Search Publications
Accretion geometry of the neutron star low mass X-ray binary Cyg X-2 from X-ray polarization measurements
Antonelli, L. A.; Costa, E.; Bianchi, S. +92 more
We report spectro-polarimetric results of an observational campaign of the bright neutron star low-mass X-ray binary Cyg X-2 simultaneously observed by IXPE, NICER, and INTEGRAL. Consistently with previous results, the broad-band spectrum is characterized by a lower-energy component, attributed to the accretion disc with kTin ≈ 1 keV, p…
Constraints on light decaying dark matter candidates from 16 yr of INTEGRAL/SPI observations
Calore, F.; Dekker, A.; Serpico, P. D. +1 more
We apply the recently developed analysis of 16 yr of INTEGRAL/SPI data including a dark matter spatial template to derive bounds on dark matter candidates lighter than weakly interacting massive particles (like sterile neutrinos or axion-like particles) decaying into line or continuum electromagnetic final state channels. The bounds obtained are t…
Evidence for mass-dependent peculiar velocities in compact object binaries: towards better constraints on natal kicks
Maccarone, Thomas J.; Gandhi, Poshak; Zhao, Yue +4 more
We compile a catalogue of low-mass and high-mass X-ray binaries, some recently reported binaries that likely host a neutron star (NS) or a black hole (BH), and binary pulsars (a pulsar and a non-degenerated companion) that have measured systemic radial velocities (γ). Using Gaia and radio proper motions together with γ, we integrate their Galactic…
Deciphering the unusual stellar progenitor of GRB 210704A
Troja, E.; Im, M.; Butler, N. R. +16 more
GRB 210704A is a burst of intermediate duration (T90 ~ 1-4 s) followed by a fading afterglow and an optical excess that peaked about 7 d after the explosion. Its properties, and in particular those of the excess, do not easily fit into the well-established classification scheme of gamma-ray bursts (GRBs) as being long or short, leaving …
A catalogue of unusually long thermonuclear bursts on neutron stars
Degenaar, N.; in't Zand, J. J. M.; Kuulkers, E. +10 more
Rare, energetic (long) thermonuclear (Type I) X-ray bursts are classified either as intermediate-duration or 'supern' bursts, based on their duration. Intermediate-duration bursts lasting a few to tens of minutes are thought to arise from the thermonuclear runaway of a relatively thick (≈1010 g cm-2) helium layer, while super…
An investigation of the '10 keV feature' in the spectra of accretion powered X-ray pulsars with NuSTAR
Paul, Biswajit; Rana, Vikram; Manikantan, Hemanth
Some of the accreting X-ray pulsars are reported to exhibit a peculiar spectral feature at ~10 keV, known as the '10 keV feature'. The feature has been characterized as either an emission line or an absorption line, and its origin is unknown. It has been found in multiple observations of the same source by different observatories, but not all the …
Comprehensive coverage of particle acceleration and kinetic feedback from the stellar mass black hole V404 Cygni
Motta, S. E.; Miller-Jones, J. C. A.; Williams, D. R. A. +8 more
We present analysis of comprehensive radio observations of the black hole V404 Cyg during its 2015 outburst. These data represent the best ever coverage of jet production and particle acceleration from any black hole. We report for the first time a clear and near-linear flux-rms correlation in the radio flux densities. Investigation of individual …
XTE J1906+090: a persistent low-luminosity Be X-ray binary
Sidoli, L.; La Palombara, N.; Bird, A. J. +1 more
We present new results from INTEGRAL and Swift observations of the hitherto poorly studied and unidentified X-ray source XTE J1906+090. A bright hard X-ray outburst (luminosity of ~1036 erg s-1 above 20 keV) has been discovered with INTEGRAL observations in 2010, this being the fourth outburst ever detected from the source. S…
Automated classification of Chandra X-ray point sources using machine learning methods
Bhattacharyya, Sudip; Kumaran, Shivam; Mandal, Samir +1 more
A large number of unidentified sources found by astronomical surveys and other observations necessitate the use of an automated classification technique based on machine learning (ML) methods. The aim of this paper is to find a suitable automated classifier to identify the point X-ray sources in the Chandra Source Catalogue (CSC) 2.0 in the catego…
Accretion disc evolution in GRO J1655-40 and LMC X-3 with relativistic and non-relativistic disc models
Grinberg, Victoria; Dovčiak, Michal; Boorman, Peter G. +3 more
Black hole X-ray binaries are ideal environments to study the accretion phenomena in strong gravitational potentials. These systems undergo dramatic accretion state transitions and analysis of the X-ray spectra is used to probe the properties of the accretion disc and its evolution. In this work, we present a systematic investigation of ~1800 spec…