Rise and fall of the X-ray flash 080330: an off-axis jet?

	Rise and fall of the X-ray flash 080330: an off-axis jet?
	Guidorzi, C 1,2,3; Clemens, C 4; Kobayashi, S 2; Granot, J 5; Melandri, A 2; D'Avanzo, P 1; Kuin, NPM 6; Klotz, A 7,8; Fynbo, JPU 9; Covino, S 1
刊名	ASTRONOMY & ASTROPHYSICS
	2009-05
卷号	499 期号:2 页码:439-U108
关键词	gamma rays: bursts X-rays: individual: XRF 080330
ISSN号	0004-6361
通讯作者	Guidorzi, C (reprint author), INAF Osservatorio Astron Brera, Via E Bianchi 46, I-23807 Merate, LC, Italy.
产权排序	第十完成单位
英文摘要	Context. X-ray flashes (XRFs) are a class of gamma-ray bursts (GRBs) with a peak energy of the time-integrated. F. spectrum, E(p), typically below 30 keV, whereas classical GRBs have Ep of a few hundreds of keV. Apart from Ep and the systematically lower luminosity, the properties of XRFs, such as their duration or spectral indices, are typical of the classical GRBs. Yet, the nature of XRFs and their differences from GRBs are not understood. In addition, there is no consensus on the interpretation of the shallow decay phase observed in most X-ray afterglows of both XRFs and GRBs. Aims. We examine in detail the case of XRF 080330 discovered by Swift at redshift 1.51. This burst is representative of the XRF class and exhibits an X-ray shallow decay. The rich broadband (from NIR to UV) photometric data set we collected during this phase makes it an ideal candidate for testing the off-axis jet interpretation proposed to explain both the softness of XRFs and the shallow decay phase. Methods. We present prompt gamma-ray, early and late NIR/visible/UV and X-ray observations of the XRF 080330. We derive a spectral energy distribution from NIR to X-ray bands across the shallow/plateau phase and describe the temporal evolution of the multiwavelength afterglow within the context of the standard afterglow model. Results. The multiwavelength evolution of the afterglow is achromatic from similar to 10(2) s to similar to 8 x 10(4) s. The energy spectrum from NIR to X-ray is reproduced well by a simple power-law, F(v) proportional to v(-beta ox), with beta(ox) = 0.79 +/- 0.01 and negligible rest-frame dust extinction. The light curve can be modelled by either a piecewise power-law or the combination of a smoothly broken power law with an initial rise up to similar to 600 s, a plateau lasting up to similar to 2 ks, followed by a gradual steepening to a power-law decay index of similar to 2 until 82 ks. At this point, a bump appears to be modelled well with a second component, while the corresponding optical energy spectrum, F(v) proportional to v(-beta o), reddens Delta beta(o) = 0.26 +/- 0.06. Conclusions. A single-component jet viewed off-axis can explain the light curve of XRF 080330, the late-time reddening being due to the reverse shock of an energy injection episode and its being an XRF. Other possibilities, such as the optical rise marking the pre-deceleration of the fireball within a wind environment, cannot be excluded definitely, but appear to be contrived. We exclude the possibility of a dust decreasing column density being swept up by the fireball as explaining the rise of the afterglow.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	AFTERGLOW LIGHT CURVES ; BURST ALERT TELESCOPE ; LORENTZ FACTOR ; E-P,E-I-E-ISO CORRELATION ; SWIFT OBSERVATIONS ; SPECTRAL CATALOG ; 2-COMPONENT JET ; CENTRAL ENGINE ; EMISSION ; MODELS
收录类别	SCI ; EI
原文出处	http://www.aanda.org/articles/aa/abs/2009/20/aa11719-09/aa11719-09.html
语种	英语
WOS记录号	WOS:000266730500010
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/4983]
专题	云南天文台_高能天体物理研究组
作者单位	1.INAF – Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy 2.Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Birkenhead CH41 1LD, UK 3.Dipartimento di Fisica, Università di Ferrara, via Saragat 1, 44100 Ferrara, Italy 4.Max-Planck-Institut für extraterrestrische Physik, 85740 Garching, Germany 5.Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB, UK 6.Mullard Space Science Laboratory/UCL, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK 7.Observatoire de Haute-Provence, 04870 Saint-Michel l'Observatoire, France 8.CESR, Observatoire Midi-Pyrénées, CNRS, Université de Toulouse, BP 4346, 31028 Toulouse Cedex 04, France 9.Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, 2100 København Ø, Denmark 10.Yunnan Observatory, National Astronomical Observatories, Chinese Academy of Sciences, PO Box 110, Kunming, Yunnan Province 650011, PR China
推荐引用方式 GB/T 7714	Guidorzi, C,Clemens, C,Kobayashi, S,et al. Rise and fall of the X-ray flash 080330: an off-axis jet?[J]. ASTRONOMY & ASTROPHYSICS,2009,499(2):439-U108.
APA	Guidorzi, C.,Clemens, C.,Kobayashi, S.,Granot, J.,Melandri, A.,...&Gehrels, N.(2009).Rise and fall of the X-ray flash 080330: an off-axis jet?.ASTRONOMY & ASTROPHYSICS,499(2),439-U108.
MLA	Guidorzi, C,et al."Rise and fall of the X-ray flash 080330: an off-axis jet?".ASTRONOMY & ASTROPHYSICS 499.2(2009):439-U108.