Very High Energy Gamma-Ray Emission from the Blazar Markarian 421

Schubnell, M.; Akerlof, C.; Biller, S. D.; Buckley, J.; Carter‐Lewis, D. A.; Cawley, M. F.; Chantell, M.; Connaughton, V.; Fegan, D. J.; Fennell, S.; Gaidos, J. A.; Hillas, A. M.; Kerrick, A. D.; Lamb, R. C.; Meyer, D. I.; Mohanty, G.; Rose, J.; Rovero, A. C.; Sembroski, G. H.; Weekes, T. C.; Wilson, C.; Zweerink, J.

doi:10.1086/176998

Cited by 44 publications

(22 citation statements)

References 20 publications

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“…Publicly available lightcurve data from 1992 until today were collected from the Whipple (Kerrick et al 1995;Schubnell et al 1996;Buckley et al 1996;Maraschi et al 1999a), HEGRA (Aharonian et al 1999b,a;Krawczynski et al 2001b;Aharonian et al 2001Aharonian et al , 2002Aharonian et al , 2003Aharonian et al , 2004Kestel 2002), CAT (Piron 2000;Piron et al 2001), HESS (Aharonian et al 2005(Aharonian et al , 2006, MAGIC (Albert et al 2008a;Donnarumma et al 2009), and VERITAS (Rebillot et al 2006;Donnarumma et al 2009) experiments. We are also working on collecting more data from these and other experiments such as the Crimean GT-48 Cherenkov telescope (e.g.…”

Section: Lightcurve Datamentioning

confidence: 99%

Long-term lightcurves from combined unified very high energyγ-ray data

Tluczykont

Bernardini²,

Satalecka³

et al. 2010

A&A

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Context. Very high-energy (VHE, E > 100 GeV) γ-ray data are a valuable input for multi-wavelength and multi-messenger (e.g. combination with neutrino data) studies. Aims. We aim at the conservation and homogenization of historical, current, and future VHE γ-ray-data on active galactic nuclei (AGN). Methods. We have collected lightcurve data taken by major VHE experiments since 1991 and combined them into long-term lightcurves for several AGN, and now provide our collected datasets for further use. Due to the lack of common data formats in VHE γ-ray astronomy, we have defined relevant datafields to be stored in standard data formats. The time variability of the combined VHE lightcurve data was investigated, and correlation with archival X-ray data collected by RXTE/ASM tested.Results. The combination of data on the prominent blazar Mrk 421 from different experiments yields a lightcurve spanning more than a decade. From this combined dataset we derive an integral baseline flux from Mrk 421 that must be lower than 33% of the Crab Nebula flux above 1 TeV. The analysis of the time variability yields log-normal flux variations in the VHE-data on Mrk 421. Conclusions. Existing VHE data contain valuable information concerning the variability of AGN and can be an important ingredient for multi-wavelength or multi-messenger studies. In the future, upcoming and planned experiments will provide more data from many transient objects, and the interaction of VHE astronomy with classical astronomy will intensify. In this context a unified and exchangeable data format will become increasingly important.

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Section: Lightcurve Datamentioning

confidence: 99%

Long-term lightcurves from combined unified very high energyγ-ray data

Tluczykont

Bernardini²,

Satalecka³

et al. 2010

A&A

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“…Two sources from the B2 sample which were not included by Parma et al (1987) are particularly important to the present analysis: 1101+38 (Markarian 421) and 1652+39 (Markarian 501). These are both classified as BL Lac objects, have very bright radio cores and show blazar characteristics from radio to high‐energy γ‐ray wavebands (Quinn et al 1996; Schubnell et al 1996). They are thought to be examples of the (rare) class of end‐on sources, and their extreme core and jet properties set important constraints on the parameters of relativistic jet models.…”

Section: Data and Observational Parametersmentioning

confidence: 99%

Asymmetries in the jets of weak radio galaxies

Laing

Parma

Ruiter

et al. 1999

Monthly Notices of the Royal Astronomical Society

121

175

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We describe a study of the side‐to‐side asymmetries on kpc scales in the jets of FR I radio galaxies selected from the B2 sample. The basic data are jet surface brightnesses and widths determined by fitting transverse profiles to Very Large Array (VLA) images at a range of distances from the core. Differences between the jets at a given distance from the nucleus are interpreted as effects of Doppler beaming on intrinsically symmetrical flows and are compared with the model derived for 3C31 by Laing & Bridle and with simpler variants. The jet/counterjet brightness ratios where the main jet first brightens are correlated with core prominence, as expected for a relativistic flow. From the distribution of brightness ratios, we infer that jets have a maximum velocity ≈0.9c where they first flare and brighten, but there is also evidence for additional slower material. Deceleration to subrelativistic speeds occurs on scales which increase with radio power. Jets in the majority of sources with luminosities <1024 WHz‐1 at 1.4 GHz become essentially symmetrical (and therefore subrelativistic) within 2 kpc of the core. In more powerful sources, jets that flare within the first 2 kpc become symmetrical by 10 kpc, but a subset of the most luminous objects has jets which remain asymmetrical to larger distances. The point at which the brighter jet flares appears to correspond to a sudden increase in rest‐frame emissivity, but the ratio of distances to the flaring point in main and counterjets is anticorrelated with brightness ratio, as expected for a decelerating relativistic flow. Brightness and full width at half‐maximum (FWHM) ratios are also anticorrelated, an effect which we interpret as a result of Doppler beaming for a flow in which the velocity decreases radially outwards from the jet axis. Jet deceleration by entrainment of external material provides a natural explanation for these velocity gradients. The jet energy flux is roughly consistent with energy supply to the lobes over a source lifetime estimated from spectral index measurements. Our results are qualitatively consistent with unified models of FR I radio galaxies and BL Lac objects, but require some modifications to the standard picture.

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“…Schubnell et al 1996;Petry et al 1996). Our data and analysis of the optical behaviour of Mrk 421 are presented by Tosti et al (1998a) and hence only the light curve is shown (Fig.…”

Section: Mrk 421mentioning

confidence: 99%

Tuorla quasar monitoring

Katajainen

Takalo

Sillanpää

et al. 2000

Astron. Astrophys. Suppl. Ser.

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Abstract. We present results of optical monitoring of quasars and blazars obtained at Tuorla Observatory between September 1995 and May 1997. The aim of our monitoring is to provide well sampled optical light curves for quasar and blazar studies. During the observing period the V -band brightness of S2 0109+224, 3C 66A, and ON 231 (W Comae) reached some of the brightest values ever measured for these objects. A strong outburst was observed in Mrk 421 and the large outburst, which was predicted earlier, in OJ 287 was confirmed. CTA 102 had over one magnitude outburst which happened in a timescale of a few days. For OI 090.4 we measured one of the faintest V -band brightness values ever.

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Very High Energy Gamma-Ray Emission from the Blazar Markarian 421

Cited by 44 publications

References 20 publications

Long-term lightcurves from combined unified very high energyγ-ray data

Long-term lightcurves from combined unified very high energyγ-ray data

Asymmetries in the jets of weak radio galaxies

Tuorla quasar monitoring

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