2010 Pushkarev, A. B. AGN的喷流张角和Lorentz因子

主要内容:
最后有个表格，其中alpha是喷流张角，还有观测角，Lorentz因子。
居然有Gamma和alpha成反比这个现象。
观测角基本上总是比喷流的张角大(alpha_int)。
张角还有看上去的张角和内禀张角之分。

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Title:		Jet opening angles and gamma-ray brightness of AGN
Authors:		Pushkarev, A. B.; Kovalev, Y. Y.; Lister, M. L.; Savolainen, T.
Affiliation:		AA(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany ; Pulkovo Astronomical Observatory, Pulkovskoe Chaussee 65/1, 196140 St. Petersburg, Russia; Crimean Astrophysical Observatory, 98688 Nauchny, Crimea, Ukraine apushkar@mpifr.de), AB(Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 86/32, 117997 Moscow, Russia; Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany), AC(Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907, USA), AD(Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany)
Publication:		Astronomy and Astrophysics, Volume 507, Issue 2, 2009, pp.L33-L36 (A&A Homepage)
Publication Date:		11/2009
Origin:		EDP Sciences
Astronomy Keywords:		galaxies: active, galaxies: jets, quasars: general, radio continuum: galaxies
DOI:		10.1051/0004-6361/200913422
Bibliographic Code:		2009A&A...507L..33P

Abstract

Aims: We have investigated the differences in apparent opening angles between the parsec-scale jets of the active galactic nuclei (AGN) detected by the Fermi Large Area Telescope during its first three months of operations and those of non-LAT-detected AGN.
Methods: We used 15.4 GHz VLBA observations of sources from the 2 cm VLBA MOJAVE program, a subset of which comprises the statistically complete flux density limited MOJAVE sample. We determined the apparent opening angles by analyzing transverse jet profiles from the data in the image plane and by applying a model fitting technique to the data in the (u,v) plane. Both methods provided comparable opening angle estimates.
Results: The apparent opening angles of γ-ray bright blazars are preferentially larger than those of γ-ray weak sources. At the same time, we have found the two groups to have similar intrinsic opening angle distributions, based on a smaller subset of sources. This suggests that the jets in γ-ray bright AGN are oriented at preferentially smaller angles to the line of sight resulting in a stronger relativistic beaming. The intrinsic jet opening angle and the bulk flow Lorentz factor are found to be inversely proportional, as predicted by standard models of compact relativistic jets. If a gas dynamical jet acceleration model is assumed, the ratio of the initial pressure of the plasma in the core region P₀ to the external pressure P_ext lies within the range 1.1 to 34.6, with a best fit estimate of P_0/P_ext≈ 2. Table [see full text] is only available in electronic form at http://www.aanda.org

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De Colle, Fabio 2011 伽马暴喷流的数值模拟

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Title:		Simulations of GRB Jets in a Stratified External Medium: Dynamics, Afterglow Lightcurves, Jet Breaks and Radio Calorimetry
Authors:		De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego
Publication:		eprint arXiv:1111.6667
Publication Date:		11/2011
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		10 pages, 13 figures, submitted to ApJ
Bibliographic Code:		2011arXiv1111.6667D

Abstract

The dynamics of GRB jets during the afterglow phase is most reliably and accurately modelled using hydrodynamic simulations. All published simulations, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with $\rho \propto r^{-k}$ for k = 0, 1, 2. The simulations are performed in 2D using the special relativistic version of the Mezcal code. The dynamics for stratified external media are broadly similar to those derived for expansion into a uniform external medium. The jet half-opening angle start increasing logarithmically with time once the Lorentz factor drops below 1/theta_0. For larger k values the lateral expansion is faster at early times and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that contrary to analytic expectations, there is a reasonably sharp jet break in the lightcurve for k = 2 although the shape of the break is affected more by the viewing angle than by the slope of the external density profile. Steeper density profiles are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counter-jet becomes visible as it becomes sub-relativistic, and for k=0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more gradually, causing only a mild flattening in the radio light curve that might be hard to discern when k=2. Late time radio calorimetry is likely to consistently over-estimate the true energy by up to a factor of a few for k=2, and either over-predict or under-predict it by a smaller factor for k = 0,1.

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Granot 2011 关于侧向膨胀新的解析解

主要内容:
以前的解析解认为在gamma=1/theta_j的时候就开始进入指数阶段，侧向膨胀很显著；但数值模拟发现不是这样的。Granot和Piran给出了新的解析解，得到了和数值解一致的结果。

结果是再共动系中侧向膨胀的速度 beta_theta ~ 1/(Gamma^2 delta_theta) ~ 1/(Gamma^2 theta)

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Title:		On the lateral expansion of GRB jets
Authors:		Granot, Jonathan; Piran, Tsvi
Publication:		eprint arXiv:1109.6468
Publication Date:		09/2011
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		33 pages, 11 figures, submitted to MNRAS
Bibliographic Code:		2011arXiv1109.6468G

Abstract

The dynamics of GRB jets during the afterglow phase have an important effect on the interpretation of their observations and for inferring key physical parameters such as their true energy and event rate. Semi-analytic models generally predict a fast lateral expansion, where the jet opening angle asymptotically grows exponentially with its radius. Numerical simulations, however, show a much more modest lateral expansion, where the jet retains memory of its initial opening angle for a very long time, and the flow remains non-spherical until it becomes sub-relativistic, and only then gradually approaches spherical symmetry. Here we suggest a new analytic model based on a new physically derived recipe for the lateral expansion. We also generalize the model by relaxing the common approximations of ultra-relativistic motion and a narrow jet opening angle. We find that the new analytic model fits much better the results of numerical simulations, mainly because it remains valid also in the mildly relativistic, quasi spherical regime. This model shows that for modest initial jet half-opening angles, \theta_0, the outflow is not sufficiently ultra-relativistic when its Lorentz factor reaches \Gamma = 1/\theta_0 and therefore the sideways expansion is rather slow, showing no rapid, exponential phase. On the other hand, we find that jets with a very narrow initial half-opening angle, \theta_0 << 1, which are still ultra-relativistic at \Gamma = 1/\theta_0, do show a phase of rapid, exponential lateral expansion. However, even such jets that expand sideways exponentially are still not spherical when they become sub-relativistic.

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Nicuesa Guelbenzu 2001 短暴GRB 090426的喷流拐折

主要内容:
时间是0.4天

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x射线和光学的光变，有拐折

红色的是短暴，灰色的是长暴

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Title:		GRB 090426: Discovery of a jet break in a short burst afterglow
Authors:		Nicuesa Guelbenzu, A.; Klose, S.; Rossi, A.; Kann, D. A.; Krühler, T.; Greiner, J.; Rau, A.;Olivares E., F.; Afonso, P. M. J.; Filgas, R.; Küpcü Yoldaş, A.; McBreen, S.; Nardini, M.; Schady, P.;Schmidl, S.; Updike, A. C.; Yoldaş, A.
Affiliation:		AA(Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778, Tautenburg, Germany ana@tls-tautenburg.de), AB()
Publication:		Astronomy & Astrophysics, Volume 531, id.L6 (A&A Homepage)
Publication Date:		07/2011
Origin:		EDP Sciences
Keywords:		gamma-ray burst: individual: GRB 090426
DOI:		10.1051/0004-6361/201116657
Bibliographic Code:		2011A&A...531L...6N

Abstract

Context. The link between the duration of GRBs and the nature of their progenitors remains disputed. Short bursts (with durations of less than ~2 s) are less frequently observed, technically more difficult to localize, and exhibit significantly fainter afterglows.
Aims: It is of critical importance to establish whether the burst duration can reliably distinguish the different GRB population models of collapsars and compact stellar mergers. The Swift GRB 090426 provides an unique opportunity to address this question. Its duration (T₉₀ = 1.28 s) places GRB 090426 firmly in the short burst population, while the high redshift (z = 2.609), host galaxy properties, and prompt emission spectral characteristics are more similar to those of long-duration GRBs.
Methods: On the basis of data obtained with the Tautenburg 2 m telescope (Germany) and the 7-channel imager GROND (La Silla, Chile), we compiled the most finely sampled light curve available for a short burst optical/NIR afterglow. The light curve was then analysed in a standard fashion. GROND and XRT data were used to determine the broad-band spectral energy distribution of the afterglow across more than three orders of magnitude.
Results: Our data show that a light curve break exists at 0.4 days, which is followed by a steep decay. This light curve decay is achromatic in the optical/NIR bands, and interpreted as a post-jet break phase. The X-ray data do not disagree with this interpretation.
Conclusions: The half-opening angle of the suspected jet as well as the luminosity of the optical afterglow provide additional evidence that GRB 090426 is probably linked to the death of a massive star rather than to the merger of two compact objects.Appendix A is available in electronic form at http://www.aanda.org

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Lyutikov 2011 侧向膨胀对余辉的影响

主要内容:
说只有张角特小 theta_j<1/Gamma^2（为什么是平方呢）或者张角大但在中等相对论的时候，才有影响。

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Title:		On the sideways expansion of relativistic non-spherical shocks and GRB afterglows
Authors:		Lyutikov, Maxim
Publication:		eprint arXiv:1106.0025
Publication Date:		05/2011
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Bibliographic Code:		2011arXiv1106.0025L

Abstract

Expansion of non-spherical relativistic blast waves is considered in the Kompaneets (the thin shell) approximation. We find that the relativistic motion effectively "freezes out" the lateral dynamics of the shock front: only extremely strongly collimated shocks, with the opening angles $\Delta \theta \leq 1/\Gamma^2$, show appreciable modification of profiles due to sideways expansion. For less collimated profiles the propagation is nearly ballistic; the sideways expansion of relativistic shock becomes important only when they become mildly relativistic.

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Granot 2010 伽马暴的喷流

主要内容:
书的一章。

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Title:		Jets and Gamma-Ray Burst Unification Schemes
Authors:		Granot, Jonathan; Ramirez-Ruiz, Enrico
Publication:		eprint arXiv:1012.5101
Publication Date:		12/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		46 pages, 12 figures; book chapter, to appear in "Gamma-ray Bursts" (CUP)
Bibliographic Code:		2010arXiv1012.5101G

Abstract

There are several lines of evidence indicating that the ultra-relativistic outflows powering gamma-ray bursts (GRBs) are collimated into narrow jets. However, these are indirect, and the jet structure is rather poorly constrained. What is more, the jet dynamics have still not been investigated in detail. It has been suggested that the observed variety between different long duration events, ranging from bright spectrally hard GRBs, to dimmer and spectrally softer X-ray flashes (XRFs) may be largely due to different viewing angles (or lines of sight) relative to rather similar relativistic jets. Here we describe the current state of knowledge on these topics, explain some of the most relevant physics behind some of the basic principles, and discuss prospects for the future.

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Filgas 2010 GRB 080413B的余辉观测

主要内容:
用双成分的喷流解释增亮。

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Title:		The two-component jet of GRB 080413B
Authors:		Filgas, R.; Krühler, T.; Greiner, J.; Rau, A.; Palazzi, E.; Klose, S.; Schady, P.; Rossi, A.; Afonso, P. M. J.;Antonelli, L. A.; Clemens, C.; Covino, S.; D'Avanzo, P.; Küpcü Yoldaş, A.; Nardini, M.; Nicuesa Guelbenzu, A.;Olivares, F.; Updike, E. A. C.; Yoldaş, A.
Affiliation:		AA(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany,filgas@mpe.mpg.de), AB(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany; Universe Cluster, Technische Universität München, Boltzmannstraße 2, 85748 Garching, Germany), AC(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AD(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AE(INAF - IASF di Bologna, via Gobetti 101, 40129 Bologna, Italy), AF(Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany), AG(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AH(Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany), AI(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AJ(INAF - Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monteporzio Catone (Roma), Italy), AK(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AL(INAF - Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy), AM(INAF - Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy), AN(European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching, Germany ; Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK), AO(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AP(Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany), AQ(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany), AR(Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA), AS(Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany; Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA Cambridge, UK)
Publication:		Astronomy and Astrophysics, Volume 526, id.A113 (A&A Homepage)
Publication Date:		02/2011
Origin:		EDP Sciences
Keywords:		ISM: jets and outflows, gamma rays: general, X-rays: individuals: GRB 080413B
DOI:		10.1051/0004-6361/201015320
Bibliographic Code:		2011A&A...526A.113F

Abstract

Aims: The quick and precise localization of GRBs by the Swift telescope allows the early evolution of the afterglow light curve to be captured by ground-based telescopes. With GROND measurements we can investigate the optical/near-infrared light curve of the afterglow of gamma-ray burst 080413B in the context of late rebrightening.
Methods: Multi-wavelength follow-up observations were performed on the afterglow of GRB 080413B. X-ray emission was detected by the X-ray telescope onboard the Swift satellite and obtained from the public archive. Optical and near-infrared photometry was performed with the seven-channel imager GROND mounted at the MPG/ESO 2.2 m telescope and additionally with the REM telescope, both in La Silla, Chile. The light curve model was constructed using the obtained broad-band data.
Results: The broad-band light curve of the afterglow of GRB 080413B is well fitted with an on-axis two-component jet model. The narrow ultra-relativistic jet is responsible for the initial decay, while the rise of the moderately relativistic wider jet near its deceleration time is the cause of the rebrightening of the light curve. The later evolution of the optical/NIR light curve is then dominated by the wide component, the signature of which is almost negligible in the X-ray wavelengths. These components have opening angles of θ_n ~ 1.7° and θ_w ~ 9°, and Lorentz factors of Γ_n > 188 and Γ_w ~ 18.5. We calculated the beaming-corrected energy release to be E_γ = 7.9 × 10⁴⁸ erg.Tables 1-3 are only available in electronic form at http://www.aanda.org

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Gao, Yan 2009 伽马暴喷流张角的统计

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Title:		GRB jet beaming angle statistics
Authors:		Gao, Yan; Dai, Zi-Gao
Affiliation:		AA(Department of Astronomy, Nanjing University, Nanjing 210093, China), AB(Department of Astronomy, Nanjing University, Nanjing 210093, China)
Publication:		Research in Astronomy and Astrophysics, Volume 10, Issue 2, pp. 142-150 (2010).
Publication Date:		02/2010
Origin:		IOP
DOI:		10.1088/1674-4527/10/2/005
Bibliographic Code:		2010RAA....10..142G

Abstract

Existing theory and models suggest that a Type I (merger) GRB should have a larger jet beaming angle than a Type II (collapsar) GRB, but so far no statistical evidence is available to support this suggestion. In this paper, we obtain a sample of 37 beaming angles and calculate the probability that this is true. A correction is also devised to account for the scarcity of Type I GRBs in our sample. The probability is calculated to be 83% without the correction and 71% with it.

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Komissarov 2009 磁场的稀释波可以加速喷流的速度

主要内容:
当磁化喷流穿出恒星包层之后失去外部压力支撑，可以产生稀释波，它能加速喷流（不是加热）

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Title:		Rarefaction acceleration of ultrarelativistic magnetized jets in gamma-ray burst sources
Authors:		Komissarov, Serguei S.; Vlahakis, Nektarios; Königl, Arieh
Affiliation:		AA(Department of Applied Mathematics, The University of Leeds, Leeds LS2 9GT), AB(Section of Astrophysics, Astronomy and Mechanics, Physics Department, University of Athens, 15784 Zografos, Athens, Greece), AC(Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA)
Publication:		Monthly Notices of the Royal Astronomical Society, Volume 407, Issue 1, pp. 17-28. (MNRAS Homepage)
Publication Date:		09/2010
Origin:		WILEY
MNRAS Keywords:		MHD, relativistic processes, methods: numerical, gamma-ray: burst: general
Abstract Copyright:		(c) Journal compilation © 2010 RAS
DOI:		10.1111/j.1365-2966.2010.16779.x
Bibliographic Code:		2010MNRAS.407...17K

Abstract

When a magnetically dominated superfast-magnetosonic long/soft gamma-ray burst (GRB) jet leaves the progenitor star, the external pressure support will drop and the jet may enter the regime of ballistic expansion, during which additional magnetic acceleration becomes ineffective. However, recent numerical simulations by Tchekhovskoy et al. have suggested that the transition to this regime is accompanied by a spurt of acceleration. We confirm this finding numerically and attribute the acceleration to a sideways expansion of the jet, associated with a strong magnetosonic rarefaction wave that is driven into the jet when it loses pressure support, which induces a conversion of magnetic energy into kinetic energy of bulk motion. This mechanism, which we dub rarefaction acceleration, can only operate in a relativistic outflow because in this case the total energy can still be dominated by the magnetic component even in the superfast-magnetosonic regime. We analyse this process using the equations of relativistic magnetohydrodynamics and demonstrate that it is more efficient at converting internal energy into kinetic energy when the flow is magnetized than in a purely hydrodynamic outflow, as was found numerically by Mizuno et al. We show that, just as in the case of the magnetic acceleration of a collimating jet that is confined by an external pressure distribution - the collimation-acceleration mechanism - the rarefaction-acceleration process in a magnetized jet is a consequence of the fact that the separation between neighbouring magnetic flux surfaces increases faster than their cylindrical radius. However, whereas in the case of effective collimation-acceleration the product of the jet opening angle and its Lorentz factor does not exceed ~1, the addition of the rarefaction-acceleration mechanism makes it possible for this product to become >>1, in agreement with the inference from late-time panchromatic breaks in the afterglow light curves of long/soft GRBs.

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Suwa 2010 伽马暴的喷流可以穿过第一代恒星的包层

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Title:		Can Gamma-Ray Burst Jets Break Out the First Stars?
Authors:		Suwa, Yudai; Ioka, Kunihito
Publication:		eprint arXiv:1009.6001
Publication Date:		09/2010
Origin:		ARXIV
Keywords:		Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Comment:		19 pages, 2 figures
Bibliographic Code:		2010arXiv1009.6001S

Abstract

We show that a relativistic gamma-ray burst (GRB) jet can potentially pierce the envelope of very massive first generation star (Population III; Pop III) by using the stellar density profile to estimate both the jet luminosity (via accretion) and its penetrability. The jet breakout is possible even if the Pop III star has a supergiant hydrogen envelope without mass loss, thanks to the long-lived powerful accretion of the envelope itself. While the Pop III GRB is estimated to be energetic $E_{\gamma,\mathrm{iso}}\sim 10^{55}$ erg, the supergiant envelope hides the initial bright phase into the cocoon component, leading to a GRB with a long duration $\sim 1000(1+z)$ sec and an ordinary isotropic luminosity $\sim 10^{52}$ erg s$^{-1}$ ($\sim 10^{-9}$ erg cm$^{-2}$ s$^{-1}$ at redshift $z\sim 20$). The neutrino-annihilation is not effective for Pop III GRBs because of a low central temperature, while the magnetic mechanism is viable. We also derive analytic estimates of the breakout conditions, which are applicable to various progenitor models. The GRB luminosity and duration are found to be very sensitive to the core and envelope mass, providing possible probes of the first luminous objects at the end of the high redshift dark ages.

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Metzger 2010 双星并合的电磁辐射

主要内容:
考虑并合后的喷流中的元素裂变辐射。

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Title:		Electromagnetic counterparts of compact object mergers powered by the radioactive decay of r-process nuclei
Authors:		Metzger, B. D.; Martínez-Pinedo, G.; Darbha, S.; Quataert, E.; Arcones, A.; Kasen, D.; Thomas, R.; Nugent, P.; Panov, I. V.; Zinner, N. T.
Affiliation:		AA(Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA), AB(GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, D-64291 Darmstadt, Germany), AC(Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, 601 Campbell Hall, Berkeley, CA 94720, USA), AD(Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, 601 Campbell Hall, Berkeley, CA 94720, USA), AE(GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, D-64291 Darmstadt, Germany; Institut für Kernphysik, TU Darmstadt, Schlossgartenstr. 9, D-64289 Darmstadt, Germany), AF(University of California, Santa Cruz, CA 95064, USA), AG(Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS50B-4206, Berkeley, CA 94720, USA), AH(Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS50B-4206, Berkeley, CA 94720, USA), AI(Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland; Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya St. 25, 117259 Moscow, Russia; Russian Research Centre Kurchatov Institute, pl. Kurchatova 1, 123182 Moscow, Russia), AJ(Department of Physics, Harvard University, Cambridge, MA 02138, USA)
Publication:		Monthly Notices of the Royal Astronomical Society, Volume 406, Issue 4, pp. 2650-2662. (MNRAS Homepage)
Publication Date:		08/2010
Origin:		WILEY
MNRAS Keywords:		gravitation, nuclear reactions, nucleosynthesis, abundances, binaries: close, gamma-ray burst: general, stars: neutron, supernovae: general
Abstract Copyright:		(c) Journal compilation © 2010 RAS
DOI:		10.1111/j.1365-2966.2010.16864.x
Bibliographic Code:		2010MNRAS.406.2650M

Abstract

The most promising astrophysical sources of kHz gravitational waves (GWs) are the inspiral and merger of binary neutron star(NS)/black hole systems. Maximizing the scientific return of a GW detection will require identifying a coincident electromagnetic (EM) counterpart. One of the most likely sources of isotropic EM emission from compact object mergers is a supernova-like transient powered by the radioactive decay of heavy elements synthesized in ejecta from the merger. We present the first calculations of the optical transients from compact object mergers that self-consistently determine the radioactive heating by means of a nuclear reaction network; using this heating rate, we model the light curve with a one-dimensional Monte Carlo radiation transfer calculation. For an ejecta mass ~10^-2M_solar (10^-3M_solar) the resulting light-curve peaks on a time-scale ~1d at a V-band luminosity νL_ν ~ 3 × 10⁴¹ (10⁴¹)ergs^-1 [M_V = -15(-14)] this corresponds to an effective `f' parameter ~3 × 10<sup>-6</sup> in the Li-Paczynski toy model. We argue that these results are relatively insensitive to uncertainties in the relevant nuclear physics and to the precise early-time dynamics and ejecta composition. Since NS merger transients peak at a luminosity that is a factor of ~10<sup>3</sup> higher than a typical nova, we propose naming these events `kilo-novae'. Because of the rapid evolution and low luminosity of NS merger transients, EM counterpart searches triggered by GW detections will require close collaboration between the GW and astronomical communities. NS merger transients may also be detectable following a short-duration gamma-ray burst or `blindly' with present or upcoming optical transient surveys. Because the emission produced by NS merger ejecta is powered by the formation of rare r-process elements, current optical transient surveys can directly constrain the unknown origin of the heaviest elements in the Universe.

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