Catanese, M. and Akerlof, C.W. and Badran, H.M. and Biller, S.D. and Bond, I.H. and Boyle, P.J. and Bradbury, S.M. and Buckley, J.H. and Burdett, A.M. and Bussons Gordo, J. and Carter-Lewis, D.A. and Cawley, Michael F. and Connaughton, V. and Fegan, D.J. and Finley, J.P. and Gaidos, J.A. and Hall, T. and Hillas, A.M. and Krennrich, F. and Lamb, R.C. and Lessard, R.W. and Masterson, C. and McEnery, J.E. and Mohanty, G. and Quinn, J. and Rodgers, A.J. and Rose, H.J. and Samuelson, F.W. and Schubnell, M.S. and Sembroski, G.H. and Srinivasan, R. and Weekes, T.C. and Wilson, C.W. and Zweerink, J. (1998) Discovery of Gamma-Ray Emission above 350 GeV from the BL Lacertae Object 1ES 2344+514. Astrophysical Journal, 501 (616). ISSN 0004-637X

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Abstract

We present the discovery of gamma-ray emission greater than 350 GeV from the BL Lacertae (BL Lac) object 1ES 2344+514 with the Whipple Observatory 10 m gamma-ray telescope. This is the third BL Lac object detected at very high energies (VHE, E > 300 GeV), the other two being Markarian 421 (Mrk 421) and Mrk 501. These three active galactic nuclei are all X-ray selected and have the lowest known redshifts of any BL Lac objects currently identified with declination greater than 0°. The evidence for emission from 1ES 2344+514 comes mostly from an apparent flare on 1995 December 20 (UT) during which a 6 σ excess was detected with an average flux of I(>350 GeV) = 6.6 ± 1.9 × 10-11 photons cm-2 s-1. This is approximately 63% of the VHE emission from the Crab Nebula, the standard candle in this field. Observations taken between 1995 October and 1996 January, excluding the night of the flare, yield a 4 σ detection indicating a flux level of I(>350 GeV) = 1.1 ± 0.4 × 10-11 photons cm-2 s-1, or about 11% of the VHE Crab Nebula flux. Observations taken between 1996 September and 1997 January on this object did not yield a significant detection of a steady flux or any evidence of flaring activity. The 99.9% confidence level upper limit from these observations is I(>350 GeV) < 8.2 × 10-12 photons cm-2 s-1, lesssim8% of the Crab Nebula flux. The low baseline emission level and variation in the nightly and yearly flux of 1ES 2344+514 are the same as the VHE emission characteristics of Mrk 421 and Mrk 501.

Item Type:	Article
Additional Information:	Citation: M. Catanese et al 1998 ApJ 501 616
Keywords:	BL Lacertae objects : individual; 1ES 2344+514; gamma rays : observations;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	9948
Identification Number:	https://doi.org/10.1086/305857
Depositing User:	Dr. Michael Cawley
Date Deposited:	18 Sep 2018 15:36
Journal or Publication Title:	Astrophysical Journal
Publisher:	American Astronomical Society
Refereed:	Yes
URI:	http://iopscience.iop.org/
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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