Intraday variability of three flat-spectrum radio sources

2009 ◽  
Vol 53 (5) ◽  
pp. 389-400 ◽  
Author(s):  
A. G. Gorshkov ◽  
A. V. Ipatov ◽  
I. A. Ipatova ◽  
V. K. Konnikova ◽  
V. V. Mardyshkin ◽  
...  
Keyword(s):  
Radio Sources ◽  
Spectrum Radio ◽  
Intraday Variability

scholarly journals Multifrequency Polarization Variations in 0917+624

2001 ◽  
Vol 182 ◽  
pp. 119-122
Author(s):  
S.J. Qian ◽  
A. Kraus ◽  
T.P. Krichbaum ◽  
A. Witzel ◽  
J.A. Zensus
Keyword(s):  
Radio Sources ◽  
Apparent Brightness ◽  
Brightness Temperatures ◽  
Interstellar Scintillation ◽  
Spectrum Radio ◽  
Bl Lac ◽  
Show Evidence ◽  
Intraday Variability

AbstractIntraday variability in compact flat-spectrum radio sources has been intensively studied in recent years. For most IDV events the apparent brightness temperatures derived from the observed timescales are in the range of Tb,app ~ 1016−18 K. For extremely rapid variations, Tb,app can reach up to ~ 1021 K (e.g. Kedziora-Chudczer et al., 1997). Refractive interstellar scintillation may be the most likely extrinsic mechanism (Rickett et al., 1995; Qian, 1994a; Qian, 1994b). Especially for the case of extreme Tb,app (> 1018 K) RISS may be dominant (Dennet-Thorpe and de Bruyn, 2000). However, some IDV events with Tapp ~ 1017−18 K show evidence for an intrinsic origin e.g. the correlated radio-optical intraday variations observed in the BL Lac object 0716+714 (Wagner and Witzel, 1995, Qian et al, 1996). It seems important to distinguish between IDV which is a phenomenon intrinsic to the compact radio sources and IDV which is primarily due to RISS. Multifrequency polarization and VLB I observations would be most helpful (Gabuzda and Kochanev, 1997).

Intraday Variability of Flat-Spectrum Radio Sources

1998 ◽  
Vol 164 ◽  
pp. 257-264
Author(s):  
S. J. Wagner
Keyword(s):  
High Frequency ◽  
Large Fraction ◽  
Small Scale ◽  
Electromagnetic Spectrum ◽  
Radio Sources ◽  
Rapid Variability ◽  
Spectrum Radio ◽  
Interstellar Scattering ◽  
Polarization Characteristics ◽  
Intraday Variability

AbstractThe characteristics of rapid variability of flat-spectrum radio sources are reviewed. A large fraction of the blazar population is found to show variability on timescales shorter than one day throughout the entire electromagnetic spectrum. The spectral indices and polarization characteristics change equally fast.Structure functions of the well-monitored sources show pronounced breaks on scales of about 10 to 50 hours, with flatter slopes towards the fast end. This illustrates that Intraday Variability (IDV), i.e. the high frequency end of the power spectrum is qualitatively different and requires different mechanisms than slower variations.While intrinsic IDV provides direct clues on small-scale structure over fifteen decades in frequency, extrinsic contributions from interstellar scattering contributes at the lowest frequencies, and remains difficult to disentangle from the intrinsic effects.

CTD 93 and the Nature of Gigahertz Peaked Spectrum Radio Sources

1999 ◽  
Vol 515 (2) ◽  
pp. 558-566 ◽  
Author(s):  
David B. Shaffer ◽  
K. I. Kellermann ◽  
T. J. Cornwell
Keyword(s):  
Radio Sources ◽  
Spectrum Radio

scholarly journals Bulk Relativistic Motion in a Complete Sample of Radio Selected AGN

1987 ◽  
Vol 121 ◽  
pp. 287-293
Author(s):  
C.J. Schalinski ◽  
P. Biermann ◽  
A. Eckart ◽  
K.J. Johnston ◽  
T.Ph. Krichbaum ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Radio Sources ◽  
Relativistic Motion ◽  
Complete Sample ◽  
Superluminal Motion ◽  
Spectrum Radio ◽  
Wide Range ◽  
Show Evidence

A complete sample of 13 flat spectrum radio sources is investigated over a wide range of frequencies and spatial resolutions. SSC-calculations lead to the prediction of bulk relativistic motion in all sources. So far 6 out of 7 sources observed with sufficient dynamic range by means of VLBI show evidence for apparent superluminal motion.

scholarly journals Optical and Near-Infrared Imaging of Ultra–Steep-Spectrum Radio Sources: The [ITAL]K[/ITAL]-[CLC][ITAL]z[/ITAL][/CLC] Diagram of Radio-selected and Optically Selected Galaxies

2002 ◽  
Vol 123 (2) ◽  
pp. 637-677 ◽  
Author(s):  
Carlos De Breuck ◽  
Wil van Breugel ◽  
S. A. Stanford ◽  
Huub Röttgering ◽  
George Miley ◽  
...  
Keyword(s):  
Near Infrared ◽  
Infrared Imaging ◽  
Radio Sources ◽  
Near Infrared Imaging ◽  
Spectrum Radio

scholarly journals Spatially resolved studies of extragalactic jets in high redshift radio galaxies

2014 ◽  
Vol 10 (S313) ◽  
pp. 231-235
Author(s):  
Leah K. Morabito ◽  
Adam Deller ◽  
J. B. R. Oonk ◽  
Huub Röttgering ◽  
George Miley
Keyword(s):  
High Redshift ◽  
Low Frequency ◽  
Radio Galaxies ◽  
Radio Sources ◽  
Spatially Resolved ◽  
Long Baseline ◽  
Early Results ◽  
Spectrum Radio ◽  
Extragalactic Jets ◽  
Frequency Survey

AbstractThe correlation between radio spectral steepness and redshift has been successfully used to find high redshift (z ⩾ 2) radio galaxies, but the origin of this relation is unknown. The ultra-steep spectra of high-z radio sources make them ideally suited for studies with the Low Band Antenna of the new Low Frequency Array, which covers 10–80 MHz and has baselines up to about 1300 km. As part of an ongoing survey, we use the longest baselines to map the low-frequency (< 70 MHz) spatial distributions along the jets of 5 bright extended steep spectrum high-z radio sources. From this, we will determine whether the spectra change over these spatially resolved sources, thereby constraining particle acceleration processes. We present early results from our low-frequency survey of ultra-steep spectrum radio galaxies. The first low frequency long baseline images of these objects are presented.

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