Identification of the TeV gamma-ray source ARGO J2031+4157 with the Cygnus Cocoon

Journal Article · Fri Aug 01 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/790/2/152· OSTI ID:22365469

Bartoli, B.; Catalanotti, S.; D'Ettorre Piazzoli, B.; Di Girolamo, T. ^[1]; Bernardini, P.; D'Amone, A.; De Mitri, I. ^[2]; Bi, X. J.; Cao, Z.; Chen, S. Z. ^[3]; Branchini, P.; Budano, A. ^[4]; Camarri, P. ^[5]; Cardarelli, R.; Di Sciascio, G. ^[6]; Chen, T. L.; Danzengluobu, ^[7]; Creti, P. ^[8]; Cui, S. W. ^[9]; others, and

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1. Dipartimento di Fisica dell'Università di Napoli "Federico II," Complesso Universitario di Monte Sant'Angelo, via Cinthia, I-80126 Napoli (Italy)
2. Dipartimento Matematica e Fisica "Ennio De Giorgi," Università del Salento, via per Arnesano, I-73100 Lecce (Italy)
3. Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, 100049 Beijing (China)
4. Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy)
5. Dipartimento di Fisica dell'Università di Roma "Tor Vergata," via della Ricerca Scientifica 1, I-00133 Roma (Italy)
6. Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata, via della Ricerca Scientifica 1, I-00133 Roma (Italy)
7. Tibet University, 850000 Lhasa, Xizang (China)
8. Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, via per Arnesano, I-73100 Lecce (Italy)
9. Hebei Normal University, Shijiazhuang 050016, Hebei (China)

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° × 10°, finding a source extension σ{sub ext}= 1.°8 ± 0.°5. The observed differential energy spectrum is dN/dE = (2.5 ± 0.4) × 10{sup –11}(E/1 TeV){sup –2.6±0.3} photons cm{sup –2} s{sup –1} TeV{sup –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.

• OSTI ID: 22365469
• Journal Information: Astrophysical Journal, Vol. 790, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCELERATION
COSMIC RADIATION
DISTRIBUTION
ENERGY SPECTRA
GAMMA RADIATION
GAMMA SOURCES
GAUSS FUNCTION
GEV RANGE
PHOTONS
STARS
SUPERNOVA REMNANTS
TEV RANGE
TWO-DIMENSIONAL CALCULATIONS