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Article: Diffuse gamma-ray emission from the Galactic center - A multiple energy injection model

TitleDiffuse gamma-ray emission from the Galactic center - A multiple energy injection model
Authors
KeywordsBlack hole physics
Cosmic rays
Galaxy: center
Gamma rays: theory
Radiation mechanisms: non-thermal
Issue Date2007
PublisherE D P Sciences. The Journal's web site is located at http://www.aanda.org
Citation
Astronomy And Astrophysics, 2007, v. 473 n. 2, p. 351-356 How to Cite?
AbstractWe suggest that the energy source of the observed diffuse gamma-ray emission from the direction of the Galactic center is the Galactic black hole Sgr A*, which becomes active when a star is captured at a rate of ∼10-5 yr-1. Subsequently the star is tidally disrupted and its matter is accreted into the black hole. During the active phase relativistic protons with a characteristic energy ∼6 × 1052 erg per capture are ejected. Over 90% of these relativistic protons disappear due to proton-proton collisions on a timescale τpp ∼ 10 4 years in the small central bulge region with radius ∼50 pc within Sgr A*, where the density is ≥103 cm-3. The gamma-ray intensity, which results from the decay of neutral pions produced by proton-proton collisions, decreases according to e-t/ τpp, where t is the time after last stellar capture. Less than 5% of relativistic protons escaped from the central bulge region can survive and maintain their energy for >107 years due to much lower gas density outside, where the gas density can drop to ∼1 cm-3. They can diffuse to a ∼500 pc region before disappearing due to proton-proton collisions. The observed diffuse GeV gamma-rays resulting from the decay of neutral pions produced via collision between these escaped protons and the gas in this region is expected to be insensitive to time in the multiinjection model with the characteristic injection rate of 10-5 yr-1. Our model calculated GeV and 511 keV gamma-ray intensities are consistent with the observed results of EGRET and INTEGRAL, however, our calculated inflight annihilation rate cannot produce sufficient intensity to explain the COMPTEL data. © ESO 2007.
Persistent Identifierhttp://hdl.handle.net/10722/80781
ISSN
2014 Impact Factor: 4.378
2015 SCImago Journal Rankings: 2.446
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorCheng, KSen_HK
dc.contributor.authorChernyshov, DOen_HK
dc.contributor.authorDogiel, VAen_HK
dc.date.accessioned2010-09-06T08:10:12Z-
dc.date.available2010-09-06T08:10:12Z-
dc.date.issued2007en_HK
dc.identifier.citationAstronomy And Astrophysics, 2007, v. 473 n. 2, p. 351-356en_HK
dc.identifier.issn0004-6361en_HK
dc.identifier.urihttp://hdl.handle.net/10722/80781-
dc.description.abstractWe suggest that the energy source of the observed diffuse gamma-ray emission from the direction of the Galactic center is the Galactic black hole Sgr A*, which becomes active when a star is captured at a rate of ∼10-5 yr-1. Subsequently the star is tidally disrupted and its matter is accreted into the black hole. During the active phase relativistic protons with a characteristic energy ∼6 × 1052 erg per capture are ejected. Over 90% of these relativistic protons disappear due to proton-proton collisions on a timescale τpp ∼ 10 4 years in the small central bulge region with radius ∼50 pc within Sgr A*, where the density is ≥103 cm-3. The gamma-ray intensity, which results from the decay of neutral pions produced by proton-proton collisions, decreases according to e-t/ τpp, where t is the time after last stellar capture. Less than 5% of relativistic protons escaped from the central bulge region can survive and maintain their energy for >107 years due to much lower gas density outside, where the gas density can drop to ∼1 cm-3. They can diffuse to a ∼500 pc region before disappearing due to proton-proton collisions. The observed diffuse GeV gamma-rays resulting from the decay of neutral pions produced via collision between these escaped protons and the gas in this region is expected to be insensitive to time in the multiinjection model with the characteristic injection rate of 10-5 yr-1. Our model calculated GeV and 511 keV gamma-ray intensities are consistent with the observed results of EGRET and INTEGRAL, however, our calculated inflight annihilation rate cannot produce sufficient intensity to explain the COMPTEL data. © ESO 2007.en_HK
dc.languageengen_HK
dc.publisherE D P Sciences. The Journal's web site is located at http://www.aanda.orgen_HK
dc.relation.ispartofAstronomy and Astrophysicsen_HK
dc.subjectBlack hole physicsen_HK
dc.subjectCosmic raysen_HK
dc.subjectGalaxy: centeren_HK
dc.subjectGamma rays: theoryen_HK
dc.subjectRadiation mechanisms: non-thermalen_HK
dc.titleDiffuse gamma-ray emission from the Galactic center - A multiple energy injection modelen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0004-6361&volume=473&spage=351&epage=356&date=2007&atitle=Diffuse+gamma-ray+emission+from+the+Galactic+center+-+a+multiple+energy+injection+modelen_HK
dc.identifier.emailCheng, KS: hrspksc@hkucc.hku.hken_HK
dc.identifier.authorityCheng, KS=rp00675en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1051/0004-6361:20077538en_HK
dc.identifier.scopuseid_2-s2.0-34948824996en_HK
dc.identifier.hkuros137810en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-34948824996&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume473en_HK
dc.identifier.issue2en_HK
dc.identifier.spage351en_HK
dc.identifier.epage356en_HK
dc.identifier.isiWOS:000249957900003-
dc.publisher.placeFranceen_HK
dc.identifier.scopusauthoridCheng, KS=9745798500en_HK
dc.identifier.scopusauthoridChernyshov, DO=14059433800en_HK
dc.identifier.scopusauthoridDogiel, VA=6603566238en_HK

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