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Detailed investigation of broadband flux variability in the blazar 3C 273 allows us to probe the location and size of emission regions and their physical conditions. We report the results on correlation studies of the flaring activity…

Starting from December 2004, a program for the monitoring of intraday variable sources at a frequency of 5 GHz was performed at the Urumqi Observatory. The analysis of the variability characteristics of the flat-spectrum radio source AO…

Solar and Stellar Astrophysics · Physics 2015-05-27 N. Marchili , T. P. Krichbaum , X. Liu , H. -G. Song , J. M. Anderson , A. Witzel , J. A. Zensus

We use the Expanded Very Large Array to image radio continuum emission from local luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in 1 GHz windows centered at 4.7, 7.2, 29, and 36 GHz. This allows us to probe the integrated…

This paper contains an analysis of short Chandra observations of 19 3C sources with redshifts between 0.3 and 0.5 not previously observed in the X-rays. This sample is part of a project to obtain Chandra data for all of the extragalactic…

High Energy Astrophysical Phenomena · Physics 2015-06-15 F. Massaro , D. E. Harris , G. Tremblay , E. Liuzzo , A. Bonafede , A. Paggi

We have shown previously that a broad correlation between the peak radio luminosity and the variability time-scales, approximately L ~ t^5, exists for variable synchrotron emitting sources and that different classes of astrophysical source…

High Energy Astrophysical Phenomena · Physics 2017-08-30 M. Pietka , T. D. Staley , M. L. Pretorius , R. P. Fender

A 3-dimensional model of the synchrotron emissivity of the cocoons of powerful extragalactic radio sources of type FRII is constructed. Bulk backflow and energy losses of the relativistic electrons, radiative and adiabatic, are…

Astrophysics · Physics 2007-05-23 Christian R. Kaiser

We present parameterized broadband spectral models valid at frequencies between 30-300 MHz for six bright radio sources selected from the 3C survey, spread in Right Ascension from 0-24 hours. For each source, data from the literature are…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 Anna M. M. Scaife , George H. Heald

The goal of this work is to constrain the strength and structure of the magnetic field associated with the environment of the radio source 3C 449, using observations of Faraday rotation, which we model with a structure function technique…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 D. Guidetti , R. A. Laing , M. Murgia , F. Govoni , L. Gregorini , P. Parma

We analyze the light curves of 413 radio sources at submillimeter wavelengths using data from the Submillimeter Array calibrator database. The database includes more than 20,000 observations at 1.3 and 0.8 mm that span 13 years. We model…

High Energy Astrophysical Phenomena · Physics 2015-09-23 Geoffrey C. Bower , Jason Dexter , Sera Markoff , Mark A. Gurwell , Ramprasad Rao , Ian McHardy

Refraction and diffraction of incoming radio waves by the ionosphere induce time variability in the angular positions, peak amplitudes and shapes of radio sources, potentially complicating the automated cross-matching and identification of…

We have characterized the energy-dependent X-ray variability properties of the Seyfert~1 galaxy NGC 3783 using archival XMM-Newton and Rossi X-ray Timing Explorer data. The high-frequency fluctuation power spectral density function (PSD)…

Astrophysics · Physics 2009-11-13 A. Markowitz

In the paper, we investigate correlation between broad-line and radio variations for broad-line radio galaxy 3C 120. By the z-transformed discrete correlation function method and the model-independent flux randomization/random subset…

High Energy Astrophysical Phenomena · Physics 2014-01-10 H. T. Liu , J. M. Bai , J. M. Wang , S. K Li

Models of radio galaxy physics have been primarily based on high frequency ($\geqslant$1 GHz) observations of their jets, hotspots, and lobes. Without highly resolved low frequency observations, which provide information on older plasma,…

Astrophysics of Galaxies · Physics 2023-02-15 V. H. Mahatma , A. Basu , M. J. Hardcastle , L. K. Morabito , R. J. van Weeren

We report on the very first radio detection associated with the peculiar hourglass-morphology X-rays surrounding 3C 294 at z=1.8. Using International Low Frequency Array (LOFAR) data at 144 MHz and Chandra data at 0.3-6 keV, we find that…

Astrophysics of Galaxies · Physics 2025-12-19 Vijay H. Mahatma , Andrew C. Fabian , Leah K. Morabito

We report a search for linear polarization in the active galactic nucleus (AGN) 3C 84 (NGC 1275) at observed frequencies of 239 GHz and 348 GHz, corresponding to rest-frame frequencies of 243 GHz and 354 GHz. We collected polarization data…

Astrophysics of Galaxies · Physics 2015-06-05 S. Trippe , M. Bremer , T. P. Krichbaum , M. Krips , R. Neri , V. Pietu , J. M. Winters

Variability of a galaxy's core radio source can be a significant consequence of AGN accretion. However, this variability has not been well studied, particularly at high radio frequencies. As such, we report on a campaign monitoring the high…

Deep long-slit spectroscopic data are presented for a sample of 14 3CR radio galaxies at redshift z ~ 1, previously studied in detail using the Hubble Space Telescope, the Very Large Array, and UKIRT. Analysis of the [OII] 3727 emission…

Astrophysics · Physics 2009-10-31 P. N. Best , H. J. A. R"ottgering , M. S. Longair

Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac…

High Energy Astrophysical Phenomena · Physics 2021-08-23 Xiang Liu , Xin Wang , Ning Chang , Jun Liu , Lang Cui , Xiaofeng Yang , Thomas P. Krichbaum

A Suzaku observation of a giant radio galaxy, 3C 326, which has a physical size of about 2 Mpc, was conducted on 2008 January 19 -- 21. In addition to several X-ray sources, diffuse emission was significantly detected associated with its…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Naoki Isobe , Makoto S. Tashiro , Poshak Gandhi , Asami Hayato , Hiroshi Nagai , Kazuhiro Hada , Hiromi Seta , Keiko Matsuta

We search for variable sources, using the data of the surveys conducted on the RATAN-600 radio telescope in 1980-1994 at 3.94 GHz. To test the radio sources of the RCR (RATAN Cold Refined) catalog for variability, we estimated the long-term…

Astrophysics of Galaxies · Physics 2014-09-15 E. K. Majorova , O. P. Zelenkova