Veritas observations of the BL Lac object 1ES 1218+304

V. A. Acciari; E. Aliu; T. Arlen; M. Beilicke; W. Benbow; S. M. Bradbury; J. H. Buckley; V. Bugaev; Y. Butt; K. L. Byrum; O. Celik; A. Cesarini; L. Ciupik; Y. C.K. Chow; P. Cogan; P. Colin; W. Cui; M. K. Daniel; T. Ergin; A. D. Falcone; S. J. Fegan; J. P. Finley; P. Fortin; L. F. Fortson; A. Furniss; G. H. Gillanders; J. Grube; R. Guenette; G. Gyuk; D. Hanna; E. Hays; J. Holder; D. Horan; C. M. Hui; T. B. Humensky; A. Imran; P. Kaaret; N. Karlsson; M. Kertzman; D. B. Kieda; J. Kildea; A. Konopelko; H. Krawczynski; F. Krennrich; M. J. Lang; S. LeBohec; G. Maier; A. McCann; M. McCutcheon; P. Moriarty

doi:10.1088/0004-637X/695/2/1370

Veritas observations of the BL Lac object 1ES 1218+304

V. A. Acciari, E. Aliu, T. Arlen, M. Beilicke, W. Benbow, S. M. Bradbury, J. H. Buckley, V. Bugaev, Y. Butt, K. L. Byrum, O. Celik, A. Cesarini, L. Ciupik, Y. C.K. Chow, P. Cogan, P. Colin, W. Cui, M. K. Daniel, T. Ergin, A. D. FalconeS. J. Fegan, J. P. Finley, P. Fortin, L. F. Fortson, A. Furniss, G. H. Gillanders, J. Grube, R. Guenette, G. Gyuk, D. Hanna, E. Hays, J. Holder, D. Horan, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. B. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. LeBohec, G. Maier, A. McCann, M. McCutcheon, P. Moriarty

Physics and Astronomy (Twin Cities)

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Abstract

The VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the highfrequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4σ) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ∼ 160 GeV and ∼ 1.8 TeV is well described by a power law with an index of Γ = 3.08 ± 0.34_stat ± 0.2_sys. The integral flux is Φ (E > 200 GeV) = (12.2 ± 2.6) × 10^-12 cm^-2 s^-1, which corresponds to ∼ 6% of that of the Crab Nebula. The light curve does not show any evidence for very high energy flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared, we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Γ = 2.32 ± 0.37_stat. When including constraints from the spectra of 1ES 1101-232 and 1ES 0229+200, the spectrum of 1ES 1218+304 is likely to be harder than Γ = 1.86 ± 0.37_stat.

Original language	English (US)
Pages (from-to)	1370-1375
Number of pages	6
Journal	Astrophysical Journal
Volume	695
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/695/2/1370
State	Published - Apr 20 2009

Bibliographical note

Publisher Copyright:
© 2009 The American Astronomical Society. All rights reserved. Printed in the U.S.A.

Keywords

BL Lacertae objects: individual (1ES 1218+304)
Galaxies: active
Gamma rays: observations

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Acciari, V. A., Aliu, E., Arlen, T., Beilicke, M., Benbow, W., Bradbury, S. M., Buckley, J. H., Bugaev, V., Butt, Y., Byrum, K. L., Celik, O., Cesarini, A., Ciupik, L., Chow, Y. C. K., Cogan, P., Colin, P., Cui, W., Daniel, M. K., Ergin, T., ... Moriarty, P. (2009). Veritas observations of the BL Lac object 1ES 1218+304. Astrophysical Journal, 695(2), 1370-1375. https://doi.org/10.1088/0004-637X/695/2/1370

Acciari, VA, Aliu, E, Arlen, T, Beilicke, M, Benbow, W, Bradbury, SM, Buckley, JH, Bugaev, V, Butt, Y, Byrum, KL, Celik, O, Cesarini, A, Ciupik, L, Chow, YCK, Cogan, P, Colin, P, Cui, W, Daniel, MK, Ergin, T, Falcone, AD, Fegan, SJ, Finley, JP, Fortin, P, Fortson, LF, Furniss, A, Gillanders, GH, Grube, J, Guenette, R, Gyuk, G, Hanna, D, Hays, E, Holder, J, Horan, D, Hui, CM, Humensky, TB, Imran, A, Kaaret, P, Karlsson, N, Kertzman, M, Kieda, DB, Kildea, J, Konopelko, A, Krawczynski, H, Krennrich, F, Lang, MJ, LeBohec, S, Maier, G, McCann, A, McCutcheon, M & Moriarty, P 2009, 'Veritas observations of the BL Lac object 1ES 1218+304', Astrophysical Journal, vol. 695, no. 2, pp. 1370-1375. https://doi.org/10.1088/0004-637X/695/2/1370

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title = "Veritas observations of the BL Lac object 1ES 1218+304",

abstract = "The VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the highfrequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4σ) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ∼ 160 GeV and ∼ 1.8 TeV is well described by a power law with an index of Γ = 3.08 ± 0.34stat ± 0.2sys. The integral flux is Φ (E > 200 GeV) = (12.2 ± 2.6) × 10-12 cm-2 s-1, which corresponds to ∼ 6% of that of the Crab Nebula. The light curve does not show any evidence for very high energy flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared, we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Γ = 2.32 ± 0.37stat. When including constraints from the spectra of 1ES 1101-232 and 1ES 0229+200, the spectrum of 1ES 1218+304 is likely to be harder than Γ = 1.86 ± 0.37stat.",

keywords = "BL Lacertae objects: individual (1ES 1218+304), Galaxies: active, Gamma rays: observations",

author = "Acciari, {V. A.} and E. Aliu and T. Arlen and M. Beilicke and W. Benbow and Bradbury, {S. M.} and Buckley, {J. H.} and V. Bugaev and Y. Butt and Byrum, {K. L.} and O. Celik and A. Cesarini and L. Ciupik and Chow, {Y. C.K.} and P. Cogan and P. Colin and W. Cui and Daniel, {M. K.} and T. Ergin and Falcone, {A. D.} and Fegan, {S. J.} and Finley, {J. P.} and P. Fortin and Fortson, {L. F.} and A. Furniss and Gillanders, {G. H.} and J. Grube and R. Guenette and G. Gyuk and D. Hanna and E. Hays and J. Holder and D. Horan and Hui, {C. M.} and Humensky, {T. B.} and A. Imran and P. Kaaret and N. Karlsson and M. Kertzman and Kieda, {D. B.} and J. Kildea and A. Konopelko and H. Krawczynski and F. Krennrich and Lang, {M. J.} and S. LeBohec and G. Maier and A. McCann and M. McCutcheon and P. Moriarty",

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doi = "10.1088/0004-637X/695/2/1370",

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T1 - Veritas observations of the BL Lac object 1ES 1218+304

AU - Acciari, V. A.

AU - Aliu, E.

AU - Arlen, T.

AU - Beilicke, M.

AU - Benbow, W.

AU - Bradbury, S. M.

AU - Buckley, J. H.

AU - Bugaev, V.

AU - Butt, Y.

AU - Byrum, K. L.

AU - Celik, O.

AU - Cesarini, A.

AU - Ciupik, L.

AU - Chow, Y. C.K.

AU - Cogan, P.

AU - Colin, P.

AU - Cui, W.

AU - Daniel, M. K.

AU - Ergin, T.

AU - Falcone, A. D.

AU - Fegan, S. J.

AU - Finley, J. P.

AU - Fortin, P.

AU - Fortson, L. F.

AU - Furniss, A.

AU - Gillanders, G. H.

AU - Grube, J.

AU - Guenette, R.

AU - Gyuk, G.

AU - Hanna, D.

AU - Hays, E.

AU - Holder, J.

AU - Horan, D.

AU - Hui, C. M.

AU - Humensky, T. B.

AU - Imran, A.

AU - Kaaret, P.

AU - Karlsson, N.

AU - Kertzman, M.

AU - Kieda, D. B.

AU - Kildea, J.

AU - Konopelko, A.

AU - Krawczynski, H.

AU - Krennrich, F.

AU - Lang, M. J.

AU - LeBohec, S.

AU - Maier, G.

AU - McCann, A.

AU - McCutcheon, M.

AU - Moriarty, P.

PY - 2009/4/20

Y1 - 2009/4/20

N2 - The VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the highfrequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4σ) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ∼ 160 GeV and ∼ 1.8 TeV is well described by a power law with an index of Γ = 3.08 ± 0.34stat ± 0.2sys. The integral flux is Φ (E > 200 GeV) = (12.2 ± 2.6) × 10-12 cm-2 s-1, which corresponds to ∼ 6% of that of the Crab Nebula. The light curve does not show any evidence for very high energy flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared, we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Γ = 2.32 ± 0.37stat. When including constraints from the spectra of 1ES 1101-232 and 1ES 0229+200, the spectrum of 1ES 1218+304 is likely to be harder than Γ = 1.86 ± 0.37stat.

AB - The VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the highfrequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4σ) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between ∼ 160 GeV and ∼ 1.8 TeV is well described by a power law with an index of Γ = 3.08 ± 0.34stat ± 0.2sys. The integral flux is Φ (E > 200 GeV) = (12.2 ± 2.6) × 10-12 cm-2 s-1, which corresponds to ∼ 6% of that of the Crab Nebula. The light curve does not show any evidence for very high energy flux variability. Using lower limits on the density of the extragalactic background light in the near to mid-infrared, we are able to limit the range of intrinsic energy spectra for 1ES 1218+304. We show that the intrinsic photon spectrum has an index that is harder than Γ = 2.32 ± 0.37stat. When including constraints from the spectra of 1ES 1101-232 and 1ES 0229+200, the spectrum of 1ES 1218+304 is likely to be harder than Γ = 1.86 ± 0.37stat.

KW - BL Lacertae objects: individual (1ES 1218+304)

KW - Galaxies: active

KW - Gamma rays: observations

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UR - http://www.scopus.com/inward/citedby.url?scp=84893254418&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/695/2/1370

DO - 10.1088/0004-637X/695/2/1370

M3 - Article

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SN - 0004-637X

VL - 695

SP - 1370

EP - 1375

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

ER -

Veritas observations of the BL Lac object 1ES 1218+304

Abstract

Bibliographical note

Keywords

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