Chandra 2009 GRB 090423的射电余辉观测

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Title:		Discovery of Radio Afterglow from the Most Distant Cosmic Explosion
Authors:		Chandra, Poonam; Frail, Dale A.; Fox, Derek; Kulkarni, Shrinivas; Berger, Edo; Cenko, S. Bradley; Bock, Douglas C.-J.; Harrsion, Fiona; Kasliwal, Mansi
Affiliation:		AA(Department of Physics, Royal Military College of Canada, Kingston, ON, Canada poonam.chandra@rmc.ca), AB(National Radio Astronomy Observatory, 1003 Lopezville Road, Socorro, NM 87801, USA ), AC(Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802, USA ), AD(Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA ), AE(Harvard University, 60 Garden Street, Cambridge, MA 02138, USA ), AF(Department of Astronomy, 601 Campbell Hall, University of California, Berkeley, CA 94720-3411, USA ), AG(Combined Array for Research in Millimeter-wave Astronomy, P.O. Box 968, Big Pine, CA 93513, USA), AH(Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA ), AI(Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA )
Publication:		The Astrophysical Journal Letters, Volume 712, Issue 1, pp. L31-L35 (2010). (ApJL Homepage)
Publication Date:		03/2010
Origin:		IOP
ApJ Keywords:		cosmology: observations, gamma-ray burst: general, hydrodynamics, radio continuum: general, stars: early-type
DOI:		10.1088/2041-8205/712/1/L31
Bibliographic Code:		2010ApJ...712L..31C

Abstract

We report on the discovery of radio afterglow emission from the gamma-ray burst GRB 090423, which exploded at a redshift of 8.3, making it the object with the highest known redshift in the universe. By combining our radio measurements with existing X-ray and infrared observations, we estimate the kinetic energy of the afterglow, the geometry of the outflow, and the density of the circumburst medium. Our best-fit model suggests a quasi-spherical, high-energy explosion in a low, constant-density medium. GRB 090423 had a similar energy release to the other well-studied high redshift GRB 050904 (z = 6.26), but their circumburst densities differ by 2 orders of magnitude. We compare the properties of GRB 090423 with a sample of gamma-ray bursts (GRBs) at moderate redshifts. We find that the high energy and afterglow properties of GRB 090423 are not sufficiently different from other GRBs to suggest a different kind of progenitor, such as a Population III (Pop III) star. However, we argue that it is not clear that the afterglow properties alone can provide convincing identification of Pop III progenitors. We suggest that the millimeter and centimeter radio detections of GRB 090423 at early times contained emission from the reverse shock. If true, this may have important implications for the detection of high-redshift GRBs by the next generation of radio facilities.

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Chincarini, G. 2010 GRB 090423和X射线耀

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两个独立的内容。 小review

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Title:		Swift highlights and flares (Back to the drawing board?)
Authors:		Chincarini, G.; Margutti, R.
Publication:		eprint arXiv:1005.4507
Publication Date:		05/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		"1st Galileo Xu Guangqi Meeting" conference proceeding
Bibliographic Code:		2010arXiv1005.4507C

Abstract

Swift opened up a new era in the study of gamma-ray burst sources (GRB). Among a variety of discoveries made possible by Swift, here we focus on GRB090423, the event at z=8.2 which currently holds the record of the most distant celestial object ever caught by human instrumentation. This GRB allowed us to have a direct look at the early Universe. The central engine activity giving origin to the GRB emission is also discussed starting from the observational findings of an updated GRB X-ray flares catalog.

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Stanway 2010 限制高红移暴的宿主星系的分子气

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通过谱的没有某些发射线，从而限制宿主星系的相应分子的含量。得到的结论是像 090423这样的高红移的暴并不诞生于星暴星系中，而是比较普通的恒星形成区。

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Title:		Constraining the Molecular Gas in the Environs of a z~8 Gamma Ray Burst Host Galaxy
Authors:		Stanway, Elizabeth R.; Bremer, Malcolm N.; Tanvir, Nial R.; Levan, Andrew J.; Davies, Luke J. M.
Publication:		eprint arXiv:1008.3383
Publication Date:		08/2010
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		7 pages, 3 figures, MNRAS accepted
Bibliographic Code:		2010arXiv1008.3383S

Abstract

GRB 090423 is the most distant spectroscopically-confirmed source observed in the universe. Using observations at 37.5 GHz, we place constraints on molecular gas emission in the CO(3-2) line from its host galaxy and immediate environs. The source was not detected either in line emission or in the rest-frame 850 micron continuum, yielding an upper limit of S_{8mm}=9.3 milli-Jy and M(H_2)<4.3x10^9 M_sun (3 sigma), applying standard conversions. This implies that the host galaxy of GRB 090423 did not possess a large reservoir of warm molecular gas but was rather modest either in star formation rate or in mass. It suggests that this was not an extreme starburst, and hence that gamma ray bursts at high redshift trace relatively modest star formation rates, in keeping with the behaviour seen at lower redshifts. We do, however, identify a millimetre emission line source in the field of GRB 090423. Plausible interpretations include a CO(1-0) emitting galaxy at z=2.1, CO(2-1) at z=5.2 and CO(3-2) at z=8.3. Efforts to identify a counterpart for the molecular line emitter and to further characterise this source are continuing.

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Lin 2009 GRB 090423的谱

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BAT和GBM的.

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Title:		GRB 090423: Marking the Death of a Massive Star at z=8.2
Authors:		Lin, Lin; Wei, Liang En; Shuang Nan, Zhang
Publication:		eprint arXiv:0906.3057
Publication Date:		06/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Comment:		accepted for publication in Science in China G
Bibliographic Code:		2009arXiv0906.3057L

Abstract

GRB 090423 is the new high-z record holder of Gamma-ray bursts (GRBs) with z~ 8.2. We present a detailed analysis of both the spectral and temporal features of GRB 090423 observed with Swift/BAT and Fermi/GBM. We find that the T90 observed with BAT in the 15-150 keV band is 13.2 s, corresponding to ~ 1.4 s at z=8.2. It once again gives rise to an issue whether the progenitors of high-z GRBs are massive stars or mergers since the discovery of GRB 080913 at z=6.7. In comparison with T90 distribution in the burst frame of current redshift-known GRB sample, we find that it is marginally grouped into the long group (Type II GRBs). The spectrum observed with both BAT and GBM is well fitted by a power-law with exponential cutoff, which yields an Ep=50.4+/-7.0 keV. The event well satisfies the Amati-relation for the Type II GRBs within their 3 siggma uncertainty range. Our results indicate that this event would be produced by the death of a massive star. Based on the Amati-relation, we derive its distance modulus, which follows the Hubble diagram of the concordance cosmology model at a redshift of ~8.2.

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Salvaterra 2009 高红移伽玛暴GRB 090423的观测

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红移为8.1, 意味着发生在再电离还没结束的时候(而再电离之前的时期, 即中性氢时代被成为dark age, 再电离之后就没有再复合了, 今天的宇宙是处于完全电离态的(from here)。).

什么意思啊? 是电离度上升还没结束? 还是复合回到中性还没结束? 不过从这里看, 应该是前者. "the first sources of light began to form at a redshift z = 30 and reionized most of the hydrogen in the universe by z = 7."

这个暴的观测, 应该还加上其它几个高红移暴, 说明早期宇宙的伽玛暴诞生率比现在高. 那么要么是伽玛暴和恒星形成率不成比例, 要么是早期恒星形成率高.

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From pictures

和别的伽玛暴比较, 没有什么特别的

From pictures

红移得到的方式

From pictures

满足Amati关系

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X射线和光学的光变曲线

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Title:		GRB 090423 reveals an exploding star at the epoch of re-ionization
Authors:		Salvaterra, R.; Della Valle, M.; Campana, S.; Chincarini, G.; Covino, S.; D'Avanzo, P.; Fernandez-Soto, A.; Guidorzi, C.; Mannucci, F.; Margutti, R.; Thoene, C. C.; Antonelli, L. A.; Barthelmy, S. D.; De Pasquale, M.; D'Elia, V.; Fiore, F.; Fugazza, D.; Hunt, L. K.; Maiorano, E.; Marinoni, S.; Marshall, F. E.; Molinari, E.; Nousek, J.; Pian, E.; Racusin, J. L.; Stella, L.; Amati, L.; Andreuzzi, G.; Cusumano, G.; Fenimore, E. E.; Ferrero, P.; Giommi, P.; Guetta, D.; Holland, S. T.; Hurley, K.; Israel, G. L.; Mao, J.; Markwardt, C. B.; Masetti, N.; Pagani, C.; Palazzi, E.; Palmer, D. M.; Piranomonte, S.; Tagliaferri, G.; Testa, V.
Publication:		eprint arXiv:0906.1578
Publication Date:		06/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		Submitted to Nature. The astro-ph paper includes the main text (8 pages, 2 figures) and supplementary material (13 pages, 6 figures). Please note that this manuscript is subject to press embargo
Bibliographic Code:		2009arXiv0906.1578S

Abstract

The observation of the very early stages of the Universe represents one of the main challenges of modern cosmology. 200-300 million years after the Big Bang stars began to form, thus providing the Universe with the first sources of light and heat after the Big Bang. This event marks the transition between the epoch when the Universe was dark and neutral and the time when the Universe became fully ionized. The direct investigation of this cosmic epoch, usually accomplished by observing distant quasars, has been revolutionized in the last decade through the study of Gamma-ray Bursts (GRBs). GRBs are gamma-ray flashes, detected from space, produced by rare types of massive stellar explosions. Their rapidly fading afterglows are often bright at optical wavelengths, such that GRBs are detectable up to cosmological distances. Here we report on the Swift observation of GRB 090423 and the near-infrared spectroscopic measurement of its redshift z=8.1^{+0.1}_{-0.3} obtained with the Telescopio Nazionale Galileo (TNG). This GRB was produced in a cosmic explosion that occurred before the re-ionization process was completed, when the Universe was only ~4% of its current age. Unexpectedly, this primordial object exhibits properties similar to those of GRBs observed at low/intermediate redshifts, indicating that the mechanisms and progenitors which gave rise to GRBs about 600 million years after the Big Bang are not markedly different from those producing GRBs ~10 billion years later. The detection of this GRB at z=8.1 indicates either that the GRBs are not good tracers of the cosmic star formation or that the number of bright GRBs was greater at high redshift.

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Tanvir 2009 GRB 090423的观测

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Title:		A glimpse of the end of the dark ages: the gamma-ray burst of 23 April 2009 at redshift 8.3
Authors:		Tanvir, N. R.; Fox, D. B.; Levan, A. J.; Berger, E.; Wiersema, K.; Fynbo, J. P. U.; Cucchiara, A.; Kruehler, T.; Gehrels, N.; Bloom, J. S.; Greiner, J.; Evans, P.; Rol, E.; Olivares, F.; Hjorth, J.; Jakobsson, P.; Farihi, J.; Willingale, R.; Starling, R. L. C.; Cenko, S. B.; Perley, D.; Maund, J. R.; Duke, J.; Wijers, R. A. M. J.; Adamson, A. J.; Allan, A.; Bremer, M. N.; Burrows, D. N.; Castro Tirado, A. J.; Cavanagh, B.; de Ugarte Postigo, A.; Dopita, M. A.; Fatkhullin, T. A.; Fruchter, A. S.; Foley, R. J.; Gorosabel, J.; Holland, S. T.; Kennea, J.; Kerr, T.; Klose, S.; Krimm, H. A.; Komarova, V. N.; Kulkarni, S. R.; Moskvitin, A. S.; Naylor, T.; Penprase, B. E.; Perri, M.; Podsiadlowski, P.; Roth, K.; Rutledge, R. E.; Sakamoto, T.; Schady, P.; Schmidt, B. P.; Soderberg, A. M.; Sollerman, J.; Stephens, A. W.; Stratta, G.; Ukwatta, T. N.; Watson, D.; Westra, E.; Wold, T.; Wolf, C.
Publication:		eprint arXiv:0906.1577
Publication Date:		06/2009
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Comment:		Submitted to Nature. Under press embargo
Bibliographic Code:		2009arXiv0906.1577T

Abstract

It is thought that the first generations of massive stars in the Universe were an important, and quite possibly dominant, source of the ultra-violet radiation that reionized the hydrogen gas in the intergalactic medium (IGM); a state in which it has remained to the present day. Measurements of cosmic microwave background anisotropies suggest that this phase-change largely took place in the redshift range z=10.8 +/- 1.4, while observations of quasars and Lyman-alpha galaxies have shown that the process was essentially completed by z=6. However, the detailed history of reionization, and characteristics of the stars and proto-galaxies that drove it, remain unknown. Further progress in understanding requires direct observations of the sources of ultra-violet radiation in the era of reionization, and mapping the evolution of the neutral hydrogen fraction through time. The detection of galaxies at such redshifts is highly challenging, due to their intrinsic faintness and high luminosity distance, whilst bright quasars appear to be rare beyond z~7. Here we report the discovery of a gamma-ray burst, GRB 090423, at redshift z=8.26 -0.08 +0.07. This is well beyond the redshift of the most distant spectroscopically confirmed galaxy (z=6.96) and quasar (z=6.43). It establishes that massive stars were being produced, and dying as GRBs, ~625 million years after the Big Bang. In addition, the accurate position of the burst pinpoints the location of the most distant galaxy known to date. Larger samples of GRBs beyond z~7 will constrain the evolving rate of star formation in the early universe, while rapid spectroscopy of their afterglows will allow direct exploration of the progress of reionization with cosmic time.

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GRB 090423

z=8.2 迄今为止最远的暴