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In this paper we investigate the X-ray spectra and X-ray spectral variability of compact X-ray sources for 3 Chandra observations of the Local Group galaxy M33. The observations are centered on the nucleus and the star forming region NGC…

Astrophysics · Physics 2009-11-13 H. -J. Grimm , J. McDowell , A. Zezas , D. -W. Kim , G. Fabbiano

We present near-infrared long-slit spectra of eight optically-dim X-ray sources obtained with ISAAC on the Very Large Telescope. Six of the sources have hard X-ray emission with a significant fraction of the counts emerging above 2 keV. All…

Astrophysics · Physics 2009-09-17 P. Gandhi , C. S. Crawford , A. C. Fabian

We present the data and analysis of VLBI observations at 1.6, 5 and 15 GHz of a sample of faint Gigahertz Peaked Spectrum (GPS) sources selected from the Westerbork Northern Sky Survey (WENSS). The 5 GHz observations involved a global array…

Astrophysics · Physics 2016-08-30 Ignas Snellen , Richard Schilizzi , Huib-Jan van Langevelde

In this Paper we present the source catalog obtained from a 942 ks exposure of the Chandra Deep Field South (CDFS), using ACIS-I on the Chandra X-ray Observatory. Catalog generation proceeded simultaneously using two different methods; a…

We observed with the VLBA at 2.3 and 8.6 GHz a complete flux-density limited sample of 482 radio sources with declination >+75 degrees brighter than 200 mJy at 1.4 GHz drawn from the NVSS catalog. 34% of the sources show parsec-scale…

Astrophysics of Galaxies · Physics 2021-02-01 Alexander V. Popkov , Yuri Y. Kovalev , Leonid Y. Petrov , Yuri A. Kovalev

The Very Small Array (VSA) has been used to survey the l = 27 to 46 deg, |b|<4 deg region of the Galactic plane at a resolution of 13 arcmin. The survey consists of 44 pointings of the VSA, each with a r.m.s. sensitivity of ~90 mJy/beam.…

The first results from the Tenth Cambridge (10C) Survey of Radio Sources, carried out using the AMI Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of approximately 27 sq. degrees to a…

We present a spectroscopic study of 41 hard X-ray sources detected serendipitously with high significance (> 5 sigma in the 2-10 keV band) in seven EPIC performance/verification phase observations. The large collecting area of EPIC allows…

Astrophysics · Physics 2009-11-07 E. Piconcelli , M. Cappi , L. Bassani , F. Fiore , G. DiCocco , J. B. Stephen

We have detected 18 sources over 6 sigma threshold within two regions 8.3X16.9 arcmin^2 and 8.3X33.6 arcmin^2 in the vicinity of the point with alpha=03h31m02.45s (J2000) and delta=+43degree47arcmin58.5arcsec (J2000) using a CHANDRA ACIS…

Astrophysics · Physics 2009-11-07 A. Kupcu Yoldas , S. Balman

We review the effects of source size in interferometric observations and focus on the cases of very compact sources. If a source is extremely compact and/or weak (so it is not possible to detect signature of source structure in the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 I. Marti-Vidal , M. A. Perez-Torres , A. P. Lobanov

We discuss the X-ray properties of the radio sources detected in a deep 1.4 and 5 GHz VLA Radio survey of the Extended Chandra Deep Field South (E-CDFS). Among the 266 radio sources detected, we find 89 sources (1/3 of the total) with X-ray…

We show the results of the fluctuation analysis applied to the off-source areas from the two 1 Million second Chandra Deep Fields, including our new results on the Chandra Deep Field-South (CDF-S) in the 0.5-2 keV band in addition to those…

Astrophysics · Physics 2007-05-23 Takamitsu Miyaji , Richard E. Griffiths

Radio source counts constrain galaxy populations and evolution, as well as the global star formation history. However, there is considerable disagreement among the published 1.4-GHz source counts below 100 microJy. Here we present a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 T. Vernstrom , Douglas Scott , J. V. Wall , J. J. Condon , W. D. Cotton , E. B. Fomalont , K. I. Kellermann , N. Miller , R. A. Perley

Foreground radio sources are a major contaminant for centimetre-wave cosmic microwave background (CMB) measurements and the 9C survey was set up as part of the observing strategy of the CMB telescope, the Very Small Array. Prior to this…

Astrophysics · Physics 2007-05-23 E. M. Waldram , G. G. Pooley

We have used VLBA fringe visibility data obtained at 15 GHz to examine the compact structure in 250 extragalactic radio sources. For 171 sources in our sample, more than half of the total flux density seen by the VLBA remains unresolved on…

We started a follow-up investigation of the Deep X-ray Radio Blazar Survey objects with declination >-10 deg. We undertook a survey with the EVN at 5GHz to make the first images of a complete sample of weak blazars, aiming at a comparison…

Astrophysics of Galaxies · Physics 2015-04-29 F. Mantovani , M. Bondi , K. -H. Mack , W. Alef , E. Ros , J. A. Zensus

In order to determine the relationship between the faint X-ray and faint radio source populations, and hence to help understand the X-ray and radio emission mechanisms in those faint source populations, we have made a deep 1.4GHz Very Large…

Astrophysics · Physics 2009-11-10 N. Seymour , I. M. McHardy , K. F. Gunn

Aims - We report new Very Large Array polarimetric observations of Compact Steep-Spectrum (CSS) sources at 8.4, 15, and 23GHz. Methods - Using multi-frequency VLA observations we have derived sub-arcsecond resolution images of the total…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 F. Mantovani , A. Rossetti , W. Junor , D. J. Saikia , C. J. Salter

We present a source catalogue and first results from a deep, blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array, with follow-up observations at 5.5, 9 and 18 GHz. The Australia Telescope 20 GHz (AT20G) deep…

Astrophysics of Galaxies · Physics 2014-06-19 T. M. O. Franzen , E. M. Sadler , R. Chhetri , R. D. Ekers , E. K. Mahony , T. Murphy , R. P. Norris , E. M. Waldram , I. H Whittam

We present results from a large 86GHz global VLBI survey of compact radio sources. The main goal of the survey is to increase by factors of 3--5 the total number of objects accessible for future 3-mm VLBI imaging. The survey observations…