An Empirical Framework Characterizing the Metallicity and Star-formation History Dependence of X-Ray Binary Population Formation and Emission in Galaxies

Abstract We present a new empirical framework modeling the metallicity and star formation history (SFH) dependence of X-ray luminous ( L ≳ 10 36 erg s −1 ) point-source population X-ray luminosity functions (XLFs) in normal galaxies. We expect that the X-ray point-source populations are dominated by X-ray binaries (XRBs), with contributions from supernova remnants near the low luminosity end of our observations. Our framework is calibrated using the collective statistical power of 3731 X-ray detected point sources within 88 Chandra-observed galaxies at D ≲ 40 Mpc that span broad ranges of metallicity ( Z ≈ 0.03–2 Z ⊙ ), SFH, and morphology (dwarf irregulars, late types, and early types). Our best-fitting models indicate that the XLF normalization per unit stellar mass declines by ≈2–3 dex from 10 Myr to 10 Gyr, with a slower age decline for low-metallicity populations. The shape of the XLF for luminous X-ray sources ( L ≳ 10 38 erg s −1 ) significantly steepens with increasing age and metallicity, while the lower-luminosity XLF appears to flatten with increasing age. Integration of our models provides predictions for X-ray scaling relations that agree very well with past results presented in the literature, including, e.g., the L X –SFR– Z relation for high-mass XRBs in young stellar populations as well as the L X / M ⋆ ratio observed in early-type galaxies that harbor old populations of low-mass XRBs. The model framework and data sets presented in this paper further provide unique benchmarks that can be used for calibrating binary population synthesis models.

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Publication Details

Journal
The Astrophysical Journal
Published
2024-12-01
DOI
https://doi.org/10.3847/1538-4357/ad8de7
Citations
7
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
2.32

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article

An Empirical Framework Characterizing the Metallicity and Star-formation History Dependence of X-Ray Binary Population Formation and Emission in Galaxies

Bret Lehmer, Margaret Lazzarini, Antara Basu‐Zych, Keith Doore et al.
7 citations
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
2.32
article

An Empirical Framework Characterizing the Metallicity and Star-formation History Dependence of X-Ray Binary Population Formation and Emission in Galaxies

Bret Lehmer, Margaret Lazzarini, Antara Basu‐Zych, Keith Doore, Jenny E. Greene, Rafael T. Eufrasio, Erik B. Monson, Jeff J. Andrews, A. Amiri, Konstantinos Kovlakas, Kristen Garofali, Chris T. Richardson, L. M. Oskinova, Vallia Antoniou, Robel Geda
article en
7 citations

Abstract

Abstract We present a new empirical framework modeling the metallicity and star formation history (SFH) dependence of X-ray luminous ( L ≳ 10 36 erg s −1 ) point-source population X-ray luminosity functions (XLFs) in normal galaxies. We expect that the X-ray point-source populations are dominated by X-ray binaries (XRBs), with contributions from supernova remnants near the low luminosity end of our observations. Our framework is calibrated using the collective statistical power of 3731 X-ray detected point sources within 88 Chandra-observed galaxies at D ≲ 40 Mpc that span broad ranges of metallicity ( Z ≈ 0.03–2 Z ⊙ ), SFH, and morphology (dwarf irregulars, late types, and early types). Our best-fitting models indicate that the XLF normalization per unit stellar mass declines by ≈2–3 dex from 10 Myr to 10 Gyr, with a slower age decline for low-metallicity populations. The shape of the XLF for luminous X-ray sources ( L ≳ 10 38 erg s −1 ) significantly steepens with increasing age and metallicity, while the lower-luminosity XLF appears to flatten with increasing age. Integration of our models provides predictions for X-ray scaling relations that agree very well with past results presented in the literature, including, e.g., the L X –SFR– Z relation for high-mass XRBs in young stellar populations as well as the L X / M ⋆ ratio observed in early-type galaxies that harbor old populations of low-mass XRBs. The model framework and data sets presented in this paper further provide unique benchmarks that can be used for calibrating binary population synthesis models.

The Astrophysical JournalVol. 977(2)
National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Gordon and Betty Moore Foundation, Yale University, Vanderbilt University, Princeton University, University of Pennsylvania, Ohio State University, California Institute of Technology, Harvard University, University of Washington, Johns Hopkins University, Carnegie Mellon University, Pennsylvania State University, University of Portsmouth, New Mexico State University, Space Telescope Science Institute, York University, University College London, University of Sussex, Queen's University Belfast, Durham University, Indian Space Research Organisation, Deutsche Forschungsgemeinschaft, Centre National d’Etudes Spatiales, Queen's University, Ministério da Ciência, Tecnologia e Inovação, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Nuclear Safety and Security Commission, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Financiadora de Estudos e Projetos, National Central University, Eötvös Loránd Tudományegyetem, Institut de Física d'Altes Energies, Max-Planck-Institut für Astronomie, University of Illinois at Urbana-Champaign, Office of Science, Jet Propulsion Laboratory, Goddard Space Flight Center, College of Engineering, Michigan State University, University of California, Los Angeles, Smithsonian Astrophysical Observatory, Science Mission Directorate, Science and Technology Facilities Council, Integrated Electronics Engineering Center, Binghamton University, Astrophysics Division, Planetary Science Division, Argonne National Laboratory, Fermilab, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, SLAC National Accelerator Laboratory
Openalex Percentile: Top 12%
Galaxies: Formation, Evolution, Phenomena
2.32
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