CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ

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	CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ
	ARGO-YBJ Collaboration
刊名	ASTROPHYSICAL JOURNAL
	2015
卷号	798 期号:2 页码:119
关键词	gamma rays: stars pulsars: individual (Crab Nebula)
英文摘要	The ARGO-YBJ air shower detector monitored the Crab Nebula gamma-ray emission from 2007 November to 2013 February. The integrated signal, consisting of similar to 3.3 x 10(5) events, reached the statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I-0 (E/2TeV)(-alpha), with a flux normalization I-0 = (5.2 +/- 0.2) x 10(-12) photons cm(-2) s(-1) TeV (1) and alpha = 2.63 +/- 0.05, corresponding to an integrated flux above 1 TeV of 1.97 x 10(-11) photons cm(-2) s(-1). The systematic error is estimated to be less than 30% for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I-0 (E/2 TeV)(-alpha) exp (-E/E-cut), the lower limit of the cutoff energy E-cut is 12 TeV, at 90% confidence level. Our extended data set allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 x 10(-2). A correlated analysis with Fermi-LAT data over similar to 4.5 yr using the light curves of the two experiments gives a Pearson correlation coefficient r = 0.56 +/- 0.22. Concerning flux variations on timescales of days, a "blind" search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 +/- 91 photons day(-1), consistent with the average value of 137 +/- 10 day(-1).
学科主题	Astronomy & Astrophysics
类目[WOS]	Astronomy & Astrophysics
收录类别	SCI
WOS记录号	WOS:000350853700054
公开日期	2016-05-03
内容类型	期刊论文
源URL	[http://ir.ihep.ac.cn/handle/311005/228277]
专题	高能物理研究所_粒子天体物理中心
推荐引用方式 GB/T 7714	ARGO-YBJ Collaboration. CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ[J]. ASTROPHYSICAL JOURNAL,2015,798(2):119.
APA	ARGO-YBJ Collaboration.(2015).CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ.ASTROPHYSICAL JOURNAL,798(2),119.
MLA	ARGO-YBJ Collaboration."CRAB NEBULA: FIVE-YEAR OBSERVATION WITH ARGO-YBJ".ASTROPHYSICAL JOURNAL 798.2(2015):119.