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binary evolution may lead to the production of more hot, luminous stars in a stellar population than expected for single star evolution. these hot luminous objects significantly contribute to the sed in b and uv bands, and then affect the determination of some basic parameters based on the sed. in a population synthesi... | advances in binary evolution and their roles in the synthetic seds |
binaries are important in the galaxy studies. binaries, during their evolutions, can produce some kinds of hot and luminous objects (for example, helium star) and eject different amounts of energy and elements via stellar wind or sn ejections.%therefore, the inclusion of binaries would affect the determinations of gala... | binaries on the galaxy parameters and studies related to hii regions |
detailed evolutionary models predict that massive stars (m > 20 m⊙) at low metallicity remain small throughout most of their lifetimes and do not expand significantly until just before core collapse. if this is true, interaction should occur late for a large fraction of binaries and may also proceed differently due ... | testing late stellar expansion with populations of stars stripped in binaries |
this talk will link the radio pulsars population of small magellanic cloud (smc) with the accreting x-ray pulsar population, using population synthesis models to predict what we might observe through future surveys of the smc. | the neutron star populations of the small magellanic cloud |
we performed population synthesis of cvs composed of highly magnetized wds (i.e. polars) and non-magnetic wds, and predicted period and mass transfer rate distributions, as well as space densities for both populations. the presented calculations are the first binary population models that properly include reduced magne... | vizier online data catalog: evidenced reduced magnetic braking in polars (belloni+, 2020) |
bipos1 (binary population synthesizer) efficiently calculates binary distribution functions after the dynamical processing of a realistic population of binary stars during the first few myr in the hosting embedded star cluster. it is particularly useful for generating a realistic birth binary population as an input for... | bipos1: dynamical processing of the initial binary star population |
recently, we have found, in the chandra deep field-south, that the emission from x-ray binary (xrb) populations in galaxies evolves significantly with cosmic time, most likely due to changes in the physical properties of galaxies like star-formation rate, stellar mass, stellar age, and metallicity. however, it has been... | tracing x-ray binary population evolution by galaxy dissection: first results from m51 |
we present the results recently published byhttps://doi.org/10.1051/0004-6361/202141980 {marfil et al. (2021, a&a, 656, a162)} regarding the determination of the stellar atmospheric parameters ($t_{\rm eff}$, $\log{g}$, and [fe/h]) of 343 m dwarfs observed with carmenes. we employed steparsyn, a bayesian spectral s... | written in the stars: spectral synthesis on carmenes gto m-dwarf spectra |
disk instability remains the leading formation pathway for some of observed giant planets. in particular, this model can more naturally explain giant planets at large separation, giant planets around m stars, and very young giant planets. however, there are still many open questions regarding this formation mechanism, ... | dipsy: a new disc instability population synthesis |
the merger of two neutron stars (a nsns merger) is suspected to be the most likely source of short-duration gamma-ray bursts (grbs) powerful explosions that can be seen from billions of light-years away. but whether a grb is launched is dependent on what remnant is created by the merging nss. do they form another ns? o... | what do you get when two neutron stars merge? |
we will survey with chandra and hst 11 nearby elliptical galaxies to make first-ever robust empirical measurements of how field lmxbs evolve as their parent stellar populations age. our observations will robustly test (to the 96.5-99.4% confidence level) theoretical population synthesis models, which predict a decline ... | a statistically robust constraint on the evolution of field lmxbs |
the origin of the metal enrichment of the intracluster medium (icm) represents a fundamental problem in extragalactic astrophysics, with implications for our understanding of how stars and galaxies form, the nature of type ia supernova (snia) progenitors, and the thermal history of the icm. these heavy elements are ult... | a detailed study of chemical enrichment history of galaxy clusters out to virial radius |
in astrophysics, population synthesis models are tools used to determine what mix of stars could be consistent with the observations, e.g. how the intrinsic mass-to-light ratio changes by the measurement process. a similar technique could be used to understand the production of tgfs. the models used for this type of po... | a population synthesis study of terrestrial gamma-ray flashes |
metal-poor stars allow us to establish the early history of the milky way, furthermore the stars on advanced evolution stage (e.g. giants, agb stars etc.) give the opportunity to research the peculiarities of stellar evolution at low metallicity. on the base of the 11m southern african large telescope (salt) spectra ob... | manifestation of stellar evolution in metal-deficient stars |
stellar evolution can nowadays be modelled with a high degree of accuracy and completeness up to the most advanced stages. however in spite of the progresses, complex physical processes exist that still suffer of large uncertainties even in the most placid evolutionary phases. the straightforward drawback is that model... | convective mixing in intermediate mass stars |
stellar rotation period (prot) studies have produced numerous insights into the angular momentum evolution of low-mass stars, but previous investigations have focused on single stars even though roughly half of sun-like stars are in stellar binaries. we examine the impact of unresolved stellar binaries on the stellar p... | reproducing stellar rotation periods in the kepler field via magnetic braking and tidal torques |
with analysis of gw190521 potentially indicating the existence of a high eccentricity stellar black hole binary, the idea that active galactic nuclei (agn) are the birthplaces for binary black holes (bbhs) has picked up a lot of steam in recent months. an accretion disk of gas circling around the super massive black ho... | gas dynamical friction as a binary formation mechanism in agn disks |
because of their dense stellar environments, globular clusters are an important place for investigating stellar evolution and stellar dynamics, but there is much yet to learn about their formation. in this project, we considered the globular cluster ngc 6681 (m70) with the goal of characterizing its stellar population.... | from the ultraviolet to the infrared: the stellar population of the globular cluster m70 |
we review the properties of observed populations of radio pulsars in the milky way field and globular clusters, contrasting in particular binary properties and taking into account selection effects. using a combination of monte carlo dynamical modeling for dense star clusters and population synthesis for the field, we ... | comparing binary pulsar properties in the field and in globular clusters |
according to stellar evolution models, massive ob stars form neutron stars after the end of their life. but does the initial magnetic field of a neutron star depend on the magnetic field of a predecessor star? some pulsar population synthesis (e.g. gullón et al. 2015) which included thermally emitting neutron stars sho... | is a number of strongly magnetised ob stars enough to produce all known magnetars? |
a significant obstacle to improving the quality of education is the lack of easy-to-use assessments of higher-order thinking. most existing assessments focus on recall and understanding questions, which demonstrate lower-order thinking. traditionally, higher-order thinking is assessed with practical tests and written r... | assessing complex learning objectives through analytics |
the origin and evolution of magnetic fields (mfs) of young neutron stars (nss) is an open question. mfs could be generated through a dynamo during the formation of nss, or they could be a relic of a pre-supernova magnetic field. we want to test whether mfs of young nss are the relics of their progenitors, massive ob st... | from ancestors to offspring: tracing the connection between magnetic fluxes of ob and neutron stars |
in the galaxy studies, binaries are often neglected. however, binaries are common in the universe.%stellar populations (sps) and galaxies, comprising binaries, would produce some kinds of hot and luminous objects (such as, helium star) and eject different amounts of energy and elements via stellar wind or sn ejections ... | binaries on the galaxy sfh |
star formation rate (sfr) inferences are based in the so-called constant sfr approximation, where synthesis models are require to provide a calibration; we aims to study the key points of such approximation to produce accurate sfr inferences. we use the intrinsic algebra used in synthesis models, and we explore how sfr... | about recent star formation rates inferences |
the halogas (hydrogen accretion in local galaxies) survey with the westerbork synthesis radio telescope is the most sensitive systematic survey of the diffuse neutral hydrogen component in nearby spiral galaxies so far. the 5-sigma column density sensitivity reached for the sample of 22 galaxies is 10^19 atoms cm^-2 ov... | hi disks in nearby galaxies from the halogas survey |
x-ray observations of nearby galaxies provide one of the best laboratories in the universe for studying the populations of two exotic classes of object: black holes and neutron stars. because they are directly connected to past and current stellar populations through binary synthesis modeling, studies of accreting blac... | identifying compact objects in the x-ray binary population of andromeda's disc |
using hard x-ray observations attainable with nustar, we are able to differentiate between the accretion states, and thus compact object types, of x-ray binaries (xrbs) in the andromeda galaxy, our nearest spiral neighbor. because they are directly connected to past and current stellar populations through binary synthe... | characterizing the x-ray binary population of the m31 disk |
the origin of half of the elements heavier than iron -- the so-called r-process elements -- is a central unsolved mystery in astrophysics. these atoms include both precious metals (e.g. gold) as well as radioactive elements required for geophysical processes on the earth (e.g. thorium) and even some which are necessary... | do collapsars make the heavy elements: a sensitive search in a nearby gamma-ray burst? |
we investigate the internal structure of elliptical galaxies at z~0.2 from a joint lensing-dynamics analysis. we model hubble space telescope images of a sample of 23 galaxy-galaxy lenses selected from the sloan lens acs (slacs) survey. whereas the original slacs analysis estimated the logarithmic slopes by combining t... | massive elliptical galaxies at z 0.2 live inside uncontracted nfw halos and follow the salpeter stellar imf |
the study of the rest-frame ultraviolet (uv) is fundamental to our understanding of star-forming galaxies, as it provides a unique window on massive stellar populations, chemical evolution, and reionization. the success of james webb space telescope (jwst) programs, with star-forming galaxies at high redshifts, hinges ... | cluster-scale versus galaxy-scale ultraviolet spectral properties of star forming galaxies |
using hst/wfc3 grism spectroscopy from the candels lyman-alpha emission at reionization (clear) survey, we constrain the metallicities and ages of massive quiescent galaxies, at z ~ 1.5. clear provides deep spectroscopy (12 hst orbits per pointing) with the wfc3/g102 grism over the wavelength range ~ 7,500 < λ < ... | constraining metallicity and age for massive quiescent galaxies in a redshift range of 1 |
the metal content of high redshift galaxies is typically measured in the gas phase using strong optical emission line diagnostics that are calibrated locally, suffering significant uncertainties. for direct estimates of gas-phase metallicities, faint auroral lines need to be detected to determine the electron temperatu... | the stellar mass-metallicity relation of star-forming galaxies at z 2.5 |
we present a new set of synthesis models for stellar populations obtained with starburst99, which are based on new stellar evolutionary tracks with rotation. we discuss models with zero rotation velocity and with velocities of 40% of the break-up velocity on the zero-age main-sequence. these values are expected to brac... | the effects of stellar rotation in starburst99 models |
detections of gravitational waves have revolutionized the understanding of black-hole binaries and double neutron stars, as well as their coalescence. these detections have provided a new way to test our best predictions for the evolution of binary stars which ultimately merge as black-hole or neutron-star binaries. ho... | impact of the pre-supernova stellar compactness in gravitational-wave populations |
the properties of gas and dust in galaxies' interstellar media are a valuable tool for understanding their cosmic evolution. unfortunately, for many ism tracers the signal that is detected from any individual galaxy tends to be very faint (i.e., the ratio of signal to noise [s/n] is low). by using stacking, a technique... | probing the evolution of galaxies by stacking stellar mass selected samples |
classical, hydrogen-depleted wolf-rayet (wr) stars mark an evolved stage of massive stars with major impacts to their environment. the high temperatures of wr stars, the progenitors of massive black holes, turn them into major sources of ionizing flux. in the last two decades, the discovery of strong high-ionization em... | benchmarking early-type wolf-rayet stars as sources of he ii ionizing flux in stellar populations |
the companion mass ratio distribution (cmrd) of main sequence binaries is a crucial physical quantity for understanding the evolution of stars in binary systems and for constraining models of binary star formation. however, although much work has been done during the last years, the shape of the cmrd remains rather unc... | a population synthesis study of white dwarf-main sequence binaries in the galactic disk |
we analyze the intrinsic flux ratios of simple and composite stellar populations for various visible--near-infrared filters with respect to ∼3.5μm (l-band), and their dependence on metallicity, star-formation history, and effective mean age. this study is motivated by the fact that light from galaxies is reddened and a... | predicting intrinsic mid-ir to optical flux ratios for galaxies of different types using spectral synthesis models of composite stellar populations |
we will survey with chandra and hst 11 nearby elliptical galaxies to make first-ever robust empirical measurements of how field lmxbs evolve as their parent stellar populations age. our observations will robustly test (to the 96.5-99.4% confidence level) theoretical population synthesis models, which predict a decline ... | a statistically robust constraint on the evolution of field lmxbs |
we present the new approach to the ionisation structure modelling for the high-metallicity hii regions. the method is based on the multicomponent photoionisation modelling (mphm) of these objects that takes into account their complicate structure due to superwind from the central star-forming region. the complex struct... | photoionisation modelling of the hii regions surrounding star-forming regions within the metallicity range z=0.003-0.012 |
spops is a database of populations synthesis simulations of spinning black-hole binary systems, together with a python module to query it. data are obtained with the startrack and precession [ascl:1611.004] numerical codes to consistently evolve binary stars from formation to gravitational-wave detection. spops allows ... | spops: spinning black-hole binary population synthesis |
using the yunnan-ii evolutionary population synthesis models comprising binary stars, we find that the inclusion of binary stars can raise the derived stellar metallicity z* and/or age t (degeneracy problem), raise the stellar mass m*, lower the gaseous metallicity z gas and star formation rate (sfr) of galaxies. this ... | binary stars on the galaxy sfh |
we present a new set of planetary population syntheses with an updated model compared to alibert, 2013. in particular, changes to the collisonal treatment, stellar evolution and disk photoevaporation can shape the resulting population. the influence of the stellar mass is studied and the distribution of resulting plane... | the next generation planetary population synthesis - stellar mass influence |
population synthesis models can be used to create artificial star clusters through monte carlo modeling of input functions that include the star-formation history, initial mass function, and reddening from circumstellar disk excess. observed quantities such as k-band luminosity functions and stellar colors can be compa... | a new synthetic model for studying young star clusters |
table 3 provides the cluster name (column 1), object identification (column 2), position (column 3), stellar mass (column 4, assuming a bruzual & charlot (2003mnras.344.1000b) stellar population synthesis model with solar metallicity and salpeter initial mass function), log10 of half-light radius (column 5), and th... | vizier online data catalog: red-sequence early-type galaxies in clusters (andreon+, 2016) |
over the last several years, surprising detections of strong high-ionization nebular emission lines in star-forming galaxies ranging in distance from a few megaparsecs to deep into the reionization era have challenged the accuracy of modern stellar population synthesis models. meanwhile, deep spectroscopy of massive ob... | painting the first empirical picture of massive stars below the metallicity of the smc with ullyses |
young star clusters are a promising environment for forming binary black holes. such binaries may form dynamically or via binary star evolution or through the interplay of these two channels. to study these formation pathways, we have performed high precision direct n-body simulations of low-mass (m < 1000 m⊙) young... | black hole dynamics in young star clusters |
interpreting the photometry and spectroscopy of galaxies often requires consideration of their integrated light. for this, models which accurately represent the emission from a stellar population as a function of its age, metallicity and other properties are essential. such stellar population modelling is a mature fiel... | key uncertainties in modelling emission line galaxies |
a galaxy can be broadly decomposed into a few baryonic components: gas disc, stellar disc, and bulge (if present). the conversion from 21cm flux to atomic gas mass is specified by the physics of the spin-flip transition, fixing the gas contribution. the conversion from stellar light to stellar mass is less well determi... | vizier online data catalog: quantifying maximum discs in galaxies (starkman+, 2018) |
as population iii (pop. iii) stars die in supernovae, they pollute the interstellar clouds of dust and gas from which next generation, pop. ii stars, form. during their deaths, elements heavier than li are ejected, increasing the metallicity of subsequent stellar generations. which elements are synthesized both in the ... | deriving the first stellar mass function from the light-element abundances of metal-poor stars |
with the aid of a detailed monte carlo simulator we built a thorough population synthesis model of the thin disc, thick disc, and halo white dwarf population of our galaxy. our synthetic models incorporate updated evolutionary sequences for both co-core and one-core white dwarfs, as well as hydrogen-rich and hydrogen-d... | vizier online data catalog: a white dwarf catalogue from gaia-dr2 (jimenez-esteban+, 2018) |
we trained a neural network that can obtain selected starlight parameters directly from s-plus photometry. the training set consisted of over 55 thousand galaxies with their stellar population parameters obtained from a starlight application by cid fernandes et al. (2005). these galaxies were crossmatched with the s-pl... | stellar population photometric synthesis with ai of s-plus galaxies |
thermally-pulsing (tp-)agb stars and red helium-burning (rheb) stars dominate the near-infrared (nir) flux in star-forming galaxies (up to 70%) and thus have a strong impact on the appearance of galaxies. these stars are notoriously difficult to model, and the only empirical constraints on their evolution come from the... | solving the metallicity dependence of evolved star evolution and completing hst's near-ir legacy in the local volume |
the hydrogen ionizing photon production rate $q_h$ of massive stars ($ m > 8 \: m_{\odot}$) must be known to interpret important observable quantities including galaxy star formation rates, the energy budget for nebular emission and the re-ionization epoch of the universe. recently it has been shown that stellar pop... | using distant galaxies to constrain the ionizing photon budget of massive stars |
in the past few years, several clusters of red supergiants have been discovered in a small region of the milky way, close to the base of the scutum-crux arm and the tip of the long bar, between l=24º and l=29º. according to the number of observed red supergiants and using population synthesis models, they must contain ... | a starburst region at the tip of the galactic bar around l=347-350 |
neutron stars present a wide variety from the observational point of view. the advent of new and powerful detectors and instruments has opened a new era where the classical picture of neutrons stars seen as radio-pulsars has been modified with new classes such as magnetars, x-ray isolated neutron stars (xinss) or centr... | population synthesis of isolated neutron stars |
accreting neutron star binary (ansb) systems can provide some important information about neutron stars (nss), especially on the structure and the equation of state of nss. however, only a few ansbs are known so far. the upcoming chinese space station telescope (csst) provides an opportunity to search for a large numbe... | machine learning to search for accreting neutron star binary candidates using chinese space station telescope photometric system |
the lyman continuum (lyc = hydrogen-ionizing radiation at wavelengths < 912 ang) of galaxies plays a fundamental role in determining the physical and observational properties of the ism and igm, including cosmic reionization. yet it is basically inaccessible to direct observations, and one therefore heavily relies o... | a new window on the uv sed of star-forming galaxies: direct measurements of ionizing spectra in the lyman continuum |
rotation is a fundamental property of stars. the kepler mission revolutionized the field of stellar rotation, delivering periods of over 50,000 stars near the plane of the milky way. the distribution of periods revealed unexpected gaps, dips, and edges that cannot be described by current rotational evolution models, de... | rotational characterization of tess stars with deep learning |
gravitational lensing studies have radically improved our understanding of the internal structure of galaxies and cluster-scale systems. in particular, the combination of strong lensing and stellar dynamics or stellar population synthesis models have made it possible to characterize numerous fundamental properties of t... | investigating the internal structure of galaxies and clusters through strong gravitational lensing |
using a novel, mcmc-driven inference framework, we have modeled the stellar and dust emission of 32 composite spectral energy distributions (seds), which span from the near-ultraviolet (nuv) to far infrared (fir). the composite seds were originally constructed in a previous work from the photometric catalogs of the new... | modeling well sampled composite spectral energy distributions of distant galaxies via an mcmc-driven inference framework |
in recent years, observations have shown that multiple-star systems such as hierarchical triple and quadruple-star systems are common, especially among massive stars. they are potential sources of interesting astrophysical phenomena such as compact object mergers, leading to supernovae, and gravitational wave events. h... | multiple stellar evolution: a population synthesis algorithm to model the stellar, binary, and dynamical evolution of multiple-star systems |
the recent discovery of a neutron star accretor in the ultra-luminous x-ray (ulx) source m82 x-2 challenges our understanding of high-mass x-ray binary formation and evolution. by combining binary population synthesis and detailed mass-transfer models, however, we show that the binary parameters of m82 x-2 are not surp... | the formation of ultraluminous x-ray sources with neutron star accretors |
the globular clusters that orbit the milky way are a treasure trove, providing evidence on a wide range of topics of astrophysical interest, from the scale of individual stars to the entire galaxy itself. the relative ease with which they can be observed, the massive volume of published data on them, and their very nat... | seeing red: spectroscopy of galactic globular clusters from 6500 å to 1 µm |
the structure of our galaxy has been studied from ultraviolet (uv) star counts obtained with the ultra-violet imaging telescope (uvit) on board the astrosat satellite, in far-uv (fuv) and near-uv (nuv) bands. the f154w (baf2) and n263m (nuvb4) filters were used in the fuv and nuv bands, respectively. the point sources ... | study of galactic structure using uvit/astrosat star counts |
the advancement of infrared (ir) detectors opened a range of observational probes of galaxy physics. one of the most important advancements in recent years is the measurement of a variable imf in certain high-mass, high-metallicity systems. however, the models used to make imf measurements lagged in their ability to pr... | testing the extremes of imf variability with new stellar population models |
in this work, we investigate the reliability of spectral synthesis methods in the estimation of the mean stellar age and metallicity, addressing the question of which signal-to-noise ratios (s/n) are needed to determine these quantities. to address this problem we used simulated spectra containing stellar and nebular e... | self-consistent population spectral synthesis with fado: mean stellar metallicity of galaxies in spectral synthesis methods |
planet population synthesis is a statistical approach that serves as a bridge between theoretical planet formation and the observed population of exoplanets. it has led to testable predictions, such as the now-confirmed minimum in the planetary mass distribution between a few earth masses and 40 earth masses. in order ... | planet population synthesis: the cradle of the trappist-1 multiplanet system |
we present here a short summary of a forthcoming paper on photoionization models based on califa observations of hii regions. for each of the ∼ 20,000 sources of the califa h ii regions catalog, a grid of photoionization models is computed assuming the ionizing sed being described by the underlying stellar population o... | photoionization models of the califa hii regions |
classical novae are optical transients powered by thermonuclear processes in the surface layers of accreting white dwarfs (wds) in binary stellar systems termed cataclysmic variables (cvs). with dozens of outbursts per year in the milky way, classical novae have been observed by humans for millenia. however, despite th... | classical novae in the modern era |
the catalog of gravitational-wave events is growing, and so are our hopes of constraining the underlying astrophysics of stellar-mass black-hole mergers by inferring the distributions of, e.g., masses and spins. while conventional analyses parametrize this population with simple phenomenological models, we propose an i... | machine learning and the origin of ligo's black holes |
ligo/virgo/kagra's gravitational wave revolution ushered in a novel and independent way to constrain large-scale structure and cosmology. notably, compact object binaries have already been used to measure the hubble constant; with only a few dozen detections and poor sky localization, however, the hubble constant uncer... | spatial distribution of binary black hole mergers in illustris |
the galaxy ugc10205 is analyzed using integral field spectroscopy (ifs) data from the calar alto legacy integral field area survey (califa). the understanding of the current state of this object represents a challenge because it is an extremely isolated galaxy, located in a void, which shows evidence of a possible rece... | testing the merging hypothesis for the isolated galaxy ugc10205 using califa data |
m dwarfs are the most common type of stars in the galaxy, and seem to host a higher number of planets on average, compared to fgk stars. yet, due to their lower stellar (and disk) masses — and associated slower formation time scales — gas giants are expected to be infrequent around m dwarfs. in this presentation, we di... | do short-period gas giants predominantly form around metal-rich early m dwarfs? |
we model x-ray luminosity functions (xlf) of accreting neutron stars and black holes in 1035 ≤ lx ≤ 1041 erg s−1 range in star-forming galaxies and galaxies with the initial star formation burst. xlfs are obtained by combining a fast generation of compact object+normal star population using the binary population synthe... | x-ray luminosity function of accreting neutron stars and black holes |
unique clues about the formation processes of giant planets can be found in their bulk compositions. transiting planets provide us with bulk density determinations that can then be compared to models of planetary structure and evolution, to deduce planet bulk metallicities. at a given mass, denser planets have a higher... | the metallicity of giant planets |
we have modeled the universal x-ray luminosity function (xlf) of high mass x-ray binaries (hmxbs) in star-forming galaxies with an evolutionary population synthesis code. we compare the simulated hmxb population under both common envelope mechanisms usually adopted, i.e., the αce formalism and the γ algorithm, and sugg... | use hmxb luminosity function to constrain the common envelope mechanisms |
asymptotic giant branch (agb) stars represent one of the main stellar sources for dust production in the universe. we provide a description of the formation and growth of dust particles in the circumstellar envelope of agbs, based on detailed calculations of the agb evolutionary phase. we use stellar population synthes... | from agbs to pne: understanding the observations of evolved stars in the large magellanic cloud |
we model the mass distribution of newborn black holes (bhs) using a new population synthesis code for massive stars in the milky way. the calculated distributions agree well with those obtained for the galactic bhs in binary systems. the explosions of wolf-rayet (wr) precursors may be responsible for the origin of bhs. | massive stars and black holes |
we present the host galaxy properties of a large sample of ~ 4000 x-ray selected active galactic nuclei (agn) in the chandra cosmos legacy survey to investigate the connection between bh accretion and host galaxy. the cosmos legacy survey reaching x-ray fluxes of 2x10-16 (cgs) in the 0.5-2 kev band, bridges the gap bet... | a spectral energy distribution analysis of agn host galaxies in the chandra-cosmos legacy survey |
it is widely anticipated that the first direct detections of gravitational waves will be made by advanced gravitational-wave detectors, such as the two laser interferometer gravitational-wave observatories (ligo) and the virgo interferometer. in preparation for the advanced detector era, i have worked on both detection... | gravitational waves from rotating neutron stars and compact binary systems |
the modality of disc dispersal is thought to be of fundamental importance to planet formation, yet the responsible mechanism is still largely unconstrained. photoevaporation from the central star is currently a promising avenue to investigate, but the models developed to date do not yet have enough predictive power for... | the dispersal of planet-forming discs. a new generation of x-ray photoevaporation models. |
light from galaxies is extincted by dust via scattering and absorbtion. studying galaxies without correcting for this extinction could lead to incorrect results. therefore, a careful study of dust correction in the nearby universe should be done first. tamura et al. (2009) developed an approximate method, dubbed the "β... | analysis of the intrinsic βλ,0 ratio using spectral synthesis models of composite stellar populations |
the stellar initial mass function (imf) is one of the fundamental pillars in studies of stellar populations. it is the mass distribution of stars at birth, and it is traditionally assumed to be universal, adopting generic functions constrained by resolved (i.e. nearby) stellar populations (e.g., salpeter 1955; kroupa 2... | the imf-sfh connection in massive early-type galaxies |
we present the first direct comparison between balmer line and panchromatic sed-based star-formation rates (sfrs) for z ~ 2 galaxies. while dust-corrected sfrs(hα,hβ) using balmer decrements are commonly used at low redshift, it has been argued that balmer lines may miss optically thick star-forming regions at high red... | the mosdef survey: the strong agreement between hα and uv-to-fir star formation rates for z ~ 2 star-forming galaxies |
pox 186, a local dwarf starburst galaxy with properties analogous to those expected in reionization-era galaxies, has been the focus of numerous optical spectroscopic studies. extending wavelength coverage to the uv permits a detailed study of the stellar population and outflow in this extraordinary galaxy. we present ... | hst uv spectroscopy of the dwarf starburst galaxy pox 186 |
with the detection of gravitational waves from merging compact objects, a new observational window onto the fates of massive stars has been opened. to explain the observed mergers of compact objects, we need accurate knowledge about the evolution of massive binary stars. yet, current population synthesis calculations o... | smoking guns in massive binary evolution: the hunt for black holes and stripped stars |
the presence of double red clumps (rcs) in the milky way bulge is interpreted as an evidence for the x-shaped structure originated from the disk and bar instabilities. here we show, however, that this double rcs phenomenon is another manifestation of multiple populations observed in globular clusters (gcs) in the metal... | super-helium-rich stars and the origin of the double red clumps in the bulge: implications on the population synthesis |
the satellites of jupiter are thought to have formed in a circumplanetary disc. here we study their formation and orbital evolution with a population synthesis approach, by varying the dust-to-gas ratio, the disc dispersal timescale and the dust refilling timescale of the cpd. the initial conditions of the disc (densit... | satellites form fast and late: a population synthesis for the galilean moons |
the correlation between stellar mass and metal abundance (or mzr, the mass-metallicity relation) reflects the balance between galactic feedback and gravitational potential. feedback ejects metals out of galaxies, while gravitational potential retains the produced metals, which enrich later generations of stars. because... | evolution of the stellar mass - stellar metallicity relation |
type-1 nuclear activity has been thought to be rare in cluster of galaxies since the earliest works in the 1970s. however, clear specimen of type-1 activity have been found in recent spectroscopic surveys of cluster galaxies. seven seyfert 1 and intermediate seyfert nuclei have been discovered in the wide field nearby ... | seyfert 1 galaxies in wings |
the old metal-rich open cluster ngc 6791 is characterized by a cmd in which the horizontal branch is bimodal and for which canonical stellar models fail to reproduce the requisite number of hb stars and morphology. it is also thought that ngc 6791 has a large binary population. a series of binary population synthesis (... | ehb stars and ngc 6791 |
sunnynet learns the mapping the between lte and nlte populations of a model atom and predicts the nlte populations based on lte populations for an arbitrary 3d atmosphere. to use sunnynet, one must already have a set of lte and nlte populations computed in 3d, to train the network. these must come from another code, as... | sunnynet: neural network framework for solving 3d nlte radiative transfer in stellar atmospheres |
understanding how galaxy growth is regulated by gas exchange between galaxies and their surrounding halos is a key priority area highlighted by the astro2020 decadal survey report. the proposed research program aims to probe feeding and feedback in the diffuse circumgalactic medium (cgm) using a legacy sample of h 400 ... | probing feeding and feedback in the circumgalactic medium using ovi as a tracer |
in population synthesis calculations of close binary stars, the common envelope (ce) phase is modeled using a standard prescription based upon conservation of energy. in this prescription, the orbital separation of the secondary and giant core at the end of the ce phase is taken to be the orbital separation when the en... | the post-ejection evolution of the orbital components during a common envelope phase |
young, extremely metal-poor stellar populations are central to our quest to characterize the faintest star-forming galaxies in the universe at all redshifts. ongoing efforts to model the nebular and stellar wind lines in extremely metal-poor (< 10% zsun) star-forming galaxies have revealed substantial disagreements ... | uncovering extremely metal-poor massive stars in leo a |
the first glimpse of the spectra of z 7-10 galaxies has revealed intense nebular emission that has proven challenging to interpret owing to shortcomings in our understanding of low metallicity stellar populations. recent work with hst/cos in the local universe has provided a way forward, characterizing the uv spectra t... | ultra-deep hst/cos spectroscopy of extremely metal-poor galaxies |
massive stars play a critical role in the evolution of galaxies and star clusters. recent observations of the latter have highlighted the need for systematic studies dedicated to probing the impact of massive stellar evolution on the properties of stellar populations. while the use of fitting formulae to stellar tracks... | can uncertainties in the evolution of massive stars explain properties of gravitational wave progenitors? |
the physical processes governing the formation of the seeds of supermassive black holes, as well as how they grow in the early universe, are two fundamental unanswered questions in galaxy formation and cosmology. the unprecedented sensitivity of jwst's instruments hold exciting potential for probing the growth of galax... | constraining the seeding and growth of first black holes via observable signatures from the early universe |
mechanical feedback from massive stars is strongly metallicity-dependent, and therefore low metallicity feedback should vary dramatically from that at solar. we examine the following effects relevant at low metallicity: reduced stellar winds, core-collapse supernovae starting at ages much later than 3 myr, feedback fro... | mechanical feedback starts later in low metallicity starbursts |
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