scholarly journals New Radio Observations of Circinus X-1: A Summary

1998 ◽  
Vol 164 ◽  
pp. 343-344
Author(s):  
R. P. Fender
Keyword(s):  
Flux Density ◽  
Radio Flux ◽  
Radio Observations ◽  
X Ray ◽  
New Radio ◽  
Compact Array

AbstractNew radio observations from the Australia Telescope Compact Array of the radio jet X-ray binary Circinus X-1 are summarized. Radio flux density monitoring around nearly an entire orbit is presented, confirming continued radio flaring around phase 0.1 (near periastron passage) as well as a lesser enhancement half an orbit later.

scholarly journals Simultaneous X-ray and radio observations of the transitional millisecond pulsar candidate CXOU J110926.4–650224

2021 ◽  
Vol 655 ◽  
pp. A52
Author(s):  
F. Coti Zelati ◽  
B. Hugo ◽  
D. F. Torres ◽  
D. de Martino ◽  
A. Papitto ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Density ◽  
Millisecond Pulsar ◽  
Radio Emissions ◽  
X Ray ◽  
Link Type ◽  
Upper Limit ◽  
Variability Pattern ◽  
Average Flux ◽  
Compact Array

We present the results of simultaneous observations of the transitional millisecond pulsar (tMSP) candidate CXOU J110926.4–650224 with the XMM-Newton satellite and the MeerKAT telescope. The source was found at an average X-ray luminosity of LX ≃ 7 × 1033 erg s−1 over the 0.3−10 keV band (assuming a distance of 4 kpc) and displayed a peculiar variability pattern in the X-ray emission, switching between high, low and flaring modes on timescales of tens of seconds. A radio counterpart was detected at a significance of 7.9σ with an average flux density of ≃33 μJy at 1.28 GHz. It showed variability over the course of hours and emitted a ≃10-min long flare just a few minutes after a brief sequence of multiple X-ray flares. No clear evidence for a significant correlated or anticorrelated variability pattern was found between the X-ray and radio emissions over timescales of tens of minutes and longer. CXOU J110926.4–650224 was undetected at higher radio frequencies in subsequent observations performed with the Australia Telescope Compact Array, when the source was still in the same X-ray sub-luminous state observed before, down to a flux density upper limit of 15 μJy at 7.25 GHz (at 3σ). We compare the radio emission properties of CXOU J110926.4–650224 with those observed in known and candidate tMSPs and discuss physical scenarios that may account for its persistent and flaring radio emissions.

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 XXL Survey

2019 ◽  
Vol 633 ◽  
pp. A6 ◽  
Author(s):  
R. A. J. Eyles ◽  
M. Birkinshaw ◽  
V. Smolčić ◽  
C. Horellou ◽  
M. Huynh ◽  
...  
Keyword(s):  
General Population ◽  
Flux Density ◽  
Primary Beam ◽  
Spectral Indices ◽  
Number Density ◽  
X Ray ◽  
Density Limit ◽  
Linear Polarisation ◽  
Compact Array

Aims. We investigate the properties of the polarised radio population in the central 6.5 deg2 of the XXL-South field observed at 2.1 GHz using the Australia Telescope Compact Array (ATCA) in 81 pointings with a synthesised beam of FWHM 5.2″. We also investigate the ATCA’s susceptibility to polarisation leakage. Methods. We performed a survey of a 5.6 deg2 subregion and calculated the number density of polarised sources. We derived the total and polarised spectral indices, in addition to comparing our source positions with those of X-ray-detected clusters. We measured the polarisation of sources in multiple pointings to examine leakage in the ATCA. Results. We find 39 polarised sources, involving 50 polarised source components, above a polarised flux density limit of 0.2 mJy at 1.332 GHz. The number density of polarised source components is comparable with recent surveys, although there is an indication of an excess at ∼1 mJy. We find that those sources coincident with X-ray clusters are consistent in their properties with regard to the general population. In terms of the ATCA leakage response, we find that ATCA mosaics with beam separation of ≲2/3 of the primary beam FWHM have off-axis linear polarisation leakage ≲1.4% at 1.332 GHz.

Radio Observations of the Einstein Deep X-ray Field in Pavo

1990 ◽  
Vol 8 (04) ◽  
pp. 348-352 ◽  
Author(s):  
T. R. Bedding ◽  
A. J. Turtle
Keyword(s):  
Flux Density ◽  
Radio Sources ◽  
Radio Observations ◽  
X Ray ◽  
Object A ◽  
Multi Wavelength ◽  
Radio Map ◽  
Einstein Observatory

AbstractThe most sensitive X-ray survey available is a deep exposure made by theEinstein Observatoryof a 40 arcmin field in the southern constellation of Pavo. This survey revealed 33 X-ray sources, most of which were optically identified with quasars. Here, we report radio observations of the Pavo region at 843 MHz made with the Molonglo Observatory Synthesis Telescope. Eight overlapping fields were combined to produce the most sensitive radio map of the region to date, revealing 33 radio sources above a flux density of 2.4 mJy. Only one of these radio sources corresponded to an X-ray object: a quasar atz= 1.13. We also used the Parkes-Tidbinbilla Interferometer, at 2.29 GHz and 8.41 GHz, to observe some of the stronger radio sources.From these multi-wavelength observations of the Pavo field it is apparent that, to the sensitivity of the surveys involved, (i) there is little correlation between X-ray and radio detections, and (ii) most of the X-ray sources have optical counterparts while few of the radio ones do, and (iii) there is some confirmation that X-ray emission is higher for objects with flat radio spectra (i.e., a dominant core) than for steep spectrum sources.

scholarly journals Radio study of the extended TeV source VER J1907+062

2019 ◽  
Vol 491 (4) ◽  
pp. 5732-5739
Author(s):  
L Duvidovich ◽  
A Petriella ◽  
E Giacani
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Clouds ◽  
Supernova Remnant ◽  
Molecular Gas ◽  
Radio Observations ◽  
Very Large Array ◽  
X Ray ◽  
New Radio ◽  
Γ Ray ◽  
Pulsar Wind

ABSTRACT This paper aims to provide new insights on the origin of the TeV source VER J1907+062 through new high-quality radio observations. We used the Karl G. Jansky Very Large Array (VLA) to observe the whole extension of VER J1907+062 at 1.5 GHz with a mosaicking technique and the PSR J1907+0602 in a single pointing at 6 GHz. These data were used together with 12CO and atomic hydrogen observations obtained from public surveys to investigate the interstellar medium in the direction of VER J1907+062. The new radio observations do not show any evidence of a pulsar wind nebula (PWN) driven by the pulsars present in the field and no radio counterpart to the proposed X-ray PWN powered by PSR J1907+0602 is seen in the new VLA image at 6 GHz down to a noise level of 10 $\mu$Jy beam−1. Molecular clouds were discovered over the eastern, southern, and western borders of the radio shell of G40.5−0.5, suggesting an association with this supernova remnant. We explored several scenarios for the origin of VER J1907+062. We propose as the most probable scenario one in which the TeV emission is produced by two separated γ-ray sources located at different distances: one of leptonic origin and associated with a PWN powered by PSR J1907+0602 at ∼3.2 kpc and another of hadronic origin and produced by the interaction between G40.5−0.5 and the surrounding molecular gas at ∼8.7 kpc.

scholarly journals Rapid-response radio observations of short GRB 181123B with the Australia Telescope Compact Array

2021 ◽  
Author(s):  
G E Anderson ◽  
M E Bell ◽  
J Stevens ◽  
M D Aksulu ◽  
J C A Miller-Jones ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Early Time ◽  
Rapid Response ◽  
Radio Flux ◽  
Radio Observations ◽  
Forward Shock ◽  
Radio Band ◽  
Short Grbs ◽  
Compact Array

Abstract We introduce the Australia Telescope Compact Array (ATCA) rapid-response mode by presenting the first successful trigger on the short-duration gamma-ray burst (GRB) 181123B. Early-time radio observations of short GRBs may provide vital insights into the radio afterglow properties of Advanced LIGO- and Virgo-detected gravitational wave events, which will in turn inform follow-up strategies to search for counterparts within their large positional uncertainties. The ATCA was on target within 12.6 hr post-burst, when the source had risen above the horizon. While no radio afterglow was detected during the 8.3 hr observation, we obtained force-fitted flux densities of 7 ± 12 and 15 ± 11μJy at 5.5 and 9 GHz, respectively. Afterglow modelling of GRB 181123B showed that the addition of the ATCA force-fitted radio flux densities to the Swift X-ray Telescope detections provided more stringent constraints on the fraction of thermal energy in the electrons (log $\epsilon _e = -0.75^{+0.39}_{-0.40}$ rather than log $\epsilon _e = -1.13^{+0.82}_{-1.2}$ derived without the inclusion of the ATCA values), which is consistent with the range of typical εe derived from GRB afterglow modelling. This allowed us to predict that the forward shock may have peaked in the radio band ∼10 days post-burst, producing detectable radio emission ≳ 3 − 4 days post-burst. Overall, we demonstrate the potential for extremely rapid radio follow-up of transients and the importance of triggered radio observations for constraining GRB blast wave properties, regardless of whether there is a detection, via the inclusion of force-fitted radio flux densities in afterglow modelling efforts.

scholarly journals New radio observations of the Type IIn Supernova 1978K

2016 ◽  
Vol 12 (S329) ◽  
pp. 444-444
Author(s):  
Stuart D. Ryder ◽  
Erik C. Kool ◽  
Rubina Kotak
Keyword(s):  
Blast Wave ◽  
Spatial Resolution ◽  
High Frequency ◽  
Very Long Baseline Interferometry ◽  
Expansion Velocity ◽  
Radio Observations ◽  
The Past ◽  
Long Baseline ◽  
New Radio ◽  
Compact Array

AbstractSN 1978K is the oldest-known Type IIn supernova, and one of the closest. We report new radio observations at high frequency and spatial resolution. SN 1978K has been detected at 34 and 94 GHz with the Australia Telescope Compact Array, while Very Long Baseline Interferometry at 8.4 GHz has allowed us to derive the past average expansion velocity, which indicates significant deceleration as the blast wave interacts with the dense circumstellar medium.

scholarly journals A new radio catalogue for M83: supernova remnants and H ii regions

2020 ◽  
Vol 495 (1) ◽  
pp. 479-501 ◽  
Author(s):  
Thomas D Russell ◽  
Richard L White ◽  
Knox S Long ◽  
William P Blair ◽  
Roberto Soria ◽  
...  
Keyword(s):  
Spiral Galaxy ◽  
Supernova Remnants ◽  
Radio Sources ◽  
H Ii Regions ◽  
Dual Frequency ◽  
X Ray ◽  
New Radio ◽  
The Face ◽  
Approximate Power ◽  
Compact Array

ABSTRACT We present a new catalogue of radio sources in the face-on spiral galaxy M83. Radio observations taken in 2011, 2015, and 2017 with the Australia Telescope Compact Array at 5.5 and 9 GHz have detected 270 radio sources. Although a small number of these sources are background extragalactic sources, most are either H ii regions or supernova remnants (SNRs) within M83 itself. Three of the six historical supernovae are detected, as is the very young remnant that had been identified in a recent study, which is likely the result of a supernova that exploded in the last ∼100 yr but was missed. All of these objects are generally fading with time. Confusion limits our ability to measure the radio emission from a number of the SNRs in M83, but 64 were detected in unconfused regions, and these have the approximate power-law luminosity function that has been observed in other galaxies. The SNRs in M83 are systematically smaller in diameter and brighter than those that have been detected at radio wavelengths in M33. A number of the radio sources are coincident with X-ray sources in M83; most of these coincident sources turn out to be SNRs. Our dual frequency observations are among the most sensitive to date for a spiral galaxy outside the Local Group; despite this we were not able to place realistic constraints on the spectral indices, and as a result, it was not possible to search for SNRs based on their radio properties alone.

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 Radio/X-ray correlations and variability in the X-ray binary LS I +61°303

2020 ◽  
Vol 500 (3) ◽  
pp. 4166-4172
Author(s):  
R Sharma ◽  
M Massi ◽  
M Chernyakova ◽  
D Malyshev ◽  
Y C Perrott ◽  
...  
Keyword(s):  
Time Scales ◽  
High Mass ◽  
Large Array ◽  
Radio Observations ◽  
X Ray ◽  
Radio Monitoring ◽  
New Radio ◽  
Short Time ◽  
First Time ◽  
The Relationship

ABSTRACT The high-mass X-ray binary LS I +61°303 exhibits variability in its radio and X-ray emissions, ranging from minute to hour time-scales. At such short time-scales, not much is known about the possible correlations between these two emissions from this source, which might offer hints to their origin. Here, we study the relationship between these emissions using simultaneous X-ray and radio monitoring. We present new radio observations using the Arcminute Microkelvin Imager Large Array telescope at two frequency bands, 13–15.5 and 15.5–18 GHz. We also describe new X-ray observations performed using the XMM–Newton telescope. These X-ray and radio observations overlapped for five hours. We find for the first time that the radio and X-ray emission are correlated up to 81${{\ \rm per\ cent}}$ with their few per cent variability correlated up to 40 ${{\ \rm per\ cent}}$. We discuss possible physical scenarios that produces the observed correlations and variability in the radio and X-ray emission of LS I +61°303.

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