Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514
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 (...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
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Institute of Physics Publishing
1998
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| _version_ | 1797065072838705152 |
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| author | Catanese, M Akerlof, C Badran, H Biller, S Bond, I Boyle, P Bradbury, S Buckley, J Burdett, A Bussóns Gordo, J Carter-Lewis, D Cawley, M Connaughton, V Fegan, D Finley, J Gaidos, J Hall, T Hillas, A Krennrich, F Lamb, R Lessard, R Masterson, C McEnery, J Mohanty, G Quinn, J |
| author_facet | Catanese, M Akerlof, C Badran, H Biller, S Bond, I Boyle, P Bradbury, S Buckley, J Burdett, A Bussóns Gordo, J Carter-Lewis, D Cawley, M Connaughton, V Fegan, D Finley, J Gaidos, J Hall, T Hillas, A Krennrich, F Lamb, R Lessard, R Masterson, C McEnery, J Mohanty, G Quinn, J |
| author_sort | Catanese, M |
| collection | OXFORD |
| description | 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. |
| first_indexed | 2024-03-06T21:23:25Z |
| format | Journal article |
| id | oxford-uuid:42426dec-bb2a-43c0-ab3c-0c3ffd9e3020 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:23:25Z |
| publishDate | 1998 |
| publisher | Institute of Physics Publishing |
| record_format | dspace |
| spelling | oxford-uuid:42426dec-bb2a-43c0-ab3c-0c3ffd9e30202022-03-26T14:48:25ZDiscovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:42426dec-bb2a-43c0-ab3c-0c3ffd9e3020EnglishSymplectic Elements at OxfordInstitute of Physics Publishing1998Catanese, MAkerlof, CBadran, HBiller, SBond, IBoyle, PBradbury, SBuckley, JBurdett, ABussóns Gordo, JCarter-Lewis, DCawley, MConnaughton, VFegan, DFinley, JGaidos, JHall, THillas, AKrennrich, FLamb, RLessard, RMasterson, CMcEnery, JMohanty, GQuinn, JWe 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. |
| spellingShingle | Catanese, M Akerlof, C Badran, H Biller, S Bond, I Boyle, P Bradbury, S Buckley, J Burdett, A Bussóns Gordo, J Carter-Lewis, D Cawley, M Connaughton, V Fegan, D Finley, J Gaidos, J Hall, T Hillas, A Krennrich, F Lamb, R Lessard, R Masterson, C McEnery, J Mohanty, G Quinn, J Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title | Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title_full | Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title_fullStr | Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title_full_unstemmed | Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title_short | Discovery of gamma-ray emission above 350 GeV from the BL lacertae object 1ES 2344+514 |
| title_sort | discovery of gamma ray emission above 350 gev from the bl lacertae object 1es 2344 514 |
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