scholarly journals The MAVERIC survey: a hidden pulsar and a black hole candidate in ATCA radio imaging of the globular cluster NGC 6397

2020 ◽  
Vol 493 (4) ◽  
pp. 6033-6049 ◽  
Author(s):  
Yue Zhao ◽  
Craig O Heinke ◽  
Vlad Tudor ◽  
Arash Bahramian ◽  
James C A Miller-Jones ◽  
...  
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
Radio Observation ◽  
Millisecond Pulsar ◽  
Radio Flux ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Imaging ◽  
Low Mass ◽  
Compact Array

ABSTRACT Using a 16.2-h radio observation by the Australia Telescope Compact Array and archival Chandra data, we found >5σ radio counterparts to four known and three new X-ray sources within the half-light radius (rh) of the Galactic globular cluster NGC 6397. The previously suggested millisecond pulsar (MSP) candidate, U18, is a steep-spectrum (Sν ∝ να; $\alpha =-2.0^{+0.4}_{-0.5}$) radio source with a 5.5-GHz flux density of 54.7 ± 4.3 $\mu \mathrm{ Jy}$. We argue that U18 is most likely a ‘hidden’ MSP that is continuously hidden by plasma shocked at the collision between the winds from the pulsar and companion star. The non-detection of radio pulsations so far is probably the result of enhanced scattering in this shocked wind. On the other hand, we observed the 5.5-GHz flux of the known MSP PSR J1740−5340 (U12) to decrease by a factor of >2.8 during epochs of 1.4-GHz eclipse, indicating that the radio flux is absorbed in its shocked wind. If U18 is indeed a pulsar whose pulsations are scattered, we note the contrast with U12’s flux decreases in eclipse, which argues for two different eclipse mechanisms at the same radio frequency. In addition to U12 and U18, we also found radio associations for five other Chandra X-ray sources, four of which are likely background galaxies. The last, U97, which shows strong H α variability, is mysterious; it may be either a quiescent black hole low-mass X-ray binary or something more unusual.

scholarly journals THE FIRST LOW-MASS BLACK HOLE X-RAY BINARY IDENTIFIED IN QUIESCENCE OUTSIDE OF A GLOBULAR CLUSTER

2016 ◽  
Vol 825 (1) ◽  
pp. 10 ◽  
Author(s):  
B. E. Tetarenko ◽  
A. Bahramian ◽  
R. M. Arnason ◽  
J. C. A. Miller-Jones ◽  
S. Repetto ◽  
...  
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
X Ray ◽  
Low Mass

scholarly journals Low-Mass X-ray Binaries—Recent Developments

1996 ◽  
Vol 165 ◽  
pp. 301-312
Author(s):  
M. Van Der Klis
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Neutron Stars ◽  
X Ray ◽  
Black Hole Candidate ◽  
Recent Developments ◽  
Low Mass ◽  
Low Magnetic Field ◽  
X Ray Binaries ◽  
Black Hole Candidates

Recent developments in the field of low-mass X-ray binaries are briefly reviewed, with particular emphasis on a comparison between the systems that contain accreting low magnetic-field neutron stars and those that contain black-hole candidates. The possibility that inclination effects play a role in black-hole candidate phenomenology is explored.

scholarly journals X-Ray Variability from the Ultraluminous Black Hole Candidate X-Ray Binary in the Globular Cluster RZ 2109

2018 ◽  
Vol 862 (2) ◽  
pp. 108 ◽  
Author(s):  
Kristen C. Dage ◽  
Stephen E. Zepf ◽  
Arash Bahramian ◽  
Arunav Kundu ◽  
Thomas J. Maccarone ◽  
...  
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
X Ray ◽  
Black Hole Candidate

scholarly journals Low-Mass X-Ray Binaries in the LMC

1987 ◽  
Vol 93 ◽  
pp. 689-689
Author(s):  
M.W. Pakull ◽  
K. Beuermann ◽  
L.P. Angebault ◽  
L. Bianchi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Interstellar Medium ◽  
Compact Objects ◽  
X Rays ◽  
X Ray ◽  
Black Hole Candidate ◽  
Low Mass ◽  
X Ray Binaries

AbstractWe report results on three low-mass X-ray binaries (LMXB) in the LMC, obtained with EXOSAT, IUE and ground-based (ESO) telescopes: LMC X-2 which appears to be “Sco X-l”-like, LHG 83 and LHG 87. The latter are two weaker sources first detected in the course of the HEAO-B LMC survey. They have faint optical counterparts of which LHG 87 was only recently identified by us. In X-rays, they are characterized by ultrasoft X-ray spectra possibly characteristic of black-hole primaries. LHG 83 furthermore shows evidence for X-ray ionization of the surrounding interstellar medium, similar to the He III region around the black-hole candidate LMC X-l. X-ray binaries with masses of compact objects in excess of 3 M⊙ and ultrasoft X-ray spectra are comparatively frequent in the LMC. We suggest that subcritical accretion onto black holes takes place in LHG 83 and LHG 87.

scholarly journals Simultaneous detection of an intrinsic absorber and a compact jet emission in the X-ray binary IGR J17091−3624 during a hard accretion state

2019 ◽  
Vol 491 (4) ◽  
pp. 4857-4868 ◽  
Author(s):  
E Gatuzz ◽  
M Díaz Trigo ◽  
J C A Miller-Jones ◽  
S Migliari
Keyword(s):  
Black Hole ◽  
Detailed Analysis ◽  
Simultaneous Detection ◽  
The Other ◽  
Radio Observations ◽  
X Ray ◽  
Other Hand ◽  
Low Mass ◽  
Ionization Parameter ◽  
Compact Array

ABSTRACT We present a detailed analysis of three XMM–Newton observations of the black hole low-mass X-ray binary IGR J17091−3624 taken during its 2016 outburst. Radio observations obtained with the Australia Telescope Compact Array indicate the presence of a compact jet during all observations. From the best X-ray data fit results, we concluded that the observations were taken during a transition from a hard accretion state to a hard-intermediate accretion state. For Observations 1 and 2, a local absorber can be identified in the EPIC-pn spectra but not in the RGS spectra, preventing us from distinguishing between absorption local to the source and that from the hot ISM component. For Observation 3, on the other hand, we have identified an intrinsic ionized static absorber in both EPIC-pn and RGS spectra. The absorber, observed simultaneously with a compact jet emission, is characterized by an ionization parameter of 1.96 < log ξ < 2.05 and traced mainly by Ne x, Mg xii, Si xiii, and Fe xviii.

scholarly journals A black hole X-ray binary at ∼100 Hz: multiwavelength timing of MAXI J1820+070 with HiPERCAM and NICER

2019 ◽  
Vol 490 (1) ◽  
pp. L62-L66 ◽  
Author(s):  
J A Paice ◽  
P Gandhi ◽  
T Shahbaz ◽  
P Uttley ◽  
Z Arzoumanian ◽  
...  
Keyword(s):  
Black Hole ◽  
Time Scales ◽  
X Rays ◽  
X Ray ◽  
Black Hole Candidate ◽  
Optical Wavelength ◽  
The Third ◽  
Binary Black Hole ◽  
Internal Shock ◽  
Low Mass

ABSTRACT We report on simultaneous sub-second optical and X-ray timing observations of the low-mass X-ray binary black hole candidate MAXI J1820+070. The bright 2018 outburst rise allowed simultaneous photometry in five optical bands (ugrizs) with HiPERCAM/GTC (Optical) at frame rates over 100 Hz, together with NICER/ISS observations (X-rays). Intense (factor of 2) red flaring activity in the optical is seen over a broad range of time-scales down to ∼10 ms. Cross-correlating the bands reveals a prominent anticorrelation on time-scales of ∼seconds, and a narrow sub-second correlation at a lag of ≈ +165 ms (optical lagging X-rays). This lag increases with optical wavelength, and is approximately constant over Fourier frequencies of ∼0.3–10 Hz. These features are consistent with an origin in the inner accretion flow and jet base within ∼5000 Gravitational radii. An additional ∼+5 s lag feature may be ascribable to disc reprocessing. MAXI J1820+070 is the third black hole transient to display a clear ∼0.1 s optical lag, which may be common feature in such objects. The sub-second lag variation with wavelength is novel, and may allow constraints on internal shock jet stratification models.

scholarly journals Deep radio imaging of 47 Tuc identifies the peculiar X-ray source X9 as a new black hole candidate

2015 ◽  
Vol 453 (4) ◽  
pp. 3919-3932 ◽  
Author(s):  
J. C. A. Miller-Jones ◽  
J. Strader ◽  
C. O. Heinke ◽  
T. J. Maccarone ◽  
M. van den Berg ◽  
...  
Keyword(s):  
Black Hole ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Imaging

scholarly journals Puzzling blue dips in the black hole candidate Swift J1357.2 − 0933, from ULTRACAM, SALT, ATCA, Swift, and NuSTAR

2019 ◽  
Vol 488 (1) ◽  
pp. 512-524 ◽  
Author(s):  
J A Paice ◽  
P Gandhi ◽  
P A Charles ◽  
V S Dhillon ◽  
T R Marsh ◽  
...  
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Radio Observations ◽  
X Ray ◽  
Black Hole Candidate ◽  
Low Mass ◽  
Absorption Features

Abstract We present rapid, multiwavelength photometry of the low-mass X-ray binary Swift J1357.2-0933 during its 2017 outburst. Using several sets of quasi-simultaneous ULTRACAM/NTT (optical), NuSTAR (X-ray), XRT/Swift (X-ray), SALT (optical), and ATCA (radio) observations taken during outburst decline, we confirm the frequent optical dipping that has previously been noted both in outburst and in quiescence. We also find: (1) that the dip frequency decreases as the outburst decays, similar to what was seen in the previous outburst, (2) that the dips produce a shape similar to that in binary systems with partial disc occultations, (3) that the source becomes significantly bluer during these dips, indicating an unusual geometry compared to other LMXB dippers, and (4) that dip superposition analysis confirms the lack of an X-ray response to the optical dips. These very unusual properties appear to be unique to Swift J1357.2−0933, and are likely the result of a high binary inclination, as inferred from features such as its very low outburst X-ray luminosity. From this analysis as well as X-ray/optical timing correlations, we suggest a model with multicomponent emission/absorption features with differing colours. This could include the possible presence of a sporadically occulted jet base and a recessed disc. This source still hosts many puzzling features, with consequences for the very faint X-ray transients population.

Sign in / Sign up

Export Citation Format

Share Document