330 research outputs found
The Evolution of the Mass and Velocity Functions of Clusters of Galaxies: Implications for Cosmological Models
No full text
Simulation Analysis of High-Mass X-Ray Binaries as Merging Binary Black Hole Progenitors
No full textBinary black holes (BBHs) as observed by the Laser Interferometer Gravitational–Wave Observatory (LIGO) and the Virgo Interferometer are thought to experience a high mass x–ray binary (HMXB) phase. However, at most 3 HMXBs observed in x–ray are predicted to be LIGO–Virgo BBH progenitors, and there are uncertainties regarding these predictions. The lack of x–ray observations of these progenitors raises the question of whether we expect to see such systems in standard models of stellar evolution. It also opens the possibility that we can constrain uncertainties in binary evolution through the absence of HMXB detections and determine if these systems could be targets for future x–ray surveys. We use the COSMIC population synthesis code to simulate a large population of double compact object systems at 1/10 Z _{\odot}, and find that 99.98% of LIGO–Virgo BBH progenitors achieve HMXB luminosities above the 10^{35} erg s^{−1} observable threshold. Most of these binaries emit above this threshold for 0.5-2.0 Myr, and their luminosities exceed 10^{37} erg s^{−1} for a majority of that time. We identify clear correlations between the peak luminosity, duration of observable emission, system mass, and binary separation for LIGO–Virgo BBH progenitors. Finally, we calculate that, at low metallicity, 41.8% of observable HMXBs will become LIGO–Virgo BBHs
Large Scale Structure in ACDM Cosmology: The Mass and Correlation Function of Clusters of Galaxies and Their Evolution
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Keep Calm and Baryon: The Distribution of Baryons and Dark Matter on Cosmic Scales
No full textHow are baryons distributed in the universe? Where, and in what abundances, are
they located in large, virialized systems such as galaxies, groups, and clusters? Here
we determine the distribution of baryons, relative to dark matter, in systems ranging
in size from galaxies to groups, clusters, and large-scale structure. We use observed
X-ray and SZ measurements of the hot intracluster medium (ICM) to determine the
hot gas contribution in groups and clusters; weak lensing and optical constraints on
the cluster stellar fraction; and absorption measurements of the cool circumgalactic
medium (CGM) to determine the gas mass in galaxies. Using direct observations
when possible, and extrapolations of observed density pro les when necessary, we
show that the baryon content within the virial radius is consistent with the cosmic
baryon fraction (0:164 0:004) for systems ranging over three orders of magnitude
in mass, from galaxies to groups and massive clusters. The baryon distribution is
less extended in massive systems and more broadly distributed in low-mass systems.
Averaged on scales larger than the virial radius, the baryonic mass is a strong tracer
of the underlying dark matter distribution, and the dark matter, stellar, and gaseous
components of groups, clusters, and large-scale structure may be comprised only of
the contributions from the individual constituent galaxies of these larger systems.
Baryons, which initially fell into the gravitational potentials formed by dark matter,
have not been removed significantly from these systems, but remain in roughly the
cosmic fraction in galaxies, groups, clusters, and large-scale structure
Simulation Analysis of High-Mass X-Ray Binaries as Merging Binary Black Hole Progenitors
No full textBinary black holes (BBHs) as observed by the Laser Interferometer Gravitational–Wave Observatory (LIGO) and the Virgo Interferometer are thought to experience a high mass x–ray binary (HMXB) phase. However, at most 3 HMXBs observed in x–ray are predicted to be LIGO–Virgo BBH progenitors, and there are uncertainties regarding these predictions. The lack of x–ray observations of these progenitors raises the question of whether we expect to see such systems in standard models of stellar evolution. It also opens the possibility that we can constrain uncertainties in binary evolution through the absence of HMXB detections and determine if these systems could be targets for future x–ray surveys. We use the COSMIC population synthesis code to simulate a large population of double compact object systems at 1/10 Z _{\odot}, and find that 99.98% of LIGO–Virgo BBH progenitors achieve HMXB luminosities above the 10^{35} erg s^{−1} observable threshold. Most of these binaries emit above this threshold for 0.5-2.0 Myr, and their luminosities exceed 10^{37} erg s^{−1} for a majority of that time. We identify clear correlations between the peak luminosity, duration of observable emission, system mass, and binary separation for LIGO–Virgo BBH progenitors. Finally, we calculate that, at low metallicity, 41.8% of observable HMXBs will become LIGO–Virgo BBHs
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