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. Furniss; N. 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

doi:10.1088/2041-8205/709/2/L163

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

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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 language	English (US)
Pages (from-to)	L163-L167
Journal	Astrophysical Journal Letters
Volume	709
Issue number	2 PART 2
DOIs	https://doi.org/10.1088/2041-8205/709/2/L163
State	Published - 2010

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/2041-8205/709/2/L163

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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., ... 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

@article{267f460f46f34ff18fbb6f7366861bc6,

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

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.",

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

year = "2010",

doi = "10.1088/2041-8205/709/2/L163",

language = "English (US)",

volume = "709",

pages = "L163--L167",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

number = "2 PART 2",

}

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

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

Y1 - 2010

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.

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

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

AN - SCOPUS:77949525253

SN - 2041-8205

VL - 709

SP - L163-L167

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2 PART 2

ER -

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

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