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 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 VLA observations of water maser emission associated with SVS 13

2002 ◽  
Vol 206 ◽  
pp. 59-62
Author(s):  
Luis F. Rodríguez ◽  
Guillem Anglada ◽  
José M. Torrelles ◽  
J. Eduardo Mendoza-Torres ◽  
Aubrey D. Haschick ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Radio Source ◽  
Angular Resolution ◽  
Radio Continuum ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Water Maser ◽  
East West ◽  
Made In

The young stellar object SVS 13 has been proposed as the powering source of the HH 7-11 objects. Recent observations have revealed that in the radio continuum (3.6-cm) the source is a binary separated by about 0.3 in the east-west direction. We present Very Large Array observations, made in the highest angular resolution A configuration, of H2O maser emission toward this source. Our data show that the H2O spots appear to be segregated in two velocity groups: a group with radial velocity similar to that of the ambient cloud (VLSR ⋍ 8 km s−1) that is associated with the western radio source, and a blueshifted (by ∼20 km s−1) velocity group that is associated with the eastern radio source. We discuss the possible implications of this observation.

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.

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.

scholarly journals Fluctuations in the Microwave Sky

1996 ◽  
Vol 168 ◽  
pp. 59-70
Author(s):  
R. B. Partridge
Keyword(s):  
Radio Emission ◽  
Large Array ◽  
Microwave Background ◽  
Very Large Array ◽  
Cosmic Background ◽  
Upper Limits ◽  
Great Progress ◽  
Sunyaev Zel'dovich Effect ◽  
Made In

This paper reviews the great progress recently made in searches for and the characterization of anisotropies in the cosmic microwave background. We now have secure detections on some angular scales and improved upper limits on others. As the sensitivity of such searches increases, understanding sources of foreground noise (e.g., Galactic and extragalactic radio emission) becomes more important. Also reviewed are the contributions aperture synthesis (interferometric) observations can make in characterizing cosmic background fluctuations and foreground sources of noise. Some recent results from the Very Large Array at λ = 3.6 cm are given; these set a limit δT/T ≲ 1.4 × 10−5on fluctuations at θ ~ 80′. Recent work on the Sunyaev-Zel'dovich effect is summarized.

Bipolar outflow of gas in the spiral galaxy NGC 3079

1986 ◽  
Vol 64 (4) ◽  
pp. 531-535 ◽  
Author(s):  
Nebojsa Duric ◽  
E. R. Seaquist
Keyword(s):  
Spectral Index ◽  
Spiral Galaxy ◽  
Central Region ◽  
Qualitative Description ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Bipolar Outflow ◽  
The Galaxy

Very large array, radio-continuum observations of the edge-on spiral galaxy NGC 3079 are presented. The observations reveal that the nucleus has windlike properties and that the central region of the galaxy exhibits an unusual figure-eight morphology that shows evidence of severe depolarization and a flattening spectral index away from the nucleus. A qualitative description of a model is presented to account for the observed radio properties. It is shown that a wind-driven shock propagating away from the nucleus and focused by the ambient disk gas can give rise to the observed morphology.

scholarly journals Low frequency (74 MHz) radio continuum observations of the inner 13° × 7° of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 464-466
Author(s):  
M. Rickert ◽  
F. Yusef-Zadeh ◽  
C. Brogan
Keyword(s):  
High Resolution ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Galactic Center ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Array ◽  
Very Large Array ◽  
Image Displays ◽  
Western Side

AbstractWe analyze a high resolution (114″ × 60″) 74 MHz image of the Galactic center taken with the Very Large Array (VLA). We have identified several absorption and emission features in this region, and we discuss preliminary results of two Galactic center sources: the Sgr D complex (G1.1–0.1) and the Galactic center lobe (GCL).The 74 MHz image displays the thermal and nonthermal components of Sgr D and we argue the Sgr D supernova remnant (SNR) is consistent with an interaction with a nearby molecular cloud and the location of the Sgr D Hii region on the near side of the Galactic center. The image also suggests that the emission from the eastern side of the GCL contains a mixture of both thermal and nonthermal sources, whereas the western side is primarily thermal.

scholarly journals The relation between the diffuse X-ray luminosity and the radio power of the central AGN in galaxy groups

2020 ◽  
Vol 497 (2) ◽  
pp. 2163-2174
Author(s):  
T Pasini ◽  
M Brüggen ◽  
F de Gasperin ◽  
L Bîrzan ◽  
E O’Sullivan ◽  
...  
Keyword(s):  
Radio Emission ◽  
Galaxy Clusters ◽  
Active Galactic Nucleus ◽  
Statistical Tests ◽  
Control Sample ◽  
Radio Galaxies ◽  
Very Large Array ◽  
X Ray ◽  
Galaxy Groups ◽  
Hydrodynamical Simulations

ABSTRACT Our understanding of how active galactic nucleus feedback operates in galaxy clusters has improved in recent years owing to large efforts in multiwavelength observations and hydrodynamical simulations. However, it is much less clear how feedback operates in galaxy groups, which have shallower gravitational potentials. In this work, using very deep Very Large Array and new MeerKAT observations from the MIGHTEE survey, we compiled a sample of 247 X-ray selected galaxy groups detected in the COSMOS field. We have studied the relation between the X-ray emission of the intra-group medium and the 1.4 GHz radio emission of the central radio galaxy. For comparison, we have also built a control sample of 142 galaxy clusters using ROSAT and NVSS data. We find that clusters and groups follow the same correlation between X-ray and radio emission. Large radio galaxies hosted in the centres of groups and merging clusters increase the scatter of the distribution. Using statistical tests and Monte Carlo simulations, we show that the correlation is not dominated by biases or selection effects. We also find that galaxy groups are more likely than clusters to host large radio galaxies, perhaps owing to the lower ambient gas density or a more efficient accretion mode. In these groups, radiative cooling of the intra-cluster medium could be less suppressed by active galactic nucleus heating. We conclude that the feedback processes that operate in galaxy clusters are also effective in groups.

scholarly journals Radio morphology of southern narrow-line Seyfert 1 galaxies with Very Large Array observations*

2020 ◽  
Vol 498 (1) ◽  
pp. 1278-1297
Author(s):  
S Chen ◽  
E Järvelä ◽  
L Crepaldi ◽  
M Zhou ◽  
S Ciroi ◽  
...  
Keyword(s):  
Star Formation ◽  
Radio Emission ◽  
Large Mass ◽  
Large Array ◽  
Narrow Line ◽  
Diffuse Emission ◽  
Jets And Outflows ◽  
Very Large Array ◽  
Radio Jets ◽  
New Radio

ABSTRACT We present the results of new radio observations carried out with the Karl G. Jansky Very Large Array C-configuration at 5.5 GHz for a sample of southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases the number of known radio-detected NLS1s in the Southern hemisphere, and confirms that the radio emission of NLS1s is mainly concentrated in a central region at kpc-scale and only a few sources show diffuse emission. In radio-quiet NLS1s, the radio luminosity tends to be higher in steep-spectrum sources and be lower in flat-spectrum sources, which is opposite to radio-loud NLS1s. This may be because the radio emission of steep NLS1s is dominated by misaligned jets, active galactic nucleus driven outflows, or star formation superposing on a compact core. Instead the radio emission of flat NLS1s may be produced by a central core that has not yet developed radio jets and outflows. We discover new NLS1s harbouring kpc-scale radio jets and confirm that a powerful jet does not require a large-mass black hole to be generated. We also find sources dominated by star formation. These NLS1s could be new candidates in investigating the radio emission of different mechanisms.

scholarly journals VLA and ALMA observations of the lensed radio-quiet quasar SDSS J0924+0219: a molecular structure in a 3 μJy radio source

2020 ◽  
Vol 496 (1) ◽  
pp. 138-151 ◽  
Author(s):  
Shruti Badole ◽  
Neal Jackson ◽  
Philippa Hartley ◽  
Dominique Sluse ◽  
Hannah Stacey ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Ratio ◽  
Radio Continuum ◽  
Mass Model ◽  
Extended Source ◽  
Very Large Array ◽  
Optical Continuum ◽  
Ordered Motion ◽  
Optical Flux ◽  
Marginal Detection

ABSTRACT We present Karl G. Jansky Very Large Array (VLA) and Atacama Large Millimetre Array (ALMA) observations of SDSS J0924+0219, a z = 1.524 radio-quiet lensed quasar with an intrinsic radio flux density of about 3 $\, \mu$Jy. The four lensed images are clearly detected in the radio continuum and the CO(5–4) line, whose centroid is at z = 1.5254 ± 0.0001, with a marginal detection in the submillimetre continuum. The molecular gas displays ordered motion, in a structure approximately 1–2.5 kpc in physical extent, with typical velocities of 50–100 km s−1. Our results are consistent with the radio emission being emitted from the same region, but not with a point source of radio emission. SDSS J0924+0219 shows an extreme anomaly in the flux ratios of the two merging images in the optical continuum and broad emission lines, suggesting the influence of microlensing by stars in the lensing galaxy. We find the flux ratio in the radio, submillimetre continuum and CO lines to be slightly greater than 1 but much less than that in the optical, which can be reproduced with a smooth galaxy mass model and an extended source. Our results, supported by a microlensing simulation, suggest that the most likely explanation for the optical flux anomaly is indeed microlensing.

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