A Synthetic Population of Ultra-Luminous X-ray Sources: Optical-X-ray Correlation

Abstract

This paper presents an analysis of the predicted optical-to-X-ray spectral index (${\alpha }_{\mathrm{ox}}$) within the context of ultra-luminous X-ray sources (ULXs) associated with stellar mass black holes and neutron stars. We use the population synthesis code COSMIC to simulate the evolution of binary systems and investigate the relationship between UV and X-ray emission during the ULX phase, namely the ${\alpha }_{\mathrm{ox}}$ relation. The study investigates the impact of metallicity on ${\alpha }_{\mathrm{ox}}$ values. Notably, it predicts a significant anti-correlation between ${\alpha }_{\mathrm{ox}}$ and UV luminosity ($L_{\mathrm{UV}}$), consistent with observations, with the slope of this relationship varying with metallicity for BH-ULXs. The NS-ULX population shows a relatively consistent slope around $-0.33$ across metallicities, with minor variations. The number of ULXs decreases with increasing metallicity, consistent with observational data, and the X-ray luminosity function shows a slight variation in its slope with metallicity, exhibiting a relative excess of high-luminosity ULXs at lower metallicities. Inclusion of beaming effect in the analysis shows a significant impact on the XLF and ${\alpha }_{\mathrm{ox}}$, particularly at high accretion rates, where the emission is focused into narrower cones. Furthermore, the study finds that UV emission in ULXs is predominantly disk-dominated, which is the likely origin of the ${\alpha }_{\mathrm{ox}}$ relation, with the percentage of disk-dominated ULXs increasing as metallicity rises.

arXiv comment16 pages, 18 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (53)

• Modules for Experiments in Stellar Astrophysics (MESA)
• How Massive Single Stars End their Life
• Compact Remnant Mass Function: Dependence on the Explosion Mechanism and Metallicity
• An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
• Compact Object Modeling with the StarTrack Population Synthesis Code
• Ultraluminous X-Ray Sources in External Galaxies
• The Nature of Accreting Black Holes in Nearby Galaxy Nuclei
• Super-critically accreting stellar-mass black holes as ultraluminous X-ray sources
• Ultraluminous X-Ray Sources
• The VLT-FLAMES Tarantula Survey VIII. Multiplicity properties of the O-type star population
• Discovery of coherent pulsations from the Ultraluminous X-ray Source NGC 7793 P13
• Three-Dimensional General Relativistic Radiation Magnetohydrodynamical Simulation of Super-Eddington Accretion, using a new code HARMRAD with M1 Closure
• COSMIC Variance in Binary Population Synthesis
• A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source
• On the rarity of double black hole binaries: consequences for gravitational-wave detection
• Masses, Beaming and Eddington Ratios in Ultraluminous X-ray Sources
• A spectral-timing model for ULXs in the super-critical regime
• The role of mass transfer and common envelope evolution in the formation of merging binary black holes
• Powerful radiative jets in super-critical accretion disks around non-spinning black holes
• Ultraluminous X-ray sources
• X-ray irradiation in XTE J1817-330 and the inner radius of the truncated disc in the hard state
• POSYDON: A General-Purpose Population Synthesis Code with Detailed Binary-Evolution Simulations
• 2XMM Ultraluminous X-Ray Source Candidates in Nearby Galaxies
• Reprocessing of X-rays in the outer accretion disc of the black hole binary XTE J1817--330
• External Compton emission from relativistic jets in Galactic black hole candidates and ultraluminous X-ray sources
• Bright radio emission from an ultraluminous stellar-mass microquasar in M31
• Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1
• Towards a Realistic Explosion Landscape for Binary Population Synthesis
• A Theory of Gamma-Ray Bursts
• The optical counterpart of an Ultra-luminous X-Ray Source in NGC 5204
• Super-Eddington Atmospheres that Don't Blow Away
• Optical counterparts of the nearest ultraluminous X-ray sources
• The Metallicity Dependence of the High-Mass X-ray Binary Luminosity Function
• The origin of variability of the intermediate-mass black-hole ULX system HLX-1 in ESO 243-49
• The origin of the Ultraluminous X-ray Sources
• The 2019 super-Eddington outburst of RX J0209.6-7427: Detection of pulsations and constraints on the magnetic field strength
• Discovery of a red supergiant donor star in SN2010da/NGC 300 ULX-1
• Radio observations of extreme ULXs: revealing the most powerful ULX radio nebula ever or the jet of an intermediate-mass black hole?
• New Hubble Space Telescope imaging of the counterparts to six ultraluminous X-ray sources
• XMM-Newton Campaign On Ultraluminous X-ray Source NGC 1313 X-1: Wind vs. State Variability
• Pulsating ULXs: large pulsed fraction excludes strong beaming
• Discovery of a red supergiant counterpart to RX~J004722.4-252051, a ULX in NGC 253
• The slimming effect of advection on black-hole accretion flows
• Chandra reveals a possible ultra-fast outflow in the super-Eddington Be/X-ray binary Swift J0243.6+6124
• Orbital decay in M82 X-2
• Solar models in light of new high metallicity measurements from solar wind data
• Ultra-luminous X-ray Sources as Supercritical Accretion Disks: Spectral Energy Distributions
• X-ray Spectral Signatures of the Photon Bubble Model for Ultraluminous X-ray Sources
• Binary Black Hole Merger Rates Inferred from Luminosity Function of Ultra-Luminous X-ray Sources
• Remnants of massive metal-poor stars: viable engines for ultra-luminous X-ray sources
• Chandra and HST Observations of the Supersoft ULX in NGC 247: Candidate for Standard Disk Emission
• The Binary Black Hole Merger Rate from Ultraluminous X-ray Source Progenitors
• The largest bright ULX population in a galaxy: X-ray variability and Luminosity Function in the Cartwheel ring Galaxy