ALBERT

Description: We present observations of Swift J1112.2–8238, and identify it as a candidate relativistic tidal disruption flare. The outburst was first detected by Swift /Burst Alert Telescope (BAT) in 2011 June as an unknown, long-lived (order of days) gamma-ray transient source. We show that its position is consistent with the nucleus of a faint galaxy for which we establish a likely redshift of z  = 0.89 based on a single emission line that we interpret as the blended [O  ii ] 3727 doublet. At this redshift, the peak X-ray/gamma-ray luminosity exceeded 10 47 erg s –1 , while a spatially coincident optical transient source had i '  ~ 22 ( M g  ~ –21.4 at z  = 0.89) during early observations, ~20 d after the Swift trigger. These properties place Swift J1112.2–8238 in a very similar region of parameter space to the two previously identified members of this class, Swift J1644+57 and Swift J2058+0516. As with those events the high-energy emission shows evidence for variability over the first few days, while late-time observations, almost 3 yr post-outburst, demonstrate that it has now switched off. Swift J1112.2–8238 brings the total number of such events observed by Swift to three, interestingly all detected by Swift over a ~3 month period (〈3 per cent of its total lifetime as of 2015 March). While this suggests the possibility that further examples may be uncovered by detailed searches of the BAT archives, the lack of any prime candidates in the years since 2011 means these events are undoubtedly rare.

Description: Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Racusin, J L -- Karpov, S V -- Sokolowski, M -- Granot, J -- Wu, X F -- Pal'shin, V -- Covino, S -- van der Horst, A J -- Oates, S R -- Schady, P -- Smith, R J -- Cummings, J -- Starling, R L C -- Piotrowski, L W -- Zhang, B -- Evans, P A -- Holland, S T -- Malek, K -- Page, M T -- Vetere, L -- Margutti, R -- Guidorzi, C -- Kamble, A P -- Curran, P A -- Beardmore, A -- Kouveliotou, C -- Mankiewicz, L -- Melandri, A -- O'Brien, P T -- Page, K L -- Piran, T -- Tanvir, N R -- Wrochna, G -- Aptekar, R L -- Barthelmy, S -- Bartolini, C -- Beskin, G M -- Bondar, S -- Bremer, M -- Campana, S -- Castro-Tirado, A -- Cucchiara, A -- Cwiok, M -- D'Avanzo, P -- D'Elia, V -- Valle, M Della -- de Ugarte Postigo, A -- Dominik, W -- Falcone, A -- Fiore, F -- Fox, D B -- Frederiks, D D -- Fruchter, A S -- Fugazza, D -- Garrett, M A -- Gehrels, N -- Golenetskii, S -- Gomboc, A -- Gorosabel, J -- Greco, G -- Guarnieri, A -- Immler, S -- Jelinek, M -- Kasprowicz, G -- La Parola, V -- Levan, A J -- Mangano, V -- Mazets, E P -- Molinari, E -- Moretti, A -- Nawrocki, K -- Oleynik, P P -- Osborne, J P -- Pagani, C -- Pandey, S B -- Paragi, Z -- Perri, M -- Piccioni, A -- Ramirez-Ruiz, E -- Roming, P W A -- Steele, I A -- Strom, R G -- Testa, V -- Tosti, G -- Ulanov, M V -- Wiersema, K -- Wijers, R A M J -- Winters, J M -- Zarnecki, A F -- Zerbi, F -- Meszaros, P -- Chincarini, G -- Burrows, D N -- England -- Nature. 2008 Sep 11;455(7210):183-8. doi: 10.1038/nature07270.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, USA. racusin@astro.psu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18784718" target="_blank"〉PubMed〈/a〉

Description: Long-duration gamma-ray bursts (GRBs) are thought to result from the explosions of certain massive stars, and some are bright enough that they should be observable out to redshifts of z 〉 20 using current technology. Hitherto, the highest redshift measured for any object was z = 6.96, for a Lyman-alpha emitting galaxy. Here we report that GRB 090423 lies at a redshift of z approximately 8.2, implying that massive stars were being produced and dying as GRBs approximately 630 Myr after the Big Bang. The burst also pinpoints the location of its host galaxy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tanvir, N R -- Fox, D B -- Levan, A J -- Berger, E -- Wiersema, K -- Fynbo, J P U -- Cucchiara, A -- Kruhler, T -- Gehrels, N -- Bloom, J S -- Greiner, J -- Evans, P A -- 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 -- Kennea, J -- Kerr, T -- Klose, S -- Krimm, H A -- Komarova, V N -- Kulkarni, S R -- Moskvitin, A S -- Mundell, C G -- Naylor, T -- Page, K -- 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 -- England -- Nature. 2009 Oct 29;461(7268):1254-7. doi: 10.1038/nature08459.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK. nrt3@star.le.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19865165" target="_blank"〉PubMed〈/a〉

Description: Variable x-ray and gamma-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique gamma-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any gamma-ray burst, whereas its peak luminosity was approximately 100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Levan, A J -- Tanvir, N R -- Cenko, S B -- Perley, D A -- Wiersema, K -- Bloom, J S -- Fruchter, A S -- Postigo, A de Ugarte -- O'Brien, P T -- Butler, N -- van der Horst, A J -- Leloudas, G -- Morgan, A N -- Misra, K -- Bower, G C -- Farihi, J -- Tunnicliffe, R L -- Modjaz, M -- Silverman, J M -- Hjorth, J -- Thone, C -- Cucchiara, A -- Ceron, J M Castro -- Castro-Tirado, A J -- Arnold, J A -- Bremer, M -- Brodie, J P -- Carroll, T -- Cooper, M C -- Curran, P A -- Cutri, R M -- Ehle, J -- Forbes, D -- Fynbo, J -- Gorosabel, J -- Graham, J -- Hoffman, D I -- Guziy, S -- Jakobsson, P -- Kamble, A -- Kerr, T -- Kasliwal, M M -- Kouveliotou, C -- Kocevski, D -- Law, N M -- Nugent, P E -- Ofek, E O -- Poznanski, D -- Quimby, R M -- Rol, E -- Romanowsky, A J -- Sanchez-Ramirez, R -- Schulze, S -- Singh, N -- van Spaandonk, L -- Starling, R L C -- Strom, R G -- Tello, J C -- Vaduvescu, O -- Wheatley, P J -- Wijers, R A M J -- Winters, J M -- Xu, D -- New York, N.Y. -- Science. 2011 Jul 8;333(6039):199-202. doi: 10.1126/science.1207143. Epub 2011 Jun 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, University of Warwick, Coventry, UK. a.j.levan@warwick.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21680811" target="_blank"〉PubMed〈/a〉

Description: Short-duration gamma-ray bursts are intense flashes of cosmic gamma-rays, lasting less than about two seconds, whose origin is unclear. The favoured hypothesis is that they are produced by a relativistic jet created by the merger of two compact stellar objects (specifically two neutron stars or a neutron star and a black hole). This is supported by indirect evidence such as the properties of their host galaxies, but unambiguous confirmation of the model is still lacking. Mergers of this kind are also expected to create significant quantities of neutron-rich radioactive species, whose decay should result in a faint transient, known as a 'kilonova', in the days following the burst. Indeed, it is speculated that this mechanism may be the predominant source of stable r-process elements in the Universe. Recent calculations suggest that much of the kilonova energy should appear in the near-infrared spectral range, because of the high optical opacity created by these heavy r-process elements. Here we report optical and near-infrared observations that provide strong evidence for such an event accompanying the short-duration gamma-ray burst GRB 130603B. If this, the simplest interpretation of the data, is correct, then it confirms that compact-object mergers are the progenitors of short-duration gamma-ray bursts and the sites of significant production of r-process elements. It also suggests that kilonovae offer an alternative, unbeamed electromagnetic signature of the most promising sources for direct detection of gravitational waves.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tanvir, N R -- Levan, A J -- Fruchter, A S -- Hjorth, J -- Hounsell, R A -- Wiersema, K -- Tunnicliffe, R L -- England -- Nature. 2013 Aug 29;500(7464):547-9. doi: 10.1038/nature12505. Epub 2013 Aug 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK. nrt3@le.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23912055" target="_blank"〉PubMed〈/a〉

Description: Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wiersema, K -- Covino, S -- Toma, K -- van der Horst, A J -- Varela, K -- Min, M -- Greiner, J -- Starling, R L C -- Tanvir, N R -- Wijers, R A M J -- Campana, S -- Curran, P A -- Fan, Y -- Fynbo, J P U -- Gorosabel, J -- Gomboc, A -- Gotz, D -- Hjorth, J -- Jin, Z P -- Kobayashi, S -- Kouveliotou, C -- Mundell, C -- O'Brien, P T -- Pian, E -- Rowlinson, A -- Russell, D M -- Salvaterra, R -- di Serego Alighieri, S -- Tagliaferri, G -- Vergani, S D -- Elliott, J -- Farina, C -- Hartoog, O E -- Karjalainen, R -- Klose, S -- Knust, F -- Levan, A J -- Schady, P -- Sudilovsky, V -- Willingale, R -- England -- Nature. 2014 May 8;509(7499):201-4. doi: 10.1038/nature13237. Epub 2014 Apr 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK. ; INAF/Brera Astronomical Observatory, via Bianchi 46, I-23807 Merate (LC), Italy. ; 1] Department of Earth and Space Science, Osaka University, Toyonaka 560-0043, Japan [2] Astronomical Institute, Tohoku University, Sendai 980-8578, Japan [3] Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan. ; Astronomical Institute 'Anton Pannekoek', University of Amsterdam, PO Box 94248, 1090 SJ Amsterdam, The Netherlands. ; Max-Planck-Institut fur extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany. ; International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia. ; Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008, China. ; Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK 2100 Copenhagen, Denmark. ; 1] Instituto de Astrofisica de Andalucia (IAA-CSIC), Glorieta de la Astronomia s/n, E-18008 Granada, Spain [2] Unidad Asociada Grupo Ciencia Planetarias UPV/EHU-IAA/CSIC, Departamento de Fisica Aplicada I, ETS Ingenieria, Universidad del Pais Vasco UPV/EHU, Alameda de Urquijo s/n, E-48013 Bilbao, Spain [3] Ikerbasque, Basque Foundation for Science, Alameda de Urquijo 36-5, E-48008 Bilbao, Spain. ; Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia. ; AIM (UMR 7158 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d'Astrophysique, Saclay, F-91191 Gif-sur-Yvette Cedex, France. ; Astrophysics Research Institute, Liverpool John Moores University, Liverpool Science Park, IC2 Building, 146 Brownlow Hill, Liverpool L3 5RF, UK. ; Space Science Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, Alabama 35812, USA. ; 1] Scuola Normale Superiore, 7, I-56126 Pisa, Italy [2] INAF/IASF Bologna, via Gobetti 101, I-40129 Bologna, Italy. ; 1] Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife, Spain [2] Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain [3] New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates. ; INAF/IASF Milano, via E. Bassini 15, 20133 Milano, Italy. ; INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze, Italy. ; Isaac Newton Group of Telescopes, Apartado de Correos 321, E-38700 Santa Cruz de la Palma, Canary Islands, Spain. ; Thuringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany. ; Department of Physics, University of Warwick, Coventry CV4 7AL, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24776800" target="_blank"〉PubMed〈/a〉

Description: Gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, but most MBHs are considered dormant. Occasionally, a star passing too near an MBH is torn apart by gravitational forces, leading to a bright tidal disruption flare (TDF). Although the high-energy transient Sw 1644+57 initially displayed none of the theoretically anticipated (nor previously observed) TDF characteristics, we show that observations suggest a sudden accretion event onto a central MBH of mass about 10(6) to 10(7) solar masses. There is evidence for a mildly relativistic outflow, jet collimation, and a spectrum characterized by synchrotron and inverse Compton processes; this leads to a natural analogy of Sw 1644+57 to a temporary smaller-scale blazar.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bloom, Joshua S -- Giannios, Dimitrios -- Metzger, Brian D -- Cenko, S Bradley -- Perley, Daniel A -- Butler, Nathaniel R -- Tanvir, Nial R -- Levan, Andrew J -- O'Brien, Paul T -- Strubbe, Linda E -- De Colle, Fabio -- Ramirez-Ruiz, Enrico -- Lee, William H -- Nayakshin, Sergei -- Quataert, Eliot -- King, Andrew R -- Cucchiara, Antonino -- Guillochon, James -- Bower, Geoffrey C -- Fruchter, Andrew S -- Morgan, Adam N -- van der Horst, Alexander J -- New York, N.Y. -- Science. 2011 Jul 8;333(6039):203-6. doi: 10.1126/science.1207150. Epub 2011 Jun 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA. jbloom@astro.berkeley.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21680812" target="_blank"〉PubMed〈/a〉

Description: The intrinsic X-ray emission of gamma-ray bursts (GRBs) is often found to be absorbed over and above the column density through our own Galaxy. The extra component is usually assumed to be due to absorbing gas lying within the host galaxy of the GRB itself. There is an apparent correlation between the equivalent column density of hydrogen, N H,intrinsic (assuming it to be at the GRB redshift), and redshift, z , with the few z  〉 6 GRBs showing the greatest intrinsic column densities. We investigate the N H, intrinsic - z relation using a large sample of Swift GRBs, as well as active galactic nuclei and quasar samples, paying particular attention to the spectral energy distributions of the two highest redshift GRBs. Various possible sample biases and systematics that might produce such a correlation are considered, and we conclude that the correlation is very likely to be real. This may indicate either an evolutionary effect in the host galaxy properties, or a contribution from gas along the line of sight, in the diffuse intergalactic medium (IGM) or intervening absorbing clouds. Employing a more realistic model for IGM absorption than in previous works, we find that this may explain much of the observed opacity at z 3 providing it is not too hot, likely between 10 5 and 10 6.5 K, and moderately metal enriched, Z  ~ 0.2 Z . This material could therefore constitute the warm–hot intergalactic medium. However, a comparable level of absorption is also expected from the cumulative effect of intervening cold gas clouds, and given current uncertainties it is not possible to say which, if either, dominates. At lower redshifts, we conclude that gas in the host galaxies must be the dominant contributor to the observed X-ray absorption.