scholarly journals Multi-wavelength observations of the Galactic X-ray binaries IGR J20155+3827 and Swift J1713.4−4219

2021 ◽  
Author(s):  
F Onori ◽  
M Fiocchi ◽  
N Masetti ◽  
A F Rojas ◽  
A Bazzano ◽  
...  
Keyword(s):  
Lower Energy ◽  
Gamma Ray ◽  
Physical Characterization ◽  
Archival Data ◽  
X Ray ◽  
Photometric Observations ◽  
Multi Wavelength ◽  
X Ray Binaries

Abstract In recent years, thanks to the continuous surveys performed by INTEGRAL and Swift satellites, our knowledge of the hard X-ray/soft gamma-ray sky has greatly improved. As a result it is now populated with about 2000 sources, both Galactic and extra-galactic, mainly discovered by IBIS and BAT instruments. Many different follow-up campaigns have been successfully performed by using a multi-wavelength approach, shedding light on the nature of a number of these new hard X-ray sources. However, a fraction are still of a unidentified nature. This is mainly due to the lack of lower energy observations, which usually deliver a better constrained position for the sources, and the unavailability of the key observational properties, needed to obtain a proper physical characterization. Here we report on the classification of two poorly studied Galactic X-ray transients IGR J20155+3827 and Swift J1713.4−4219, for which the combination of new and/or archival X-ray and Optical/NIR observations have allowed us to pinpoint their nature. In particular, thanks to XMM-Newton archival data together with new optical spectroscopic and archival Optical/NIR photometric observations, we have been able to classify IGR J20155+3827 as a distant HMXB. The new INTEGRAL and Swift data collected during the 2019 X-ray outburst of Swift J1713.4−4219, in combination with the archival optical/NIR observations, suggest a LMXB classification for this source.

scholarly journals Surrounded by spiders! New black widows and redbacks in the Galactic field

2012 ◽  
Vol 8 (S291) ◽  
pp. 127-132 ◽  
Author(s):  
Mallory S. E. Roberts
Keyword(s):  
Mass Transfer ◽  
Transfer Process ◽  
Gamma Ray ◽  
Mass Transfer Process ◽  
Millisecond Pulsar ◽  
X Ray ◽  
Galactic Field ◽  
Multi Wavelength ◽  
Low Mass ◽  
X Ray Binaries

AbstractOver the last few years, the number of known eclipsing radio millisecond pulsar systems in the Galactic field has dramatically increased, with many being associated with Fermi gamma-ray sources. All are in tight binaries (orbital period < 24 hr) with many being classical “black widows” which have very low mass companions (companion mass Mc ≪ 0.1 M⊙) but some are “redbacks” with low mass (Mc ~ 0.2-0.4 M⊙) companions which are probably non-degenerate. These latter are systems where the mass transfer process may have only temporarily halted, and so are transitional systems between low mass X-ray binaries and ordinary binary millisecond pulsars. Here we review the new discoveries and their multi-wavelength properties, and briefly discuss models of shock emission, mass determinations, and evolutionary scenarios.

The SALT Transient Programme

2017 ◽  
Vol 14 (S339) ◽  
pp. 176-180
Author(s):  
D. A. H. Buckley
Keyword(s):  
Gamma Ray ◽  
Cataclysmic Variables ◽  
Gamma Ray Bursts ◽  
High Mass ◽  
Core Collapse ◽  
Tidal Disruption ◽  
X Ray ◽  
Wide Range ◽  
X Ray Binaries

AbstractThe SALT transient follow-up programme began in 2016 and will continue for 5 semesters (until 31 Oct 2018), with an expectation of renewal thereafter. It is currently the only SALT Large Science Programme, and was awarded ~250 ksec. per semester, with a significant fraction (60%) given for the highest priority target-of-opportunity time. The aim is to characterise and study transients across a wide range of classes, currently including (from closest to most distant) cataclysmic variables, novæ and other associated eruptive variables, low- and high-mass X-ray binaries, OGLE and Gaia transients (including tidal disruption events), super-luminous and unusual core-collapse supernovæ, kilonovæ and other candidate optical counterparts to gravitational-wave events, flaring blazars and AGN, and gamma-ray bursts. This programme currently involves four SALT partners, of which South Africa is the major contributor of time (74%) and resources and includes five institutions with over 30 co-investigators. This talk reviewed the nature of the programme and highlighted some of the results to date.

Classification of Fresh Fractures of the Lunate

1988 ◽  
Vol 13 (4) ◽  
pp. 458-462
Author(s):  
H. TEISEN ◽  
J. HJARBAEK
Keyword(s):  
Vascular Anatomy ◽  
X Rays ◽  
Lunate Bone ◽  
X Ray

The X-rays of 17 patients with fresh fractures of the lunate bone have been reviewed. The fractures were classified according to their radiological appearances and according to the vascular anatomy of the lunate. A long term X-ray follow-up examination was performed.

scholarly journals Unveiling the Nature of INTEGRAL Objects: a Review

2014 ◽  
Vol 1 (1) ◽  
pp. 240-245
Author(s):  
Pietro Parisi
Keyword(s):  
Ir Spectroscopy ◽  
Energy Range ◽  
Southern Hemisphere ◽  
Cross Correlation ◽  
Active Galaxies ◽  
X Ray ◽  
The Real ◽  
Real Nature ◽  
X Ray Binaries

Since its launch in October 2002, the <em>INTEGRAL</em> observatory has improved our knowledge of the hard X-ray sky above 20 keV, carrying out more than ten years of observations in the energy range from 5 keV to 8 MeV. The most recently published <em>INTEGRAL</em>/IBIS surveys listed more than seven hundred sources in the 20-100 keV band. Most of these objects are either Active Galaxies (AGNs) or X-ray binaries; a fraction of both classes is made of highly absorbed sources, often associated with dim optical counterparts. Despite the big eort in the identication process, a large part of these IBIS objects (~25% of them) still remains unclassied. Cross-correlation with archival catalogues and/or multiwaveband follow-up observations are of invaluable help to identify and properly classify this unknown objects, but only optical or IR spectroscopy with ground based telescopes in the Northern and Southern Hemisphere can reveal the real nature of these objects. In this work we report on source types that we nd among the unidentied objects in the most recent <em>INTEGRAL</em> surveys.

scholarly journals Prolonged sub-luminous state of the new transitional pulsar candidate CXOU J110926.4−650224

2019 ◽  
Vol 622 ◽  
pp. A211 ◽  
Author(s):  
Francesco Coti Zelati ◽  
Alessandro Papitto ◽  
Domitilla de Martino ◽  
David A. H. Buckley ◽  
Alida Odendaal ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Broad Band ◽  
Optical Emission ◽  
Bimodal Distribution ◽  
X Ray ◽  
The Past ◽  
Upper Limits ◽  
Photon Index ◽  
Multi Wavelength ◽  
Absorbed Power

We report on a multi-wavelength study of the unclassified X-ray source CXOU J110926.4−650224 (J1109). We identified the optical counterpart as a blue star with a magnitude of ∼20.1 (3300–10500 Å). The optical emission was variable on timescales from hundreds to thousands of seconds. The spectrum showed prominent emission lines with variable profiles at different epochs. Simultaneous XMM-Newton and NuSTAR observations revealed a bimodal distribution of the X-ray count rates on timescales as short as tens of seconds, as well as sporadic flaring activity. The average broad-band (0.3–79 keV) spectrum was adequately described by an absorbed power law model with photon index of Γ = 1.63  ±  0.01 (at 1σ c.l.), and the X-ray luminosity was (2.16  ±  0.04)  ×  1034 erg s−1 for a distance of 4 kpc. Based on observations with different instruments, the X-ray luminosity has remained relatively steady over the past ∼15 years. J1109 is spatially associated with the gamma-ray source FL8Y J1109.8−6500, which was detected with Fermi at an average luminosity of (1.5  ±  0.2)  ×  1034 erg s−1 (assuming the distance of J1109) over the 0.1–300 GeV energy band between 2008 and 2016. The source was undetected during ATCA radio observations that were simultaneous with NuSTAR, down to a 3σ flux upper limit of 18 μJy beam−1 (at 7.25 GHz). We show that the phenomenological properties of J1109 point to a binary transitional pulsar candidate currently in a sub-luminous accretion disk state, and that the upper limits derived for the radio emission are consistent with the expected radio luminosity for accreting neutron stars at similar X-ray luminosities.

scholarly journals Astrophysical implications of neutron star inspiral and coalescence

2020 ◽  
Vol 29 (11) ◽  
pp. 2041015
Author(s):  
John L. Friedman ◽  
Nikolaos Stergioulas
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Maximum Mass ◽  
X Ray ◽  
Spectral Bands ◽  
Heaviest Elements ◽  
X Ray Binaries

The first inspiral of two neutron stars observed in gravitational waves was remarkably close, allowing the kind of simultaneous gravitational wave and electromagnetic observation that had not been expected for several years. Their merger, followed by a gamma-ray burst and a kilonova, was observed across the spectral bands of electromagnetic telescopes. These GW and electromagnetic observations have led to dramatic advances in understanding short gamma-ray bursts; determining the origin of the heaviest elements; and determining the maximum mass of neutron stars. From the imprint of tides on the gravitational waveforms and from observations of X-ray binaries, one can extract the radius and deformability of inspiraling neutron stars. Together, the radius, maximum mass, and causality constrain the neutron-star equation of state, and future constraints can come from observations of post-merger oscillations. We selectively review these results, filling in some of the physics with derivations and estimates.

Directions for Future X-Ray, Optical, and Radio Follow-up Observations of Gamma-Ray Burst Counterparts

1995 ◽  
Vol 452 (1) ◽  
Author(s):  
B. J. McNamara ◽  
T. E. Harrison ◽  
C. L. Williams
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Burst ◽  
X Ray

GW170817: Swift UV detection of a blue kilonova, and improving the search in O3

2017 ◽  
Vol 13 (S338) ◽  
pp. 53-60
Author(s):  
Aaron Tohuvavohu ◽  
Jamie A. Kennea ◽  
Keyword(s):  
Health And Safety ◽  
X Ray ◽  
Operational Capabilities ◽  
Observation Strategy ◽  
Ongoing Work ◽  
The Galaxy ◽  
Multi Wavelength ◽  
Flexible Planning ◽  
The Impact

AbstractSwift’s rapid slewing, flexible planning, and multi-wavelength instruments make it the most capable space-based follow-up engine for finding poorly localized sources. During O1 and O2 Swift successfully tiled hundreds of square-degrees of sky in the LVC localization regions, searching for, and identifying, possible X-ray and UV/O transients in the field. Swift made important contributions to the discovery and characterization of the kilonova AT 2017gfo, discovering the UV emission and providing the deepest X-ray upper limits in the first 24 hours after the trigger, strongly constraining the dynamics and geometry of the counterpart. Swift tiled 92% of the galaxy convolved error region down to average X-ray flux sensitivities of 10−12 erg cm−2 s−1, significantly increasing our confidence that AT 2017gfo is indeed the counterpart to GW 170817 and sGRB 170817. However, there remains significant room for improvement of Swift’s follow-up in preparation for O3. This will take the form of both revised observation strategy based on detailed analysis of the results from O2, and significant changes to Swift’s operational capabilities. These improvements are necessary both for maximizing the likelihood that Swift finds a counterpart, and minimizing the impact that follow-up activities have on other Swift science priorities. We outline areas of improvement to the observing strategy itself for optimal tiling of the LVC localization regions. We also discuss ongoing work on operational upgrades that will decrease latency in our response time, and minimize impact on pre-planned observations, while maintaining spacecraft health and safety.

scholarly journals Observational Evidence for the Origin of X-ray Sources in Globular Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 301-310 ◽  
Author(s):  
Frank Verbunt ◽  
Dave Pooley ◽  
Cees Bassa
Keyword(s):  
Statistical Method ◽  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Observational Evidence ◽  
X Ray ◽  
Cluster Mass ◽  
Low Mass ◽  
Optical Identifications ◽  
X Ray Binaries

AbstractLow-mass X-ray binaries, recycled pulsars, cataclysmic variables and magnetically active binaries are observed as X-ray sources in globular clusters. We discuss the classification of these systems, and find that some presumed active binaries are brighter than expected. We discuss a new statistical method to determine from observations how the formation of X-ray sources depends on the number of stellar encounters and/or on the cluster mass. We show that cluster mass is not a proxy for the encounter number, and that optical identifications are essential in proving the presence of primordial binaries among the low-luminosity X-ray sources.

Sign in / Sign up

Export Citation Format

Share Document