72 research outputs found
Revealing a new symbiotic X-ray binary with Gemini NIFS
We use K-band spectroscopy of the counterpart to the rapidly variable X-ray
transient XMMU J174445.5-295044 to identify it as a new symbiotic X-ray binary.
XMMU J174445.5-295044 has shown a hard X-ray spectrum (we verify its
association with an Integral/IBIS 18-40 keV detection in 2013 using a short
Swift/XRT observation), high and varying N, and rapid flares on timescales
down to minutes, suggesting wind accretion onto a compact star. We observed its
near-infrared counterpart using the Near-infrared Integral Field Spectrograph
(NIFS) at Gemini-North, and classify the companion as ~ M2 III. We infer a
distance of kpc (conservative 1-sigma errors), and
therefore calculate that the observed X-ray luminosity (2-10 keV) has reached
to at least 4 erg/s. We therefore conclude that the source is a
symbiotic X-ray binary containing a neutron star (or, less likely, black hole)
accreting from the wind of a giant.Comment: 7 pages, 3 figures, MNRAS in pres
Rapid population synthesis of black-hole high-mass X-ray binaries: implications for binary stellar evolution
We conduct binary population synthesis to investigate the formation of
wind-fed high-mass X-ray binaries containing black holes (BH-HMXBs). We evolve
multiple populations of high-mass binary stars and consider BH-HMXB formation
rates, masses, spins and separations. We find that systems similar to Cygnus
X-1 likely form after stable Case A mass transfer (MT) from the main sequence
progenitors of black holes, provided such MT is characterised by low accretion
efficiency, , with modest orbital angular momentum losses
from the non-accreted material. Additionally, efficient BH-HMXB formation
relies on a new simple treatment for Case A MT that allows donors to retain
larger core masses compared to traditional rapid population-synthesis
assumptions. At solar metallicity, our Preferred model yields
observable BH-HMXBs in the Galaxy today, consistent with observations. In this
simulation, of BH-HMXBs go on to merge as binary black holes or neutron
star-black hole binaries within a Hubble time; however, none of the merging
binaries have BH-HMXB progenitors with properties similar to Cygnus X-1. With
our preferred settings for core mass growth, mass transfer efficiency and
angular momentum loss, accounting for an evolving metallicity, and integrating
over the metallicity-specific star formation history of the Universe, we find
that BH-HMXBs may have contributed -- BBH merger signals to
detections reported in the third gravitational-wave transient catalogue of the
LIGO-Virgo-KAGRA Collaboration. We also suggest MT efficiency should be higher
during stable Case B MT than during Case A MT.Comment: 17 pages, 10 figure
Health literacy and its influencing factors in Iranian diabetic patients
Acknowledgements We would like to present our special thanks to all participants of this study. This study was supported by the Institute of Endocrinology and Metabolism (IEM) in Iran University of Medical Sciences.Peer reviewedPublisher PD
An HI absorption distance to the black hole candidate X-ray binary MAXI J1535-571
With the Australian Square Kilometre Array Pathfinder (ASKAP) we monitored
the black hole candidate X-ray binary MAXI J1535--571 over seven epochs from 21
September to 2 October 2017. Using ASKAP observations, we studied the HI
absorption spectrum from gas clouds along the line-of-sight and thereby
constrained the distance to the source. The maximum negative radial velocities
measured from the HI absorption spectra for MAXI J1535--571 and an
extragalactic source in the same field of view are km s and
km s, respectively. This rules out the far kinematic distance
( kpc), giving a most likely distance of
kpc, with a strong upper limit of the tangent point at kpc.
At our preferred distance, the peak unabsorbed luminosity of MAXI J1535--571
was per cent of the Eddington luminosity, and shows that the soft-to-hard
spectral state transition occurred at the very low luminosity of 1.2 -- 3.4
10 times the Eddington luminosity. Finally, this study
highlights the capabilities of new wide-field radio telescopes to probe
Galactic transient outbursts, by allowing us to observe both a target source
and a background comparison source in a single telescope pointing.Comment: Revised after favorable referee report from MNRAS Letter
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