Very high energy gamma-ray observations of strong flaring activity in M87 in 2008 february

dc.contributor.authorAntoranz Canales, Pedro
dc.contributor.authorBarrio Uña, Juan Abel
dc.contributor.authorContreras González, José Luis
dc.contributor.authorFonseca González, Mª Victoria
dc.contributor.authorMiranda Pantoja, José Miguel
dc.contributor.authorNieto, Daniel
dc.description© The American Astronomical Society. We would like to thank the Instituto de Astrofisica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, and Spanish MCI is gratefully acknowledged. This work was also supported by ETH research grant TH 34/043, by the Polish MNiSzW grant N N203 390834, and by the YIP of the Helmholtz Gemeinschaft. We thank Dan Harris for providing preliminary results on Chandra observations.
dc.description.abstractM87 is the only known nonblazar radio galaxy to emit very high energy (VHE) gamma rays. During a monitoring program of M87, a rapid flare in VHE gamma-rays was detected by the MAGIC telescope in early 2008. The flux was found to be variable above 350 GeV on a timescale as short as 1 day at a significance level of 5.6 sigma. The highest measured flux reached 15% of the Crab Nebula flux. We observed several substantial changes of the flux level during the 13 day observing period. The flux at lower energies (150-350 GeV), instead, is compatible with being constant. The energy spectrum can be described by a power law with a photon index of 2.30 +/- 0.11(stat) +/- 0.20(syst). The observed day-scale flux variability at VHE prefers the M87 core as source of the emission and implies that either the emission region is very compact (just a few Schwarzschild radii) or the Doppler factor of the emitting blob is rather large in the case of a nonexpanding emission region.
dc.description.departmentDepto. de Estructura de la Materia, Física Térmica y Electrónica
dc.description.facultyFac. de Ciencias Físicas
dc.description.sponsorshipGerman BMBF
dc.description.sponsorshipGerman MPG
dc.description.sponsorshipItalian INFN
dc.description.sponsorshipSpanish MCI
dc.description.sponsorshipPolish MNiSzW
dc.description.sponsorshipYIP of the Helmholtz Gemeinschaft
dc.identifier.citationAcciari, V. A., et al. (VERITAS Collaboration). 2008, ApJ, 679, 397. Aharonian, F. A. 2000, NewA, 5, 377. Aharonian, F. A., et al. (HEGRA Collaboration). 2003, A&A, 403, L1. Aharonian, F. A., et al. (H. E. S. S. Collaboration). 2006, Science, 314, 1424. Albert, J., et al. (MAGIC Collaboration). 2007, Nucl. Instrum. Methods Phys. Res. A, 583, 494 ———. 2008a, ApJ, 674, 1037 ———. 2008b, Nucl. Instrum. Methods Phys. Res. A, 558, 424 ———. 2008c, preprint (astro-ph/0702475). Beall, J. H., Bednarek, W. 1999, ApJ, 510, 188. Biretta, J. A. 1996, in ASP Conf. Ser. 100, Energy Transport in Radio Galaxies and Quasars, ed. P. E. Hardee et al. (San Francisco: ASP), 187. Bityukov, S., et al. 2006, preprint (physics/0612178). Curtis, H. D. 1918, Publ. Lick Obs., 13, 31. Dar, A., Laor, A. 1997, ApJ, 478, L5. Daum, A., et al. (HEGRA Collaboration). 1997, Astropart. Phys., 8, 1. Fanaroff, B. L., Riley, J. M. 1974, MNRAS, 167, 31P. Forman, W., et al. 2007, ApJ, 665, 1057. Georganopoulos, M., Perlman, E. S., Kazanas, D. 2005, ApJ, 634, L33. Ghisellini, G., Tavecchio, F., Chiaberge, M. 2005, A&A, 432, 401. Harris, D. E. 2006, ApJ, 640, 211. Hillas, A. M. 1985, in Proc. 19th Int. Cosmic Ray Conf. (La Jolla), 3, 445. Honda, M., Honda, Y. S. 2007, ApJ, 654, 885. Lenain, J.-P., Boisson, C., Sol, H., Katarzyński, K. 2008, A&A, 478, 111. Li, T.-P., Ma, Y.-Q. 1983, ApJ, 272, 317. Macchetto, F., et al. 1997, ApJ, 489, 579. Macri, L. M., et al. 1999, ApJ, 521, 155. Mannheim, K. 1993, A&A, 269, 67. Maraschi, L., Ghisellini, G., Celotti, A. 1992, ApJ, 397, L5. Marshall, H. L., et al. 2002, ApJ, 564, 683. Mu¨cke, A., Protheroe, R. J. 2001, Astropart. Phys., 15, 121. Neronov, A., Aharonian, F. A. 2007, ApJ, 671, 85. Perlman, E. S., Harris, D. E., Biretta, J. A. 2003, ApJ, 599, L65. Protheroe, R. J., Donea, A.-C., Reimer, A. 2003, Astropart. Phys., 19, 559. Rieger, F. M., Aharonian, F. A. 2008, A&A, 479, L5. Stawarz, Ł., Sikora, M., Ostrowski, M. 2003, ApJ, 597, 186. Tavecchio, F., Ghisellini, G. 2008, MNRAS, 385, L98. Tescaro, D., et al. (MAGIC Collaboration). 2007, preprint(arXiv:0709.1410). Tsvetanov, Z. I., et al. 1998, ApJ, 493, L83. Wilson, A. S., Yang, Y. 2002, ApJ, 568, 133.
dc.journal.titleAstrophysical journal letters
dc.publisherIOP Publishing
dc.relation.projectIDTH 34/043
dc.relation.projectIDN203 390834
dc.rights.accessRightsopen access
dc.subject.keywordSupermassive Black-Hole
dc.subject.keywordTEV Emission
dc.subject.keywordLAC Objects
dc.subject.keywordGalaxy M87
dc.subject.ucmElectrónica (Física)
dc.subject.ucmFísica nuclear
dc.subject.unesco2202.03 Electricidad
dc.subject.unesco2207 Física Atómica y Nuclear
dc.titleVery high energy gamma-ray observations of strong flaring activity in M87 in 2008 february
dc.typejournal article
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
153.71 KB
Adobe Portable Document Format