The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10 degrees x 10 degrees, finding a source extension sigma(ext) = 1 degrees.8 +/- 0 degrees.5. The observed differential energy spectrum is dN/dE = (2.5 +/- 0.4) x 10(-11)(E/1 TeV)(-2.6 +/- 0.3) photons cm(-2) s(-1) TeV-1, in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates that the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.

IDENTIFICATION OF THE TeV GAMMA-RAY SOURCE ARGO J2031+4157 WITH THE CYGNUS COCOON / Iuppa, Roberto; ARGO YBJ, Collaboration. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 790:2(2014), pp. 15201-15205. [10.1088/0004-637X/790/2/152]

IDENTIFICATION OF THE TeV GAMMA-RAY SOURCE ARGO J2031+4157 WITH THE CYGNUS COCOON

Iuppa, Roberto;
2014-01-01

Abstract

The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10 degrees x 10 degrees, finding a source extension sigma(ext) = 1 degrees.8 +/- 0 degrees.5. The observed differential energy spectrum is dN/dE = (2.5 +/- 0.4) x 10(-11)(E/1 TeV)(-2.6 +/- 0.3) photons cm(-2) s(-1) TeV-1, in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates that the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.
2014
2
Iuppa, Roberto; ARGO YBJ, Collaboration
IDENTIFICATION OF THE TeV GAMMA-RAY SOURCE ARGO J2031+4157 WITH THE CYGNUS COCOON / Iuppa, Roberto; ARGO YBJ, Collaboration. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - 790:2(2014), pp. 15201-15205. [10.1088/0004-637X/790/2/152]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/162620
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