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prediction of sunspots has been an everlasting interest in the space science community since the discovery of the sunspot cycle. the sunspot number is an indirect indicator of many different solar phenomena, e.g., total and spectral solar radiation, coronal mass ejections, solar flares and magnetic active regions. its ... | prediction of even and odd sunspot cycles: implications for cycles 25 and 26 |
to reliably predict the space weather due to the impact of solar transients, it is imperative to accurately model the solar wind background into which these solar transients propagate. the alfven wave solar atmosphere model (awsom) within the space weather modeling framework (swmf) is a physics-based 3d extended mhd mo... | modeling and validating the solar wind using the alfven wave solar atmosphere model |
sunquakes are seismic waves observed on the sun's photosphere connected to the occurrence of some large solar flares. the exact physical mechanism that causes sunquakes is still a topic of discussion, but it is thought to be related to the release of magnetic energy during a flare. this study investigates the temporal ... | the role of photospheric magnetic field variations in sunquake generation |
the sun's activity varies over timescales ranging from the very short to the very long. long-term solar activity variations impact the earth's atmosphere and climate and have implications for space mission planning and life-time estimates. this variability across different scales is driven by solar magnetic fields whic... | long-term solar variability and solar cycle predictions: current state of understanding |
charged-current scattering of νe below 100 mev from 16 o nucleus is not yet measured. this interaction is a νe detection channel for water cherenkov detectors in case of a supernova burst. furthermore, in super-kamiokande diffuse supernova neutrino background (dsnb) is being searched with the inverse beta decay process... | νe - 16 o interactions in super-kamiokande with low energy atmospheric neutrinos |
charged-current scattering of νe below 100 mev from 16o nucleus is not yet measured. this interaction is a νe detection channel for water cherenkov detectors in case of a supernova burst. furthermore, in super-kamiokande diffuse supernova neutrino background (dsnb) is being searched with the inverse beta decay process ... | search for νe -16o interactions from low energy atmospheric neutrinos in super-kamiokande |
astronomers can get a better view of more distant supernova explosions by searching for high-energy neutrinos, according to a study conducted by researchers at uppsala university in sweden.detecting ghostly particles from collapsing starsthe icecube laboratory at the amundsen-scott south pole station in antarctica. [fe... | more supernova detections may be on the horizon with high-energy neutrinos |
charged-current scattering of νe below 100 mev from 16o nucleus is not yet measured. this interaction is an important background for diffuse supernova background searches (dsnb) with inverse beta decay process in water cherenkov detectors, a useful νe detection channel in case of a supernova burst, and a possible way t... | search for νe - 16o interactions from low energy atmospheric neutrinos in super-kamiokande |
hyper-kamiokande is a proposed next-generation water cherenkov detector. if a galactic supernova happens, it will deliver a high event rate ({\mathscr{o}}(105) neutrino events in total) as well as event-by-event energy information. recent supernova simulations exhibit the standing accretion shock instability (sasi) whi... | simulating fast time variations in the supernova neutrino flux in hyper-kamiokande |
the icecube neutrino observatory is designed to detect high-energy neutrinos of astrophysical origin via cherenkov radiation detectors located deep within the antarctic ice. the wavelength-shifting optical module (wom), a cherenkov light detector with scalable photosensitive area and very low noise has been proposed to... | simulated optical efficiency of the icecube matryoshka wom |
the liquid argon time projection chamber (lartpc) is a unique technology well suited for large scale neutrino detectors. it allows for millimeter scale 3d precision particle tracking and calorimetry with good de/dx resolution, which provides excellent efficiency of particle identification and background rejection. whil... | probing mev physics in lartpcs with radioactive calibration sources |
detection of the diffuse supernova neutrino background (dsnb) is of great importance, which will greatly help the understanding of both core-collapse physics and neutrino physics. however, after tens of years' effort of super-kamiokande (sk), dsnb is still hidden in the remaining backgrounds, dominated by decay electro... | distinguishing dsnb signal from atmospheric neutrino backgrounds in super-kamiokande and future sk-gd |
sbnd is a liquid argon detector being constructed along the fermilab booster neutrino beamline. as a part of the short baseline neutrino program, it will attempt to resolve the miniboone low energy excess hinting at possible oscillations into sterile neutrinos. sbnd will install a light detection system with a much hig... | scintillation light background discrimination in the sbnd experiment |
core-collapse supernovae (ccsne) are among the most energetic processes in our universe and are crucial for the understanding of the formation and chemical composition of the universe. the precise measurement of the neutrino light curve from ccsne is crucial to understanding the hydrodynamics and fundamental processes ... | prospects for the detection of the standing accretion shock instability in icecube-gen2 |
the icecube neutrino observatory is uniquely sensitive to mev neutrinos emitted during a core-collapse supernova. the supernova data acquisition system (sndaq) monitors in real-time the detector rate deviation searching for bursts of mev neutrinos. we present a new analysis stream that uses sndaq to respond to external... | realtime follow-up of external alerts with the icecube supernova data acquisition system |
the icecube observatory at the south pole has been operating in its full configuration since may 2011 with a duty cycle of about 99%. its main component consists of a cubic-kilometer array of optical sensors deployed deep in the glacial ice designed for the detection of high-energy astrophysical neutrinos. a surface ar... | the icecube collaboration -- contributions to the 38th international cosmic ray conference (icrc2023) |
the next galactic core-collapse supernova (ccsn) presents a once-in-a-lifetime opportunity to make astrophysical measurements using neutrinos, gravitational waves, and electromagnetic radiation. ccsne local to the milky way are extremely rare, so it is paramount that detectors are prepared to observe the signal when it... | galactic core-collapse supernovae at icecube: "fire drill" data challenges and follow-up |
supernova neutrino detection in neutrino and dark matter experiments is usually implemented as a real-time trigger system based on counting neutrino interactions within a moving time window. the sensitivity reach of such experiments can be improved by taking into account the time profile of the expected signal. we prop... | combined detection of supernova neutrino signals |
core-collapse supernovae are expected to produce multimessenger signals. low-energy neutrinos and gravitational waves are important to study the explosion mechanism of these events. the simulations and detections of gravitational waves from these events are still challenging due to broad range of expected progenitors a... | core-collapse supernova search strategy: gravitational waves and low-energy neutrinos |
americium-beryllium (ambe), a well-known tagged neutron source, is commonly used for evaluating the neutron detection efficiency of detectors used in ultralow background particle physics experiments, such as reactor neutrino and diffuse supernova neutrino background experiments. in particular, ambe sources are used to ... | analyzing the neutron and γ-ray emission properties of an americium-beryllium tagged neutron source |
the haze is an excess of microwave intensity emission surrounding the galactic centre. it is spatially correlated with the γ-ray fermi bubbles, and with the s-pass radio polarization plumes, suggesting a possible common provenance. the models proposed to explain the origin of the haze, including energetic events at the... | quijote scientific results - vi. the haze as seen by quijote |
most searches for dark matter primarily focus on the wimp paradigm, which predicts dark matter masses in the gev - 10 tev range. however, these relatively low energy searches continue to produce null results, possibly suggesting that dark matter is something other than wimps. gravitinos, on the other hand, can satisfy ... | dark matter decays from the galactic center using icecube-86 |
we report the spectroscopic classification of ztf19aamdmcs flagged by a custom filter on the antares alert-broker (https://antares.noao.edu/) as a promising stellar explosive event from the public alert stream of the ztf survey. | spectroscopic classification of the transient ztf19aamdmcs/at2020nef |
we present the results of our analysis of multiwavelength observations for the long gamma-ray burst grb 200829a. the burst redshift $z≈ 1.29± 0.04$ has been determined photometrically at the afterglow phase. in gamma rays the event is one of the brightest (in isotropic equivalent), $e_{\textrm{iso}}\gtrsim 10^{54}$ erg... | chromatic afterglow of grb 200829a |
the second gamma-ray burst catalogue (2flgc) was announced by the fermi large area telescope (fermi-lat) collaboration. it includes 29 bursts with photon energy higher than 10 gev. gamma-ray burst (grb) afterglow observations have been adequately explained by the classic synchrotron forward-shock model, however, photon... | closure relations of synchrotron self-compton in afterglow-stratified medium and fermi-lat detected gamma-ray bursts |
the transiting exoplanet survey satellite (tess; ricker et al. 2015) observed the location of the bright gamma-ray burst grb230307a during the second orbit of observation sector 62. images of the burst region, located in tess camera 4, ccd 4, were captured in the tess full-frame images (ffis). the observations of the f... | tess detection of the optical afterglow of grb230307a |
as the most energetic explosions in the universe, gamma-ray bursts (grbs) are commonly believed to be generated by relativistic jets. recent observational evidence suggests that the jets producing grbs are likely to have a structured nature. some studies have suggested that non-axisymmetric structured jets may be forme... | characteristics of gamma-ray burst afterglows in the context of non-axisymmetric structured jets |
many high-energy astrophysical sources accelerate electrons to relativistic velocities, resulting in broadband emission from synchrotron and other radiation processes. gamma-ray burst afterglow observations provide a unique probe of electron acceleration due to the relativistic nature of their collimated outflows. the ... | probing electron acceleration in gamma-ray burst afterglows |
grb 221009a is an exceptionally bright gamma-ray burst that reached earth on october 9th 2022. a fraction of the soft x-rays of the bright prompt emission were scattered by galactic dust clouds along the line of sight and produced halo rings echoing for a few days after the initial trigger. the imaging x-ray polarimetr... | the ixpe view of grb 221009a |
grb 221009a was the brightest gamma-ray burst (grb) detected since the start of grb observations in the 1960s. even though it saturated fermi-gbm, it presents a rich and unique data set to test theoretical models of gamma-ray production. we present spectral analysis of the pulses not affected by instrumental saturation... | physical properties of the brightest gamma-ray burst based on observations by the fermi gamma-ray burst monitor |
swift-xrt has performed follow-up observations of the fermi/gbm-detected burst grb 230911a, collecting 2.8 ks of photon counting (pc) mode data between t0+215.5 ks and t0+326.2 ks. an uncatalogued x-ray source is detected consistent with the goto position (gcn circ. 34681) of the fading optical counterpart candidate, a... | grb 230911a: swift-xrt afterglow detection |
x-ray polarization probes the particle acceleration zone in relativistic jets as well as the geometry of the central region of active galactic nuclei. in its first year of operations, the imaging x-ray polarimetry explorer (ixpe) has completed a first-time characterization of the x-ray polarization properties of a samp... | active galactic nuclei revealed by x-ray polarization measurements from the imaging x-ray polarimetry explorer (ixpe) |
swift-xrt has performed follow-up observations of thefermi/gbm and ipn detected burst grb 200826a (gupta et al. gcn circ. 28288, hurley et al., gcn circ. 28291) in a series of observations tiled on the sky. the total exposure time is 7.4 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 5.... | grb 200826a: swift-xrt afterglow detection |
we report previously-unpublished director's discretionary time xmm-newton observations of neutron star merger gw170817 (pi: schartel). this xmm-newton observation at 162 days post-merger confirms previous chandra observations of a plateau in the x-ray light curve of gw170817's non-thermal synchrotron afterglow, before ... | combined xmm-newton and chandra observations of the x-ray light curve plateau in gw170817 |
gamma-ray bursts (grbs) are bright extragalactic flashes of gamma-ray radiation and briefly the most energetic explosions in the universe. their catastrophic origin —the merger of compact objects or the collapse of massive stars— drives the formation of a newborn compact remnant (black hole or magnetar) that powers two... | the role of the magnetic fields in grb outflows |
observations of the afterglows of grbs are used to infer properties of the jet and local environment through model fitting. short grbs were first discovered in the 1960s, but only recently were confirmed to come from relativistic jets produced by the merger of compact objects. however, the angular structure of the jet ... | finding best fit models of afterglows of gamma ray bursts |
more than 10000 gamma-ray bursts (grbs) have been detected since discovery. long-term observations of about 850 grb afterglow in optic since 1998 have shown that a core-collapse supernova (sn) accompanies about 50 nearby grb sources. we have collected about two dozen sne' multicolor light curves associated with grbs. t... | the diversity of light curves of supernovae associated with gamma-ray bursts |
in this paper, the temporal evolution of three-dimensional relativistic current sheets in poynting-dominated plasma is studied for the first time. over the past few decades, a lot of efforts have been conducted on studying the evolution of current sheets in two-dimensional space, and concluded that sufficiently long cu... | evolution of three-dimensional relativistic current sheets and development of self-generated turbulence |
simulations generally show that non-self-gravitating clouds have a lognormal column density ($\sigma$) probability distribution function (pdf), while self-gravitating clouds with active star formation develop a distinct power-law tail at high column density. although the growth of the power law can be attributed to gra... | the effect of magnetic fields and ambipolar diffusion on the column density probability distribution function in molecular clouds |
we previously proposed that betelgeuse might have been spun up by accreting a companion of about 1 m⊙. here we explore in more detail the possible systematics of such a merger and a larger range of accreted masses. we use the stellar evolutionary code mesa to add angular momentum to a primary star in core helium burnin... | the betelgeuse project. iii. merger characteristics |
fragmentation of highly differentially rotating massive stars that undergo collapse has been suggested as a possible channel for binary black hole formation. such a scenario could explain the formation of the new population of massive black holes detected by the ligo/virgo gravitational wave laser interferometers. we p... | magnetic braking and damping of differential rotation in massive stars |
neutron stars (nss) play essential roles in modern astrophysics. the magnetic fields and spin periods of newborn (zero-age) nss have a large impact on the further evolution of nss, which are, however, poorly explored in observations due to the difficulty of finding newborn nss. in this work, we aim to infer the magneti... | back to the starting point: on the simulation of the initial magnetic fields and spin periods of nonaccreting pulsars |
firehose-like instabilities (fis) are cited in multiple astrophysical applications. of particular interest are the kinetic manifestations in weakly collisional or even collisionless plasmas, where these instabilities are expected to contribute to the evolution of macroscopic parameters. relatively recent studies have i... | mixing the solar wind proton and electron scales. theory and 2d-pic simulations of firehose instability |
ngc 300 ulx1 is a pulsating ultraluminous x-ray source (pulx) with the longest spin period of $p\simeq 31.6\, \rm s$ and a high spin-up rate of $\dot{p}\simeq -5.56\times 10^{-7}\, \rm s\, s^{-1}$ that is ever seen in the confirmed pulxs. in this paper, the inferred magnetic field of ngc 300 ulx1 is $\sim 3.0\times 10^... | study on the magnetic field strength of ngc 300 ulx1 |
context. magnetic fields are predicted to have a crucial impact on the structure, evolution, and chemistry of protoplanetary disks. however, a direct detection of the magnetic field toward these objects has yet to be achieved.aims: in order to characterize the magnetic fields of protoplanetary disks, we investigate the... | three-dimensional magnetic field imaging of protoplanetary disks using zeeman broadening and linear polarization observations |
aims: we study the acceleration of the stellar winds of rapidly rotating low mass stars and the transition between the slow magnetic rotator and fast magnetic rotator regimes. we aim to understand the properties of stellar winds in the fast magnetic rotator regime and the effects of magneto-centrifugal forces on wind s... | on the fast magnetic rotator regime of stellar winds |
gravitational instability (gi) features in several aspects of protostellar disc evolution, most notably in angular momentum transport, fragmentation, and the outbursts exemplified by fu ori and ex lupi systems. the outer regions of protostellar discs may also be coupled to magnetic fields, which could then modify the d... | gravitoturbulence in magnetized protostellar discs |
theory of fossil magnetic field is based on the observations, analytical estimations and numerical simulations of magnetic flux evolution during star formation in the magnetized cores of molecular clouds. basic goals, main features of the theory and manifestations of mhd effects in young stellar objects are discussed. | theory of fossil magnetic field |
combining numerical simulations and analytical modelling, we investigate whether close binary systems form by the effect of magnetic braking. using magnetohydrodynamics simulations, we calculate the cloud evolution with a sink, for which we do not resolve the binary system or binary orbital motion to realize long-term ... | impact of magnetic braking on high-mass close binary formation |
we numerically model evolution of magnetic fields inside a neutron star under the influence of ambipolar diffusion in the weak-coupling mode in the one-fluid mhd approximation. our simulations are 3d and performed in spherical coordinates. our model covers the neutron star core and includes crust where the magnetic fie... | three-dimensional numerical simulations of ambipolar diffusion in ns cores in the one-fluid approximation: instability of poloidal magnetic field |
context. the stellar winds of the massive stars in high-mass microquasars are thought to be inhomogeneous. the interaction of these inhomogeneities, or clumps, with the jets of these objects may be a major factor in gamma-ray production.aims: our goal is to characterize a typical scenario of clump-jet interaction, and ... | gamma rays from clumpy wind-jet interactions in high-mass microquasars |
we present a systematic study of magnetized neutron star head-on collisions. we investigate the resulting magnetic field geometries as the two neutron stars merge. furthermore, we analyze the luminosity produced in these collisions and monitor the evolution of the magnetic fields from the time of merger until the subse... | a toy model for the electromagnetic output of neutron-star merger prompt collapse to a black hole: magnetized neutron-star collisions |
we used our newly developed magnetohydrodynamic (mhd) code to perform 2.5d simulations of a fast-mode mhd wave interacting with coronal holes (chs) of varying alfvén speed that result from assuming different ch densities. we find that this interaction leads to effects like reflection, transmission, stationary fronts at... | numerical simulation of coronal waves interacting with coronal holes. ii. dependence on alfvén speed inside the coronal hole |
in nearby star-forming clouds, amplification and dissipation of the magnetic field are known to play crucial roles in the star-formation process. the star-forming environment varies from place to place and era to era in galaxies. in this study, amplification and dissipation of magnetic fields in star-forming clouds are... | evolution of magnetic fields in collapsing star-forming clouds under different environments |
the magnetic fields observed in ap stars, white dwarfs, and neutron stars are known to be stable for long times. however, the physical conditions inside the stellar interiors that allow these states are still a matter of research. it has been formally demonstrated that both purely toroidal and purely poloidal magnetic ... | stability of axially symmetric magnetic fields in stars |
we have performed a full time and luminosity-resolved spectral analysis of the high-mass x-ray binary 4u 1538-522 using the available rxte, integral, and suzaku data, examining both phase-averaged and pulse-phase-constrained data sets and focusing on the behaviour of the cyclotron resonance scattering feature (crsf). n... | evidence for an evolving cyclotron line energy in 4u 1538-522 |
we study the evolution of the field on the surface of proto-neutron stars in the immediate aftermath of stellar core collapse by analyzing the results of self-consistent, axisymmetric simulations of the cores of rapidly rotating high-mass stars. to this end, we compare the field topology and the angular spectra of the ... | evolution of the surface magnetic field of rotating proto-neutron stars |
context. magnetic fields play a very important role in the evolution of galaxies through their direct impact on star formation and stellar feedback-induced turbulence. however, their co-evolution with these processes has still not been thoroughly investigated, and the possible effect of the initial conditions is largel... | magnetic fields in massive spirals: the role of feedback and initial conditions |
context. recently, compact black hole x-ray binaries xte j 1118+480 and a0620-00 have been reported to be experiencing a fast orbital period decay, which is two orders of magnitude higher than expected with gravitational wave radiation. magnetic braking of an ap/bp star has been suggested to account for the period chan... | orbital period decay of compact black hole x-ray binaries: the influence of circumbinary disks? |
close-in gas giants are expected to have a strong magnetic field of ∼10-100 g. magnetic fields in extrasolar giant planets are detectable by future radio observations in ≳10 mhz and the spectropolarimetry of atomic lines. in contrast, the elusive interiors of exoplanets remain largely unknown. here we consider the poss... | the linkage between the core mass and the magnetic field of an extrasolar giant planet from future radio observations |
we investigate the temporal evolution of an axisymmetric magnetosphere around a rapidly rotating stellar-mass black hole by applying a two-dimensional particle-in-cell simulation scheme. adopting homogeneous pair production and assuming that the mass accretion rate is much less than the eddington limit, we find that th... | two-dimensional particle-in-cell simulations of axisymmetric black hole magnetospheres |
when magnetohydrodynamic turbulence evolves in the presence of a large-scale mean magnetic field, an anisotropy develops relative to that preferred direction. the well-known tendency is to develop stronger gradients perpendicular to the magnetic field, relative to the direction along the field. this anisotropy of the s... | a detailed examination of anisotropy and timescales in three-dimensional incompressible magnetohydrodynamic turbulence |
we apply theoretical spin-down models of magnetospheric evolution and magnetic field decay to simulate the possible evolution of psr j0250+5854, which is the slowest-spinning radio pulsar detected to date. considering the alignment of inclination angle in a 3d magnetosphere, it is possible that psr j0250+5854 has a hig... | rotational evolution of the slowest radio pulsar, psr j0250+5854 |
recent timing observation reported that the radio pulsar psr j1734-3333 with a rotating period p = 1.17 s is slowing down with a period derivative dot{p}=2.28× 10^{-12} s s^{-1}. its derived braking index n = 0.9 ± 0.2 is the lowest value among young radio pulsars with the measured braking indices. in this letter, we a... | low braking index of psr j1734-3333: an interaction between fall-back disc and magnetic field? |
to understand the essential physics needed to reproduce magnetic reconnection events in 2.5-d particle-in-cell (pic) simulations, we revisit the geospace environmental modeling (gem) setup. we set up a 2-d harris current sheet (that also specifies the initial conditions) to evolve the reconnection of antiparallel magne... | catalog of fine-structured electron velocity distribution functions - part 1: antiparallel magnetic-field reconnection (geospace environmental modeling case) |
context. x-ray observations of protostellar jets show evidence of strong shocks heating the plasma up to temperatures of a few million degrees. in some cases, the shocked features appear to be stationary. they are interpreted as shock diamonds.aims: we investigate the physics that guides the formation of x-ray emitting... | formation of x-ray emitting stationary shocks in magnetized protostellar jets |
we investigate the accretion-induced spin-up of the black hole via numerical simulations. our method is based on general relativistic magnetohydrodynamics of the slowly rotating flows in the kerr metric, where possibly transonic shock fronts may form. we account for the changing black hole mass and spin during accretio... | accretion-induced black hole spin-up revised by numerical general relativistic mhd |
the magnetic inclination angle χ, namely the angle between the spin and magnetic axes of a neutron star, plays a vital role in its observational characteristics. however, there are few systematic investigations of its long-term evolution, especially for accreting nss in binary systems. applying the model of biryukov &a... | magnetic inclination evolution of accreting neutron stars in intermediate/low-mass x-ray binaries |
in this paper we present the first set of 3d magnetohydrodynamic (mhd) simulations performed with the riemann geomesh code. we study the dynamics of the magnetically channeled winds of magnetic massive stars in full three dimensions using a code that is uniquely suited to spherical problems. specifically, we perform is... | modelling magnetically channeled winds in 3d - i. isothermal simulations of a magnetic o supergiant |
we investigate dispersive and kinetic effects on the evolution of a two-dimensional kinked alfvén wave packet by comparing results from mhd, hall-mhd and hybrid simulations of a low-$\beta$ plasma. we find that the hall term determines the overall evolution of the wave packet over a characteristic time $\tau^*=\tau_a\e... | dispersive and kinetic effects on kinked alfvén wave packets: a comparative study with fluid and hybrid models |
thermal performance maximization is a necessity in various systems that are dealing with any scale of heat flux. this requirement has been intensified due to introduction of more complex and highly crammed products, making heat dissipation a daunting task. addressing this challenge, a curved porous star-shaped enclosur... | radiation and convection heat transfer optimization with mhd analysis of a hybrid nanofluid within a wavy porous enclosure |
exploding granules constitute the strongest horizontal flows on the quiet sun and contribute to the structure of the surface horizontal velocity fields which build the large-scale organization of the discrete magnetic field. in this work we explore exploding granule expansion through the observations of the ground-base... | evolution of exploding granules from coordinated observations by themis, iris, sdo/hmi, and hinode, and a simulation |
we use 2.5d magnetohydrodynamic simulations to investigate the spectral signatures of the non-linear disruption of a tearing unstable current sheet via the generation of multiple secondary current sheets and magnetic islands. during the non-linear phase of tearing mode evolution, there develops a regime in which the ma... | spectral signatures of recursive magnetic field reconnection |
context. the recent mass measurements of two binary millisecond pulsars, psr j1614-2230 and psr j0751+1807 with a mass m = 1.97 ± 0.04 m⊙ and m = 1.26 ± 0.14 m⊙, respectively, indicate a wide range of masses for such objects and possibly also a broad spectrum of masses of neutron stars born in core-collapse supernovae.... | progenitor neutron stars of the lightest and heaviest millisecond pulsars |
context. recent spectropolarimetric surveys of main-sequence intermediate-mass stars have exhibited a dichotomy in the distribution of the observed magnetic field between the kg dipoles of ap/bp stars and the sub-gauss magnetism of vega and sirius.aims: we would like to test whether this dichotomy is linked to the stab... | evolution of a magnetic field in a differentially rotating radiative zone |
the regulation of galactic-scale star formation rates (sfrs) is a basic problem for theories of galaxy formation and evolution: which processes are responsible for making observed star formation rates so inefficient compared to maximal rates of gas content divided by dynamical timescale? here we study the effect of mag... | magnetic fields and galactic star formation rates |
aims: we conduct simulations of the inner regions of protoplanetary disks (ppds) to investigate the effects of protostellar magnetic fields on their long-term evolution. we use an inner boundary model that incorporates the influence of a stellar magnetic field. the position of the inner disk is dependent on the mass ac... | time-dependent, long-term hydrodynamic simulations of the inner protoplanetary disk. i. the importance of stellar magnetic torques |
we analyze the forces that control the dynamic evolution of a flux rope eruption in a three-dimensional radiative magnetohydrodynamic simulation. the confined eruption of the flux rope gives rise to a c8.5 flare. the flux rope rises slowly with an almost constant velocity of a few kilometers per second in the early sta... | radiative magnetohydrodynamic simulation of the confined eruption of a magnetic flux rope: unveiling the driving and constraining forces |
we study the evolution of abelian electromagnetic as well as non-abelian gauge fields, in the presence of space-time oscillations. in the non-abelian case, we consider linear approximation, to analyse the time evolution of the field modes. in both abelian and non-abelian, the mode equations, show the presence of the sa... | parametric resonance in abelian and non-abelian gauge fields via space-time oscillations |
we study the photospheric evolution of an exploding granule observed in the quiet sun at high spatial (∼0"3) and temporal (31.5 s) resolution by the imaging magnetograph sunrise/imax in 2009 june. these observations show that the exploding granule is cospatial to a magnetic flux emergence event occurring at mesogranula... | on the magnetic nature of an exploding granule as revealed by sunrise/imax |
ultraluminous x-ray sources are usually believed to be black holes with mass about 102-3 m⊙. however, the recent discovery of nustar j095551+6940.8 in m82 by bachetti et al. shows that it holds the spin period p = 1.37 s and period derivative \dot{p}≈ -2× 10^{-10} s s^{-1}, which provides a strong evidence that some ul... | the magnetic field evolution of ulx nustar j095551+6940.8 in m82 - a legacy of accreting magnetar |
we investigate the dependence of the gamma-ray burst (grb) jet structure and its evolution on the properties of the accreting torus in the central engine. our models numerically evolve the accretion disk around a kerr black hole using three-dimensional general relativistic magnetohydrodynamic simulations. we use two di... | modeling the gamma-ray burst jet properties with 3d general relativistic simulations of magnetically arrested accretion flows |
we carry out three-dimensional and two-dimensional particle-in-cell simulations of the expansion of a magnetized plasma that initially uniformly fills a half-space and contains a semicylindrical region of heated electrons elongated along the surface of the plasma boundary. this geometry is related, for instance, to abl... | multiscale magnetic field structures in an expanding elongated plasma cloud with hot electrons subject to an external magnetic field |
context. in the absence of an initial seed, the biermann battery term of a non-ideal induction equation acts as a source that generates weak magnetic fields. these fields are then amplified via a dynamo mechanism. the kelvin-helmholtz instability is a fluid phenomenon that takes place in many astrophysical scenarios an... | simulations of the biermann battery mechanism in two-fluid partially ionised plasmas |
a pulsating ultraluminous x-ray source (pulx) is a new kind of pulsar (psr) whose characteristics are different from all known neutron stars. the magnetic field of pulx is suspected to be the main reason to support its supper eddington luminosity of pulx. ngc 7793 p13, which is the second confirmed pulx, can be easily ... | research on the magnetic field of ngc 7793 p13 and other confirmed pulsating ultraluminous x-ray sources |
galaxy mergers are expected to play a central role for the evolution of galaxies and may have a strong effect on their magnetic fields. we present the first grid-based 3d magnetohydrodynamical simulations investigating the evolution of magnetic fields during merger events. for this purpose, we employed a simplified mod... | magnetic fields during galaxy mergers |
context. recent sunrise/imax observations have revealed supersonic magnetic flows.aims: our aim is to determine the origin of these flows by using realistic magnetohydrodynamics simulations.methods: we simulated cancellation and emergence of magnetic flux through the solar photosphere. our first numerical experiment st... | simulated magnetic flows in the solar photosphere |
context. conservation properties of magnetic helicity and energy in the quasi-ideal and low-β solar corona make these two quantities relevant for the study of solar active regions and eruptions.aims: based on a decomposition of the magnetic field into potential and nonpotential components, magnetic energy and relative ... | energy and helicity fluxes in line-tied eruptive simulations |
context. while non-potential (free) magnetic energy is a necessary element of any active phenomenon in the solar corona, its role as a marker of the trigger of the eruptive process remains elusive. meanwhile, recent analyses of numerical simulations of solar active events have shown that quantities based on relative ma... | comparison of magnetic energy and helicity in coronal jet simulations |
using two-dimensional simulations, we numerically explore the dependences of kelvin-helmholtz (kh) instability upon various physical parameters, including viscosity, the width of the sheared layer, flow speed, and magnetic field strength. in most cases, a multi-vortex phase exists between the initial growth phase and t... | numerical simulations of kelvin-helmholtz instability: a two-dimensional parametric study |
using two-dimensional hybrid expanding box simulations we study the competition between the continuously driven parallel proton temperature anisotropy and fire hose instabilities in collisionless homogeneous plasmas. for a quasi-radial ambient magnetic field the expansion drives tp\vert >tp\bot and the system become... | proton fire hose instabilities in the expanding solar wind |
we investigate the role of ambipolar diffusion (ad) in collisions between magnetized giant molecular clouds (gmcs), which may be an important mechanism for triggering star cluster formation. three-dimensional simulations of gmc collisions are performed using a version of the enzo magnetohydrodynamics code that has been... | gmc collisions as triggers of star formation. iv. the role of ambipolar diffusion |
kinetic plasma simulations are nowadays commonly used to study a wealth of nonlinear behaviours and properties in laboratory and space plasmas. in particular, in high-energy physics and astrophysics, the plasma usually evolves in ultra-strong electromagnetic fields produced by intense laser beams for the former or by r... | a relativistic particle pusher for ultra-strong electromagnetic fields |
magnetohydrodynamics simulation of active region noaa 11515 is performed to examine the initiation of the m5.6 flaring event that starts around 10:43 ut on 2 july 2012. the simulation is conducted using an extrapolated non-force-free magnetic field generated from the photospheric vector magnetogram of the active region... | magnetohydrodynamics evolution of three-dimensional magnetic null in noaa active region 11515 initiated using non-force-free field extrapolation |
turbulent dynamo theories have faced difficulties in obtaining evolution of large-scale magnetic fields on short dynamical time-scales due to the constraint imposed by magnetic helicity balance. this has critical implications for understanding the large-scale magnetic field evolution in astrophysical systems like the s... | saturation of large-scale dynamo in anisotropically forced turbulence |
we examine the temporary evolution of axisymmetric magnetospheres around rapidly rotating black holes (bhs), by applying our two-dimensional particle-in-cell simulation code. assuming a stellar-mass bh, we find that the created pairs fail to screen the electric field along the magnetic field, provided that the mass acc... | two-dimensional particle-in-cell simulations of axisymmetric black hole magnetospheres: angular dependence of the blandford-znajek flux |
theories for the origins of the statistical properties of binary stellar systems are reviewed. the observed properties of binary stellar systems are briefly summarized, followed by the mechanisms by which binary systems may be formed. the role that accretion is thought to play in determining the final properties of bin... | origins of the statistical properties of binary systems |
context. the vertical component of the magnetic field was found to reach a constant value at the boundary between penumbra and umbra of stable sunspots in a recent statistical study of hinode/sp data. this finding has profound implications as it can serve as a criterion to distinguish between fundamentally different ma... | characterization of the umbra-penumbra boundary by the vertical component of the magnetic field. analysis of ground-based data from the gregor infrared spectrograph |
we perform 2.5d particle-in-cell simulations of decaying turbulence in the presence of a guide (out-of-plane) background magnetic field. the fluctuating magnetic field initially consists of fourier modes at low wavenumbers (long wavelengths). with time, the electromagnetic energy is converted to plasma kinetic energy (... | role of parallel solenoidal electric field on energy conversion in 2.5d decaying turbulence with a guide magnetic field |
at present, j1819-1458 is the only rotating radio transient (rrat) detected in x-rays. we have studied the long-term evolution of this source in the fallback disc model. the model can reproduce the period, period derivative, and x-ray luminosity of j1819-1458 simultaneously in the accretion phase at ages ∼2 × 105 yr. w... | long-term evolution of rrat j1819-1458 |
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