The observed vs total population of ULXs

Abstract

We have analyzed how anisotropic emission of radiation affects the observed sample of ultraluminous X-ray sources (ULXs) by performing simulations of the evolution of stellar populations, employing recent developments in stellar and binary physics, and by utilizing a geometrical beaming model motivated by theory and observation. Whilst ULXs harboring black hole accretors (BH ULXs) are typically emitting isotropically, the majority of ULXs with neutron star accretors (NS ULXs) are found to be beamed. These findings confirm previous assertions that a significant fraction of ULXs are hidden from view due to a substantial misalignment of the emission beam and the line-of-sight. We find the total number of NS ULXs in regions with constant star formation, solar metallicity, and ages above ~1 Gyr to be higher than the BH ULXs, although observationally both populations are comparable. For lower metallicities BH ULX dominate both the total and observed ULX populations. As far as burst star-formation is concerned, young ULX populations are dominated by BH ULXs, but this changes as the population ages and, post star-formation, NS ULXs dominate both the observed and total population of ULXs. We also compare our simulation output to a previous analytical prediction for the relative ratio of BH to NS ULXs in idealized flux-limited observations and find broad agreement for all but the lowest metallicities. In so doing we find that in such surveys the observed ULX population should be heavily dominated by black-hole systems rather than by systems containing neutron stars.

11 pages, 8 figures, minor corrections, accepted to ApJ

References in corpus (28)

• Binary interaction dominates the evolution of massive stars
• An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
• Super-critically accreting stellar-mass black holes as ultraluminous X-ray sources
• An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907
• Discovery of coherent pulsations from the Ultraluminous X-ray Source NGC 7793 P13
• The Nature of SS433 and the Ultraluminous X-ray Sources
• Masses, Beaming and Eddington Ratios in Ultraluminous X-ray Sources
• The critical accretion luminosity for magnetized neutron stars
• Global simulations of axisymmetric radiative black hole accretion disks in general relativity with a sub-grid magnetic dynamo
• A spectral-timing model for ULXs in the super-critical regime
• Pulsing ULXs: tip of the iceberg?
• Pulsator-like spectra from Ultraluminous X-ray sources and the search for more ultraluminous pulsars
• Ultra-luminous X-ray sources and neutron-star-black-hole mergers from very massive close binaries at low metallicity
• Optically thick envelopes around ULXs powered by accreating neutron stars
• ULX spectra revisited: Accreting, highly magnetized neutron stars as the engines of ultraluminous X-ray sources
• Impact of inter-correlated initial binary parameters on double black hole and neutron star mergers
• General-Relativistic Simulations of Four States of Accretion onto Millisecond Pulsars
• No magnetars in ULXs
• A VLT/FLAMES survey for massive binaries in Westerlund 1. IV. Wd1-5 - binary product and a pre-supernova companion for the magnetar CXOU J1647-45?
• Models for the Observable System Parameters of Ultraluminous X-ray Sources
• A Population of Ultraluminous X-ray Sources with An Accreting Neutron Star
• Near-infrared counterparts of ultraluminous X-ray sources
• On the Formation of Ultraluminous X-ray Sources with Neutron Star Accretors: the Case of M82 X-2
• Modeling the light curves of ultraluminous X-ray sources as precession
• Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1
• HLX-1 may be an SS433 system
• Geometrical beaming of stellar mass ULXs
• The Binary Black Hole Merger Rate from Ultraluminous X-ray Source Progenitors

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