Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514

M. Catanese; C. W. Akerlof; H. M. Badran; S. D. Biller; I. H. Bond; P. J. Boyle; S. M. Bradbury; J. H. Buckley; A. M. Burdett; J. Bussóns Gordo; D. A. Carter-Lewis; M. F. Cawley; V. Connaughton; D. J. Fegan; J. P. Finley; J. A. Gaidos; T. Hall; A. M. Hillas; F. Krennrich; R. C. Lamb; R. W. Lessard; C. Masterson; J. E. McEnery; G. Mohanty; J. Quinn; A. J. Rodgers; H. J. Rose; F. W. Samuelson; M. S. Schubnell; G. H. Sembroski; R. Srinivasan; T. C. Weekes; C. W. Wilson; J. Zweerink

doi:10.1086/305857

Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514

M. Catanese
, C. W. Akerlof
, H. M. Badran
, S. D. Biller
, I. H. Bond
, P. J. Boyle
, S. M. Bradbury
, J. H. Buckley
, A. M. Burdett
, J. Bussóns Gordo
, D. A. Carter-Lewis
, M. F. Cawley
, V. Connaughton
, D. J. Fegan
, J. P. Finley
, J. A. Gaidos
, T. Hall
, A. M. Hillas
, F. Krennrich
, R. C. Lamb

R. W. Lessard, C. Masterson, J. E. McEnery, G. Mohanty, J. Quinn, A. J. Rodgers, H. J. Rose, F. W. Samuelson, M. S. Schubnell, G. H. Sembroski, R. Srinivasan, T. C. Weekes, C. W. Wilson, J. Zweerink

Department of Physics

Research output: Contribution to journal › Article › peer-review

152 Scopus citations

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, ≲8% 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.

Original language	English
Pages (from-to)	616-623
Number of pages	8
Journal	Astrophysical Journal
Volume	501
Issue number	2 PART 1
DOIs	https://doi.org/10.1086/305857
State	Published - Jul 10 1998

Keywords

Gamma rays: observations

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10.1086/305857

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Catanese, M., Akerlof, C. W., Badran, H. M., Biller, S. D., Bond, I. H., Boyle, P. J., Bradbury, S. M., Buckley, J. H., Burdett, A. M., Bussóns Gordo, J., Carter-Lewis, D. A., Cawley, M. F., Connaughton, V., Fegan, D. J., Finley, J. P., Gaidos, J. A., Hall, T., Hillas, A. M., Krennrich, F., ... Zweerink, J. (1998). Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514. Astrophysical Journal, 501(2 PART 1), 616-623. https://doi.org/10.1086/305857

@article{0fc2e0199baf4c5e9e2c7e727271351c,

title = "Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514",

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, ≲8\% 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.",

keywords = "Gamma rays: observations",

author = "M. Catanese 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 \{Buss{\'o}ns Gordo\}, J. and Carter-Lewis, \{D. A.\} and Cawley, \{M. F.\} and V. Connaughton and Fegan, \{D. J.\} and Finley, \{J. P.\} and Gaidos, \{J. A.\} and T. Hall and Hillas, \{A. M.\} and F. Krennrich and Lamb, \{R. C.\} and Lessard, \{R. W.\} and C. Masterson and McEnery, \{J. E.\} and G. Mohanty and J. Quinn and Rodgers, \{A. J.\} and Rose, \{H. J.\} and Samuelson, \{F. W.\} and Schubnell, \{M. S.\} and Sembroski, \{G. H.\} and R. Srinivasan and Weekes, \{T. C.\} and Wilson, \{C. W.\} and J. Zweerink",

year = "1998",

month = jul,

day = "10",

doi = "10.1086/305857",

language = "English",

volume = "501",

pages = "616--623",

journal = "Astrophysical Journal",

issn = "0004-637X",

number = "2 PART 1",

}

Catanese, M, Akerlof, CW, Badran, HM, Biller, SD, Bond, IH, Boyle, PJ, Bradbury, SM, Buckley, JH, Burdett, AM, Bussóns Gordo, J, Carter-Lewis, DA, Cawley, MF, Connaughton, V, Fegan, DJ, Finley, JP, Gaidos, JA, Hall, T, Hillas, AM, Krennrich, F, Lamb, RC, Lessard, RW, Masterson, C, McEnery, JE, Mohanty, G, Quinn, J, Rodgers, AJ, Rose, HJ, Samuelson, FW, Schubnell, MS, Sembroski, GH, Srinivasan, R, Weekes, TC, Wilson, CW & Zweerink, J 1998, 'Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514', Astrophysical Journal, vol. 501, no. 2 PART 1, pp. 616-623. https://doi.org/10.1086/305857

TY - JOUR

T1 - Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514

AU - Catanese, M.

AU - Akerlof, C. W.

AU - Badran, H. M.

AU - Biller, S. D.

AU - Bond, I. H.

AU - Boyle, P. J.

AU - Bradbury, S. M.

AU - Buckley, J. H.

AU - Burdett, A. M.

AU - Bussóns Gordo, J.

AU - Carter-Lewis, D. A.

AU - Cawley, M. F.

AU - Connaughton, V.

AU - Fegan, D. J.

AU - Finley, J. P.

AU - Gaidos, J. A.

AU - Hall, T.

AU - Hillas, A. M.

AU - Krennrich, F.

AU - Lamb, R. C.

AU - Lessard, R. W.

AU - Masterson, C.

AU - McEnery, J. E.

AU - Mohanty, G.

AU - Quinn, J.

AU - Rodgers, A. J.

AU - Rose, H. J.

AU - Samuelson, F. W.

AU - Schubnell, M. S.

AU - Sembroski, G. H.

AU - Srinivasan, R.

AU - Weekes, T. C.

AU - Wilson, C. W.

AU - Zweerink, J.

PY - 1998/7/10

Y1 - 1998/7/10

N2 - 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, ≲8% 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.

AB - 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, ≲8% 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.

KW - Gamma rays: observations

UR - https://www.scopus.com/pages/publications/0032503812

U2 - 10.1086/305857

DO - 10.1086/305857

M3 - Article

AN - SCOPUS:0032503812

SN - 0004-637X

VL - 501

SP - 616

EP - 623

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2 PART 1

ER -

Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514

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