Pulsating ULXs: large pulsed fraction excludes strong beaming
arXiv:2011.09710 · doi:10.1093/mnras/staa3809
Abstract
The recent discovery of pulsating ultra-luminous X-ray sources (ULXs) shows that the apparent luminosity of accreting neutron stars (NSs) can exceed the Eddington luminosity by a factor of hundreds. The relation between the actual and apparent luminosity is a key ingredient in theoretical models of ULXs but it is still under debate. A typical feature of the discovered pulsating ULXs is a large pulsed fraction (PF). Using Monte Carlo simulations, we consider a simple geometry of accretion flow and test the possibility of simultaneous presence of a large luminosity amplification due the geometrical beaming and a high PF. We argue that these factors largely exclude each other and only a negligible fraction of strongly beamed ULX pulsars can show PF above 10 per cent. Discrepancy between this conclusion and current observations indicate that pulsating ULXs are not strongly beamed and their apparent luminosity is close to the actual one.
6 pages, 5 figures; accepted for publication in MNRAS
References in corpus (18)
- 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 a 0.42-s pulsar in the ultraluminous X-ray source NGC 7793 P13
- Discovery of coherent pulsations from the Ultraluminous X-ray Source NGC 7793 P13
- Masses, Beaming and Eddington Ratios in Ultraluminous X-ray Sources
- Pulsing ULXs: tip of the iceberg?
- The ultra luminous X-ray source NuSTAR J095551+6940.8: A magnetar in a high mass X-ray binary
- Optically thick envelopes around ULXs powered by accreating neutron stars
- NuSTAR J095551+6940.8: a highly magnetised neutron star with super-Eddington mass accretion
- A new, clean catalogue of extragalactic non-nuclear X-ray sources in nearby galaxies
- Searching for Outflows in Ultraluminous X-ray Sources Through High-Resolution X-ray Spectroscopy
- No magnetars in ULXs
- Super-Eddington accretion discs with advection and outflows around magnetized neutron stars
- M51 ULX-7: super-orbital periodicity and constraints on the neutron star magnetic field
- On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation
- Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT
- General relativistic radiation magnetohydrodynamics simulations of supercritical accretion onto magnetized neutron star; -modeling of ultra luminous x-ray pulsars
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- Radiative MHD Simulations of Photon Bubbles in Radiation-Supported Magnetized Atmospheres of Neutron Stars with Isotropic Thomson Scattering
- The impact of precession on the observed population of ULXs
- High-Mass X-Ray Binaries with Be Donors as Ultraluminous X-Ray Sources