Detection of the BL Lacertae Object H1426+428 at TeV Gamma‐Ray Energies

Horan, D.; Badran, H. M.; Bond, I. H.; Bradbury, S. M.; Buckley, J. H.; Carson, M.; Carter‐Lewis, D. A.; Catanese, M.; Cui, Wei; Dunlea, S.; Das, D.; Pérez, I. de la Calle; D'Vali, M.; Fegan, D. J.; Fegan, S. J.; Finley, J. P.; Gaidos, J. A.; Gibbs, K.; Gillanders, G. H.; Hall, T. A.; Hillas, A. M.; Holder, J.; Jordan, M.; Kertzman, M.; Kieda, D.; Kildea, J.; Knapp, J.; Kosack, K.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Lessard, R. W.; Lloyd‐Evans, J.; McKernan, Barry; Moriarty, P.; Müller, D.; Ong, R. A.; Pallassini, R.; Petry, D.; Quinn, J.; Reay, N. W.; Reynolds, P. T.; Rose, H. J.; Sembroski, G. H.; Sidwell, R. A.; Stanton, N. R.; Swordy, S. P.; Vassiliev, V. V.; Wakely, S. P.; Weekes, T. C.

doi:10.1086/340019

Cited by 89 publications

(57 citation statements)

References 32 publications

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“…Detections in the TeV energy regime from this object have been reported by the Whipple collaboration (Horan et al 2002) the HEGRA collaboration (Aharonian et al 2002b) and the CAT collaboration 7.5 σ level (Aharonian et al 2003a), consistent with the analysis presented here (6.6 σ). 1ES 2344+514 was one of the first BL Lac type objects to be reported as an extreme synchrotron blazar with synchrotron peak energy reaching up to 100 keV (Giommi et al 2000).…”

Section: Resultssupporting

confidence: 88%

Observations of 54 Active Galactic Nuclei with the HEGRA system of Cherenkov telescopes

Aharonian¹,

Akhperjanian²,

Beilicke³

et al. 2004

A&A

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Abstract.A sample of 54 selected Active Galactic Nuclei (AGN) has been observed with the HEGRA stereoscopic system of Cherenkov Telescopes between 1996 and 2002 in the TeV energy regime. The observations were motivated by the positive results obtained for Mkn 421 and Mkn 501. The distances of the selected objects vary over a large range of redshifts between z = 0.004 and z = 0.7. Among the observed AGN are the now-established TeV-emitting BL Lac type objects H 1426+428 and 1ES 1959+650. Furthermore the BL Lac object 1ES 2344+514 and the radio galaxy M 87 show evidence for a signal on a 4 σ level. The observation of 1ES 2344+514 together with the Whipple results firmly establishes this AGN as a TeV source. Several objects (PKS 2155-304, BL Lacertae, 3C 066A) that have been claimed as TeV γ-ray emitters by other groups are included in this data sample but could not be confirmed using data analysed here. The upper limits from several AGN included in this analysis are compared with predictions in the frame-work of SSC models.

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Section: Resultssupporting

confidence: 88%

Observations of 54 Active Galactic Nuclei with the HEGRA system of Cherenkov telescopes

Aharonian¹,

Akhperjanian²,

Beilicke³

et al. 2004

A&A

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“…In this region there are two sources already detected by LAT, RBS 0723 and 1ES 1426+428. The latter is already a well established TeV source (Horan et al 2002). Although its SED is coherent with our picture, it can be considered a transition object towards the "bright X-ray"-"bright radio" corner of the plot, populated by the bright blazars of Costamante & Ghisellini (2002) therefore will be omitted in the following discussion.…”

Section: Selection Of Tev Candidates Ehblsupporting

confidence: 65%

An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes?

Bonnoli

Tavecchio

Ghisellini

et al. 2015

Monthly Notices of the Royal Astronomical Society

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High energy observations of extreme BL Lac objects, such as 1ES 0229+200 or 1ES 0347-121, recently focused interest both for blazar and jet physics and for the implication on the extragalactic background light and intergalactic magnetic field estimate. However, the number of these extreme highly peaked BL Lac objects (EHBL) is still rather small. Aiming at increase their number, we selected a group of EHBL candidates starting from the BL Lac sample of Plotkin et al. (2011), considering those undetected (or only barely detected) by the Large Area Telescope onboard Fermi and characterized by a high X-ray vs. radio flux ratio. We assembled the multi-wavelength spectral energy distribution of the resulting 9 sources, profiting of publicly available archival observations performed by Swift, Galex, and Fermi satellites, confirming their nature. Through a simple one-zone synchrotron self-Compton model we estimate the expected VHE flux, finding that in the majority of cases it is within the reach of present generation of Cherenkov arrays or of the forthcoming Cherenkov Telescope Array (CTA).

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“…For these objects, the low-energy component peaks in the soft to hard X-ray regime and the high-energy component peaks in the VHE regime. The six confirmed VHE BL Lac objects are Mrk 421 (Punch et al 1992;Petry et al 1996), Mrk 501 (Quinn et al 1996;Bradbury et al 1997), 1ES 2344+ 514 (Catanese et al 1998;Tluczykont et al 2003), 1ES 1959+ 650 ( Nishiyama et al 1999;Holder et al 2003;Aharonian et al 2003), PKS 2155À 304 (Chadwick et al 1999;Aharonian et al 2005), and H1426+ 428 (Horan et al 2002;Aharonian et al 2002a). The emission level around the two peaks is highly variable, and changes in the spectral shape with flux level have been measured for Mrk 421 ( Krennrich et al 2002( Krennrich et al , 2003Aharonian et al 2002b), Mrk 501 (Djannati-Atai et al 1999;Aharonian et al 2001), and1ES 1959+ 650 (Aharonian et al 2003.…”

Section: Introductionmentioning

confidence: 99%

A Very High Energy Gamma‐Ray Spectrum of 1ES 2344+514

Schroedter

Badran

Buckley

et al. 2005

ApJ

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The BL Lacertae ( BL Lac) object 1ES 2344+514 (1ES 2344), at a redshift of 0.044, was discovered as a source of very high energy ( VHE) gamma rays by the Whipple collaboration in 1995 (Catanese et al.). This detection was recently confirmed by the HEGRA collaboration (Tluczykont et al.). As is typical for high-frequency-peaked blazars, the VHE gamma-ray emission is highly variable. On the night of 1995 December 20, a gamma-ray flare of 5.3 significance was detected, the brightest outburst from this object to date. The emission region is compatible with a point source. The spectrum between 0.8 and 12.6 TeV can be described by a power law, If we compare the spectral index with that of the other five confirmed TeV blazars, the spectrum of 1ES 2344 is similar to that of 1ES 1959+650, which is located at almost the same distance. The spectrum of 1ES 2344 is steeper than the brightest flare spectra of Markarian 421 ( Mrk 421) and Markarian 501 ( Mrk 501), both of which are located at a distance about two-thirds that of 1ES 2344, and harder than the spectra of PKS 2155À304 and H1426+428, which are located almost 3 times as far away. This trend is consistent with attenuation caused by the infrared extragalactic background radiation.

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Detection of the BL Lacertae Object H1426+428 at TeV Gamma‐Ray Energies

Abstract: 1 Fred Lawrence Whipple Observatory, Harvard-Smithsonian CfA,

Cited by 89 publications

References 32 publications

Observations of 54 Active Galactic Nuclei with the HEGRA system of Cherenkov telescopes

Observations of 54 Active Galactic Nuclei with the HEGRA system of Cherenkov telescopes

An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes?

A Very High Energy Gamma‐Ray Spectrum of 1ES 2344+514

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