(2012) AGILE detection of Cygnus X-3γ-ray active states during the period mid-2009/mid-2010. Astronomy & Astrophysics, Vol.538 . A63. doi:10.1051/0004-6361/201016129 ISSN 0004-6361.

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Abstract

Context. Cygnus X-3 (Cyg X-3) is a well-known microquasar producing variable emission at all wavelengths. Cyg X-3 is a prominent X-ray binary producing relativistic jets, and studying its high energy emission is crucial for the understanding of the fundamental acceleration processes in accreting compact objects.
Aims. Our goal is to study extreme particle acceleration and γ-ray production above 100 MeV during special spectral states of Cyg X-3 usually characterized by a low hard X-ray flux and enhanced soft X-ray states.
Methods. We observed Cyg X-3 with the AGILE satellite in extended time intervals from 2009 Jun.–Jul., and 2009 Nov.–2010 Jul. We report here the results of the AGILE γ-ray monitoring of Cyg X-3 as well as the results from extensive multiwavelength campaigns involving radio (RATAN-600, AMI-LA and Metsähovi Radio Observatories) and X-ray monitoring data (XTE and Swift).
Results. We detect a series of repeated γ-ray flaring activity from Cyg X-3 that correlate with the soft X-ray states and episodes of decreasing or non-detectable hard X-ray emission. Furthermore, we detect γ-ray enhanced emission that tends to be associated with radio flares greater than 1 Jy at 15 GHz, confirming a trend already detected in previous observations. The source remained active above 100 MeV for an extended period of time (almost 1.5 months in 2009 Jun.–Jul. and 1 month in 2010 May). We study in detail the short timescale γ-ray flares that occurred before or near the radio peaks.
Conclusions. Our results confirm the transient nature of the extreme particle acceleration from the microquasar Cyg X-3. A series of repeated γ-ray flares shows correlations with radio and X-ray emission confirming a well established trend of emission. We compare our results with Fermi-LAT and MAGIC TeV observations of Cyg X-3.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Quasars, X-ray binaries
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Official Date:	February 2012
Dates:	Date Event February 2012 Published
Volume:	Vol.538
Page Range:	A63
DOI:	10.1051/0004-6361/201016129
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Date of first compliant deposit:	20 December 2015
Date of first compliant Open Access:	20 December 2015
Funder:	Agenzia spaziale italiana [Italian Space Agency] (ASI), Istituto nazionale di astrofisica (Italy) (INAF), Suomen Akatemia [Academy of Finland]
Grant number:	I/089/06/2 (ASI), I/042/10/0 (ASI), I/009/10/0 (ASI-INAF), 212656 (SA), 210338 (SA)

Data sourced from Thomson Reuters' Web of Knowledge

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