Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution

A. A. Abdo; M. Ackermann; M. Ajello; L. Baldini; J. Ballet; G. Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; B. Berenji; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; A. Bouvier; J. Bregeon; A. Brez; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; A. Cannon; P. A. Caraveo; S. Carrigan; J. M. Casandjian; E. Cavazzuti; C. Cecchi; Ö Çelik; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; S. Cutini; A. De Angelis; F. De Palma; C. D. Dermer; E. Do Couto E Silva; P. S. Drell; R. Dubois; D. Dumora; L. Escande; C. Favuzzi; S. J. Fegan; J. Finke; W. B. Focke; P. Fortin; M. Frailis; L. Fuhrmann; Y. Fukazawa; T. Fukuyama; S. Funk; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; M. Georganopoulos; S. Germani; B. Giebels; N. Giglietto; P. Giommi; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; I. A. Grenier; S. Guiriec; D. Hadasch; M. Hayashida; E. Hays; D. Horan; R. E. Hughes; G. Jóhannesson; A. S. Johnson; W. N. Johnson; M. Kadler; T. Kamae; H. Katagiri; J. Kataoka; J. Knödlseder; M. Kuss; J. Lande; L. Latronico; S. H. Lee; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; A. Makeev; W. Max-Moerbeck; M. N. Mazziotta; J. E. Mcenery; J. Mehault; P. F. Michelson; Luis Font Guiteras

doi:10.1088/0004-637X/736/2/131

Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution

A. A. Abdo, M. Ackermann, M. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, A. Bouvier, J. Bregeon, A. Brez, M. Brigida, P. Bruel, R. BuehlerS. Buson, G. A. Caliandro, R. A. Cameron, A. Cannon, P. A. Caraveo, S. Carrigan, J. M. Casandjian, E. Cavazzuti, C. Cecchi, Ö Çelik, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, J. Conrad, S. Cutini, A. De Angelis, F. De Palma, C. D. Dermer, E. Do Couto E Silva, P. S. Drell, R. Dubois, D. Dumora, L. Escande, C. Favuzzi, S. J. Fegan, J. Finke, W. B. Focke, P. Fortin, M. Frailis, L. Fuhrmann, Y. Fukazawa, T. Fukuyama, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, M. Georganopoulos, S. Germani, B. Giebels, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, S. Guiriec, D. Hadasch, M. Hayashida, E. Hays, D. Horan, R. E. Hughes, G. Jóhannesson, A. S. Johnson, W. N. Johnson, M. Kadler, T. Kamae, H. Katagiri, J. Kataoka, J. Knödlseder, M. Kuss, J. Lande, L. Latronico, S. H. Lee, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, A. Makeev, W. Max-Moerbeck, M. N. Mazziotta, J. E. Mcenery, J. Mehault, P. F. Michelson, Luis Font Guiteras

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Abstract

We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk421) during the first 1.5years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3GeV can be well described by a power-law function with photon index Γ = 1.78 0.02 and average photon flux F(> 0.3GeV) = (7.23 0.16) × 10-8phcm-2s -1. Over this time period, the Fermi-LAT spectrum above 0.3GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor 3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk421 showed a low activity at all wavebands. The extensive multi-instrument (radio toTeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site. © 2011. The American Astronomical Society. All rights reserved.

Original language	English
Article number	131
Journal	Astrophysical Journal
Volume	736
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/736/2/131
Publication status	Published - 1 Aug 2011

Keywords

acceleration of particles
BL Lacertae objects: general
BL Lacertae objects: individual (Mrk 421)
galaxies: active
gamma rays: general
radiation mechanisms: non-thermal

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10.1088/0004-637X/736/2/131

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Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bouvier, A., Bregeon, J., Brez, A., Brigida, M., Bruel, P., ... Font Guiteras, L. (2011). Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution. Astrophysical Journal, 736(2), [131]. https://doi.org/10.1088/0004-637X/736/2/131

@article{024c5cbb56ee46238a1cf15ab0dc4f47,

title = "Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution",

abstract = "We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk421) during the first 1.5years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3GeV can be well described by a power-law function with photon index Γ = 1.78 0.02 and average photon flux F(> 0.3GeV) = (7.23 0.16) × 10-8phcm-2s -1. Over this time period, the Fermi-LAT spectrum above 0.3GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor 3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk421 showed a low activity at all wavebands. The extensive multi-instrument (radio toTeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site. {\textcopyright} 2011. The American Astronomical Society. All rights reserved.",

keywords = "acceleration of particles, BL Lacertae objects: general, BL Lacertae objects: individual (Mrk 421), galaxies: active, gamma rays: general, radiation mechanisms: non-thermal",

author = "Abdo, {A. A.} and M. Ackermann and M. Ajello and L. Baldini and J. Ballet and G. Barbiellini and D. Bastieri and K. Bechtol and R. Bellazzini and B. Berenji and Blandford, {R. D.} and Bloom, {E. D.} and E. Bonamente and Borgland, {A. W.} and A. Bouvier and J. Bregeon and A. Brez and M. Brigida and P. Bruel and R. Buehler and S. Buson and Caliandro, {G. A.} and Cameron, {R. A.} and A. Cannon and Caraveo, {P. A.} and S. Carrigan and Casandjian, {J. M.} and E. Cavazzuti and C. Cecchi and {\"O} {\c C}elik and E. Charles and A. Chekhtman and J. Chiang and S. Ciprini and R. Claus and J. Cohen-Tanugi and J. Conrad and S. Cutini and {De Angelis}, A. and {De Palma}, F. and Dermer, {C. D.} and {Do Couto E Silva}, E. and Drell, {P. S.} and R. Dubois and D. Dumora and L. Escande and C. Favuzzi and Fegan, {S. J.} and J. Finke and Focke, {W. B.} and P. Fortin and M. Frailis and L. Fuhrmann and Y. Fukazawa and T. Fukuyama and S. Funk and P. Fusco and F. Gargano and D. Gasparrini and N. Gehrels and M. Georganopoulos and S. Germani and B. Giebels and N. Giglietto and P. Giommi and F. Giordano and M. Giroletti and T. Glanzman and G. Godfrey and Grenier, {I. A.} and S. Guiriec and D. Hadasch and M. Hayashida and E. Hays and D. Horan and Hughes, {R. E.} and G. J{\'o}hannesson and Johnson, {A. S.} and Johnson, {W. N.} and M. Kadler and T. Kamae and H. Katagiri and J. Kataoka and J. Kn{\"o}dlseder and M. Kuss and J. Lande and L. Latronico and Lee, {S. H.} and F. Longo and F. Loparco and B. Lott and Lovellette, {M. N.} and P. Lubrano and Madejski, {G. M.} and A. Makeev and W. Max-Moerbeck and Mazziotta, {M. N.} and Mcenery, {J. E.} and J. Mehault and Michelson, {P. F.} and {Font Guiteras}, Luis",

year = "2011",

month = aug,

day = "1",

doi = "10.1088/0004-637X/736/2/131",

language = "English",

volume = "736",

journal = "Astrophysical Journal",

issn = "0004-637X",

number = "2",

}

Abdo, AA, Ackermann, M, Ajello, M, Baldini, L, Ballet, J, Barbiellini, G, Bastieri, D, Bechtol, K, Bellazzini, R, Berenji, B, Blandford, RD, Bloom, ED, Bonamente, E, Borgland, AW, Bouvier, A, Bregeon, J, Brez, A, Brigida, M, Bruel, P, Buehler, R, Buson, S, Caliandro, GA, Cameron, RA, Cannon, A, Caraveo, PA, Carrigan, S, Casandjian, JM, Cavazzuti, E, Cecchi, C, Çelik, Ö, Charles, E, Chekhtman, A, Chiang, J, Ciprini, S, Claus, R, Cohen-Tanugi, J, Conrad, J, Cutini, S, De Angelis, A, De Palma, F, Dermer, CD, Do Couto E Silva, E, Drell, PS, Dubois, R, Dumora, D, Escande, L, Favuzzi, C, Fegan, SJ, Finke, J, Focke, WB, Fortin, P, Frailis, M, Fuhrmann, L, Fukazawa, Y, Fukuyama, T, Funk, S, Fusco, P, Gargano, F, Gasparrini, D, Gehrels, N, Georganopoulos, M, Germani, S, Giebels, B, Giglietto, N, Giommi, P, Giordano, F, Giroletti, M, Glanzman, T, Godfrey, G, Grenier, IA, Guiriec, S, Hadasch, D, Hayashida, M, Hays, E, Horan, D, Hughes, RE, Jóhannesson, G, Johnson, AS, Johnson, WN, Kadler, M, Kamae, T, Katagiri, H, Kataoka, J, Knödlseder, J, Kuss, M, Lande, J, Latronico, L, Lee, SH, Longo, F, Loparco, F, Lott, B, Lovellette, MN, Lubrano, P, Madejski, GM, Makeev, A, Max-Moerbeck, W, Mazziotta, MN, Mcenery, JE, Mehault, J, Michelson, PF & Font Guiteras, L 2011, 'Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution', Astrophysical Journal, vol. 736, no. 2, 131. https://doi.org/10.1088/0004-637X/736/2/131

TY - JOUR

T1 - Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution

AU - Abdo, A. A.

AU - Ackermann, M.

AU - Ajello, M.

AU - Baldini, L.

AU - Ballet, J.

AU - Barbiellini, G.

AU - Bastieri, D.

AU - Bechtol, K.

AU - Bellazzini, R.

AU - Berenji, B.

AU - Blandford, R. D.

AU - Bloom, E. D.

AU - Bonamente, E.

AU - Borgland, A. W.

AU - Bouvier, A.

AU - Bregeon, J.

AU - Brez, A.

AU - Brigida, M.

AU - Bruel, P.

AU - Buehler, R.

AU - Buson, S.

AU - Caliandro, G. A.

AU - Cameron, R. A.

AU - Cannon, A.

AU - Caraveo, P. A.

AU - Carrigan, S.

AU - Casandjian, J. M.

AU - Cavazzuti, E.

AU - Cecchi, C.

AU - Çelik, Ö

AU - Charles, E.

AU - Chekhtman, A.

AU - Chiang, J.

AU - Ciprini, S.

AU - Claus, R.

AU - Cohen-Tanugi, J.

AU - Conrad, J.

AU - Cutini, S.

AU - De Angelis, A.

AU - De Palma, F.

AU - Dermer, C. D.

AU - Do Couto E Silva, E.

AU - Drell, P. S.

AU - Dubois, R.

AU - Dumora, D.

AU - Escande, L.

AU - Favuzzi, C.

AU - Fegan, S. J.

AU - Finke, J.

AU - Focke, W. B.

AU - Fortin, P.

AU - Frailis, M.

AU - Fuhrmann, L.

AU - Fukazawa, Y.

AU - Fukuyama, T.

AU - Funk, S.

AU - Fusco, P.

AU - Gargano, F.

AU - Gasparrini, D.

AU - Gehrels, N.

AU - Georganopoulos, M.

AU - Germani, S.

AU - Giebels, B.

AU - Giglietto, N.

AU - Giommi, P.

AU - Giordano, F.

AU - Giroletti, M.

AU - Glanzman, T.

AU - Godfrey, G.

AU - Grenier, I. A.

AU - Guiriec, S.

AU - Hadasch, D.

AU - Hayashida, M.

AU - Hays, E.

AU - Horan, D.

AU - Hughes, R. E.

AU - Jóhannesson, G.

AU - Johnson, A. S.

AU - Johnson, W. N.

AU - Kadler, M.

AU - Kamae, T.

AU - Katagiri, H.

AU - Kataoka, J.

AU - Knödlseder, J.

AU - Kuss, M.

AU - Lande, J.

AU - Latronico, L.

AU - Lee, S. H.

AU - Longo, F.

AU - Loparco, F.

AU - Lott, B.

AU - Lovellette, M. N.

AU - Lubrano, P.

AU - Madejski, G. M.

AU - Makeev, A.

AU - Max-Moerbeck, W.

AU - Mazziotta, M. N.

AU - Mcenery, J. E.

AU - Mehault, J.

AU - Michelson, P. F.

AU - Font Guiteras, Luis

PY - 2011/8/1

Y1 - 2011/8/1

N2 - We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk421) during the first 1.5years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3GeV can be well described by a power-law function with photon index Γ = 1.78 0.02 and average photon flux F(> 0.3GeV) = (7.23 0.16) × 10-8phcm-2s -1. Over this time period, the Fermi-LAT spectrum above 0.3GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor 3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk421 showed a low activity at all wavebands. The extensive multi-instrument (radio toTeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site. © 2011. The American Astronomical Society. All rights reserved.

AB - We report on the γ-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk421) during the first 1.5years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area Telescope (LAT) γ-ray spectrum above 0.3GeV can be well described by a power-law function with photon index Γ = 1.78 0.02 and average photon flux F(> 0.3GeV) = (7.23 0.16) × 10-8phcm-2s -1. Over this time period, the Fermi-LAT spectrum above 0.3GeV was evaluated on seven-day-long time intervals, showing significant variations in the photon flux (up to a factor 3 from the minimum to the maximum flux) but mild spectral variations. The variability amplitude at X-ray frequencies measured by RXTE/ASM and Swift/BAT is substantially larger than that in γ-rays measured by Fermi-LAT, and these two energy ranges are not significantly correlated. We also present the first results from the 4.5 month long multifrequency campaign on Mrk421, which included the VLBA, Swift, RXTE, MAGIC, the F-GAMMA, GASP-WEBT, and other collaborations and instruments that provided excellent temporal and energy coverage of the source throughout the entire campaign (2009 January 19 to 2009 June 1). During this campaign, Mrk421 showed a low activity at all wavebands. The extensive multi-instrument (radio toTeV) data set provides an unprecedented, complete look at the quiescent spectral energy distribution (SED) for this source. The broadband SED was reproduced with a leptonic (one-zone synchrotron self-Compton) and a hadronic model (synchrotron proton blazar). Both frameworks are able to describe the average SED reasonably well, implying comparable jet powers but very different characteristics for the blazar emission site. © 2011. The American Astronomical Society. All rights reserved.

KW - acceleration of particles

KW - BL Lacertae objects: general

KW - BL Lacertae objects: individual (Mrk 421)

KW - galaxies: active

KW - gamma rays: general

KW - radiation mechanisms: non-thermal

U2 - 10.1088/0004-637X/736/2/131

DO - 10.1088/0004-637X/736/2/131

M3 - Article

SN - 0004-637X

VL - 736

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 131

ER -

Fermi large area telescope observations of Markarian 421: The missing piece of its spectral energy distribution

Abstract

Keywords

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