Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas

V. A. Acciari, E. Aliu, M. Beilicke, W. Benbow, D. Boltuch, M. Böttcher, S. M. Bradbury, V. Bugaev, K. Byrum, A. Cesarini, L. Ciupik, P. Cogan, W. Cui, R. Dickherber, C. Duke, A. Falcone, J. P. Finley, G. Finnegan, L. Fortson, A. FurnissN. Galante, D. Gall, K. Gibbs, R. Guenette, G. H. Gillanders, S. Godambe, J. Grube, D. Hanna, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, S. Lebohec, G. Maier, S. McArthur, A. McCann, P. Moriarty, T. Nagai, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, A. Pichel, M. Pohl, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, S. P. Swordy, M. Theiling, S. Thibadeau, V. V. Vassiliev, S. Vincent, S. P. Wakely, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams

Research output: Contribution to journalArticle

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Abstract

We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ∼ 6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ∼ 20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices Γ≤ 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical γ-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios.

Original languageEnglish (US)
Pages (from-to)L163-L167
JournalAstrophysical Journal Letters
Volume709
Issue number2 PART 2
DOIs
StatePublished - Jan 1 2010

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blazars
rays
flares
crab
energy
Crab nebula
crabs
spectral energy distribution
viability
light curve
energy spectra
shock
photons
monitoring
modeling

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Acciari, V. A., Aliu, E., Beilicke, M., Benbow, W., Boltuch, D., Böttcher, M., ... Williams, D. A. (2010). Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas. Astrophysical Journal Letters, 709(2 PART 2), L163-L167. https://doi.org/10.1088/2041-8205/709/2/L163
Acciari, V. A. ; Aliu, E. ; Beilicke, M. ; Benbow, W. ; Boltuch, D. ; Böttcher, M. ; Bradbury, S. M. ; Bugaev, V. ; Byrum, K. ; Cesarini, A. ; Ciupik, L. ; Cogan, P. ; Cui, W. ; Dickherber, R. ; Duke, C. ; Falcone, A. ; Finley, J. P. ; Finnegan, G. ; Fortson, L. ; Furniss, A. ; Galante, N. ; Gall, D. ; Gibbs, K. ; Guenette, R. ; Gillanders, G. H. ; Godambe, S. ; Grube, J. ; Hanna, D. ; Hui, C. M. ; Humensky, T. B. ; Imran, A. ; Kaaret, P. ; Karlsson, N. ; Kertzman, M. ; Kieda, D. ; Krawczynski, H. ; Krennrich, F. ; Lang, M. J. ; Lebohec, S. ; Maier, G. ; McArthur, S. ; McCann, A. ; Moriarty, P. ; Nagai, T. ; Ong, R. A. ; Otte, A. N. ; Pandel, D. ; Perkins, J. S. ; Pichel, A. ; Pohl, M. ; Quinn, J. ; Ragan, K. ; Reyes, L. C. ; Reynolds, P. T. ; Roache, E. ; Rose, H. J. ; Schroedter, M. ; Sembroski, G. H. ; Smith, A. W. ; Steele, D. ; Swordy, S. P. ; Theiling, M. ; Thibadeau, S. ; Vassiliev, V. V. ; Vincent, S. ; Wakely, S. P. ; Weekes, T. C. ; Weinstein, A. ; Weisgarber, T. ; Williams, D. A. / Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas. In: Astrophysical Journal Letters. 2010 ; Vol. 709, No. 2 PART 2. pp. L163-L167.
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abstract = "We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ∼ 6{\%} of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ∼ 20{\%} of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices Γ≤ 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical γ-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios.",
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Acciari, VA, Aliu, E, Beilicke, M, Benbow, W, Boltuch, D, Böttcher, M, Bradbury, SM, Bugaev, V, Byrum, K, Cesarini, A, Ciupik, L, Cogan, P, Cui, W, Dickherber, R, Duke, C, Falcone, A, Finley, JP, Finnegan, G, Fortson, L, Furniss, A, Galante, N, Gall, D, Gibbs, K, Guenette, R, Gillanders, GH, Godambe, S, Grube, J, Hanna, D, Hui, CM, Humensky, TB, Imran, A, Kaaret, P, Karlsson, N, Kertzman, M, Kieda, D, Krawczynski, H, Krennrich, F, Lang, MJ, Lebohec, S, Maier, G, McArthur, S, McCann, A, Moriarty, P, Nagai, T, Ong, RA, Otte, AN, Pandel, D, Perkins, JS, Pichel, A, Pohl, M, Quinn, J, Ragan, K, Reyes, LC, Reynolds, PT, Roache, E, Rose, HJ, Schroedter, M, Sembroski, GH, Smith, AW, Steele, D, Swordy, SP, Theiling, M, Thibadeau, S, Vassiliev, VV, Vincent, S, Wakely, SP, Weekes, TC, Weinstein, A, Weisgarber, T & Williams, DA 2010, 'Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas', Astrophysical Journal Letters, vol. 709, no. 2 PART 2, pp. L163-L167. https://doi.org/10.1088/2041-8205/709/2/L163

Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas. / Acciari, V. A.; Aliu, E.; Beilicke, M.; Benbow, W.; Boltuch, D.; Böttcher, M.; Bradbury, S. M.; Bugaev, V.; Byrum, K.; Cesarini, A.; Ciupik, L.; Cogan, P.; Cui, W.; Dickherber, R.; Duke, C.; Falcone, A.; Finley, J. P.; Finnegan, G.; Fortson, L.; Furniss, A.; Galante, N.; Gall, D.; Gibbs, K.; Guenette, R.; Gillanders, G. H.; Godambe, S.; Grube, J.; Hanna, D.; Hui, C. M.; Humensky, T. B.; Imran, A.; Kaaret, P.; Karlsson, N.; Kertzman, M.; Kieda, D.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; Lebohec, S.; Maier, G.; McArthur, S.; McCann, A.; Moriarty, P.; Nagai, T.; Ong, R. A.; Otte, A. N.; Pandel, D.; Perkins, J. S.; Pichel, A.; Pohl, M.; Quinn, J.; Ragan, K.; Reyes, L. C.; Reynolds, P. T.; Roache, E.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Smith, A. W.; Steele, D.; Swordy, S. P.; Theiling, M.; Thibadeau, S.; Vassiliev, V. V.; Vincent, S.; Wakely, S. P.; Weekes, T. C.; Weinstein, A.; Weisgarber, T.; Williams, D. A.

In: Astrophysical Journal Letters, Vol. 709, No. 2 PART 2, 01.01.2010, p. L163-L167.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas

AU - Acciari, V. A.

AU - Aliu, E.

AU - Beilicke, M.

AU - Benbow, W.

AU - Boltuch, D.

AU - Böttcher, M.

AU - Bradbury, S. M.

AU - Bugaev, V.

AU - Byrum, K.

AU - Cesarini, A.

AU - Ciupik, L.

AU - Cogan, P.

AU - Cui, W.

AU - Dickherber, R.

AU - Duke, C.

AU - Falcone, A.

AU - Finley, J. P.

AU - Finnegan, G.

AU - Fortson, L.

AU - Furniss, A.

AU - Galante, N.

AU - Gall, D.

AU - Gibbs, K.

AU - Guenette, R.

AU - Gillanders, G. H.

AU - Godambe, S.

AU - Grube, J.

AU - Hanna, D.

AU - Hui, C. M.

AU - Humensky, T. B.

AU - Imran, A.

AU - Kaaret, P.

AU - Karlsson, N.

AU - Kertzman, M.

AU - Kieda, D.

AU - Krawczynski, H.

AU - Krennrich, F.

AU - Lang, M. J.

AU - Lebohec, S.

AU - Maier, G.

AU - McArthur, S.

AU - McCann, A.

AU - Moriarty, P.

AU - Nagai, T.

AU - Ong, R. A.

AU - Otte, A. N.

AU - Pandel, D.

AU - Perkins, J. S.

AU - Pichel, A.

AU - Pohl, M.

AU - Quinn, J.

AU - Ragan, K.

AU - Reyes, L. C.

AU - Reynolds, P. T.

AU - Roache, E.

AU - Rose, H. J.

AU - Schroedter, M.

AU - Sembroski, G. H.

AU - Smith, A. W.

AU - Steele, D.

AU - Swordy, S. P.

AU - Theiling, M.

AU - Thibadeau, S.

AU - Vassiliev, V. V.

AU - Vincent, S.

AU - Wakely, S. P.

AU - Weekes, T. C.

AU - Weinstein, A.

AU - Weisgarber, T.

AU - Williams, D. A.

PY - 2010/1/1

Y1 - 2010/1/1

N2 - We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ∼ 6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ∼ 20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices Γ≤ 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical γ-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios.

AB - We present results from an intensive VERITAS monitoring campaign of the high-frequency peaked BL Lac object 1ES 1218+304 in 2008/2009. Although 1ES 1218+304 was detected previously by MAGIC and VERITAS at a persistent level of ∼ 6% of the Crab Nebula flux, the new VERITAS data reveal a prominent flare reaching ∼ 20% of the Crab. While very high energy (VHE) flares are quite common in many nearby blazars, the case of 1ES 1218+304 (redshift z = 0.182) is particularly interesting since it belongs to a group of blazars that exhibit unusually hard VHE spectra considering their redshifts. When correcting the measured spectra for absorption by the extragalactic background light, 1ES 1218+304 and a number of other blazars are found to have differential photon indices Γ≤ 1.5. The difficulty in modeling these hard spectral energy distributions in blazar jets has led to a range of theoretical γ-ray emission scenarios, one of which is strongly constrained by these new VERITAS observations. We consider the implications of the observed light curve of 1ES 1218+304, which shows day scale flux variations, for shock acceleration scenarios in relativistic jets, and in particular for the viability of kiloparsec-scale jet emission scenarios.

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UR - http://www.scopus.com/inward/citedby.url?scp=77949525253&partnerID=8YFLogxK

U2 - 10.1088/2041-8205/709/2/L163

DO - 10.1088/2041-8205/709/2/L163

M3 - Article

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VL - 709

SP - L163-L167

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

SN - 2041-8205

IS - 2 PART 2

ER -

Acciari VA, Aliu E, Beilicke M, Benbow W, Boltuch D, Böttcher M et al. Discovery of variability in the very high energy γ-ray emission of 1ES 1218+304 with veritas. Astrophysical Journal Letters. 2010 Jan 1;709(2 PART 2):L163-L167. https://doi.org/10.1088/2041-8205/709/2/L163