scholarly journals The Uses of a VLT for Complementing Observations with Radio and Space Telescopes

1984 ◽  
Vol 79 ◽  
pp. 723-724
Author(s):  
Donald N.B. Hall
Keyword(s):  
Electromagnetic Spectrum ◽  
Large Array ◽  
Space Telescopes ◽  
Very Large Array ◽  
X Ray ◽  
International Ultraviolet Explorer ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

It is now evident that major advances in observational sensitivity in other regions of the electromagnetic spectrum invariably lead to heavy demand for complementary observations with existing large (3- to 5-meter) optical/infrared (O/IR) telescopes, and that such observations are often essential to the interpretation and understanding of phenomena revealed by the former. The Einstein X-ray mission, the International Ultraviolet Explorer (IUE), the Very Large Array (VLA) and the recent Infrared Astronomical Satellite (IRAS) are all clear demonstrations of this effect.

scholarly journals Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State

2021 ◽  
Vol 923 (1) ◽  
pp. 3
Author(s):  
Amruta D. Jaodand ◽  
Adam T. Deller ◽  
Nina Gusinskaia ◽  
Jason W. T. Hessels ◽  
James C. A. Miller-Jones ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Millisecond Pulsar ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limit ◽  
5 Ghz ◽  
Variable Radio

Abstract 3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L 5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L 2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.

scholarly journals Quasi-simultaneous radio and X-ray observations of Aql X-1 : probing low luminosities

2019 ◽  
Vol 492 (2) ◽  
pp. 2858-2871 ◽  
Author(s):  
N V Gusinskaia ◽  
J W T Hessels ◽  
N Degenaar ◽  
A T Deller ◽  
J C A Miller-Jones ◽  
...  
Keyword(s):  
Neutron Star ◽  
Large Array ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limits ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Low X ◽  
Power Law Index ◽  
X Ray Binaries

ABSTRACT Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio–X-ray luminosity correlation, LR ∝ LXβ, is not well constrained (β ≈ 0.4–0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1’s 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies (6 × 1034 erg s−1 < LX <3 × 1035 erg s−1, i.e. the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1’s radio emission decays more rapidly at low X-ray luminosities than previously assumed – at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data in the hard X-ray state, this can be modelled as a steep β =$1.17^{+0.30}_{-0.21}$ power-law index or as a sharp radio cut-off at LX ≲ 5 × 1035 erg s−1 (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies.

scholarly journals Is there a cluster in the massive star forming region IRAS 20126+4104?

2015 ◽  
Vol 12 (S316) ◽  
pp. 157-158
Author(s):  
V. A. Montes ◽  
Peter Hofner ◽  
C. Anderson ◽  
V. Rosero
Keyword(s):  
Surface Density ◽  
Massive Star ◽  
Radio Observation ◽  
Large Array ◽  
Very Large Array ◽  
X Ray ◽  
Star Forming ◽  
Continuum Radio

AbstractA Chandra X-ray Observatory ACIS-I observation and a 6 cm continuum radio observation with the Karl G. Jansky Very Large Array (VLA) together with a multiwavelength study in infrared (2MASS and Spitzer) and optical (USNO-B1.0) shows an increasing surface density of X-ray sources toward the massive protostar. There are at least 43 YSOs within 1.2 pc distance from the massive protostar. This number is consistent with typical B-type stars clusters (Lada & Lada 2003).

scholarly journals The variable radio counterpart of Swift J1858.6-0814

2020 ◽  
Vol 496 (4) ◽  
pp. 4127-4140 ◽  
Author(s):  
J van den Eijnden ◽  
N Degenaar ◽  
T D Russell ◽  
D J K Buisson ◽  
D Altamirano ◽  
...  
Keyword(s):  
Time Scales ◽  
Radio Spectrum ◽  
Electromagnetic Spectrum ◽  
Very Large Array ◽  
X Ray ◽  
Geometric Origin ◽  
Optical Wavelengths ◽  
X Ray Binaries ◽  
Variable Radio

ABSTRACT Swift J1858.6-0814 is a transient neutron star X-ray binary discovered in 2018 October. Multiwavelength follow-up observations across the electromagnetic spectrum revealed many interesting properties, such as erratic flaring on minute time-scales and evidence for wind outflows at both X-ray and optical wavelengths, strong and variable local absorption, and an anomalously hard X-ray spectrum. Here, we report on a detailed radio observing campaign consisting of one observation at 5.5/9 GHz with the Australia Telescope Compact Array, and nine observations at 4.5/7.5 GHz with the Karl G. Jansky Very Large Array. A radio counterpart with a flat to inverted radio spectrum is detected in all observations, consistent with a compact jet being launched from the system. Swift J1858.6-0814 is highly variable at radio wavelengths in most observations, showing significant variability when imaged on 3-to-5-min time-scales and changing up to factors of 8 within 20 min. The periods of brightest radio emission are not associated with steep radio spectra, implying they do not originate from the launching of discrete ejecta. We find that the radio variability is similarly unlikely to have a geometric origin, be due to scintillation, or be causally related to the observed X-ray flaring. Instead, we find that it is consistent with being driven by variations in the accretion flow propagating down the compact jet. We compare the radio properties of SwiftJ1858.6-0814 with those of Eddington-limited X-ray binaries with similar X-ray and optical characteristics, but fail to find a match in radio variability, spectrum, and luminosity.

scholarly journals A Decade of Radio and X-ray Observations of SN 1993J

2005 ◽  
Vol 192 ◽  
pp. 3-11
Author(s):  
Schuyler D. Van Dyk ◽  
Kurt W. Weiler ◽  
Richard A. Sramek ◽  
Nino Panagia ◽  
Christopher Stockdale ◽  
...  
Keyword(s):  
Radio Emission ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
X Ray ◽  
Radio Frequencies ◽  
Made In ◽  
Circumstellar Medium

SummaryWe review ten years of radio continuum and X-ray monitoring of the Type IIb SN 1993J in M81. The supernova (SN) has been observed continuously, since only a few days after explosion, by our group with the Very Large Array at a number of radio frequencies, as well as by other groups. As a result, it is among the best-studied radio supernovae. The observed synchrotron radio emission is thought to arise from the interaction of the SN shock with the pre-SN wind-established circumstellar medium around the progenitor star. We describe the properties of the circumstellar interaction, based on the more fully-developed dataset, and compare this to our earlier characterization made in 1994. SN 1993J has also been a target of X-ray satellites, and we briefly discuss the nature of the X-ray emission and, together with the radio emission, describe the implications for the nature of the SN’s progenitor.

scholarly journals Large-scale radio nebula around the Ultra-Luminous X-ray Source IC 342 X-1

2010 ◽  
Vol 6 (S275) ◽  
pp. 325-326 ◽  
Author(s):  
Dávid Cseh ◽  
Cornelia Lang ◽  
Stéphane Corbel ◽  
Philip Kaaret ◽  
Fabien Grisé
Keyword(s):  
Radio Emission ◽  
Large Scale ◽  
Large Array ◽  
Very Large Array ◽  
X Ray

AbstractWe present discovery of a radio nebula associated with the ultraluminous X-ray source (ULX) IC 342 X-1 using the Very Large Array (VLA). Taking the surrounding nebula as a calorimeter, one can constrain the intrinsic power of the ULX source. We compare the obtained power that is needed to supply the radio nebula with the W50 nebula powered by the microquasar SS433 and with other ULXs. We find that the power required is at least two orders of magnitude greater than that needed to power radio emission from the W50 nebula associated with the microquasar SS433. In addition, we report the detection of a compact radio core at the location of the X-ray source.

scholarly journals The radio-X-ray relation as a star formation indicator: results from the Very Large Array-Extended Chandra Deep Field-South

2012 ◽  
Vol 420 (3) ◽  
pp. 2190-2208 ◽  
Author(s):  
S. Vattakunnel ◽  
P. Tozzi ◽  
F. Matteucci ◽  
P. Padovani ◽  
N. Miller ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Array ◽  
Very Large Array ◽  
X Ray

scholarly journals Δ Andromedae (K3 III): A hybrid giant in an extended dust shell

1987 ◽  
Vol 122 ◽  
pp. 321-322
Author(s):  
C. Jordan ◽  
P. G. Judge ◽  
M. Rowan-Robinson
Keyword(s):  
Binary System ◽  
Short Wavelength ◽  
Dust Cloud ◽  
Dust Shell ◽  
Giant Star ◽  
Excess Emission ◽  
Spectroscopic Binary ◽  
International Ultraviolet Explorer ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

Observations made with the Infrared Astronomical Satellite (IRAS) showed the existence of a set of K stars with excess emission at 60 μ. The brightest star in the group is δ And (K3 III). Spectra of δ And have been obtained with the International Ultraviolet Explorer (IUE) in both the long and short wavelength regions. These spectra show several features unusual in a K giant as cool as δ And, in particular, emission from CIV, MgII h and k lines with blue wings stronger than the red and MgII absorption blue shifted to up to 300 km s−1. Overall δ And is similar to the known hybrid bright giant α TrA (K4 II). We have discovered the first ‘hybrid’ giant star. The IRAS observations are interpreted in terms of a cool (∼100 K) dust cloud surrounding δ And - a spectroscopic binary system- and a third component at 1200 A.U.

Geometry of Hα Active Region Loops Observed on the Solar Disk

1983 ◽  
Vol 5 (2) ◽  
pp. 204-208 ◽  
Author(s):  
Chen Chuan-le ◽  
R. E. Loughhead
Keyword(s):  
Active Regions ◽  
Ground Level ◽  
Optical Observations ◽  
Large Array ◽  
Very Large Array ◽  
X Ray ◽  
The Past ◽  
Geometrical Shapes ◽  
Microwave Sources ◽  
Made In

Plasma loops are the dominant structures, in the higher levels of the Sun’s atmosphere above active regions. Much of our knowledge of their properties has come from space observations made over the past decade or so in the EUV and X-ray regions of the spectrum and, more recently, from high-resolution, two-dimensional images of microwave sources obtained with the Very Large Array radio interferometer (VLA). On the other hand, the spatial resolution of rocket and satellite observations has so far generally failed to match that of ground-level optical observations made in Hα and other strong chromospheric lines. The latter permit one to study in much greater detail the morphology of individual loops, as illustrated for example in the recent work of Loughhead, Wang and Blows (1983). These authors addressed themselves to the task of determining the true geometrical shapes of individual loops, a problem which had hitherto received little attention.

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