RT Journal Article
T1 Variable very high energy gamma-ray emission from Markarian 501
A1 Antoranz Canales, Pedro
A1 Barrio Uña, Juan Abel
A1 Contreras González, José Luis
A1 Fonseca González, María Victoria
A1 López Moya, Marcos
A1 Miranda Pantoja, José Miguel
A1 Nieto Castaño, Daniel
AB The blazar Mrk 501 was observed at energies above 0.10 TeV with the MAGIC Telescope from 2005 May through July. The high sensitivity of the instrument enabled the determination of the flux and spectrum of the source on a night-by-night basis. Throughout our observational campaign, the flux from Mrk 501 was found to vary by an order of magnitude. Intranight flux variability with flux-doubling times down to 2 minutes was observed during the two most active nights, namely, June 30 and July 9. These are the fastest flux variations ever observed in Mrk 501. The similar to 20 minute long flare of July 9 showed an indication of a 4 +/- 1 minute time delay between the peaks of F(< 0.25 TeV) and F(> 1.2 TeV), which may indicate a progressive acceleration of electrons in the emitting plasma blob. The flux variability was quantified for several energy ranges and found to increase with the energy of the gamma-ray photons. The spectra hardened significantly with increasing flux, and during the two most active nights, a spectral peak was clearly detected at 0.43 +/- 0.06 and 0.25 +/- 0.07 TeV, respectively, for June 30 and July 9. There is no evidence of such a spectral feature for the other nights at energies down to 0.10 TeV, thus suggesting that the spectral peak is correlated with the source luminosity. These observed characteristics could be accommodated in a synchrotron self-Compton framework in which the increase in gamma-ray flux is produced by a freshly injected ( high energy) electron population.
PB IOP Publishing
SN 0004-637X
YR 2007
FD 2007-11-10
LK https://hdl.handle.net/20.500.14352/50890
UL https://hdl.handle.net/20.500.14352/50890
LA eng
NO © The American Astronomical Society. We would like to thank the IAC for the excellent working conditionson the La Palma Observatory Roque de los Muchachos.We are grateful to the RXTE ASMteamfor their quick-look results.The support of the German BMBF andMPG, the Italian INFN,and the Spanish CICYT is gratefully acknowledged. This workwas also supported by ETH research grant TH-34/04-3 and byPolish grant MNiI 1P03D01028. In addition, the authors wantto thank Deirdre Horan, Martin Tluczykont, and Fre´de´ric Pironfor providing Mrk 501 data from WHIPPLE, HEGRA CT1,and HEGRA CT System and CAT, respectively, and for usefuldiscussions.
NO German BMBF
NO German MPG
NO Italian INFN
NO Spanish CICYT
NO ETH
NO Polish grant MNiI
DS Docta Complutense
RD 9 abr 2025