Rapid variability of extragalactic radio sources

Heeschen, D. S.; Krichbaum, T. P.; Schalinski, C. J.; Witzel, A.

doi:10.1086/114583

Cited by 159 publications

(161 citation statements)

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“…Extrinsic mechanisms include interstellar scintillation causing radio variations (e.g. Heeschen et al 1987) at low frequencies and can therefore not be the case of optical intra-night optical variability (INOV). Small variations can be explained by turbulence behind an outgoing shock along the jet.…”

Section: Discussionmentioning

confidence: 99%

Multiband optical variability studies of BL Lacertae

Agarwal¹,

Gupta²

2015

Monthly Notices of the Royal Astronomical Society

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We monitored BL Lacertae for 13 nights in optical B, V, R, and I bands during October and November 2014 including quasi-simultaneous observations in V and R bands using two optical telescopes in India. We have studied multi-band optical flux variations, colour variation and spectral changes in this blazar. Source was found to be active during the whole monitoring period and showed significant intraday variability on 3 nights in V and R filters while displayed hints of variability on 6 other dates in R passband and on 2 nights in V filter. From the colour-magnitude analysis of the source we found that the spectra of the target gets flatter as it becomes brighter on intra-night timescale. Using discrete correlation technique, we found that intraday light curves in both V and R filters are almost consistent and well correlated with each other. We also generated spectral energy distribution (SED) of the target using the B, V, R, and I data sets for all 13 nights which could help us investigate the physical process responsible for the observed variations in BL Lacertae objects. We also discuss possible physical causes of the observed spectral variability.

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Section: Discussionmentioning

confidence: 99%

Multiband optical variability studies of BL Lacertae

Agarwal¹,

Gupta²

2015

Monthly Notices of the Royal Astronomical Society

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“…Thus C is most likely the core. (Heeschen et al, 1987), in which S is the mean and σ is the standard deviation. That gives u = 25.1% (15 GHz), 25.9% (8.4 GHz) and 30.6% (2.3 GHz).…”

Section: Cso Identification Of 2234+282mentioning

confidence: 99%

Radio properties of the γ ‐ray emitting CSO candidate 2234+282

Cui

Gabányi

et al. 2016

Astron Nachr

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Most of the γ-ray emitting active galactic nuclei (AGN) are blazars, although there is still a small fraction of non-blazar AGN in the Fermi/LAT catalog. Among these misaligned γ-ray-emitting AGN, a few can be classified as Compact Symmetric Objects (CSOs). In contrast to blazars in which γ-ray emission is generally thought to originate from highly beamed relativistic jets, the source of γ-ray emission in unbeamed CSOs remains an open question. The rarity of the γ-ray emitting CSOs is a mystery as well. Here we present the radio properties of the γ-ray CSO candidate 2234+282.

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“…After the discovery of rapid flux density variations in the radio regime (Witzel et al 1986, Heeschen et al 1987, it turned out that IDV is seen in a significant portion of compact flat-spectrum radio sources. Statistical investigations showed that IDV occurs only in sources which are compact on VLBI (mas-) scales, but no dependence on either the optical identification, the redshift, or the galactic latitude was found (Quirrenbach et al 1992).…”

Section: Observationsmentioning

confidence: 99%