Aschenbach 2007 SN 1987A的X射线演变

主要内容:
差不多8000天的观测，还在一直上升，说明肯定是遗迹的贡献。

精彩摘抄:


文章信息:

X-ray Evolution of SN 1987A

Authors: Bernd Aschenbach

(Submitted on 23 May 2007)

Abstract: The X-ray observations of SN 1987A over the previous 20 years have seen the emergence of soft X-rays from the interaction of the explosion shock wave with the ambient medium. This shock wave is now interacting strongly with the inner ring and might have passed already the highest density regions. The emission can be described by thermal models with two temperatures, with perhaps some but little change over time. Relative to the elemental abundances prevailing in the LMC the inner ring shows an overabundance of Si and S compared to the lighter elements and Fe, which suggests that the ring consists of highly processed matter dredged up in a binary merger event well before the explosion. The X-ray lightcurves between 0.5--2 keV and 3--10 keV differ significantly in slope, with the latter being much flatter but very similar to the radio light curve.

Manchester 2002 SN 1987A的射电10年观测

主要内容:
与上一篇文章相比主要是光变曲线，而不是图像的变化（也就是信息更少）。

精彩摘抄:


文章信息:
Publ. Astron. Soc. Aust., 2002, 19, 207–221

Evolution of the Radio Remnant of SN 1987A: 1990–2001

R. N. Manchester1, B. M. Gaensler2 , V. C. Wheaton1,3, L. Staveley-Smith1,
A. K. Tzioumis1, N. S. Bizunok2,4, M. J. Kesteven1 and J. E. Reynolds1

Gaensler 2007 SN 1987A的15年观测－射电图像

主要内容:
给出了射电的图像随时间的膨胀的观测。

精彩摘抄:


文章信息:
arXiv:0705.0057 [ps, pdf, other]

Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A

Authors: B. M. Gaensler (1), L. Staveley-Smith (2), R. N. Manchester (3), M. J. Kesteven (3), L. Ball (3), A. K. Tzioumis (3) ((1) U. Sydney, (2) U. Western Australia, (3) ATNF)

(Submitted on 1 May 2007 (v1), last revised 17 May 2007 (this version, v2))

Abstract: Supernova 1987A in the Large Magellanic Cloud provides a spectacularly detailed view of the aftermath of a core-collapse explosion. The supernova ejecta initially coasted outward at more than 10% of the speed of light, but in 1990 were observed to decelerate rapidly as they began to encounter dense circumstellar material expelled by the progenitor star. The resulting shock has subsequently produced steadily brightening radio synchrotron emission, which is resolved by the Australia Telescope Compact Array (ATCA) into an expanding limb-brightened shell. Here we present 15 years of ATCA imaging of Supernova 1987A, at an effective angular resolution of 0.4 arcsec. We find that the radio remnant has accelerated in its expansion over this period, from approx 3600 km/s in 1992 to approx 5200 km/s at the end of 2006. The published diameters of the evolving X-ray shell have been ~15% smaller than the corresponding radio values, but a simultaneous Fourier analysis of both radio and X-ray data eliminates this discrepancy, and yields a current diameter for the shell in both wave-bands of approx 1.7 arcsec. An asymmetric brightness distribution is seen in radio images at all ATCA epochs: the eastern and western rims have higher fluxes than the northern and southern regions, indicating that most of the radio emission comes from the equatorial plane of the system, where the progenitor star's circumstellar wind is thought to be densest. The eastern lobe is brighter than and further from the supernova site than the western lobe, suggesting an additional asymmetry in the initial distribution of supernova ejecta.

Chugai 2006 SN Ib/c 2001em晚期射电辐射的解释

主要内容:
认为是超新星的喷出物与之前抛出的氢包层的碰撞产生激波所致。

精彩摘抄:


文章信息:
The Astrophysical Journal, 641:1051–1059, 2006 April 20

LATE EMISSION FROM THE TYPE Ib/c SN 2001em: OVERTAKING THE HYDROGEN ENVELOPE

Nikolai N. Chugai and Roger A. Chevalier

Ghisellini 2007 伽玛暴标准烛光关系在宇宙学上的应用

主要内容:
总结了一些标准烛光关系，以及用于作宇宙学的步骤。

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文章信息:
arXiv:0705.4472 [ps, pdf, other] : Title: Cosmological implications of Gamma Ray Bursts
Authors: Gabriele Ghisellini (Oss. Astr. di Brera, Italy)
Comments: 8 pages, 4 figures, invited talk at the meeting of the Italian Astron. Society

The discovery that the bolometric energetics (and/or peak luminosity) of Gamma Ray Bursts correlates with their spectral properties has allowed to standardize the burst energetics to such a degree to enable their use for constraining the cosmological parameters, in the same way as SN Ia. With respect to SN Ia, there is the advantage of having sources free from extinction problems, and easily detectable also at large redshifts. On the other hand, these spectral-energy correlations are not yet understood, and bursts with a complete set of information (to standardize their energetics) are still few (two dozens). There have been already attempts to use these bursts to constrain Omega_Lambda and Omega_M, and even the dark energy equation of state. These results are very encouraging.

Elmhamdi 2004 SN Ib 1990I的观测

主要内容:
给出了这个超新星的详细光学观测，还给出了几个其他Ib/c型超新星的主要数据。

精彩摘抄:
几个Ib/c型超新星的光变曲线
几个超新星的类型

文章信息:
SN Ib 1990I: Clumping and Dust in the Ejecta?

A. Elmhamdi1,2, I.J. Danziger3, E. Cappellaro4, M. Della Valle5, C. Gouiffes6, Mark M. Phillips7, M. Turatto

arXiv:astro-ph/0407145v1, A&A 2004

Anupama 2005 Ib型SN 2005bf的观测

主要内容:
认为是一个大质量氦星的爆发，外层包围着薄的氢包层。

精彩摘抄:


文章信息:
THE PECULIAR TYPE Ib SUPERNOVA SN 2005bf: EXPLOSION OF A MASSIVE He STAR WITH A THIN HYDROGEN ENVELOPE?

G. C. Anupama,1 D. K. Sahu,1 J. Deng,2 K. Nomoto,3 N. Tominaga,3 M. Tanaka,3 P. A. Mazzali,3,4,5 and T. P. Prabhu1

The Astrophysical Journal, 631:L125–L128, 2005 October 1

Drago 2007 致密星的夸克相变和伽玛暴的联系

主要内容:


精彩摘抄:


文章信息:
arXiv:0705.4418 [ps, pdf, other] : Title: Formation of Quark Phases in compact stars and their connection to Gamma-Ray-Bursts
Authors: A. Drago, G. Pagliara, J. Schaffner-Bielich
Comments: 6 pages, 3 figures, to appear in the proceedings of 3th International Conference on Nuclear Physics in Astrophysics (NPAIII), 26 - 31 March 2007 Dresden, Germany

We analyse the occurrence of quiescent times in the temporal structure of the Gamma-Ray-Bursts (GRBs) light curves. We show that if a long quiescent time is present, it is possible to divide the total duration of GRBs into three periods: the pre-quiescence emission, the quiescent time and the post-quiescence emission. We then discuss a model of the GRBs inner engine based on the formation of quark phases during the life of an hadronic star. Within this model the pre-quiescence emission is interpreted as due to the deconfinement of quark inside an hadronic star and the formation of 2SC quark matter. The post-quiescence emission is due to the conversion of 2SC into the Color-Flavor-Locking (CFL) phase. The temporal delay between these two processes is connected with the nucleation time of the CFL phase in the 2SC phase and it can be associated with the observed quiescent times in the GRBs light curves. The stability of CFL cores in compact stars is also discussed.

Li 2007 长伽玛暴不是标准烛光之Amati关系

主要内容:
重新讨论Amati关系，用Eiso = a + b log Epeak，把长伽玛暴按红移从小到大分成4组，结果a和b变化很大，说明该关系随红移变化，不能作为标准烛光。

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文章信息:
arXiv:0705.4401 [ps, pdf, other] : Title: Are Gamma-Ray Bursts Standard Candles?
Authors: Li-Xin Li
Comments: 4 pages, including 4 figures. To appear in the proceedings of "070228: The Next Decade of GRB afterglows", Amsterdam, 19-23 March 2007

By dividing a sample of 48 long-duration gamma-ray bursts (GRBs) into four groups with redshift from low to high and fitting each group with the Amati relation log Eiso = a + b log Epeak, I find that parameters a and b vary with the mean redshift of the GRBs in each group systematically and significantly. The results suggest that GRBs evolve strongly with the cosmic redshift and hence are not standard candles.

http://www.arxiv.org/abs/0704.3128
Variation of the Amati Relation with the Cosmological Redshift: a Selection Effect or an Evolution Effect?

Authors: Li-Xin Li (MPA)

(Submitted on 24 Apr 2007)

Abstract: Because of the limit in the number of gamma-ray bursts (GRBs) with available redshifts and spectra, all current investigations on the correlation among GRB variables use burst samples with redshifts that span a very large range. The evolution and selection effects have thus been ignored, which might have important influence on the results. In this Letter, we divide the 48 long-duration GRBs in Amati (2006, 2007) into four groups with redshift from low to high, each group contains 12 GRBs. Then we fit each group with the Amati relation $\log E_\iso = a + b \log E_\p$, and check if the parameters $a$ and $b$ evolve with the GRB redshift. We find that $a$ and $b$ vary with the mean redshift of the GRBs in each group systematically and significantly. Monte-Carlo simulations show that there is only $\sim 4$ percent of chance that the variation is caused by the selection effect arising from the fluence limit. Hence, our results may indicate that GRBs evolve strongly with the cosmological redshift.

Comments:

5 pages, including 5 figures. MNRAS Letters accepted

Price 2007 GRB 060510B的宿主星系

主要内容:
给出了GRB 060510B的宿主星系的观测，给出了一些元素丰度。

精彩摘抄:


文章信息:
arXiv:0705.4101 [ps, pdf, other] : Title: Properties of a Gamma Ray Burst Host Galaxy at z ~ 5
Authors: P. A. Price, A. Songaila, L. L. Cowie, J. Bell Burnell, E. Berger, A. Cucchiara, D. B. Fox, I. Hook, S. R. Kulkarni, B. Penprase, K. C. Roth, B. Schmidt
Comments: Accepted for publication in ApJ Letters

We describe the properties of the host galaxy of the gamma-ray burst GRB060510B based on a spectrum of the burst afterglow obtained with the Gemini North 8m telescope. The galaxy lies at a redshift of z = 4.941 making it the fourth highest spectroscopically identified burst host. However, it is the second highest redshift galaxy for which the quality of the spectrum permits a detailed metallicity analysis. The neutral hydrogen column density has a logarithmic value of 21.0--21.2 cm^-2 and the weak metal lines of Ni, S and Fe show that the metallicity is in excess of a tenth of solar which is far above the metallicities in damped Lyman alpha absorbers at high redshift. The tightest constraint is from the Fe lines which place [Fe/H] in excess of -0.8. We argue that the results suggest that metallicity bias could be a serious problem with inferring star formation from the GRB population and consider how future higher quality measurements could be used to resolve this question.

Galli 2007 外激波的逆康普顿散射

主要内容:
认为可对高能的Flare和余辉的高能负责。

精彩摘抄:


文章信息:
arXiv:0705.4061 [ps, pdf, other] : Title: High energy afterglows and flares from Gamma-Ray Burst by Inverse Compton emission
Authors: A. Galli (1,2,3), L. Piro (1) ((1) IASF-Roma/INAF, (2) Univerisita' di Roma "La Sapienza", (3) INFN-Trieste)
Comments: 15 pages, 20 figures, submitted to Astronomy and Astrophysics

We perform a detailed study of Inverse Compton (IC) emission for a fireball undergoing External Shock (ES) in either a uniform or a wind-like interstellar medium, and assess the relative importance of IC and synchrotron emission. We determine the primary model parameters driving the IC to synchrotron emission ratio in the case of a short duration central engine. We then investigate the case of ES by a long duration central engine, a model that can account for some of the flares observed in Gamma-ray Bursts X-ray light curves at late times. We present model predictions, in particular in terms of GeV vs X-ray behaviour, and compare them with other models proposed to explain the origin of flares. We find that if most of the emission occurs when the fireball is in the fast cooling regime then a substantial GeV emission is expected. In particular we are able to account for the delayed emission observed in GRB940217. In the case of ES by a long duration central engine we find that IC scattering of X-ray flare photons can produce high energy flares in the GeV band, that can be detected by the Large Area Telescope aboard GLAST. Observations by Swift and GLAST will thus help in discriminating between these models.

Chattopadhyay 2007 伽玛暴可分三类

主要内容:
把原来的长暴再分为低亮度（各向同性能10^52erg）和高亮度的。认为短暴、低亮长暴和高亮长暴分别来源于：双中子星、中子星白矮星并合和大质量恒星坍缩。

精彩摘抄:


文章信息:
arXiv:0705.4020 [ps, pdf, other] : Title: Statistical Evidence for Three classes of Gamma-ray Bursts
Authors: {Tanuka Chattopadhyay (Dinobundhoo Coll.), Ranjeev Misra (IUCAA), Asis Kumar Chattopadhyay (Dept. of Statistics, Calcutta Univ.), Malay Naskar (NIRJAIT)
Comments: 7 pages, accepted for publication in the Astrophysical Journal

Two different multivariate clustering techniques, the K-means partitioning method and the Dirichlet process of mixture modeling, have been applied to the BATSE Gamma-ray burst (GRB) catalog, to obtain the optimum number of coherent groups. In the standard paradigm, GRB are classified in only two groups, the long and short bursts. However, for both the clustering techniques, the optimal number of classes was found to be three, a result which is consistent with previous statistical analysis. In this classification, the long bursts are further divided into two groups which are primarily differentiated by their total fluence and duration and hence are named low and high fluence GRB. Analysis of GRB with known red-shifts and spectral parameters suggests that low fluence GRB have nearly constant isotropic energy output of 10^{52} ergs while for the high fluence ones, the energy output ranges from 10^{52} to 10^{54} ergs. It is speculated that the three kinds of GRB reflect three different origins which may be mergers of neutron star systems, white dwarf with neutron stars and collapse of massive stars.

Li 2007 跨相对论超新星Shock Breakou处的逆康普顿散射

主要内容:
主要针对GRB 060218/SN 2006aj， 在Breakout的地方的热光子被激波化电子逆康普顿散射，产生观测到的伽玛暴辐射。

精彩摘抄:


文章信息:
arXiv:0705.3958 [ps, pdf, other] : Title: Photon Acceleration at Shock Breakout of Trans-Relativistic Supernova
Authors: Zhuo Li, Xiang-Yu Wang, Eli Waxman, Peter Meszaros
Comments: 5 pages, 2 figs, talk at Amsterdam 2007 GRB meeting. No figs in the version for the proceedings "070228: The Next Decade of Gamma-Ray Burst Afterglows", eds. Wijers, R.A.M.J., Kaper, L, and van Eerten, H.J., Elsevier (Amsterdam)

The predicted thermal flash from SN shock breakout might have been detected for the first time by Swift in GRB 060218/SN 2006aj. The detected thermal X-ray emission in this event implies emergence of a trans-relativistic (TR) SN shock with kinetic energy of E_k>1E49 erg. During TRSN shock breakout, the thermal photons could be "accelerated" by the shock through repeated bulk Compton scattering, forming a nonthermal gamma/X-ray component with dominant energy over thermal one. This mechanism of "photon acceleration" at TRSN shock breakout might also account for gamma-rays in the other similar low-luminosity GRBs, implying that they are atypical GRBs with only TR outflows. TRSNe form a peculiar type of SNe with large kinetic energy, >1E49 erg, in TR ejecta, \Gamma\beta ~2.

Middleditch 2007 SN 1987A可能也和伽玛暴成协

主要内容:
认为SN 1987A是有一对有共同包层的双致密星（简并星）并合所产生，在极向可能产生长而软的伽玛暴。

精彩摘抄:


文章信息:
arXiv:0705.3846 [ps, pdf, other] : Title: The SN 1987A Link to Gamma-Ray Bursts
Authors: John Middleditch
Comments: 5 pages, 3 figures, contributed talk proceedings for "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCray

Early measurements of SN 1987A indicate a beam/jet (BJ) which hit polar ejecta (PE) to produce the "Mystery Spot" (MS). The SN flash takes an extra 8 d to hit the MS, and this was confirmed at 2e39 ergs/s in the optical at day 8. A ramp in luminosity starting near day 10 indicates particles from the BJ hitting the PE, with the fastest particles traveling at 0.8 c, and an upper limit for the optical luminosity of the MS of 5e40 ergs/s at day 20. The details of SN 1987A suggest that it resulted from a merger of two stellar cores of a common envelope (CE) binary, i.e. a DD-initiated SN, and is thus the Rosetta Stone for 99% of MSPs in the non-core-collapsed globular clusters, GRBs, and SNe, including all recent nearby SNe except SN 1986J and the more distant SN 2006gy. Without having to blast through the CE of Sk -69 202, it is likely that the BJ would have caused a full, long-soft gamma-ray burst (lGRB) upon hitting the PE, thus DD is a mechanism which can produce lGRBs. The typical 0.5 deg collimation of a GRB, over the 22 l-d from SN 1987A to its PE, produces ~100 s of delay, MATCHING the observed delay of the non-prompt parts of lGRBs. Because DD must be the dominant SN mechanism in elliptical galaxies, where only short, hard GRBs (sGRBs) have been observed, DD without CE or PE must also produce sGRBs, and thus the initial photon spectrum of 99% of ALL GRBs is KNOWN, and neutron star (NS)-NS mergers may not make GRBs as we know them. Observational details of Ia's strongly suggest that these are also DD, implying another systematic effect in Ia Cosmology, as Ia's will appear to be Ic's when viewed from their DD merger poles, given sufficient matter above that lost to core-collapse (otherwise it would just beg the question of what ELSE they could possibly be). There is no need to invent exotica to account for GRBs.

Dessart 2007 接在吸积坍缩白矮星之后的旋转磁场可能导致伽玛暴爆发

主要内容:
AIC, 吸积导致的白矮星的塌缩本身，经过MHD数值模拟认为不太能在早期产生原始中子星的时候产生伽玛暴。可能会在接着磁星导致Poyting流的时候产生伽玛暴。

精彩摘抄:


文章信息:
arXiv:0705.3678 [ps, pdf, other] : Title: Magnetically-driven explosions of rapidly-rotating white dwarfs following Accretion-Induced Collapse
Authors: Luc Dessart, Adam Burrows, Eli Livne, Christian Ott
Comments: 15 pages, 7 figures, paper submitted to ApJ; High resolution version available at this http URL

We present 2D multi-group flux-limited diffusion magnetohydrodynamics (MHD) simulations of the Accretion-Induced Collapse (AIC) of a rapidly-rotating white dwarf. We focus on the dynamical role of MHD processes after the formation of a millisecond-period protoneutron star. We find that including magnetic fields and stresses can lead to a powerful explosion with an energy of a few Bethe, rather than a weak one of at most 0.1 Bethe, with an associated ejecta mass of ~0.1Msun, instead of a few 0.001Msun. The core is spun down by ~30% within 500ms after bounce, and the rotational energy extracted from the core is channeled into magnetic energy that generates a strong magnetically-driven wind, rather than a weak neutrino-driven wind. Baryon loading of the ejecta, while this wind prevails, precludes it from becoming relativistic. This suggests that a GRB is not expected to emerge from such AICs during the early protoneutron star phase, except in the unlikely event that the massive white dwarf has sufficient mass to lead to black hole formation. In addition, we predict both negligible 56Ni-production (that should result in an optically-dark, adiabatically-cooled explosion) and the ejection of 0.1Msun of material with an electron fraction of 0.1-0.2. Such pollution by neutron-rich nuclei puts strong constraints on the possible rate of such AICs. Moreover, being free from ``fallback,'' such highly-magnetized millisecond-period protoneutron stars may later become magnetars, and the magnetically-driven winds may later transition to Poynting-flux-dominated, relativistic winds, eventually detectable as GRBs at cosmological distances. However, the low expected event rate of AICs will constrain them to be, at best, a small subset of GRB and/or magnetar progenitors.

Berger 2003 巡天寻找超新星中的伽玛暴成分－但没找到 3

主要内容:
从1999到2002， 在33个Ibc型超新星中，给出它们的射电光变曲线，企图确认一些包含有超新星成分－－即1年左右的射电余辉会很强。但没有。

精彩摘抄:
除了980425， GRB 030329和970508的射电余辉都很强，比超新星的射电辐射至少强两个量级，说明这些超新星中没有偏轴的伽玛暴成分。


文章信息:

Title:		A Radio Survey of Type Ib and Ic Supernovae: Searching for Engine-driven Supernovae
Authors:		Berger, E.; Kulkarni, S. R.; Frail, D. A.; Soderberg, A. M.
Publication:		The Astrophysical Journal, Volume 599, Issue 1, pp. 408-418. (ApJ Homepage)
Publication Date:		12/2003
Origin:		UCP
ApJ Keywords:		Gamma Rays: Bursts, Radio Continuum: Stars, Stars: Supernovae: General
Abstract Copyright:		(c) 2003: The American Astronomical Society
DOI:		10.1086/379214
Bibliographic Code:		2003ApJ...599..408B

Abstract

The association of γ-ray bursts (GRBs) and core-collapse supernovae (SNe) of Type Ib and Ic was motivated by the detection of SN 1998bw in the error box of GRB 980425 and the now secure identification of SN 2003dh in the cosmological GRB 030329. The bright radio emission from SN 1998bw indicated that it possessed some of the unique attributes expected of GRBs, namely, a large reservoir of energy in (mildly) relativistic ejecta and variable energy input. The two popular scenarios for the origin of SN 1998bw are a typical cosmological burst observed off-axis or a member of a new distinct class of supernova explosions. In the former, about 0.5% of local Type Ib/c SNe are expected to be similar to SN 1998bw; for the latter no such constraint exists. Motivated thus, we began a systematic program of radio observations of most reported Type Ib/c SNe accessible to the Very Large Array. Of the 33 SNe observed from late 1999 to the end of 2002, at most one is as bright as SN 1998bw. From this we conclude that the incidence of such events is <~3%. Furthermore, analysis of the radio emission indicates that none of the observed SNe exhibit clear engine signatures. Finally, a comparison of the SN radio emission to that of GRB afterglows indicates that none of the SNe could have resulted from a typical GRB, independent of the initial jet orientation. Thus, while the nature of SN 1998bw remains an open question, there appears to be a clear dichotomy between the majority of hydrodynamic and engine-driven explosions.

Waxman 2004 GRB 980425的射电辐射的偏轴解释

主要内容:
GRB 980425的暴本身的流量很低，一种解释是偏轴观测。如果这样的话，在一年以后的射电辐射应该会很亮（就像GRB 970508, (970508的晚期射电很亮吗？它被确认是一个偏轴观测的暴吗？)）。不过实际射电观测SN 1998bw比预计的流量低三个量级，作者归结为环境的影响。

同样建议对近处的超新星的射电进行普查。

精彩摘抄:


文章信息:

Title:		The Nature of GRB 980425 and the Search for Off-Axis Gamma-Ray Burst Signatures in Nearby Type Ib/c Supernova Emission
Authors:		Waxman, Eli
Publication:		The Astrophysical Journal, Volume 602, Issue 2, pp. 886-891. (ApJ Homepage)
Publication Date:		02/2004
Bibliographic Code:		2004ApJ...602..886W

Abstract

The identification of Type Ib/c supernovae (SNe Ib/c) as gamma-ray burst (GRB) progenitors is motivated by the association of GRB 980425 with SN 1998bw and of GRB 030329 with SN 2003dh. While the gamma-ray luminosity of GRB 030329 was typical to cosmological GRBs, the luminosity of the nearby (40 Mpc) GRB 980425 was ~5 orders of magnitude lower. The large luminosity difference is commonly explained by hypothesizing either that SNe Ib/c produce two different classes of GRBs or that GRB 980425 was a typical cosmological GRB jet viewed off-axis. In the latter scenario, strong radio emission, L_ν~10³⁰ν^-1/2_10GHz ergs s^-1 Hz^-1, is expected at ~1 yr delay as a result of jet deceleration to subrelativistic speed, as observed from GRB 970508. The radio luminosity of SN 1998bw was 3 orders of magnitude lower than this value. We show that the low radio flux may be consistent with the off-axis jet interpretation, if the density of the wind surrounding the progenitor is lower than typically expected, m≡(M/10^-5M_solaryr^-1)/(v_w/10³kms^-1)~=0.1 instead of m>~1. The lower value of m is consistent with the observed radio emission from the SN shock driven into the wind. This interpretation predicts transition to subrelativistic expansion at ~10 yr delay, with current ~1 mJy 10 GHz flux and m_V~23 optical flux, and with ~10 mas angular source size. It also implies that in order to search for the signature of off-axis GRBs associated with nearby SNe Ib/c, follow-up observations should be carried out on a multiyear timescale.

Stockdale 2003 Ib/c型超新星的伽玛暴喷流成分

主要内容:
企图通过观测近处超新星1年后的射电辐射确认为来自伽玛暴的喷流。但这里仅仅一篇摘要，貌似也没有后续的文章。

精彩摘抄:


文章信息:

Title:		Late-Time Radio Emission from Type Ib/c Supernovae: Testing the Oblique GRB Jet Model
Authors:		Stockdale, C. J.; Van Dyk, S. D.; Weiler, K. W.; Panagia, N.; Sramek, R. A.; Paczynski, B.; Rupen, M. P.
Publication:		American Astronomical Society Meeting 203, #87.02; Bulletin of the American Astronomical Society, Vol. 35, p.1346
Publication Date:		12/2003
Abstract Copyright:		(c) 2003: American Astronomical Society

Abstract

Evidence has been accruing that long-duration GRBs may be associated with some extreme Type Ic supernovae (SNe). Theoretically, GRBs originate from directed, relativistic jets. Their afterglows, particularly in the radio, are seen as their beamed jets, while remaining collimated, decelerate and expand significantly once they become non-relativistic. Yet, most GRB jets will not be pointed along our line-of-sight, with detectable γ - or X-ray emission, but may still be associated with a SN Ic. In this case, recent predictions have been made that the decelerating jet and counterjet should produce detectable radio emission for several SNe Ibb or Ic per year within 200 Mpc, depending on the jet angle relative to the line-of-sight. Furthermore, the jet angle determines how long after the outburst/explosion radio emission will be detected, even >>1 yr for nearby SNe Ib/c. We have tested this intriguing possibility by observing a significant sample of SNe, with 1 yr ≲ age ≲ 10 yr, within 100 Mpc. Preliminary results of this survey will be presented along with their implications.

Paczynski 2001 低红移出的超新星中找伽玛暴

主要内容:
伽玛暴的余辉在1年左右进入非相对论阶段，射电余辉很强。如果对超新星在一年后观测，如果有强的射电辐射，则可能被证实为伽玛暴。

精彩摘抄:


文章信息:

2001AcA....51....1P		1.000	03/2001	A F G X R C S U
	Paczynski, Bohdan		Gamma-Ray Bursts at Low Redshift

Granot 2004 SN 2001em射电辐射的偏轴相对论喷流解释

主要内容:
SN 2001em的射电和X射电都观测到了反常高的流量，Granot 给出了两种解释: 一是与周围介质的强作用；二是相对论性的偏轴喷流。

如果是后者，那偏轴方向上就可能是个伽玛暴。

精彩摘抄:


文章信息:
The Astrophysical Journal, 609:L9–L12, 2004 July 1
THE CASE FOR A MISALIGNED RELATIVISTIC JET FROM SN 2001em
Jonathan Granot and Enrico Ramirez-Ruiz1

Stockdale 2006 M83中历史上超新星的射电和X射线观测

主要内容:
15年的观测，包括6个超新星。SN 1957D, 1923A， 1950B 都是II型超新星； SNe 1945B, 1968L, and 1983N没有在最近的观测中看到，不过没看到正和模型符合。

精彩摘抄:
超新星在M83中的位置：

光变曲线，还包括几个其他的超新星，如1987A


文章信息:

Title:		A Radio and X-Ray Study of Historical Supernovae in M83
Authors:		Stockdale, Christopher J.; Maddox, Larry A.; Cowan, John J.; Prestwich, Andrea; Kilgard, Roy; Immler, Stefan

Publication:		The Astronomical Journal, Volume 131, Issue 2, pp. 889-894. (AJ Homepage)

Abstract

We report the results of 15 years of radio observations of the six historical supernovae (SNe) in M83 using the Very Large Array. We note the near-linear decline in radio emission from SN 1957D, a Type II SN, which remains a nonthermal radio emitter. The measured flux densities from SNe 1923A and 1950B have flattened as they begin to fade below detectable limits; they are also Type II SNe. The luminosities for these three SNe are comparable with the radio luminosities of other decades-old SNe at similar epochs. SNe 1945B, 1968L, and 1983N were not detected in the most recent observations, and these nondetections are consistent with previous studies. We report the X-ray nondetections of all six historical SNe using the Chandra X-Ray Observatory, consistent with previous X-ray searches of other decades-old SNe and low inferred mass-loss rates of the progenitors [M˙~(10^-8 M_solar yr^-1)(v_w/10 km s^-1)].

Woosley 2006 核塌缩型超新星的模型

主要内容:
企图得出无旋转无磁场情况下中微子主导的核塌缩超新星模型（这是一个自然的主导模型，应该算零级近似，而旋转、磁场等应该算一级近似），但是还没有成功。指出超新星的能量来源已经公认为来自引力能；认为超新星应该来自中微子的贡献，而伽玛暴于前身星的旋转有关。（这和我前面那个条目认为伽玛暴与中心黑洞有关不同啊，不过他说得好像也很有道理，因为伽玛暴是高度极束的，只有旋转才能有方向。）

精彩摘抄:


文章信息:

The Physics of Core-Collapse Supernovae

Authors: S. Woosley (UC Santa Cruz), H.-T. Janka (MPI Astrophysics, Garching)

(Submitted on 12 Jan 2006)

Abstract: Supernovae are nature's grandest explosions and an astrophysical laboratory in which unique conditions exist that are not achievable on Earth. They are also the furnaces in which most of the elements heavier than carbon have been forged. Scientists have argued for decades about the physical mechanism responsible for these explosions. It is clear that the ultimate energy source is gravity, but the relative roles of neutrinos, fluid instabilities, rotation and magnetic fields continue to be debated.

Comments:

Review article; 17 pages, 5 figures

Subjects:

Astrophysics (astro-ph)

Journal reference:

Nature Physics 1 (2005) 147

Cite as:

arXiv:astro-ph/0601261v1

ads可以弄到ARAA的文章

这点还真是好. ARAA真吝啬，上面的文章一篇都不让下，在南大和华工都不行。不过在ADS上试了一下（86年的一篇文章），居然能下！是ads扫描的早期的araa的文章。估计是某个时间以前的就不受版权保护了，ads就扫描下来为人民服务了吧。

猜测－－与超新星成协

目前绝大多数长暴观测到于超新星成协，那么伽玛暴和超新星之间会是什么关系呢？（注：这里伽玛暴仅指长暴；超新星仅指Ib/c型超新星）

一一对应、伽玛暴包含超新星、伽玛暴包含于超新星或者伽玛暴和超新星仅仅是有交集？

我的观点是“伽玛暴包含于超新星”。就目前来看，特别是比较近的地方，总是能观测到超新星，但从没看到伽玛暴；可能超新星要多于伽玛暴。

而主要的原因在于它们的最终产物，我的观点是能产生伽玛暴的超新星，中心留下的是黑洞；不能产生伽玛暴的超新星，中心留下的是中子星。因为黑洞是天体里边最终的归宿，它释放的引力能是最大的，而观测上目前最强的爆发是伽玛暴，这二者应该有联系。而很多超新星已经看到中心是中子星。其实这样也许可以认为SN是SN，GRB是GRB，二者没有关系。但观测又说伽玛暴里都有超新星成分（先忽略GRB 060614和GRB 060610， 可能这两个只不过是双致密星并合但时间比较长而已）。于是产生这样的猜测：大质量恒星（多半是WR星）最后坍缩时先在中心产生中子星，发生超新星爆发；接着，如果外部物质足够多，又回落一些使中心变成了黑洞，接着黑洞吸积产生伽玛暴。不过这样的一个推论就是有伽玛暴的超新星中心留下的都是黑洞，没有伽玛暴的超新星中心是中子星。这和目前X射线耀的一部分观点认为是中子星的能量注入观点不一致，不过黑洞吸积盘也可以注入能量的，只要盘还在。

2007-5-26
如果中心形成黑洞就产生伽玛暴，那很大质量的恒星还是很多的，为什么可能只有一部分形成了伽玛暴，其他的没有呢？

猜测： 可能并不是所有大质量恒星最终都形成黑洞，在形成黑洞之前应该有一个阶段是中子星，如果有更多的物质回落，超出中子星的质量极限才形成黑洞。但是形成中子星的时候中子星本成可能被kick了一下，如果kick得很厉害，还没等物质回落，中子星就跑了，就不能形成黑洞了。所以可能只有一部分大质量恒星，在形成中子星的时候，kick比较微弱，能形成黑洞，进而产生伽玛暴；而大部分只有超新星爆发。

Asano 2007 暴本身高能光子、mu介子和正负电子对

主要内容:
在内激波的框架下，蒙特卡罗模拟GeV-TeV 的高能辐射。

精彩摘抄:


文章信息:
arXiv:0705.2910 [ps, pdf, other] : Title: Prompt GeV-TeV Emission of Gamma-Ray Bursts Due to High-Energy Protons, Muons and Electron-Positron Pairs
Authors: Katsuaki Asano, Susumu Inoue
Comments: 11 pages, 8 figures and 14 appendix figures

In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with electrons and protons accelerated to high energies. While inverse Compton emission from primary electrons is often dominant, different proton-induced mechanisms can also give rise to distinct high-energy components, such as synchrotron emission from protons, muons or secondary electron-positron pairs injected via photomeson interactions. In some cases, they give rise to double spectral breaks that can serve as unique signatures of ultra-high-energy protons. We discuss the conditions favorable for such emission, and how they are related to the production of ultra-high-energy cosmic rays and neutrinos in internal shocks. Ongoing and upcoming observations by {\it GLAST}, atmospheric Cerenkov telescopes and other facilities will test these expectations and provide important information on the physical conditions in GRB outflows.

Ruffini 2007 GRB 031203的precursor模型

主要内容:
认为前兆才是暴本身；观测的暴本身是外激波余辉了。

精彩摘抄:
prompt GRB-观测前兆；afterglow－观测的暴本身

文章信息:
arXiv:0705.2456 [ps, pdf, other] : Title: The role of GRB 031203 in clarifying the astrophysical GRB scenario
Authors: Remo Ruffini, Maria Grazia Bernardini, Carlo Luciano Bianco, Letizia Caito, Pascal Chardonnet, Maria Giovanna Dainotti, Federico Fraschetti, Roberto Guida, Gregory Vereshchagin, She-Sheng Xue
Comments: 8 pages, 11 figures, to appears in the proceedings of "The 6th INTEGRAL Workshop - The Obscured Universe", Moscow, 2006, ESA Special Publication, SP-622, in press

The luminosity and the spectral distribution of the afterglow of GRB 031203 have been presented within our theoretical framework, which envisages the GRB structure as composed by a proper-GRB, emitted at the transparency of an electron-positron plasma with suitable baryon loading, and an afterglow comprising the "prompt emission" as due to external shocks. In addition to the GRB emission, there appears to be a prolonged soft X-Ray emission lasting for 10^6-10^7 seconds followed by an exponential decay. This additional source has been called by us URCA-3. It is urgent to establish if this component is related to the GRB or to the Supernova (SN). In this second case, there are two possibilities: either the interaction of the SN ejecta with the interstellar medium or, possibly, the cooling of a young neutron star formed in the SN 2003lw process. The analogies and the differences between this triptych GRB 031203 / SN 2003lw / URCA-3 and the corresponding ones GRB 980425 / SN 1998bw / URCA-1 and GRB 030329 / SN 2003dh / URCA-2, as well as GRB 060218 / SN 2006aj are discussed.

Bianco 2007 GRB 011121的耀发

主要内容:
会议文章，认为GRB 011121有耀发。

精彩摘抄:


文章信息:
arXiv:0705.2417 [ps, pdf, other] : Title: Theoretical interpretation of GRB 011121
Authors: Carlo Luciano Bianco, Letizia Caito, Remo Ruffini
Comments: 2 pages, 1 figure, to appear in the proceedings of "Swift and GRBs", Venice, 2006, Il Nuovo Cimento, in press

GRB011121 is analyzed as a prototype to understand the ``flares'' recently observed by Swift in the afterglow of many GRB sources. Detailed theoretical computation of the GRB011121 light curves in selected energy bands are presented and compared and contrasted with observational BeppoSAX data.

Bernardini 2007 对伽玛暴的另一种分类

主要内容:
给出了另一种分类（具体没看），然后说GRB 970228可能属于短暴。

精彩摘抄:


文章信息:
arXiv:0705.2415 [ps, pdf, other] : Title: GRB970228 as a prototype for short GRBs with afterglow
Authors: Maria Grazia Bernardini, Carlo Luciano Bianco, Letizia Caito, Pascal Chardonnet, Alessandra Corsi, Maria Giovanna Dainotti, Federico Fraschetti, Roberto Guida, Remo Ruffini, She-Sheng Xue
Comments: 2 pages, 1 figure, to appear in the proceedings of "Swift and GRBs", Venice, 2006, Il Nuovo Cimento, in press

GRB970228 is analyzed as a prototype to understand the relative role of short GRBs and their associated afterglows, recently observed by Swift and HETE-II. Detailed theoretical computation of the GRB970228 light curves in selected energy bands are presented and compared with observational BeppoSAX data.

Bianco 2007 伽玛暴火球模型的比较

主要内容:
比较了不同人在做火球模型时的异同，包括：Shemi and Piran (1990), Piran, Shemi and Narayan (1993), Meszaros, Laguna and Rees (1993) and Ruffini, Salmonson, Wilson and Xue (1999,2000)

精彩摘抄:


文章信息:
arXiv:0705.2411 [ps, pdf, other] : Title: Equations of motion, initial and boundary conditions for GRB
Authors: Carlo Luciano Bianco, Remo Ruffini, Gregory Vereshchagin, She-Sheng Xue
Comments: 10 pages, 8 figures
Journal-ref: J.Korean Phys.Soc. 49 (2006) 722-731

We compare and contrast the different approaches to the optically thick adiabatic phase of GRB all the way to the transparency. Special attention is given to the role of the rate equation to be self consistently solved with the relativistic hydrodynamic equations. The works of Shemi and Piran (1990), Piran, Shemi and Narayan (1993), Meszaros, Laguna and Rees (1993) and Ruffini, Salmonson, Wilson and Xue (1999,2000) are compared and contrasted. The role of the baryonic loading in these three treatments is pointed out. Constraints on initial conditions for the fireball produced by electro-magnetic black hole are obtained.

Bromberg 2007 伽玛暴喷流极束的流体力学分析

主要内容:
baryon poor jet (BPJ)，但周围介质密度高一些，起到约束喷流准直的作用。

精彩摘抄:


文章信息:
arXiv:0705.2040 [ps, pdf, other] : Title: Hydrodynamic Collimation of Relativistic Outflows: Semianalytic Solutions and Application to Gamma-Ray Bursts
Authors: Omer Bromberg , Amir Levinson
Comments: 22 pages, 7 figures

A model is developed for the confinement and collimation of a baryon poor outflow by its surrounding medium. Both, confinement by kinetic pressure of a static corona, and confinement by the ram pressure of a supersonic wind emanating from a disk surrounding the inner source are considered. Solutions are presented for the structure of the shocked layers of deflected baryon poor jet (BPJ) and exterior wind. The dependence of the opening angle of the BPJ on the parameters of the confining medium are carefully examined. It is found that the BPJ shock may either converge to the symmetry axis or diverge away from it, depending on the opening angle of the BPJ injection cone. In the latter case the inner flow exhibits a non-uniform structure, consisting of an ultra-relativistic core containing the unshocked BPJ enveloped by the slower, shocked BPJ layer. The implications of our results to the prompt GRB emission are briefly discussed.

Trimble 2007 Astrophysics in 2006

主要内容:
每年一篇，蛮通俗易懂的，很多学术以外的东西，如职位任命、获奖信息等。

精彩摘抄:


文章信息:
Astrophysics in 2006

Authors: Virginia Trimble, Markus J. Aschwanden, Carl J. Hansen

(Submitted on 11 May 2007)

Abstract: The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the universe) and others of which there are always many, like meteors and molecules, black holes and binaries.

Comments:

244 pages, no figures

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.1730v1 [astro-ph]

Bucciantini 2007 磁星主导的Bubble产生超新星和伽玛暴

主要内容:
磁星主导的bubble先产生各向同性的外流，对应超新星；然后外流极束到自转轴附近，对应伽玛暴。

精彩摘抄:


文章信息:
arXiv:0705.1742 [ps, pdf, other] : Title: Magnetar Driven Bubbles and the Origin of Collimated Outflows in Gamma-ray Bursts
Authors: N. Bucciantini (1), E. Quataert (1), J. Arons (1), B.D. Metzger (1), Todd A. Thompson (2) ((1)Astronomy Department, UC Berkeley, (2)Department of Astrophysical Sciences, Princeton)
Comments: 14 pages, 8 figures, submitted to MNRAS

We model the interaction between the wind from a newly formed rapidly rotating magnetar and the surrounding supernova shock and host star. The dynamics is modeled using the two-dimensional, axisymmetric thin-shell equations. In the first ~10-100 seconds after core collapse the magnetar inflates a bubble of plasma and magnetic fields behind the supernova shock. The bubble expands asymmetrically because of the pinching effect of the toroidal magnetic field, just as in the analogous problem of the evolution of pulsar wind nebulae. The degree of asymmetry depends on E_mag/E_tot. The correct value of E_mag/E_tot is uncertain because of uncertainties in the conversion of magnetic energy into kinetic energy at large radii in relativistic winds; we argue, however, that bubbles inflated by newly formed magnetars are likely to be significantly more magnetized than their pulsar counterparts. We show that for a ratio of magnetic to total power supplied by the central magnetar L_mag/L_tot ~ 0.1 the bubble expands relatively spherically. For L_mag/L_tot ~ 0.3, however, most of the pressure in the bubble is exerted close to the rotation axis, driving a collimated outflow out through the host star. This can account for the collimation inferred from observations of long-duration gamma-ray bursts (GRBs). Outflows from magnetars become increasingly magnetically dominated at late times, due to the decrease in neutrino-driven mass loss as the young neutron star cools. We thus suggest that the magnetar-driven bubble initially expands relatively spherically, enhancing the energy of the associated supernova, while at late times it becomes progressively more collimated, producing the GRB.

Levan 2007 短暴GRB 050906的观测

主要内容:


精彩摘抄:


文章信息:
arXiv:0705.1705 [ps, pdf, other] : Title: On the nature of the short duration GRB 050906
Authors: A.J. Levan, N.R. Tanvir, P. Jakobsson, R. Chapman, J. Hjorth, R.S. Priddey, J.P.U. Fynbo, K. Hurley, B.L. Jensen, R. Johnson, J. Gorosabel, A.J. Castro-Tirado, M. Jarvis, D. Watson, K. Wiersema
Comments: 8 pages, 5 figures, accepted for publication in MNRAS

We present deep optical and infrared observations of the short duration GRB 050906. Although no X-ray or optical/IR afterglow was discovered to deep limits, the error circle of the GRB (as derived from the Swift BAT) is unusual incontaining the relatively local starburst galaxy IC328. This makes GRB 050906 a candidate burst from a soft-gamma repeater, similar to the giant flare from SGR 1806-20. The probability of chance alignment of a given BAT position with such a galaxy is small (<1%), z="0.43,">

Lipunov 2007 旋转磁场解释超长X射线耀

主要内容:
GRB 070110的X射线长达20,000秒。

精彩摘抄:


文章信息:
arXiv:0705.1648 [ps, pdf, other] : Title: Extralong X-ray Plateau in GRB and Spinar Paradigm
Authors: V. Lipunov (1,2), E. Gorbovskoy (1,2) (1-Sternberg Astronomical Institute 2-Dept. of Physics of Moscow State University)
Comments: 12 pages 3 figures submitted to ApJL

The recently discovered gamma-ray burst GRB 070110 displayed an extraordinary x-ray afterglow with x-ray radiation -- x-ray plateau -- observed for 20000 seconds. We show that the observed properties of the plateau can be naturally interpreted in terms of the model with a spinar -- a quasi-equilibrium collapsing object whose equilibrium is maintained by the balance of centrifugal and gravitational forces and whose evolution is determined by its magnetic field. Moreover, x-ray telescopes during one hour have recorded radiation from an object whose size was smaller than the Schwartaschield radius!

Abdo 2007 Milagro没有观测到短暴的高能对应辐射

主要内容:
从2000到2006年，都没有可信的信号。给出了高能辐射的上限。

精彩摘抄:


文章信息:
arXiv:0705.1554 [ps, pdf, other] : Title: Milagro Constraints on Very High Energy Emission from Short Duration Gamma-Ray Bursts
Authors: A.A. Abdo, B.T. Allen, D. Berley, E. Blaufuss, S. Casanova, B.L. Dingus, R.W. Ellsworth, M.M. Gonzalez, J.A. Goodman, E. Hays, C.M. Hoffman, B.E. Kolterman, C.P. Lansdell, J.T. Linnemann, J.E. McEnery, A.I. Mincer, P. Nemethy, D.Noyes, J.M. Ryan, F.W. Samuelson, P.M. Saz Parkinson, A. Shoup, G. Sinnis, A.J. Smith, G.W. Sullivan, V. Vasileiou, G.P. Walker, D.A. Williams, X.W. Xu, G.B. Yodh (Milagro Collaboration).
Comments: Accepted for publication in the Astrophysical Journal

Recent rapid localizations of short, hard gamma-ray bursts (GRBs) by the Swift and HETE satellites have led to the observation of the first afterglows and the measurement of the first redshifts from this type of burst. Detection of >100 GeV counterparts would place powerful constraints on GRB mechanisms. Seventeen short duration (<>100 GeV counterparts to these GRBs and find no significant emission correlated with these bursts. Due to the absorption of high-energy gamma rays by the extragalactic background light (EBL), detections are only expected for redshifts less than ~0.5. While most long duration GRBs occur at redshifts higher than 0.5, the opposite is thought to be true of short GRBs. Lack of a detected VHE signal thus allows setting meaningful fluence limits. One GRB in the sample (050509b) has a likely association with a galaxy at a redshift of 0.225, while another (051103) has been tentatively linked to the nearby galaxy M81. Fluence limits are corrected for EBL absorption, either using the known measured redshift, or computing the corresponding absorption for a redshift of 0.1 and 0.5, as well as for the case of z=0.

Gou 2007 GLAST对余辉的可探测性分析

主要内容:
一Swift暴观测为基础，考虑同步自康普顿产生的高能光子的流量，看是否在GLAST LAT或者AGILE的灵敏度之上。认为GLAST能达到5倍以上的Swift探测率，而可探测到更多的高能余辉（这不是一般意义上的孤儿余辉吧）。

精彩摘抄:


文章信息:
arXiv:0705.1545 [ps, pdf, other] : Title: GLAST Prospects for Swift-Era Afterglows
Authors: L. J. Gou, P. Meszaros
Comments: 18 pages, 5 figures, ApJ submitted

We calculate the GeV spectra of GRB afterglows produced by inverse Compton scattering of the sub-MeV emission of these objects. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST LAT, as well as AGILE.

磁场的上限估计

作为产生磁场的物质的压强应该比无磁场时的气体压要小，因为如果无磁场，气体压将抵抗引力。如果有了磁场，磁压将帮助气体，但是磁压不能太大，达到超过气体压后，磁场就可以超过引力，而使气体外溢，系统将不复存在。

所以P_B(B_max)=P_gas.
P_B(B_max) = B^2/8\pi
for ideal gas: P_gas=n R T

如地球大气
B_{uplimit} \sim \sqrt{8 \pi n k T} \sim 5*10^3 n_20^{1/2} T_2^{1/2} Gauss
k=1.38*10^-16 erg K^{-1}
星际介质 n\sim 1 cm^{-3}
B \sim 5*10^{-7} Gauss （估计很粗糙）
吸积盘上呢？

Liang 2007 Swift暴X射线的平降阶段统计分析

主要内容:
分析了从050318到070129的swift的暴的X射线余辉光变。给出了各单个暴的特征量和特征量的统计。

精彩摘抄:


文章信息:
arXiv:0705.1373 [ps, pdf, other] : Title: A Comprehensive Analysis of the Swift/XRT Data: II. Diverse Physical Origins of the Shallow Decay Segment
Authors: En-Wei Liang, Bin-Bin Zhang, Bing Zhang
Comments: 25 pages in emulateapj style, 7 figures, submitted to ApJ. This is the second paper of a series. Paper I see astro-ph/0612246

A shallow decay segment following the GRB tail is usually seen in the Swift XRT light curves, which transits to a steeper decay segment at the break time t_b. Its physical origin is a great puzzle. We present a comprehensive analysis to this segment for a sample of 48 long GRBs discovered by Swift before February 2007 that display such a distinct phase. We show that (1)no significant spectral evolution is observed across t_b, and the follow-up decay phase is consistent with the simplest external shock models for most bursts; (2)for these bursts, an empirical relation among E_iso, X, E_p, and t_b is found in the burst rest frame; (3) at least the t_b of some bursts are chromatic; (4) three outliers of the external shock models, GRBs 060413, 060607A, and 070110, have an abrupt drop at t_b, and the t_b is chromatic for the latter two bursts with simultaneous optical detections. These results suggest diverse, complicated physical origins for the shallow decay segment and its t_b. Most bursts in our sample are consistent with being due to long-lived energy injection (generally with a roughly constant injection luminosity up to t_b, although the fact that at least some breaks are chromatic raises great concern to such a scenario. The three significant outliers cannot be explained within the external shock models. These plateaus are probably due to a steady, long-lived emission component from the GRB central engine. Therefore, the XRT light curves are possibly composed of different emission components, and the competition of them makes the variety of the light curves observed by XRT (Abridged).

Furlanetto 2006 21cm氢线作为高红移宇宙的探针

主要内容:
中性氢原子基态电子可以处在于质子磁矩平行或者反平行两种状态，前者比后者能量低对应21cm光子的能量。这种跃迁几率非常小，但宇宙中中性氢非常多，还是能观测到这种禁戒线，并成为独一无二的观测中性氢丰度的探针。

文章将21cm线作为工具，综述研究宇宙中中性氢的分布，包括IGM，大尺度结构，及更早期的宇宙。

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文章信息:
Cosmology at low frequencies: The 21 cm transition and the high-redshift Universe
Pages 181-301
Steven R. Furlanetto, S. Peng Oh and Frank H. Briggs

Observations of the high-redshift Universe with the 21 cm hyperfine line of neutral hydrogen promise to open an entirely new windowonto the early phases of cosmic structure formation. Here we reviewthe physics of the 21 cm transition, focusing on processes relevant at high redshifts, and describe the insights to be gained from such observations. These include measuring the matter power spectrum at z∼50, observing the formation of the cosmic web and the first luminous sources, and mapping the reionization of the intergalactic medium. The epoch of reionization is of particular interest, because large HII regions will seed substantial fluctuations
in the 21 cm background. We also discuss the experimental challenges involved in detecting this signal, with an emphasis on the Galactic and extragalactic foregrounds. These increase rapidly toward low frequencies and are especially severe for the highest redshift applications. Assuming that these difficulties can be overcome, the redshifted 21 cm line will offer unique insight into the high-redshift Universe, complementing other probes but providing the only direct, three-dimensional view of structure formation from z∼200 to 6.

Ouyed 2007 夸克新星作为伽玛暴的中心引擎

主要内容:
考虑坍缩星在夸克相变时产生的外流作为伽玛暴的来源。

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文章信息:
arXiv:0705.1240 [ps, pdf, other] : Title: Gamma Ray Bursts within the Quark-Nova scenario: Precursor, prompt and afterglow phases
Authors: Rachid Ouyed, Denis Leahy, Jan Staff, Brian Niebergal (University of Calgary, Alberta, Canada)
Comments: 11 journal pages and 5 figures

By exploring the dynamical and thermal evolution of the iron-rich ejecta in a Quark-Nova explosion we find that the ejecta breaks up into multiple subjets. If the quark-nova occurs inside a collapsar, the interaction between these subjets and collapsar envelope, in the case of a failed and successful supernova, leads to features indicative of those observed in Gamma Ray Bursts. These features include: (i) precursor activity (optical, X-ray, gamma-ray), (ii) prompt gamma-ray emission, and (iii) afterglow emission. We discuss SN-less long duration GRBs, short hard GRBs (including association and non-association with star forming regions), dark GRBs, as well as the energetic X-ray flares detected in Swift GRBs in our model.

Achterberg 2007 AMANDA的中微子观测

主要内容:
观测1997 到 2003年的伽玛暴对应的中微子辐射，只给出了上限：E^2{\Phi}_{\nu} {\leq} 6.0 \times 10^{-9} GeV cm^{-2} s^{-1} sr^{-1}

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文章信息:
The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA

Authors: The IceCube Collaboration: A. Achterberg, et al., the IPN Collaboration: K. Hurley, et al

(Submitted on 8 May 2007)

Abstract: We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the Northern Hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of any other existing detector. Based on our observations of zero neutrinos during and immediately prior to the GRBs in the dataset, we set the most stringent upper limit on muon neutrino emission correlated with gamma-ray bursts. Assuming a Waxman-Bahcall spectrum and incorporating all systematic uncertainties, our flux upper limit has a normalization at 1 PeV of
E^2{\Phi}_{\nu} {\leq} 6.0 \times 10^{-9} GeV cm^{-2} s^{-1} sr^{-1}, with 90% of the events expected within the energy range of ~10 TeV to ~3 PeV. The impact of this limit on several theoretical models of GRBs is discussed, as well as the future potential for detection of GRBs by next generation neutrino telescopes. Finally, we briefly describe several modifications to this analysis in order to apply it to other types of transient point sources.

Comments:

44 pages, 10 figures; submitted to Astrophysical Journal

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.1186v1 [astro-ph]

Yu 2007 Shallow decay相的星风泡解释

主要内容:
用磁星主导的外流星风泡作为能量注入的机制，星风的反向激波解释早期余辉的平降阶段。

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文章信息:
Shallow decay phase of GRB X-ray afterglows from relativistic wind bubbles

Authors: Yun-Wei Yu, Zi-Gao Dai

(Submitted on 8 May 2007)

Abstract: The postburst object of a GRB is likely to be a highly magnetized, rapidly rotating compact object (e.g., a millisecond magnetar), which could produce an ultrarelativistic electron-positron-pair wind. The interaction of such a wind with an outwardly expanding fireball ejected during the burst leads to a relativistic wind bubble (RWB). We numerically calculate the dynamics and radiative properties of RWBs and use this model to explain the shallow decay phase of the early X-ray afterglows observed by Swift. We find that RWBs can fall into two types: forward-shock-dominated and reverse-shock-dominated bubbles. Their radiation during a period of $\sim 10^{2}-10^{5}$ seconds is dominated by the shocked medium and the shocked wind, respectively, based on different magnetic energy fractions of the shocked materials. For both types, the resulting light curves always have a shallow decay phase. In addition, we provide an example fit to the X-ray afterglows of GRB 060813 and GRB 060814 and show that they could be produced by forward-shock-dominated and reverse-shock-dominated bubbles, respectively. This implies that, for some early afterglows (e.g., GRB 060814), the long-lasting reverse shock emission is strong enough to explain their shallow decay phase.

Comments:

5 pages, 4 figures, Accepted for Publication in A&A

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.1108v1 [astro-ph]

Panaitescu 2007 Swift X射线的喷流拐折

主要内容:
分析了236（有的没有X射线余辉）个Swift暴的晚期X射线拐折，形态各异。60%有“好的”拐折。Swift之前有75%有“好的”光学怪折的。比例差不多。

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文章信息:
Jet-breaks in the X-ray Light-Curves of Swift GRB Afterglows

Authors: A. Panaitescu

(Submitted on 8 May 2007)

Abstract: In the set of 236 GRB afterglows observed by Swift between January 2005 and March 2007, we identify 30 X-ray light-curves whose power-law fall-off exhibit a steepening ("break") at 0.1-10 day after trigger, to a decay steeper than t^{-1.5}. For most of these afterglows, the X-ray spectral slope and the decay indices before and after the break can be accommodated by the standard jet model although a different origin of the breaks cannot be ruled out. In addition, there are 27 other afterglows whose X-ray light-curves may also exhibit a late break to a steep decay, but the evidence is not that compelling.
The X-ray emissions of 38 afterglows decay slower than t^{-1.5} until after 3 day, half of them exhibiting such a slow decay until after 10 day.
Therefore, the fraction of well-monitored Swift afterglows with potential jet-breaks is around 60 percent, whether we count only the strongest cases for each type or all of them. This fraction is comparable to the 75 percent of pre-Swift afterglows whose optical light-curves displayed similar breaks at ~1 day.
The properties of the prompt emission of Swift afterglows with light-curve breaks show the same correlations (peak energy of GRB spectrum with the burst isotropic output and with burst collimated output) as previously found for pre-Swift optical afterglows with light-curve breaks (the Amati and Ghirlanda relations, respectively). However, we find that Ghirlanda relation is largely a consequence of Amati's and that the addition of a new observable (the jet-break time) leads to a stronger correlation only when the few outliers to the Amati relation are taken into account.

Comments:

7 pages, submitted to MNRAS

Subjects:

Astrophysics (astro-ph)

Cite as:

arXiv:0705.1015v1 [astro-ph]