ARGO-YBJ is an air shower detector array with a fully covered layer of resistive plate chambers. It is operated with a high duty cycle and a large field of view. It continuously monitors the northern sky at energies above 0.3 TeV. In this paper, we report a long-term monitoring of Mrk 421 over the period from 2007 November to 2010 February. This source was observed by the satellite-borne experiments Rossi X-ray Timing Explorer and Swift in the X-ray band. Mrk 421 was especially active in the first half of 2008. Many flares are observed in both X-ray and gamma-ray bands simultaneously. The gamma-ray flux observed by ARGO-YBJ has a clear correlation with the X-ray flux. No lag between the X-ray and gamma-ray photons longer than 1 day is found. The evolution of the spectral energy distribution is investigated by measuring spectral indices at four different flux levels. Hardening of the spectra is observed in both X-ray and gamma-ray bands. The gamma-ray flux increases quadratically with the simultaneously measured X-ray flux. All these observational results strongly favor the synchrotron self-Compton process as the underlying radiative mechanism.
LONG-TERM MONITORING OF THE TeV EMISSION FROM Mrk 421 WITH THE ARGO-YBJ EXPERIMENT / Iuppa, Roberto; ARGO YBJ, Collaboration. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 734:2(2011), pp. 11001-11008.
|Titolo:||LONG-TERM MONITORING OF THE TeV EMISSION FROM Mrk 421 WITH THE ARGO-YBJ EXPERIMENT|
|Autori:||Iuppa, Roberto; ARGO YBJ, Collaboration|
|Titolo del periodico:||THE ASTROPHYSICAL JOURNAL|
|Anno di pubblicazione:||2011|
|Numero e parte del fascicolo:||2|
|Codice identificativo Scopus:||2-s2.0-79958253260|
|Codice identificativo ISI:||WOS:000291386500038|
|Digital Object Identifier (DOI):||10.1088/0004-637X/734/2/110|
|Citazione:||LONG-TERM MONITORING OF THE TeV EMISSION FROM Mrk 421 WITH THE ARGO-YBJ EXPERIMENT / Iuppa, Roberto; ARGO YBJ, Collaboration. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 734:2(2011), pp. 11001-11008.|
|Appare nelle tipologie:||03.1 Articolo su rivista (Journal article)|
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