma-ray bursts and fast radio bursts, have been used to constrain the einstein's equivalence principle (eep) through the parametrized-post-newtonian (ppn) formalism. in this approach, the time delay of photons with different energies from these cosmic transients are used to obtain upper bounds on the difference of the ppn γ parameter. in this work we assume that an important contribution to the time delay is due to the dark matter halo of the milky way and consider the dark matter mass distribution given by the navarro-frenk-white profile. we obtain the upper limit on the difference of the ppn parameter γ for the polarized gamma-ray emission of grb 110721a, δγ < 1 . 06 × 10-28, the most stringent limit to date on the eep. in addition, we show that a very similar upper bound is obtained if, instead of having a dark matter component, a visible matter density profile and a non-minimal gravitational coupling between curvature and matter are present. | cosmic transients, einstein's equivalence principle and dark matter halos |
this contribution describes the system performing the trigger and the readout of the pmts for the high energy particle detector (hepd-02) onboard the second satellite of the china seismo electromagnetic satellite (cses-02) mission. cses is a project developed to research the ionospheric perturbations associated with earthquakes. the mission aims at building a network of multi-instrument satellites to conduct a thorough study of ionospheric phenomena. the hepd-02 is designed to detect cosmic rays, i.e., electrons and protons, along with light nuclei, in the energy range between a few mev and a few hundreds of mev. the instrument consists of a tracker, a trigger and a calorimeter surrounded by a veto. all scintillating detectors are readout by a single board which also issues and manages the trigger signals for the whole apparatus. the hepd-02 trigger system must be extremely versatile because along the orbit of cses-02 particle fluxes span several orders of magnitude and data acquisition must guarantee the measurement of energy spectra with a high duty cycle. the hepd-02 trigger system features concurrent trigger configurations and prescaling capability to match the amount of data the instrument can process and send to the ground. each trigger pattern is optimized after scientific requirements about the field of view and the nature of particles impinging in hepd-02, with prescaling settings suitably adjusted. all the trigger configurations will be monitored by rate meters. in addition, a trigger configuration dedicated to gamma-rays will be tracked on a time basis of 10 ms, to measure photon fluxes in the mev-tens of mev energy range and provide sensitivity for gamma ray bursts. we provide a comprehensive description of the design criteria and the architecture of the trigger system. | trigger and data acquisition system of the high energy particle detector on board the cses-02 satellite |
gribenski et al. (2016) investigated moraines of the chagan-uzun valley in the russian altai mountains, concluding from 18 cosmic-ray exposure ages that they slightly predated ∼19 ka, within mis 2. the moraines extended below the highest stand of the kuray/chuja palaeolakes that gave rise to outburst floods down chuja river. gribenski et al. (2016) suggested that the ages from their lowest dated moraine may be minima due to shielding from cosmic-ray exposure by the lake waters for a few thousand years. they noted that their dating agrees with data from other palaeoglaciers in the region and throughout the northern hemisphere, and shows that the regional last glacial maximum (lgm) in the altai occurred during mis 2. | comment on gribenski, n. et al., 2016. complex patterns of glacier advances during the late glacial in the chagan uzun valley, russian altai. quaternary science reviews 149, 288-305 |
comparing the parameterized post-newtonian parameter γ values for different types of particles, or the same type of particles with different energies is an important method to test the einstein equivalence principle (eep). assuming that the observed time delays are dominated by the gravitational potential of the laniakea supercluster of galaxies, better results of eep constraints can be obtained. in this paper, we apply photons from three kinds of cosmic transients, including tev blazars, gamma-ray bursts as well as fast radio bursts to constrain eep. with a gravitational field far more stronger than a single galaxy, we obtain 4-5 orders of magnitude more stringent than the previous results. | testing einstein's equivalence principle with supercluster laniakea's gravitational field |
the observation of complex organic molecules (coms) in the gas phase of cold molecular clouds has coined a freeze-out paradox in astrophysics: coms should be accreted on low-temperature interstellar grains, but not observable in cold molecular clouds. still, validated mechanisms transporting molecules from the grains back into the gas phase are still elusive, but critical for our understanding of the chemical evolution of the molecular universe. here we report on the first characterization of rapid radical reactions involving methyl (ch3) and formyl (hco) radicals in interstellar analogous ices of methane (ch4) and carbon monoxide (co) upon exposure to proxies of galactic cosmic rays. rapid radical chain reactions and explosive desorption occurred once the accumulated radicals surpassed critical concentrations of about 1% in the ices at temperatures of cold molecular clouds (5-10 k). these processes may explain the ejection and observation of coms in the gas phase of cold molecular clouds and potentially rapid outbursts of comets. | rapid radical-radical induced explosive desorption of ice-coated interstellar nanoparticles |
the grapes-3 muon telescope in ooty, india had claimed detection of a 2 hour (h) high-energy (∼20 gev ) burst of galactic cosmic-rays (gcrs) through a >50 σ surge in gev muons, was caused by reconnection of the interplanetary magnetic field (imf) in the magnetosphere that led to transient weakening of earth's magnetic shield. this burst had occurred during a g4-class geomagnetic storm (storm) with a delay of 1/2 h relative to the coronal mass ejection (cme) of 22 june 2015 [p. k. mohanty et al., phys. rev. lett. 117, 171101 (2016), 10.1103/physrevlett.117.171101]. however, recently a group interpreted the occurrence of the same burst in a subset of 31 neutron monitors (nms) to have been the result of an anisotropy in interplanetary space [p. evenson et al., proc. sci., icrc2017 (2017) 133] in contrast to the claim in p. k. mohanty et al., [phys. rev. lett. 117, 171101 (2016), 10.1103/physrevlett.117.171101]. a new analysis of the grapes-3 data with a fine 10.6° angular segmentation shows the speculation of interplanetary anisotropy to be incorrect, and offers a possible explanation of the nm observations. the observed 28 minutes (min) delay of the burst relative to the cme can be explained by the movement of the reconnection front from the bow shock to the surface of earth at an average speed of 35 km /s , much lower than the cme speed of 700 km /s . this measurement may provide a more accurate estimate of the start of the storm. | was the cosmic ray burst detected by the grapes-3 muon telescope on 22 june 2015 caused by a transient weakening of the geomagnetic field or by an interplanetary anisotropy? |
in this thesis a measurement of the high energy $\gamma$-ray flux between 200 mev and 1 tev with the alpha magnetic spectrometer is presented. the alpha magnetic spectrometer (ams-02) is a multi-purpose particle detector mounted externally on the international space station. although primarily designed for the measurement of charged cosmic rays ams-02 is capable of measuring high energy $\gamma$-rays in two complementary modes. two independent analyses are presented in this thesis, one for each of the two modes. the event selection criteria and the associated resolution functions are presented in detail. the effective area is estimated from a full detector monte-carlo simulation and corrected for the most important differences between data and simulation. a full sky model for $\gamma$-rays is constructed from diffuse emission predictions and recent $\gamma$-ray source catalogs. a dedicated analysis of fermi-lat data is performed to fully enable a detailed comparison with the ams result. the measured flux of $\gamma$-rays is presented for various parts of the sky, including comparisons with fermi-lat data and with the constructed model. the inner galaxy is studied in detail, as an example of a region in which the photon flux is dominated by diffuse emission. the fluxes of several $\gamma$-ray producing sources, including vela, geminga and the crab pulsar are shown. the geminga pulsar is studied in detail, revealing its pulsed emission of $\gamma$-rays in the ams-02 data, which allows to measure its frequency of rotation and to estimate its magnetic field strength and age. finally, ams-02 observed an outburst of the flaring blazar cta-102 at the end of 2016. | measurement of high energy gamma rays from 200 mev to 1 tev with the alpha magnetic spectrometer on the international space station |
in the cannonball model of gamma-ray bursts (grbs), a highly relativistic jet of plasmoids of ordinary stellar matter that is ejected during stellar collapse or shortly after by fallback matter, produces simultaneously a grb and a cosmic-ray burst by scattering light and charged particles in its path. this association and the observed knee at ~1 tev in the energy spectrum of galactic cosmic-ray electrons imply a maximum peak energy ~2.25 mev in the energy spectrum of grbs in the 1 kev-10 mev band. such a peak energy and the amati correlation in grbs imply a maximum isotropic equivalent energy release of ~3.8 × 1054 erg in grbs, in the 1 kev-10 mev band. both predictions are in good agreement with up-to-date observations. | the maximum isotropic equivalent energy of gamma-ray bursts |
in recent years, remarkable progress has been achieved in the development of quantum computers. for further development, it is important to clarify properties of errors by quantum noise and environment noise. however, when the system scale of quantum processors is expanded, it has been pointed out that a new type of quantum error, such as nonlinear error, appears. it is not clear how to handle such new effects in information theory. first of all, one should make the characteristics of the error probability of qubits clear as communication channel error models in information theory. the purpose of this paper is to survey the progress for modeling the quantum noise effects that information theorists are likely to face in the future, to cope with such nontrivial errors mentioned above. this paper explains a channel error model to represent strange properties of error probability due to new quantum noise. by this model, specific examples on the features of error probability caused by, for example, quantum recurrence effects, collective relaxation, and external force, are given. as a result, it is possible to understand the meaning of strange features of error probability that do not exist in classical information theory without going through complex physical phenomena. | introduction to semi-classical analysis for digital errors of qubit in quantum processor |
the present work proposes a new formalism for the inner regions of a neutrino-dominated accretion flows (ndafs) by considering the self-gravity, where the neutrino opacity is high enough to make neutrinos trapped becoming a dominant factor in the transportation of energy and angular momentum over the magneto rotational instability. we investigate the possibility of gravitational instability and fragmentation to model the highly variable structure of the prompt emission in gamma-ray bursts (grbs). the results lead us to introduce the gravitational instability, in these inner regions, as a source of a new viscosity that is of the same functional form as that of the β-prescription of viscosity. such a consideration brings about fragmentation in the unstable inner disc. in addition, we find the consequent clumpy structure of this area capable to account for the temporal variability of grb's light curve, especially for the lower choices of the parameter β, ~10-5. finally, we predict the formation of gravitational waves through the migration of fragments before being tidally disrupted. these waves appear to be detectable via a range of current and future detectors from ligo to cosmic explorer. | grb variabilities and following gravitational waves induced by gravitational instability in ndafs |
the redshift and luminosity distributions of 36 swift short gamma-ray bursts (grbs) are fitted by connecting their event rates with cosmic star formation rates using power-law distributed delay times f(τ )\propto {τ }-1, where a broken-power-law luminosity function is assumed and some empirical observational selection effects are taken into account. as a result, the most-likely model parameters are constrained to be {ν }1=0.91, {ν }2=1.66 as power-law indices, with a break at {l}b=2.51× {10}51 erg s-1 for the luminosity function and {τ }c=6.0 gyr for a typical gravitational wave decay timescale of the binary orbit. the corresponding local rate of short grbs is found to be ∼ (3-4) {gpc}}-3 {yr}}-1. with these parameters, the detectable numbers of short grbs are estimated within the horizon of advanced ligo. | revisiting the event rate of short grbs and estimating their detectable number within the advanced ligo horizon |
gamma-ray bursts (grbs) are brief, intense, gamma-ray flashes in the universe, lasting from a few milliseconds to a few thousand seconds. for short gamma-ray bursts (sgrbs) with duration less than 2 seconds, the isotropic energy (e iso) function may be more scientifically meaningful and accurately measured than the luminosity (l p) function. in this work we construct, for the first time, the isotropic energy function of sgrbs and estimate their formation rate. first, we derive the l p - e p correlation using 22 sgrbs with known redshifts and well-measured spectra and estimate the pseduo redshifts of 334 fermi sgrbs. then, we adopt the lynden-bell c - method to study isotropic energy functions and formation rate of sgrbs without any assumption. a strong evolution of isotropic energy e iso ∝ (1+z)5.79 is found, which is comparable to that between l p and z. after removing effect of the cosmic evolution, the isotropic energy function can be reasonably fitted by a broken power law, which is $\phi ({e}_{{\rm{iso}},0})\propto {e}_{{\rm{iso}},0}^{-0.45}$ for dim sgrbs and $\phi ({e}_{{\rm{iso}},0})\propto {e}_{{\rm{iso}},0}^{-1.11}$ for bright sgrbs, with the break energy 4.92 × 1049 erg. we obtain the local formation rate of sgrbs is about 17.43 events gpc-3 yr-1. if assuming a beaming angle is 6° to 26°, the local formation rate including off-axis sgrbs is estimated as ρ 0,all = 155.79 - 3202.35 events gpc-3 yr-1. | the isotropic energy function and formation rate of short gamma-ray bursts |
the absorption of decimeter (dm) radio waves (wavelength ~19 cm) in the high-latitude lower ionosphere of the earth is found based on analysis of formosat-3/cosmic radio occultation data. a method is proposed to reconstruct the vertical profiles of the absorption coefficient by solving the inverse problem of radio sounding in the earth's lower ionosphere. this method is general and can be used for different radio wave bands and other global navigation satellite system (gnss) signals. during radio occultation sessions the absorption layers, which are caused by powerful x-ray bursts and strong changes in geomagnetic conditions during storms, are reliably identified. it is also found that at altitudes of ~90 to ~100 km, the absorption coefficient of dm radio waves reached values of (5.7 ± 1.4) × 10-3 db/km. the practical significance of studying the effects of radio wave absorption in the d- and e-regions of the ionosphere is associated with ensuring smooth operation of space radio communication and navigation systems. | the absorption coefficient of decimeter radio waves ( 19 cm) in the earth's ionosphere based on the inverse problem solution in radio occultation satellite studies during the june 2015 magnetic storm |
aims: low-mass galaxies radio observations show in many cases surprisingly high levels of magnetic field. the mass and kinematics of such objects do not favour the development of effective large-scale dynamo action. we attempted to check if the cosmic-ray-driven dynamo can be responsible for measured magnetization in this class of poorly investigated objects. we investigated how starburst events on the whole, as well as when part of the galactic disk, influence the magnetic field evolution.methods: we created a model of a dwarf/magellanic-type galaxy described by gravitational potential constituted from two components: the stars and the dark-matter halo. the model is evolved by solving a three-dimensional (3d) magnetohydrodynamic equation with an additional cosmic-ray component, which is approximated as a fluid. the turbulence is generated in the system via supernova explosions manifested by the injection of cosmic-rays.results: the cosmic-ray-driven dynamo works efficiently enough to amplify the magnetic field even in low-mass dwarf/magellanic-type galaxies. the e-folding times of magnetic energy growth are 0.50 and 0.25 gyr for the slow (50 km s-1) and fast (100 km s-1) rotators, respectively. the amplification is being suppressed as the system reaches the equipartition level between kinetic, magnetic, and cosmic-ray energies. an episode of star formation burst amplifies the magnetic field but only for a short time while increased star formation activity holds. we find that a substantial amount of gas is expelled from the galactic disk, and that the starburst events increase the efficiency of this process. | magnetic field evolution in dwarf and magellanic-type galaxies |
in this work, we use two gas mass fraction samples of galaxy clusters obtained from their x-ray surface brightness observations jointly with recent h(z) data in a flat λcdm framework to impose limits on cosmic opacity. {it is assumed that the galaxy clusters are in hydrostatic equilibrium and their gas mass fraction measurement is constant with redshift.} we show that the current limits on the matter density parameter obtained from x-ray gas mass fraction test are strongly dependent on the cosmic transparency assumption even for a flat scenario. our results are consistent with a transparent universe within 1σ c.l. in full agreement with other analyses which used type ia supernovae, gamma ray burst and h(z) data. | x-ray surface brightness observations of galaxy clusters, cosmic opacity and the limits on the matter density parameter |
dios (diffuse intergalactic oxygen surveyor) is a small satellite aiming for a launch around 2022 with jaxa's epsilon rocket. its main aim is a search for warm-hot intergalactic medium with high-resolution x-ray spectroscopy of redshifted emission lines from ovii and oviii ions. the superior energy resolution of tes microcalorimeters combined with a wide field of view (30' diameter) will enable us to look into gas dynamics of cosmic plasmas in a wide range of spatial scales from earth's magnetosphere to unvirialized regions of clusters of galaxies. mechanical and thermal design of the spacecraft and development of the tes calorimeter system are described. employing an enlarged x-ray telescope with a focal length of 1.2 m and fast repointing capability, dios can observe absorption features from x-ray afterglows of distant gamma-ray bursts. | dios: the dark baryon exploring mission |
gamma-ray bursts (grbs) are extremely energetic events at cosmological distances. they provide unique laboratory to investigate fundamental physical processes under extreme conditions. due to extreme luminosities, grbs are detectable at very high redshifts and potential tracers of cosmic star formation rate at early epoch. while the launch of {\it swift} and {\it fermi} has increased our understanding of grbs tremendously, many new questions have opened up. radio observations of grbs uniquely probe the energetics and environments of the explosion. however, currently only 30\% of the bursts are detected in radio bands. radio observations with upcoming sensitive telescopes will potentially increase the sample size significantly, and allow one to follow the individual bursts for a much longer duration and be able to answer some of the important issues related to true calorimetry, reverse shock emission and environments around the massive stars exploding as grbs in the early universe. | gamma-ray bursts: a radio perspective |
on april 28, 2016, the lomonosov satellite, equipped with a number of scientific instruments, was launched into orbit. here we present briefly some of the results obtained with the first orbital telescope of extreme energy cosmic rays tus and by a group of detectors aimed at multi-messenger observations of gamma-ray bursts. | first results of the lomonosov tus and grb experiments |
theseus is a space mission concept, currently under phase a study by esa as candidate m5 mission, aiming at exploiting gamma-ray bursts for investigating the early universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. in addition to fully exploiting high-redshift grbs for cosmology (pop-iii stars, cosmic re-ionization, sfr and metallicity evolution up to the "cosmic dawn"), theseus will allow the identification and study of the electromagnetic counterparts to sources of gravitational waves which will be routinely detected in the late '20s / early '30s by next generation facilities like aligo/avirgo, lisa, kagra, and einstein telescope (et), as well as of most classes of x/gamma-ray transient sources, thus providing an ideal synergy with the large e.m. facilities of the near future like, e.g., lsst, elt, tmt, ska, cta, athena. these breakthrough scientific objectives will be achieved by an unprecedented combination of x/gamma-ray monitors, providing the capabilities of detecting and accurately localize and kind of grbs and may classes of transient in an energy band as large as 0.1 kev - 10 mev, with an on-board nir telescope providing detection, localization (arcsec) and redshift measurement of the nir counterpart. a guest observer programme, further improving the scientific return and community involvement is also envisaged. we summarize the main scientific requirements of the mission and provide an overview of the updated concept, design (instruments and spacecraft) and mission profile. | the theseus space mission: updated design, profile and expected performances |
cosmic gamma-ray bursts (grbs) and soft gamma-ray repeaters (sgrs) are the brightest sources of high-energy electromagnetic radiation. for many years, grb and sgr studies have been among the major basic research areas at the ioffe institute. the physical processes that power immense luminosity of the cosmic gamma-ray sources are of utmost interest because they enable exploring physical phenomena in the vicinities of stellar-mass black holes and neutron stars, whose magnetic fields are probably larger than the critical vacuum polarization value, i.e., under conditions inaccessible in terrestrial laboratories. owing to the high luminosity, grbs can be detected at distances up to the edge of the visible universe, and thus enable studying how the first stars emerged and probing the properties of matter along the entire line of sight to the sources. we briefly review the results of modern multi-wavelength studies of cosmic grbs and sgrs. we discuss the history of the grbs and sgrs studies, a vibrant area of basic astrophysical research at the ioffe institute, their accomplishments and prospects. we describe in detail the results obtained with several generations of konus detectors that have been designed and manufactured at the ioffe institute. observational data obtained by space-based instruments are effectively complemented by theoretical modeling of astrophysical processes that exhibit extreme energy release. we also discuss prospects for grb and sgr studies, including future experiments scheduled at the ioffe institute. | cosmic gamma-ray bursts and soft gamma-repeaters - observations and modeling of extreme astrophysical phenomena: (100th anniversary of the ioffe institute) |
the scientific instruments onboard the lomonosov satellite include a complete set of detectors designed to study the gamma and optical emission of cosmic gamma-ray bursts (grbs). the bdrg gamma spectrometer ensures producing a trigger of a grb and studying grb properties in the energy range of 10-3000 kev as well as determining the grb source coordinates by comparing readings of three differently directed detectors. the shok optical cameras (with a field of view of 20 × 40 degrees) fix a set of images by the grb trigger preceding the trigger and a post-trigger set at a frequency of about five frames per second. the uffo instrument incorporates the ubat telescope with a coding mask for measurements within a range of hard x rays and soft gamma rays and the smt optical slewing mirror telescope, which can be directed at the grb source in about 1 s to measure the grb optical emission at early stages. | complete set of detectors for studying cosmic gamma-ray bursts onboard the lomonosov satellite |
short timescale variability is often associated with a black hole system. the consequence of an electromagnetic outflow suddenly generated near a kerr black hole is considered assuming that it is described by a solution of a force-free field with a null electric current. we compute charged particle acceleration induced by the burst field. we show that the particle is instantaneously accelerated to the relativistic regime by the field with a very large amplitude, which is characterized by a dimensionless number κ. our numerical calculation demonstrates how the trajectory of the particle changes with κ. we also show that the maximum energy increases with κ2/3. the typical maximum energy attained by a proton for an event near a super massive black hole is emax∼100 tev, which is enough observed high-energy flares. | particle acceleration driven by null electromagnetic fields near a kerr black hole |
the pamela and the arina experiments are carried out on the board of satellite resurs-dk1 since 2006 up to now. main goal of the pamela instrument is measurements of high energy antiparticles in cosmic rays while the arina instrument is intended studying high energy charged particle bursts in the magnetosphere. both of these experiments have a possibility to study trapped particles in the inner radiation belt. complex of these two instruments covers proton energy range from 30 mev up to trapping limit (e= ∼2 gev). continuous measurements with the pamela and the arina spectrometers include falling and rising phases of 23/24 solar cycles and maximum of 24th one. in this report we present temporal profiles of proton flux in the inner zone of the radiation belt (1.11 < l < 1.18, 0.18 < b < 0.22g). dependence of proton fluxes on a magnitude of the solar activity was studied for various phases of 23/24 solar cycles. at that it was shown that proton fluxes at the solar minimum are several times greater than at the solar maximum. | time variations of proton flux in earth inner radiation belt during 23/24 solar cycles based on the pamela and the arina data |
to use the luminous gamma-ray bursts and their afterglows as messengers from the early universe has been advocated ever since the discovery of the cosmological nature of the grb phenomenon in the late nineties. it took, however, until the advent of swift to detect high-redshift grbs in significant numbers, and to provide the localization capabilities to enable statistical samples of grbs free of selection biases and complete in redshift. i will present and discuss some of the recent progress in the field, with an emphasize on new results derived from sample studies and their implications for the nature of grbs and their host galaxies. i will particularly focus on observations made with the seven-channel imager grond and x-shooter, an optical/nir echelle spectrograph mounted at the very large telescope since 2009. | grb-selected galaxies through cosmic time |
in this work, we propose a modification of the e-model (cullen, neale, and lesser) mathematical model for aquatic photosynthesis to include the action of ionizing radiation. we evaluated, with this modified model, the perturbations that muons from neutron star fusions could cause in the biological process of aquatic photosynthesis. it is shown that neutron star fusions not far from the solar system have the potential to considerably deplete aquatic photosynthesis. | perturbation to aquatic photosynthesis due to high energy muons from cosmic ray bursts due to neutron star mergers |
long-duration gamma-ray bursts (long-grbs) can be detected throughout cosmic history and provide several unique insights into star-formation and galaxy evolution back to the era of reionization. they can be used to map star formation, identify galaxies across the luminosity function, determine detailed abundances even for the faintest of galaxies, quantify the escape fraction of ionizing radiation and track the progress of reionization. fully exploiting these techniques requires a significant increase in the number of long-grbs identified and characterised at zgtrsim6 , which can be achieved through a discovery mission with the capabilities of theseus, in combination with the powerful follow-up facilities that will be available in the 2030s. | theseus and the high redshift universe |
the cosmic gamma-ray bursts are certainly an enigma in astrophysics. the “standard fireball” scenario developed during many years has provided a possible explanation of this phenomena. the aim of this work is simply to explore a new possible interpretation by developing a coherent scenario inside the global picture of stellar evolution. at the basis of our scenario, is the fact that maybe we have not fully understood how the core of a pair instability supernova explodes. in such way, we have proposed a new paradigm assuming that the core of such massive star, instead of doing a symmetrical explosion, is completely fragmented in hot spots of burning nuclear matter. we have tested our scenario with observational data like grb spectra, lightcurves, amati relation and grb-sn connection, and for each set of data we have proposed a possible physical interpretation. we have also suggested some possible test of this scenario by measurement at high redshifts. if this scenario is correct, it tells us simply that the cosmic gamma-ray bursts are a missing link in stellar evolution, related to an unusual explosion. | cosmic gamma-ray bursts from primordial stars: a new renaissance in astrophysics? |
the gamma-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (grbs) and γ-rays from the active sun. scientific goals of gamma-400 telescope require fine angular resolution. the telescope is of a pair-production type. in the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. the method of utilising this process to improve the resolution is proposed in the presented work. | method of incident low-energy gamma-ray direction reconstruction in the gamma-400 gamma-ray space telescope |
the author - with his collaborators - already in years 1995-96 have shown - purely from the analyses of the observations - that the gamma-ray bursts (grbs) can be till redshift 20. since that time several other statistical studies of the spatial distribution of grbs were provided. remarkable conclusions concerning the star-formation rate and the validity of the cosmological principle were obtained about the regions of the cosmic dawn. in this contribution these efforts are surveyed. | spatial distribution of the gamma-ray bursts at very high redshift |
theseus is a space mission concept currently under phase a study by esa as candidate m5 mission, aiming at exploiting gamma-ray bursts for investigating the early universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. through an unprecedented combination of x-/gamma-ray monitors, an on-board ir telescope and automated fast slewing capabilities, theseus will be a wonderful machine for the detection, characterization and redshift measurement of any kind of grbs and many classes of x-ray transients. in addition to the full exploitation of high-redshift grbs for cosmology (pop-iii stars, cosmic re-ionization, sfr and metallicity evolution up to the "cosmic dawn"), theseus will allow the identification and study of the electromagnetic counterparts to sources of gravitational waves which will be routinely detected in the late '20s / early '30s by next generation facilities like aligo/avirgo, lisa, kagra, and einstein telescope (et), as well as of most classes of transient sources, thus providing an ideal synergy with the large e.m. facilities of the near future like lsst, elt, tmt, ska, cta, athena. | the transient high-energy sky and early universe surveyor (theseus) |
we discuss likely sources of cosmic rays in the 1015 -1020ev range and their possible very high energy neutrino and gamma-ray signatures which could serve to identify these sources and constrain their physics. among these sources we discuss in particular low luminosity gamma-ray bursts, including choked and shock-breakout objects, tidal disruption events and white dwarf mergers. among efforts aimed at simultaneous secondary multi-messenger detections we discuss the amon program. | multi-messenger signatures of pev-zev cosmic ray sources |
the observations of grbs over many years are discussed. the main key steps in grb investigations are the following: the first simultaneous observations of grb720117 (cosmos-461 and vela); the first bimodal distribution's discussion in 1981 by mazets, golenetskii; the first grb with optical afterglow investigations grb970228 (batse); the first prompt observations of grb by akerlof (grb990123, rotse-i response to batse alert) are demonstrated. the evolution of the coalescence rate of double neutron stars and neutron star-black hole binaries were first computed by lipunov et al. in 1995. we also discuss scenarios for long and short grbs. and there are some results of master global robotic net grb observations. | master and unsolved grb observational and theoretical problems |
the measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 mev to several tev, which will be implemented by the specially designed gamma-400 gamma-ray telescope, concern with the following broad range of science topics. searching for signatures of dark matter, surveying the celestial sphere in order to study gamma-ray point and extended sources, measuring the energy spectra of galactic and extragalactic diffuse gamma-ray emission, studying gamma-ray bursts and gamma-ray emission from the sun, as well as high precision measuring spectra of high-energy electrons and positrons, protons and nuclei up to the knee. to clarify these scientific problems with the new experimental data the gamma-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. for gamma-ray energies more than 100 gev gamma-400 provides the energy resolution of ~1% and angular resolution better than 0.02 deg. the methods developed to reconstruct the direction of incident gamma photon are presented in this paper, as well as, the capability of the gamma-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. | the gamma-400 gamma-ray telescope characteristics. angular resolution and electrons/protons separation. |
most of what is currently known about slow radio transients (supernovae, gamma-ray bursts, tidal disruption events, stellar flares, etc.) has come via radio follow-up of objects identified by synoptic telescopes at optical, x-ray or gamma-ray wavelengths. however, with the ability to capture obscured, unbeamed and magnetically-driven phenomena, radio surveys offer unique discovery strong diagnostic for cosmic transients. for the first time, we are systematically exploring the dynamic radio sky on timescales between one day to several years using multi-epoch large surveys with the karl g. jansky array (vla). we have carried out surveys in the cosmos deep field as well as wide fields like stripe 82. i have developed a unique infrastructure for near-real-time calibration, imaging, transient search, transient vetting, rapid multiwavelength follow-up, and contemporaneous optical surveys to better characterize radio transient phenomena. a large part of my thesis includes the commissioning of a new observing mode at the vla: on-the-fly mosaicking. this mode has significantly improved the survey efficiency of the vla, and it is a driver for vlass, the future all-sky survey planned with this telescope. through our radio surveys we have discovered several fascinating transients that are unique to the radio. these surveys have established the vla as an efficient transient discovery machine. my thesis has enormous implications for how to design efficient transient surveys for the next generation of radio interferometer facilities like askap, meerkat, wsrt/apertif and lofar. my work has also provided answers to key problems such as the rates of transients, demographics of variability of radio sources including agn, and false-positive foreground for future searches for the radio counterparts of gravitational-wave (gw) sources. | exploring the dynamic radio sky |
indian centre for space physics has been flying low-cost mainly meteorological balloons (both rubber and polythene) for about 10 years and successfully completed 109 such missions. some of them even had multiple balloons in order to achive longer flights at specific heights. we carry main instruments (geiger counters, bicrons, phoswiches and other x-ray detectors), gps units, degree-of-freedom measuring units, sun sensors etc. the payload is typically less than 5 kilogram and we typically reach about 40km, height being about 42km. we recover all the payloads and thus our recurring cost is less than 500 usd per flight. we have no pointing devices or ballasts as in larger and expensive counterparts. we do not require larger space for launching either. yet, we have achieved major scientific goals such as (a) monitoring cosmic ray variations year after year (b) solar flare light curves and spectra (c) x-rays from crab nebula and its pulses (d) e+e- pair annihilation lines, (e) gamma ray bursts etc. we often traced mysterious radiations spread in 20-22 km height for days on. based on out inputs we compute the aviation safety and radiation hazards. we believe that our pioneering method may be a very useful tool to test cansats, nanosats and cubesats prior to their flights. | low cost balloon borne science programme of icsp in near space and its future goals |
at 03:35:24 ut, the swift burst alert telescope (bat) triggered and located a marginal image peak (trigger=1144538). swift slewed immediately to the peak location. the bat on-board calculated location is ra, dec 54.789, -27.433 which is ra(j2000) = 03h 39m 09s dec(j2000) = -27d 25' 57" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). the bat light curve shows the count rate starting to rise as swift approaches the south atlantic anomaly (saa) but does not show a typical grb peak. the xrt position notice sent was due to xrt centroiding on a likely cosmic ray strike. there is no clear detection of an x-ray afterglow. due to the rate trigger occurring during the approach to the saa, the lack of a strong peak in the bat light curve, the marginal significance (6.55 sigma) of the bat image peak, and the lack of an xrt afterglow source, we believe that this event is a statistical fluctuation and not an astrophysical event. a final determination of the nature of this trigger will require the full ground-linked dataset. | swift trigger 1144538 is not a grb |
a theory suggests our planet earth had an extreme cooling from 5.9 to 5.33 million years ago, a most extensive glaciation "miocene glacier" since the dinosaur's era. the cosmic ray outburst from sagittarius a, ca 6 mya, emerges as the leading cause. | did outburst of supermassive black hole sagittarius a cause an extreme glaciation on earth? |
improved atmospheric ionisation measurements are needed to help quantify relationships between atmospheric electricity, weather and climate. commercial interest in small particle detectors is also driving technical development of a novel scintillator-based energetic particle detector. this method is an improvement on other low-cost, low-mass detectors such as geiger tubes in that it provides both count rate and energy discrimination, and is sensitive to almost all types of ionising radiation. it can be deployed either as a stand-alone instrument, or integrated with a meteorological radiosonde. here we describe results obtained from a test flight over reading, uk, in calm space weather conditions, where the new instrument was integrated with a vaisala rs92 radiosonde, and flown alongside two geiger counters, both sensitive to gamma and beta radiation. the flight reached an altitude of 27 km before the balloon burst, well above the regener-pfotzer ionisation maximum. ionisation profiles from the count rates measured by the geiger tubes and scintillator detector were comparable in shape. energy information from the scintillator detector indicated a dominant effect of natural radioactivity in the boundary layer, as expected and previously observed with this instrument. above the boundary layer, energy increased with height up to the maximum altitude reached, consistent with increasingly energetic cosmic ray ionisation. | ionisation profile measured over the uk with novel energy-discriminating instrumentation |
the first stars in the first galaxies created the first nuclear-powered light, the first heavy metals, and reionized the intergalactic medium. we describe studies of x-ray sources in low-metallicity star-bursting dwarfs that are local analogs of the first galaxies. we review the effect of metallicity on x-ray binary populations and the nature of x-ray sources in lyman continuum emitting galaxies. we discuss the implications for the role of accretion powered sources in the early universe. | accreting compact objects at cosmic dawn |
we present a catalog of probabilistic redshift estimates for 1366 individual long-duration gamma-ray bursts (lgrbs) detected by the burst and transient source experiment (batse). this result is based on a careful selection and modeling of the population distribution of 1366 batse lgrbs in the five-dimensional space of redshift and the four intrinsic prompt gamma-ray emission properties: the isotropic 1024ms peak luminosity (liso), the total isotropic emission (eiso), the spectral peak energy (epz), as well as the intrinsic duration (t90z), while carefully taking into account the effects of sample incompleteness and the lgrb-detection mechanism of batse. two fundamental plausible assumptions underlie our purely probabilistic approach: (1) lgrbs trace, either exactly or closely, the cosmic star formation rate, with a possibility of the excess rates of lgrbs in the nearby universe, and (2) the joint four-dimensional distribution of the aforementioned prompt gamma-ray emission properties is well described by a multivariate log-normal distribution. our modeling approach enables us to constrain the redshifts of individual batse lgrbs to within 0.36 and 0.96 average uncertainty ranges at 50% and 90% confidence levels, respectively. our redshift predictions are completely at odds with the previous redshift estimates of batse lgrbs that were computed via the proposed phenomenological high-energy relations, specifically, the apparently strong correlation of lgrbs' peak luminosity with the spectral peak energy, lightcurve variability, and spectral lag. the observed discrepancies between our predictions and the previous works can be explained by the strong influence of detector threshold and sample incompleteness in shaping these phenomenologically proposed high-energy correlations in the literature. finally, we also discuss the potential effects of an excess cosmic rate of lgrbs at low redshifts and the possibility of a luminosity evolution of lgrbs on our results. (1 data file). | vizier online data catalog: 1366 lgrb redshifts estimates with barse (osborne+, 2020) |
following the classical works on neutron stars, black holes and cosmology, i outline some recent results obtained in the irap-phd program of icranet on the "cosmic matrix": a new astrophysical phenomenon recorded by the x- and gamma-ray satellites and by the largest ground based optical telescopes all over our planet. in 3 minutes it has been recorded the occurrence of a "supernova", the "induced-gravitational-collapse" on a neutron star binary, the formation of a "black hole", and the creation of a "newly born neutron star". this presentation is based on a document describing activities of icranet and recent developments of the paradigm of the cosmic matrix in the comprehension of gamma ray bursts (grbs) presented on the occasion of the fourteenth marcel grossmann meeting on recent developments in theoretical and experimental general relativity, gravitation, and relativistic field theory. a portuguese version of this document can be downloaded at: http://www.icranet.org/documents/brochure_icranet_pt.pdf. | cosmic matrix in the jubilee of relativistic astrophysics |
more than 60 grbs at z >~ 1.5 reside in the vicinity of dense, cold gas as probed by the measured neutral hydrogen via afterglow absorption spectroscopy. we present the largest sample of grb-dlas to date in comparison with a sample of dlas along quasars: the metallicity of the grb hosts represents a unique tool to understand if this particular subset of galaxies can be the key ingredient for grb formation (and massive stars) at any redshift as well as the overall cosmic star-formation rate. we show that grb-dlas live in a metal enriched environment, especially at z >~ 4, likely the result of recent intense star formation and/or sne episodes. we also derive that our metallicity measurements are broadly consistent with a mild metallicity bias for the grb formation. | exploring the environment of the most powerful explosions |
the nuclear spectroscopic telescope array (nustar) has enabled studies of the local active galactic nuclei (agn) to extend into the hard x-ray band, up to 79 kev, with unprecedented spatial resolution and sensitivity. as a part of its extragalactic program, nustar is surveying the nearby population of agn detected at hard x-ray energies by the swift burst alert telescope (swift/bat), selecting even the most obscured local agn. i will highlight some of the results based on broadband x-ray spectroscopy of individual targets and present my work on the large representative sample of more than a hundred nearby obscured agn, which constitutes the largest available atlas of hard x-ray spectra of obscured agn to date. the high quality of the data allows us to probe the details of agn structures such as the x-ray-emitting corona and the toroidal obscurer in the under-explored spectral window above 10 kev. i will present both phenomenological results important for synthesis models of the cosmic x-ray background, and a novel approach for constraining the geometry of the gas surrounding the supermassive black hole (including the accretion disk, the broad-line region, and the torus) from the hard x-ray band. finally, i will discuss how what we learned from this survey of local agn relates to deeper high-redshift x-ray surveys and agn structure probes at other wavelengths. | hard x-ray spectroscopy of obscured agn with nustar |
lflgrb models the luminosity function (lf) of long gamma ray bursts (lgrbs) by using a sample of swift and fermi lgrbs to re-derive the parameters of the yonetoku correlation and self-consistently estimate pseudo-redshifts of all the bursts with unknown redshifts. the grb formation rate is modeled as the product of the cosmic star formation rate and a grb formation efficiency for a given stellar mass. | lflgrb: luminosity function of long gamma-ray bursts |
accretion disks of neutron stars can be heavily irradiated by type i x-ray bursts, which significantly alter the disk structure. previous work simulated the time-dependent impact of the burst on the disk for a nonspinning neutron star. here, we study the impact of spin on the burst-disk interaction through relativistic, hydrodynamic simulations. with the code cosmos++, we run two-dimensional time-dependent simulations featuring a thin accretion disk, a burst with a peak luminosity of 1038 erg s-1, and a prograde spin with a spin parameter of a = 0.2. our work shows how the spin affects the response of the disk to the burst. | impact of spin on the accretion disk response to a type i x-ray burst |
plasma with interpenetrating beams is known to exhibit electromagnetic instabilities such as the filamentation (e.g., weibel) instability. extreme astrophysical environments, such as in collisionless shocks of cosmic explosions - gamma-ray bursts and supernovae, are natural places where such beam-plasma instabilities naturally occur and affect plasma dynamics and observable light. here we investigate the case of a collisionless, unmagnetized system with relativistic counter-streaming beams with pic simulations. we present the spectral analysis of the system as it evolves. we discuss the spectrum, temporal and angular distribution of the generated plasma modes. supported by the grants: doe de-sc0019474, nsf phy-2010109. | spectral analysis of pic simulations of interpenetrating plasmas |
it has been a long-standing challenge to probe cosmic-ray particles at thecenter of our galaxy. low energy cosmic-ray protons (lecrp) with energiesof mev to gev can produce 6.4 kev fe k-alpha line and continuum x-rayemission through interaction with cold molecular materials. the fe k-alphaemission from the densest galactic center molecular cloud sgr b2 has beendecaying for the past decade, which has been dominated by reflection ofa past sgr a* x-ray outburst. however, as the x-ray reflection componentkeeps fading, a constant fe k-alpha emission component will take the stagebeginning early 2017. the flux level of the sgr b2 fe k- alpha emissionmeasured in 2017-2018 will for the first time put strong constraints onthe mev- gev cosmic-ray proton population, not previously achievable. | probing galactic center mev-gev cosmic-ray population with sgr b2 fe k emission |
correlated neutron counting using multiplicity shift register logic extracts the first three factorial moments from the detected neutron pulse train. the descriptive properties of the measurement item (mass, the ratio of (α,n) to spontaneous fission neutron production, and leakage self-multiplication) are related to the observed singles (s), doubles (d) and triples (t) rates, and this is the basis of the widely used multiplicity counting assay method. the factorial moments required to interpret and invert the measurement data in the framework of the point kinetics model may be calculated from the spontaneous fission prompt neutron multiplicity distribution p(ν). in the case of 238u very few measurements of p(ν) are available and the derived values, especially for the higher factorial moments, are not known with high accuracy. in this work, we report the measurement of the triples rate per gram of 238u based on the analysis of a set of measurements in which a collection of 10 cylinders of uo2f2, each containing about 230 g of compound, were measured individually and in groups. special care was taken to understand and compensate the recorded multiplicity histograms for the effect of random cosmic-ray induced background neutrons, which, because they also come in bursts and mimic fissions but with a different and harder multiplicity distribution. we compare our fully corrected (deadtime, background, efficiency, multiplication) experimental results with first principles expectations based on evaluated nuclear data. based on our results we suspect that the current evaluated nuclear data is biased, which points to a need to undertake new basic measurements of the 238u prompt neutron multiplicity distribution. | neutron triples counting data for uranium |
plasma with interpenetrating beams is known to exhibit instabilities such as the filamentation and two-stream instabilities. beam-plasma systems are ubiquitous in high-energy-density environments, e.g., in laser-produced plasmas and astrophysical sources, such as in collisionless shocks of cosmic explosions - gamma-ray bursts and supernovae. here we investigate the case of a collisionless, unmagnetized system with relativistic counter-streaming beams with pic simulations. we present the spectral analysis of the system as it evolves. we discuss the spectrum, temporal and angular distribution of the generated plasma modes. supported by the nsf grant phy-2010109 and the doe epscor grant de-sc0019474. | pic simulations and spectral analysis of plasma with interpenetrating beams |
earth's atmosphere, whose ionization stability plays a fundamental role for the evolution and endurance of life, is exposed to the effect of cosmic explosions producing high energy gamma-ray-bursts. being able to abruptly increase the atmospheric ionization, they might deplete stratospheric ozone on a global scale. during the last decades, an average of more than one gamma-ray-burst per day were recorded. nevertheless, measurable effects on the ionosphere were rarely observed, in any case on its bottom-side (from about 60 km up to about 350 km of altitude). here, we report evidence of an intense top-side (about 500 km) ionospheric perturbation induced by significant sudden ionospheric disturbance, and a large variation of the ionospheric electric field at 500 km, which are both correlated with the october 9, 2022 gamma-ray-burst (grb221009a). | evidence of an upper ionospheric electric field perturbation correlated with a gamma ray burst |
grbs are potential sources of uhe cosmic rays and high-energy neutrinos. recent results from icecube imply the relation between these particles is not trivial. we provide updated neutrino predictions based on realistic models. | multi-messenger light curves from gamma-ray bursts |
in this work we postulate that the process of quasi-electrostatic energy relaxation in thundercloud starts with small-scale townsend avalanches in the vicinity of colliding hydrometers and then proceeds to larger spatial scales, culminating in the formation of hot lightning seed channel. we represent the lightning initiation scenario as a sequence of two transitions of discharge activity to progressively larger spatial scale: the first one from small-scale townsend avalanches to mesoscale streamer discharges; and the second one from streamers to large-scale system of hot channels. we suggest a physically grounded refinement of the breakdown field concept and postulate the existence of ion production centers, whose appearance is caused by electric field bursts accompanying hydrometeors collisions or near collisions in turbulent thundercloud environment. we present a new mechanism of streamer generation in thunderclouds based on the instability of cloud environment in respect with the ion concentration increase due to the presence of ion production centers. the ion production centers are activated sequentially, each one passing through the residual ion spot left behind by the previously established center. the ion spot, through the effective electron detachment in the elevated electric field, leads to the rise in seed electron population just before the field amplitude reaches the breakdown value, immediately resulting in a higher level of electron and positive ion production when the next center is activated. the resultant stochastic relief of the volume charge density of ions provides local electric field enhancements and increase in pre-ionization level that are sufficient for the initiation and development of streamers. the proposed mechanism does not require the presence of super energetic cosmic ray particles, unrealistic potential difference in the cloud, or unreasonably long streamers originating from a single hydrometeor, unrealistically large hydrometeors and considerable "preionization" of unknown origin. the lightning initiation mechanism that we suggest in this study requires only one condition: the rate of occurrence of ion production centers per unit time in a unit volume should exceed the critical level of 10-1 m-3s-1, which is easily achieved in a typical thundercloud. indeed, hydrometeor collision rates three and even four orders of magnitude higher than this value have been reported from observations. | dynamics of ions in thunderclouds and lightning initiation |
at 00:17:12 ut, the swift burst alert telescope (bat) triggered on background noise during high background increase while entering the saa (trigger=1015615). the bat light curve shows the background increase near the saa, without any significant burst structure. the xrt began observing the field at 00:18:47.7 ut, 95.1 seconds after the bat trigger. no valid point source was found in the xrt data. automated position reported through gcn notices is due to a cosmic ray, and should be ignored. this event was initiated by the bat rate increase on approach to the saa, which yielded an image with a marginal (6.5 sigma) fluctuation. based on the lack of a grb-like rate increase above the ramping up bat rates on saa approach, the low significance of the image peak, and the non-detection of an xrt afterglow, we believe that this is not an astrophysical event. | swift trigger 1015615 is not a grb |
the fermi gamma-ray burst monitor (gbm) in orbit around the earth continues to detect gamma-ray bursts (grbs) from cosmic sources as well as terrestrial gamma-ray flashes (tgfs) and terrestrial electron beams (tebs) from the earth. an established localization code is currently utilized to determine the locations of grbs; however, this code does not include models for tgfs or tebs. we have extended the use of this code for tebs and testing whether they localize to the direction of the magnetic field line connecting the event with fermi. this allows us to determine a possible source location from the detection, rather than from other correlated events, including very low frequency radio emissions. this more versatile method of localization will aid in the identification of tebs, improving current methods of distinguishing tebs from tgfs. | localization of terrestrial electron beams |
in ancient greece the observations of the famous doctor hippocrates of kos had shown proved the environmental impact on human health. although the term "environment" should not only include the nature surrounding us but also space since the evolution of life depends primarily on events such supernova explosions, formation of stars and falls of meteorites. a major factor in life sustainment is also cosmic radiation, originating from supernova star explosions, γ-ray bursts and cosmic background radiation and has a major impact both on human health and technology. | cosmic radiation and its effects on technology and health |
we present results from the catalog of terrestrial gamma-ray flashes (tgfs) detected with the gamma-ray burst monitor (gbm) on the fermi gamma-ray space telescope. the first release, in january 2015, provided data on 2700 tgfs. updates are extending the catalog at a rate of ~800 tgfs per year. the tgf sample is reliable, with cosmic rays rejected using data both from fermi gbm and from the large area telescope on fermi. the online catalog include times (utc and solar), spacecraft geographic positions, durations, count intensities and other bayesian block durations. the catalog includes separate tables for bright tgfs detected by the flight software and for terrestrial electron beams (tebs). in january 2016 additional data will be released online from correlating these tgfs with sferics detected by the world wide lightning location network (wwlln). maps of sferics in the vicinity of each tgf will be provided, as will the locations and times of sferics found to be associated with tgfs. | the fermi gamma-ray burst monitor (gbm) terrestrial gamma-ray flash (tgf) catalog |
the paper considers the behavior of the upper ionosphere at heights of the f2 layer during forbush decreases in galactic cosmic rays (gcr fds) and solar cosmic ray (scr) bursts. we use the results of long-term continuous observations of cosmic rays and the ionosphere in novosibirsk for the period from 1968 to 2021. the ionospheric disturbances in the f2 layer during gcr fds, which were accompanied by a magnetic storm, took the form of an ionospheric storm negative phase. the scale of the negative phase of the ionospheric f-layer disturbance increases with increasing dst index of the geomagnetic storm. this increase in the amplitude of the ionospheric disturbance becomes more and more significant depending on the magnitude of forbush decreases. a burst of the amplitude of the daily variation in the f2-layer critical frequency occurred eight days after scr bursts and gcr fd front. we assume that this burst might have been caused by disturbances in the lower atmosphere due to significant variations in the intensity of scr and gcr fluxes. | topside ionosphere during solar cosmic ray bursts and forbush decreases in galactic cosmic rays |
magnetars are the most highly-magnetized neutron stars in the cosmos. giant flares from magnetars are rare, short-duration bursts of hard x-rays and soft gamma rays. in this talk, we report the discovery of gev emission from a magnetar giant flare (mgf) on april 15, 2020. the fermi large area telescope (lat) detected gev gamma rays from 19 seconds until 284 seconds after the initial detection of a signal in the mev band. our analysis shows that these gamma rays are spatially associated with the nearby (3.5 mpc) sculptor galaxy and are unlikely to originate from a cosmological gamma-ray burst. we infer that the gamma rays originated with the mgf in sculptor and we suggest that the gev signal is generated by an ultra-relativistic outflow that first radiates the prompt mev-band photons. | high-energy emission from a magnetar giant flare in the sculptor galaxy |
in the early universe, most of the cold neutral gas that will later form into individual stars and galaxies is practically invisible to us. these neutral gas reservoirs can, however, be illuminated by bright cosmic lightsources such as gamma-ray bursts (grbs) and quasars. the aim of this thesis is to use these luminous objects as tools to study the environments of intervening or host galaxy absorption systems through cosmic time. part i is dedicated to examining the gas, dust and metals in the immediate region surrounding grbs. part ii presents a search for and the study of cold and molecular gas in high-z grb host galaxy absorption systems. part iii focuses on using quasars to examine gas-rich intervening galaxies in the line of sight, with specific focus on absorption systems rich in dust and metals. this thesis demonstrates the importance of observing large samples of grb afterglows to 1) allow for statistical studies of the grb phenomena itself and the associated host galaxy environments and 2) to obtain spectra of peculiar or unusual grb afterglows, that is only observed rarely. in addition, it highlights that defining a complete and unbiased sample of quasars is vital to fully exploit the potential of quasars as probes of cosmic chemical evolution. in this version of the thesis only the title, author list and abstract for each published paper, presented as individual chapters, are provided. principal supervisor: prof. páll jakobsson. | galaxies through cosmic time illuminated by gamma-ray bursts and quasars |
the study of astronomical transients can offer the unique opportunity to obtain new insights into the nature of the transients themselves, their environments, or their lines of sight. we highlight the role in this field of uves, which first-light image was the sn 1987a ring. uves led to the discovery of ejecta-ring collision in sn 1987a, circumstellar material in a normal sne ia, and of novae as sources of 7be (7li). uves has been fundamental in exploiting gamma ray bursts (grbs) as cosmic probes, in particular the study of cosmic chemical evolution, detailed chemical properties of galaxies hosting the grbs and along the lines of sight, including exotic chemistry and physics, as well as unveiling the physical distancesof the grbs inside their host galaxies, thanks to the rapid response mode of the vlt. finally, we highlight the need for increased sensitivity, specially in the blue, while still keeping a broad wavelength coverage, to benefit from the full potentiall of transients science with uves in the future. | transients science with uves |
fermi large area telescope observations towards the milky way center have revealed a spatially extended source of gamma rays in excess of the modeled astrophysical backgrounds. possible explanations for this `galactic center excess' include weakly-interacting massive particle dark matter annihilations, unresolved milllisecond pulsars, and cosmic-ray outbursts from the galactic center. i will discuss an analysis comparing the spatial morphology and spectrum of the excess signal in the innermost few degrees of the galactic center versus the outlying sky regions. we find that the excess spectrum above 10 gev is spatially varying: the spectrum extends above these energies outside of 5° in galactocentric radius, but cuts off sharply by 10 gev in the innermost few degrees. if interpreted as a real feature of the excess, this radial variation in the spectrum has important implications for both astrophysical and dark matter interpretations of the galactic center excess. single-component dark matter annihilation models face challenges in reproducing this variation; on the other hand, a population of unresolved millisecond pulsars contributing both prompt and secondary inverse compton emission may be able to explain the spectrum as well as its spatial dependency. supported by nsf grfp grant no. dge-1321846. | evidence for spatial variation in the high-energy spectrum of the galactic center excess |
jets have been observed from both neutron-star and black-hole x-ray binaries. there are many similarities between the two and a few differences. i will offer a physical explanation of the formation and destruction of jets from compact objects and i will discuss the similarities and differences in the two types. the basic concept in the physical explanation is the cosmic battery, the mechanism that creates the required magnetic field for the jet ejection. the cosmic battery operates efficiently in accretion flows consisting of an inner hot flow and an outer thin accretion disk, independently of the nature of the compact object. it is therefore natural to always expect a jet in the right part of a spectral hardness - luminosity diagram and to never expect a jet in the left part. as a consequence, most of the phenomenology of an outburst can be explained with only one parameter, the mass accretion rate. | jets in black-hole and neutron-star x-ray binaries |
using integral/spi-acs realtime data, and following [1], we have performed a search for prompt gamma-ray counterparts of hawc-190806a (gcn 25284). at the time of the event (2019-08-06 13:20:48 utc, hereafter t0), integral was operating in nominal mode. the event localization was at an angle of 33 deg with respect to thespacecraft pointing axis. this orientation implies a strongly suppressed(17% of optimal) response of isgri, a strongly suppressed (31% ofoptimal) response of ibis/veto, and a near-optimal (75% of optimal)response of spi-acs. this orientation implies a favorableresponse of ibis/picsit. thebackground within +/-300 seconds around the event was ratherstable (excess variance 1.3, slightly higher than usual). we have performed a search for any impulsive events in integral spi-acs (as described in [2]) data. we detect a marginal event (s/n 3.3) at a 3.5s time scale att0-1.8s. the peak count rate of the signal in spi-acs is 713 cts/s, which corresponds to a flux between 1.2e-07 and 1.7e-07 erg/cm2/s, depending on thelocation within the source localization region, and assuming a typical short grb spectrum (an exponentially cut offpower law with alpha=-0.5 and ep=600 kev). this estimate does not take into account the uncertaintyrelated to the unknown event spectrum, the 20% systematic uncertainty on theresponse, or any dead-time correction. we derive preliminary estimate of the association fap at the level of 0.011 (2.3 sigma). this tentatively indicates a random association. further analysis, taking into account accurate far measured on the basis of the study ofthe background during days surrounding the event might be reported in aforthcoming circulars. in the ibis/picsit analysis, we do not detect any relevant signal, despite an orientation favorable for this instrument. this disfavours a cosmic origin of the observed spi-acs excess. otherwise, we estimate a 3-sigma upper limit on the 75-2000 kev fluence of 2e-07 erg/cm^2 for a burst lasting less than 1 s with a characteristic short grb spectrum occurring at any time in the interval within 300 s around t0. for a typical long grb spectrum (band function with alpha=-1, beta=-2.5, and ep=300 kev), the derived peak flux upper limit is ~1.7e-07 (6.9e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 kev energy range. in addition, we identify the following low-s/n excesses, which likely belong to thebackground: scale | t | s/n | flux ( x 1e-7 erg/cm2/s) | fap 2.9 | -135 | 3.8 | 1.9 ± 0.5 ± 0.8 | 0.2 2.7 | -238 | 4.2 | 2.1 ± 0.5 ± 0.8 | 0.231 0.1 | -9.26 | 4.2 | 10.6 ± 2.7 ± 4.4 | 0.248 0.8 | 92.7 | 4.1 | 3.6 ± 0.9 ± 1.5 | 0.341 0.5 | -113 | 3.9 | 4.5 ± 1.2 ± 1.8 | 0.786 1.1 | -275 | 3.9 | 3.0 ± 0.8 ± 1.2 | 0.896 note that fap estimates (especially at timescales above 2s) may be further affected by possibly enhanced non-stationary local background noise. this list excludes any excesses for which fap is close to unity. all results quoted are preliminary. this circular is an official product of the integral multi-messenger team. [1] savchenko et al. 2017, a&a 603, a46 [2] savchenko et al. 2012, a&a 541a, 122s | hawc-190806a: upper limits from integral spi-acs and ibis prompt observation |
there is tantalizing evidence that the jets launched from gamma-ray bursts (grbs) are narrower (more tightly collimated) at higher redshifts. this has important implications on both the physics of the jet launch, and also on estimates of the high redshift star formation rate from gamma-ray bursts. we present the observational evidence for the grb jet opening angle-redshift anti-correlation, discuss the potential physical mechanisms responsible for this correlation, and, finally, provide estimates of the high redshift star formation rate accounting for this effect. | gamma-ray burst jets: evolution over cosmic time and new predictions for the high redshift star formation rate |
the mercurian gamma-ray and neutron spectrometer (mgns) is a scientific instrument developed to study the elementary composition of the mercury's sub-surface by measurements of neutron and gamma-rays emission of the planet. mgns measures neutron fluxes in a wide energy range from thermal energy up to 10 mev and gamma-rays in the energy range of 300 kev up to 10 mev with the energy resolution of 5% fwhm at 662 kev and of 2% at 8 mev. the innovative crystal of cebr3 is used for getting such a good energy resolution for a scintillation detector of gamma-rays.during the bepicolombo long cruise to mercury, it is planned that the mgns instrument will operate practically continuously to perform measurements of neutrons and gamma-rays fluxes for achieving two main goals of investigations: monitoring of the local radiation background of the prompt spacecraft emission due to bombardment by energetic particles of galactic cosmic rays and the participation in the inter planetary network (ipn) program for the localization of sources of gamma-ray bursts in the sky.the mgns instrument will also perform special sessions of measurements during flybys of earth, venus and mercury with the objective to measure neutron and gamma-rays albedo of the upper atmosphere of earth and venus and of the surface of mercury. another objective is to test the computational model of the local background of the spacecraft using the data measured at different orbital phases of flyby trajectories. the low altitude flybys (such as the 700 km flyby for venus and three 200 km flybys for mercury) would be the most useful for such tests being bc maximally shadowed for cosmic radiation by the actual planet. neutron and gamma-rays measurements during earth flybys enable investigation of interaction between solar wind and earth environments as well as studies of spacecraft neutron and gamma-rays background upon its passage through the earth's radiation belts. | spectroscopy of gamma-rays of earth, venus and mercury: mgns instrument onboard bepicolombo mission |
cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (smbh) in galaxy nuclei. particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (lirgs/ulirgs). these dusty objects are of key importance to galaxy mass assembly over cosmic time. some (u)lirgs have deeply embedded galaxy nuclei that harbour a very active evolutionary stage of agns and/or starbursts. the nuclear activity will often drive mechanical feedback in the form of molecular winds, jets and outflows. this feedback can for example remove baryons from low-mass galaxies, prevent overgrowth of galaxies, be linked to the m_{bh}-σ relation, and explain "red-and dead" properties of local ellipticals. with the alma and noema telescopes we can use molecules as diagnostic tools to probe the properties of dust-enshrouded galaxy nuclei and their associated cold winds and outflows. their morphology, velocity structure, physical conditions and even chemistry can be studied at unprecedented sensitivity and resolution, opening new avenues to further our understanding of the growth of galaxies. i will give a brief review of the alma/noema view of agn and starburst radiative and mechanical feedback, and how it is linked to the properties of the nuclear power source. i will discuss the use of molecules (e.g. h_2o, h_3o^{+}, hcn, hco^+, h_2s) for studying dusty nuclei and the nature of the embedded activity. we can, for example, investigate ionization rates and the impact of cosmic ray-, x-ray- and pdr-chemistry and the onset of outflows and winds. interestingly, in some deeply obscured nuclei the chemistry shows strong similarities to that of galactic hot cores. finally i will show peculiar molecular jets and very recent alma observations at resolutions of tens of milli-arcseconds (few pc) of vibrationally excited hcn in opaque nuclei. these regions offer both challenges and opportunities for ir and submm studies of the nature of the buried activity - which we suggest is a deeply dust-enshrouded smbh in a high-accretion state, or an extreme, high-temperature, burst of star formation. | feeding, feedback and the growth of galaxies - molecules as tools for probing galaxy evolution |
rs ophiuchi is the first nova to be detected in the very-high-energy range. its gamma-ray emission provides evidence of proton acceleration following the thermonuclear outburst. these observations offer new insight into the origin of cosmic rays. | gamma rays reveal proton acceleration in nova explosions |
the sagittarius b2 (sgr b2) molecular cloud complex is an x-ray reflection nebula whose nonthermal x-ray emissions have continued to decrease since 2001 as it reprocesses one or more past energetic outbursts from the supermassive black hole sagittarius a* at the galactic center. the x-ray reflection model explains the observed time variability of x-ray emission from sgr b2 and provides a window into the luminous evolutionary history of our nearest supermassive black hole. in light of evidence of elevated cosmic particle populations in the galactic center, x-rays from sgr b2 are also of interest as a probe of low-energy (sub-gev) cosmic rays, which may be responsible for an increasing relative fraction of the nonthermal emission as the contribution from x-ray reflection decreases. here, we present the most recent nustar and xmm-newton observations of sgr b2, which were jointly recorded in 2018, and we emphasize the kα fluorescence line of neutral fe. these 2018 observations reveal small-scale variations within lower-density portions of the complex, including brightening features, yet still enable upper limits on x-rays from low-energy cosmic-ray interactions in sgr b2. we present fe kα line fluxes from cloud regions of different densities, facilitating comparison with models of ambient low-energy cosmic-ray interactions throughout the cloud. | new constraints on cosmic particle populations at the galactic center using x-ray observations of the molecular cloud sagittarius b2 |
in general, giant flares (gfs) produced by magnetars have a very short-hard initial spike that is followed by a weak oscillatory phase. gfs from a nearby galaxy would appear as cosmic short-hard gamma-ray bursts (grbs), such as grb 200415a. in this paper, we search for gf-originated bursts in the fermi grb category and report grb 210410a, which is presented with a very short-hard spike followed by an extended tail emission. in the e p,z- e iso plane, grb 210410a with a duration of t 90 ~ 48 s differs from long grbs, might be classified as a short grb with a redshift of z ~ 0.28, and could be regarded as a gf with a distance of ~2.7 mpc. here, e p,z , e iso, and l iso denote the rest-frame peak photon energy, the isotropic energy, and the isotropic luminosity of the burst, respectively. the radiation spectrum of grb 210410a, similar to that of grb 200415a, can be well fitted with a non-dissipative photospheric emission. however, grb 210410a in the e p,z- l iso plane is beyond the death line of cosmic grbs for non-dissipated photospheric emission with a general initial size of the fireball. since the e p,z- l iso relation of gfs is far beyond the death line of cosmic grbs, grb 210410a may have originated from the same channel that produces gfs. we also perform the analysis and discuss both the highest photon energy event (4.2 gev) and the extended tail emission in this burst. | magnetar giant flare origin for grb 210410a? |
the calorimetric proton detector of the gaseous detector with germanium tagging (gadget) system has been upgraded to operate as a time projection chamber (tpc) to detect low-energy, β-delayed single- and multi-particle emission of interest to astrophysics. the upgrade, known as gadget ii, uses micro pattern gaseous amplifier detector technology and is surrounded by an array of high-purity germanium detectors for efficient high-resolution detection of γ-rays. a new high-granularity micromegas (mm) board with 1024 pads and high density generic electronics for tpcs data acquisition system have been installed. this tpc is among the first generation of resistive mm detectors in low-energy nuclear physics and has been tested using a 228th alpha source and cosmic-ray muons. in addition, decay events in the tpc have been simulated by adapting the attpcrootv2 data analysis framework. a novel method of using 2d convolutional neural networks for event classification with gadget ii is also introduced. in november 2022, gadget ii was successfully used for in-beam measurements to investigate the nuclear physics of type i x-ray bursts. this work was supported by the u.s. national science foundation under grants no. 1565546 and 1913554, and the u.s. department of energy, under award no. de-sc0016052. | gadget ii tpc for decay spectroscopy studies at frib |
the swift satellite allows us to use gamma-ray bursts (grbs) to peer through the hearts of star forming galaxies through cosmic time. our open collaboration, representing most of the active european researchers in this field, builds a public legacy sample of grb x-shooter spectroscopy while swift continues to fly. to date, our spectroscopy of more than 100 grb afterglows covers a redshift range from 0.059 to about 8 (tanvir et al. 2009, nature 461, 1254), with more than 20 robust afterglow-based metallicity measurements (over a redshift range from 1.7 to 5.9). with afterglow spectroscopy (throughout the electromagnetic spectrum from x-rays to the sub-mm) we can hence characterize the properties of star-forming galaxies over cosmic history in terms of redshift, metallicity, molecular content, ism temperature, uv-flux density, etc.. these observations provide key information on the final evolution of the most massive stars collapsing into black holes, with the potential of probing the epoch of the formation of the first (very massive) stars. vlt/x-shooter (vernet et al. 2011, a&a 536, a105) is in many ways the ideal grb follow-up instrument and indeed grb follow-up was one of the primary science cases behind the instrument design and implementation. due to the wide wavelength coverage of x-shooter, in the same observation one can detect molecular h2 absorption near the atmospheric cut-off and many strong emission lines from the host galaxy in the near-infrared (e.g., friis et al. 2015, mnras 451, 167). for example, we have measured a metallicity of 0.1 z ⊙ for grb 100219a at z = 4.67 (thöne et al. 2013, mnras 428, 3590), 0.02 z ⊙ for grb 111008a at z = 4.99 (sparre et al. 2014, apj 785, 150) and 0.05 z ⊙ for grb 130606a at z = 5.91 (hartoog et al. 2015, a&a 580, 139). in the latter, the very high value of [al/fe]=2.40 +/- 0.78 might be due to a proton capture process and may be a signature of a previous generation of massive (perhaps even the first) stars. reconciling the abundance patterns of grb absorbers, other types of absorbers (in particular qso dlas), and old stars in the local group is an important long-term goal of this program (see sparre et al. 2014, apj 785, 150). metallicities are also measured from host emission lines (krühler et al. 2015, a&a 581, a125). grb spectroscopy also allows us to determine the dust content of their environments, both through analysis of the depletion pattern and the measurement of the associated extinction (japelj et al. 2015, a&a 451, 2050). this way one can quantify the dust-to-metals ratio and its evolution with redshift. the detection of grbs at z > 6 shows that grbs have become competitive as a tool to identifying galaxies at the highest redshifts and unsurpassed in providing detailed abundance information via absorption line spectroscopy. | the vlt/x-shooter grb afterglow legacy survey |
x-ray binary (xrb) populations in galaxies trace the demographics of close binaries, massive stars, and compact-object remnants; they provide important constraints on the accretion phase of close-binary evolution that connects to other astrophysically interesting sources (e.g., gamma-ray bursts and gravitational wave mergers); and their emission is expected to scale sensitively with the physical properties of their host galaxies (e.g., star-formation rate, stellar mass, metallicity, and stellar age). in this talk, we will present a new empirical framework modeling the metallicity and star-formation history (sfh) dependence of xrb population luminosity functions (xlfs) in normal galaxies. we test our model framework using ~2000 x-ray detected point-sources within 44 chandra-observed galaxies at d ∼< 30 mpc that span a broad range of metallicity and sfh (spanning early-to-late type morphologies). our models provide unifying quantitative context for scaling relations that have been well studied in the literature, including, e.g., the high-mass xrb (hmxb) luminosity versus sfr relation (lx(hmxb)/sfr), the lx(hmxb)-sfr-metallicity plane, the ultraluminous x-ray source frequency as a function of metallicity and age, the low-mass xrb (lmxb) luminosity scaling with stellar mass (lx(lmxb)/m*), and the observed evolution of lx(hmxb)/sfr and lx(lmxb)/m* relations with cosmic time. | x-ray binary population luminosity functions in galaxies and their dependence on star-formation history and metallicity |
there is now strong evidence that long-duration gamma-ray bursts (lgrbs) have an intrinsic preference for low-metallicity environments despite the existence of some exceptions to this trend (graham & fruchter 2013). here i will present a pair of results expanding on this work. first, a detailed effort to quantize magnitude of this effect, and characterized its change as a function of metallicity. thus we directly address a fundamental question of this subfield: how much more likely is an lgrb to form at one metallicity as compared with another? then, employing these results, we relate the lgrb rate as a function of redshift to the cosmic star-formation rate and provide a detailed breakdown of the intervening steps and their rate of occurrence. this provides interesting implications for radio search efforts to detect off axis lgrb events which will be discussed. | explaining the relative and absolute lgrb rate with metallically |
it has long been recognized that the most luminous sources in the universe, may be powered by gravitational energy, rotational energy and magnetic energy. we are still learning how the power is partitioned between theses various forms and how this is made manifest in the observations. in this talk, i will discuss some new ideas that lead to the assertion that massive black holes in elliptical galaxies with low mass supply, like that in m87, are rotation powered and involve an ejection disk. by contrast, fast radio bursts may be powered by electromagnetic processes near the surface of a magnetar. finally cosmic rays, from mev to zev energies, may be powered ultimately by gravitational energy released through strong, collisionless, shock fronts. some new physical processes, which may operate under these separate circumstances, will be briefly described. | cosmic power |
rs ophiuchi (rs oph) is a recurrent symbiotic nova. its latest outburst, on 8th of august 2021, brought to the first detection of this class of sources at very-high-energy (above 100 gev) gamma rays. we present the magic observations of rs oph during this outburst, triggered by the fermi-lat detection of high energy gamma rays from this source. we characterize the daily evolution of the emission, starting already from one day after the optical detection. using information provided by optical observations, we perform modeling of the gamma-ray spectrum with both leptonic and hadronic models. we find strong evidence for hadronic origin of the emission and discuss its implications for the contribution to the galactic cosmic rays. | hadronic gamma-ray emission of nova rs oph observed by the magic telescopes |
debate regarding venus lightning has continued for four decades, sustained by seemingly contradictory searches for radio noise bursts, whistler-mode electromagnetic signatures, and optical flashes. here we report on a possible positive detection with the lac, the lightning and airglow camera, aboard the jaxa akatsuki spacecraft. lac is the first optical sensor orbiting another planet specifically designed for lightning flash detection. the unique aspect of lac compared to previous optical searches is the high-speed sampling rate at 20 khz of a 32 pixel avalanche photodiode array, measuring a narrow waveband at the oxygen 777 nm emission line expected for lightning emission in a co2-dominated atmosphere. the measurement of high-time resolution lightcurves permits the discrimination of natural lightning from cosmic rays, stray light, or electrical noise. while there have been previous claimed optical detections, the four years of negative results from the lac provide a strong control on the false alarm rate, and demand particular scrutiny of a single flash detected in march 2020. given the area-time product of observation (now approaching 200 million km2-hrs in 2022), the prior expectation of detecting a bolide flashes of the intensity observed would be only of the order of only a few per cent, thus unlikely. furthermore, most bolide lightcurves have a slow onset with a terminal peak (i.e. negatively skewed) whereas the lac lightcurve is positively skewed. these two factors argue against a bolide origin, but do not completely exclude it. on the other hand, the detection of a flash after 100 million km2-hr (after about 40 lac observing sessions) is broadly consistent with the flash rate suggested in ground-based observations by hansell et al. (1995). the lightcurve observed is somewhat long (~100 ms) compared with terrestrial lightning discharges, but not incompatible with a lightning origin. it is quite different from cosmic rays previously detected by lac and from known stray light signals. | venus optical flash observed by the akatsuki lightning and airglow camera |
scalable quantum computing can become a reality with error correction, provided coherent qubits can be constructed in large arrays. the key premise is that physical errors can remain both small and sufficiently uncorrelated as devices scale, so that logical error rates can be exponentially suppressed. however, energetic impacts from cosmic rays and latent radioactivity violate both of these assumptions. we use the scale of google's sycamore processor to directly observe impacts of high-energy rays and identify large bursts of quasiparticles that simultaneously and severely limit the energy coherence of all qubits, causing chip-wide failure. we track the events from their initial localised impact to high error rates across the chip. our results provide direct insights into the scale and dynamics of these damaging error bursts in large-scale devices, and highlight the necessity of mitigation to enable quantum error correction at scale. | resolving catastrophic error bursts in large arrays of superconducting qubits |
based on the results of an analysis of formosat-3/cosmic radio occultation measurements, the absorption of dm-radio waves (wavelength ~19 cm) in the lower high-latitude ionosphere of the earth was detected. the maximum absorption value is ~3 db in the range from ~60 to ~90 km and, in some cases, it reaches ~10 db at altitudes from ~90 to ~95 km. a method for determining the vertical profiles of the absorption coefficient by solving the inverse problem of radiosonding in the earth's lower ionosphere is proposed. the absorption layers, caused by powerful bursts of x-ray radiation and strong changes in geomagnetic conditions during the storm, were reliably identified in individual sessions. it was found that, at altitudes from ~90 to ~100 km, the value of the absorption coefficient of dm-radio waves reached values (5.69 ± 1.35)·10-3 db/km. | gps l1 signals absorption in high-latitude lower ionosphere during severe geomagnetic storm in june 2015 |
pressure variation in lower atmosphere which take place after intensive solar proton events and forbush-decreases of galactic cosmic rays (gcrs) are analyzed for the period 1980-2006. there were plotted groups of charts (multifields) for 48 solar proton events with energies of particles ep > 90 mev and for 48 forbush-decreases of gcrs with amplitudes dn/n > 2.5%. these multifields revealed a growth of matrix norm over north atlantic region and north of european part of russia during days following the bursts of solar protons and forbush-decreases of gcrs, respectively. these results confirm hypothesis about relation of regional cyclogenesis processes with short-term variations of solar and galactic cosmic rays. | analysis of lower atmosphere pressure field response for short-time cosmic ray variations by multifield comparison measure method |
the relativity of cosmic time is developed within the framework of cosmological relativity in five dimensions of space, time and velocity. a general linearized metric element is defined to have the form $ds^2 = (1+\phi) c^2 dt^2 - dr^2 + (1+\psi) \tau^2 dv^2$, where the coordinates are time $t$, radial distance $r=\sqrt{x^2 + y^2 + z^2}$ for spatials $x$, $y$ and $z$, and velocity $v$, with $c$ the speed of light in vacuum and $\tau$ the hubble-carmeli time constant. the metric is accurate to first order in $t/\tau$ and $v/c$. the fields $\phi$ and $\psi$ are general functions of the coordinates. by showing that $\phi = \psi$, a metric of the form $ds^2 = c^2 dt^2 - dr^2 + \tau^2 dv^2$ is obtained from the general metric, implying that the universe is flat. for cosmological redshift $z$, the luminosity distance relation $d_l (z,t) = r (1 + z) / \sqrt{1 - t^2 / \tau^2}$ is used to fit combined distance moduli from type ia supernovae up to $z < 1.5$ and gamma-ray bursts up to $z < 7$, from which a value of $\omega_m = 0.800 \pm 0.080$ is obtained for the matter density parameter at the present epoch. assuming a baryon density of $\omega_b = 0.038 \pm 0.004$, a rest mass energy of $( 9.79 \pm 0.47 ) \, {\rm gev}$ is predicted for the anti-baryonic $\bar{y}$ and the $\phi^{*}$ particles which decay from a hypothetical $\bar{x}_1$ particle. the cosmic aging function $g_1(z,t)= ( 1 + z) ( 1 - t^2 / \tau^2 )$ makes good fits to light curve data from two reports of type 1a supernovae and in fitting to simulated quasar like light curve power spectra separated by redshift $\delta{z} \approx 1$. we determine the multipole of the first acoustic peak of the cosmic microwave background radiation anisotropy to be $l \approx 224 \pm 5$ and a sound horizon of $\theta_{sh0} \approx (0.805 \pm 0.020 ) {}^{\circ}$ on today's sky. | cosmic time transformations in cosmological relativity |
grbs are extremely energetic short cosmic transients. due to their huge energy output in a short time they can be observed at very large cosmological distances. actually, they sample the whole observable universe. as a consequence of their large distances, their observed duration, fluence and peak flux depend on the redshift. in the reality, however, this dependence can be observed only in the case if the intrinsic variance of these quantities in comoving frame do not exceed significantly that coming from different redhifts of the grbs. nevertheless, it is an important question whether the redshift dependence of the observed quantities could be extracted from the observational data. using a training set consisting of grbs having measured physical parameters and redshifts we are looking for the effect of the redshift on the observed data, using techniques available in multivariate data analysis. creating a 3d parameter space from duration, fluence and peak flux, we define partitions in the distribution of data points and compare the redshift distributions within these partitions. partitioning will be made by some hierarchical clustering algorithm and cutting the obtained agglomeration tree at different places to get partitions of different numbers. the distributions of redshifts within the partitions, obtained in this way, will be compared to see if there is any difference in redshift distribution between partitions at all. | redshift dependence of grbs' observed parameters |
venus has a hellish surface environment, but life may survive on the planet high in the atmosphere, within a thermal habitable zone between 62 and 48 km altitude. both ultraviolet radiation from the sun and the ionizing particle radiation of the cosmic rays are highly damaging to life, and here we study their effects on a potential aerial biosphere. we modelled galactic cosmic rays as well as intense bursts of solar particle radiation, such as the so-called 'carrington event' of 1859, and the transmission of ultraviolet light, through the venusian atmosphere. we found that though the flux of ionising radiation can be sterilizing high in the atmosphere, the total dose delivered at the top of the hz by a worst-case solar particle event is unlikely to present a hazard to life. solar uv is limiting at the top of the thermal hz, but by an altitude of ~59 km drops below that calculated for the archean earth, while still transmitting more than enough longer-wavelength light to permit photosynthesis. these results suggest that the search for aerial life on venus should focus on the atmospheric zone 59 km to 48 km altitude. | constraints on a potential aerial biosphere on venus: cosmic rays and solar ultraviolet radiation |
gamma-ray bursts (grbs) are flashes of high-energy radiation arising from energetic cosmic explosions. bursts of long (>2 s) duration are produced by the core-collapse of massive stars, those of short (< 2 s) duration by the merger of two neutron stars (nss). here i will present observations of the exceptionally bright grb211211a, a long duration burst at a distance of only 346 mpc. our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (~1042 erg s-1) kilonova formed in the ejecta of a compact binary merger. this event demonstrates that compact object mergers can power high-energy transients of over a minute long duration, and that these represent a new, although possibly rare, electromagnetic counterpart of gravitational wave radiation. | a nearby long duration gamma-ray burst from a merger of compact objects |
this article gives an overview of gamma-ray bursts (grbs) and their relation to astroparticle physics and cosmology. grbs are the most powerful explosions in the universe that occur roughly once per day and are characterized by flashes of gamma-rays typically lasting from a fraction of a second to thousands of seconds. even after more than four decades since their discovery they still remain not fully understood. two types of grbs are observed: spectrally harder short duration bursts and softer long duration bursts. the long grbs originate from the collapse of massive stars whereas the preferred model for the short grbs is coalescence of compact objects such as two neutron stars or a neutron star and a black hole. there were suggestions that grbs can produce ultrahigh energy cosmic rays and neutrinos. also a certain sub-type of grbs may serve as a new standard candle that can help constrain and measure the cosmological parameters to much higher redshift than what was possible so far. i will review the recent experimental observations. | gamma-ray bursts and their relation to astroparticle physics and cosmology |
we use gamma ray bursts (grbs) data from y. wang (2008) to put additional constraints on a set of cosmological dark energy models based on the holographic principle. grbs are among the most complex and energetic astrophysical events known in the universe offering us the opportunity to obtain information from the history of cosmic expansion up to about redshift of $z\sim 6$. these astrophysical objects provide us a complementary observational test to determine the nature of dark energy by complementing the information of data from supernovas (e.g. union 2.1 compilation). we found that the $\lambda cdm$ model gives the best fit to the observational data, although our statistical analysis ($\delta aic$ and $\delta bic$) shows that the models studied in this work ("hubble radius scale" and "ricci scale q") have a reasonable agreement with respect to the most successful, except for the "ricci scale cpl" and "future event horizon" models, which can be ruled out by the present study. however, these results reflect the importance of grbs measurements to provide additional observational constraints to alternative cosmological models, which are mandatory to clarify the way in which the paradigm of dark energy or any alternative model is correct. | constraints on holographic cosmological models from gamma ray bursts |
we present an evolutionary model for grb afterglows that includes (1) thermal particles and (2) interaction between the shock and accelerated cosmic rays. we will comment on observational signatures of this model compared to the traditional approach. | nonlinear cosmic ray acceleration during gamma-ray burst afterglows |
phase transitions within anomalous x-ray pulsars (axps) and soft γ-ray repeaters (sgrs) can lead to mini contractions. such contractions produce pulsar gliches and shock break outs from their surface accompanied by thermal x/γ -ray emission. highly relativistic dipolar e+e− bunches launched from the pulsar polar caps emit fast radio bursts (frbs) of narrowly beamed coherent curvature radiation, visible from cosmic distances if they point in the direction of earth. although the associated bursts of surface x/γ -rays are nearly isotropic, and many orders of magnitude more energetic than the frbs, they are detectable by the current all sky x-ray and γ-ray monitors only from our galaxy and nearby galaxies. | are fast radio bursts produced by large glitches of anomalous x-ray pulsars? |
we investigated serendipitous integral observations carried out at the time of the ligo/virgo burst candidate g275404. the satellite was pointing at ra=17:44:43 dec=-25:57:27 (in the direction of the galactic center region), close to the low-probability area of ligo localization. about 2% of the probability was contained in the field of view of integral ibis and spi. depending on the location within the ligo 90% localization region, as well as the assumed counterpart spectrum and duration, the best upper limit is set by the anti-coincidence shield of the spectrometer on board of integral (spi/acs), the anti-coincidence shield of the ibis instrument (ibis/veto), or by the imaging coded mask instruments (ibis and spi). the combination of these instruments covered the full ligo 90% confidence region and provided stringent constraints on the flux of a possible electromagnetic counterpart in the energy range covered by the integral instruments. the integral burst alert system (ibas) did not identify any unusual transients in coincidence with the ligo/virgo trigger. the ibas inspects both isgri field of view and all-sky spi-acs light curve. the ibas trigger closest in time to the gw candidate ("weak" isgri trigger 7706) happened at utc 2017-02-25 11:32:15.56 and it's location (ra=270.48, dec=-25.08, 3.73 arcmin radius 68% containment, statistical uncertainty only) was outside the 90% probability containment of the ligo localization region. the nearest excess over the background rate identified by spi-acs offline pipeline happened 453 seconds after the ligo/virgo trigger. it has an snr of 5.5, duration of 100 ms, and is compatible with cosmic ray origin. we investigated the spi-acs, ibis/veto, and ibis/isgri light curves between -500 and +500 s from the trigger time (2017-02-25 18:30:21.3 utc) on temporal scales from 0.1 to 100 s, and found no evidence for any deviation from the background. we estimate combined typical 3-sigma upper limits of 4.3e-7 erg/cm2 (75-2000 kev) for 8s duration assuming band model parameters alpha=-1, beta=-2.5, and e_ peak = 300 kev. to derive a limit for a typical short burst with 1 s duration, we use a harder cutoff power law spectrum with a slope of -0.5 and an epeak = 500 kev: we find a limiting fluence of 1.5e-7 erg/cm2 (75-2000 kev) at 3 sigma c.l. these limits assume a perpendicular direction of the burst to the integral pointing direction, optimal for spi-acs sensitivity. however the extent of the region with optimal response depends on the possible source spectrum: we perform a detailed calculation only for a cutoff powerlaw spectrum with a slope of -0.5 and an epeak = 500 kev: we estimate that 30% of the ligo localization probability region is covered with a range of sensitivity from optimal for spi-acs (mentioned above) to 50% worse. about 2% of the ligo localization in the field of view of ibis and spi is covered with at least factor 2 better sensitivity. the spi/acs light curves, binned at 50 ms, are derived from 91 independent detectors with different lower energy thresholds (mainly between 50 kev and 150 kev) and an upper threshold at about 100 mev. the acs response varies substantially as a function of the source incident angle with an optimal effective area of about 6000 cm2 at 1 mev. | ligo/virgo g275404: integral search for a prompt gamma-ray counterpart |
the spectacular outbursts of energy associated with supernovae (sne) have long motivated research into their potentially hazardous effects on earth and analogous environments. much of this research has focused primarily on the atmospheric damage associated with the unique circumstances of a gamma-ray burst, or the more general influx of high-energy cosmic rays that arrive thousands of years after the supernova (sn) explosion. in this study, we turn the focus to persistent high-energy sn x-ray emission observed months and/or years after the initial outburst as the shockwave interacts with a dense circumstellar medium. the influence that sn x-rays have on planetary climate and habitability has often been overlooked, likely as a consequence of scant observational datasets in the x-ray band. in the last few decades, however, increasingly sensitive x-ray telescopes have enabled a more profound understanding of sn x-ray output. we use these modern empirical observations to conduct a threat assessment of x-ray luminous sne that sits within the context of the previous literature on sne and planetary effects. we conclude that certain types of interacting sne, while rare, pose a substantial threat to life in terrestrial-like radiation environments, and may have played a role in the evolution of earth's atmosphere, climate, and biosphere. in general, the high emission of x-rays from certain sne impose additional constraints on the potential habitability of rocky planets. | x-ray luminous supernovae: effects on earth-like atmospheres, climate, and habitability |
this is the thirteenth edition of the series of frascati workshops on "multifrequency behaviour of high energy cosmic sources" which is undoubtedly a largely accepted biennial meeting in which an updated experimental and theoretical panorama will be depicted. this edition comes at the 35th anniversary of the first historical "multifrequency" workshop about "multifrequency behaviour of galactic accreting sources", held in vulcano in september 1984. this surely renders the frascati workshop series the oldest among the many devoted to "multifrequency studies of cosmic sources". the study of the physics governing the cosmic sources will be the main goal of the workshop. a session devoted to the ongoing and next generation ground- and space-based experiments will give the actual prospects for the first decades of this millennium. the following items will be reviewed: cosmology gravitational waves star formation astrophysics of high energy galactic and extragalactic cosmic sources: jet sources and gamma-ray bursts the astrophysics with the ongoing and future experiments: space-based experiments, ground-based experiments the workshop will include few 30-minute general review talks to introduce the current problems, and typically 20-minute talks discussing new experimental and theoretical results. a series of 20-minute talks will discuss the ongoing and planned ground- and space-based experiments. the cadence of the workshop is biennial. the participation will be only by invitation. all participants are kindly invited to attend the whole workshop. | multifrequency behaviour of high energy cosmic sources - xiii |
the current data acquisition rate of astronomical transient surveys and the promise for significantly higher rates in the next decade necessitate the development of novel approaches to analyze astronomical data sets and promptly detect objects of interest. the deeper, wider, faster (dwf) program is a survey focused on the identification of fast-evolving transients, such as fast radio bursts, gamma-ray bursts, and supernova shock breakouts. it employs multi-frequency simultaneous coverage of the same part of the sky over several orders of magnitude. using the dark energy camera mounted on the 4 m blanco telescope, dwf captures a 20 s g-band exposure every minute, at a typical seeing of ~1" and an air mass of ~1.5. these optical data are collected simultaneously with observations conducted over the entire electromagnetic spectrum—from radio to γ-rays—as well as cosmic-ray observations. in this paper, we present a novel real-time light-curve analysis algorithm, designed to detect transients in the dwf optical data; this algorithm functions independently from, or in conjunction with, image subtraction. we present a sample of fast transients detected by our algorithm, as well as a false-positive analysis. our algorithm is customizable and can be tuned to be sensitive to transients evolving over different timescales and flux ranges. | finding fast transient in real time using novel light curve analysis algorithm |
we present the third fermi space telescope gamma-ray burst monitor (gbm) catalog of terrestrial gamma-ray flashes (tgfs), containing almost 10 years of data. we discuss how this work builds upon the previous published and online catalogs, citing updates and improvements to the off-line search algorithms. specifically, we discuss revising the search algorithm of the continuous time-tagged event (ctte) data to find weaker tgfs for which there is only signal in one gbm bgo detector, resulting in a weaker, second category of tgfs detected by gbm. consequently, using this method to search for tgfs has resulted in an increased sample rate of ~50% over previous methods, equating to a detection rate of ~1200 tgfs/yr. we discuss these two categories of tgfs, present new methods for measuring their temporal profiles (including the number of pulses with each event), their spectral behavior, and show other tgf parameters, such as the spacecraft altitude and offset from the spacecraft footprint for each event. we also describe how we reject cosmic rays in our sample. finally, we will present a complete list of tgfs than are accompanied by a very-low frequency "sferic" by the world-wide lightning location network (wwlln), reporting the sferic energy, location and times associated with each accompanying tgf. this work will provide collaborators in the atmospheric electricity and tgf communities with the largest, comprehensive tgf data set currently available. | the 3rd fermi-gbm terrestrial gamma-ray flash catalog |
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