ALBERT

Description: A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximately 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximately 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves. Here we report the detection of emission up to approximately 31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space-time on a very small scale linearly alters the speed of light.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abdo, A A -- Ackermann, M -- Ajello, M -- Asano, K -- Atwood, W B -- Axelsson, M -- Baldini, L -- Ballet, J -- Barbiellini, G -- Baring, M G -- Bastieri, D -- Bechtol, K -- Bellazzini, R -- Berenji, B -- Bhat, P N -- Bissaldi, E -- Bloom, E D -- Bonamente, E -- Bonnell, J -- Borgland, A W -- Bouvier, A -- Bregeon, J -- Brez, A -- Briggs, M S -- Brigida, M -- Bruel, P -- Burgess, J M -- Burnett, T H -- Caliandro, G A -- Cameron, R A -- Caraveo, P A -- Casandjian, J M -- Cecchi, C -- Celik, O -- Chaplin, V -- Charles, E -- Cheung, C C -- Chiang, J -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Cominsky, L R -- Connaughton, V -- Conrad, J -- Cutini, S -- Dermer, C D -- de Angelis, A -- de Palma, F -- Digel, S W -- Dingus, B L -- do Couto E Silva, E -- Drell, P S -- Dubois, R -- Dumora, D -- Farnier, C -- Favuzzi, C -- Fegan, S J -- Finke, J -- Fishman, G -- Focke, W B -- Foschini, L -- Fukazawa, Y -- Funk, S -- Fusco, P -- Gargano, F -- Gasparrini, D -- Gehrels, N -- Germani, S -- Gibby, L -- Giebels, B -- Giglietto, N -- Giordano, F -- Glanzman, T -- Godfrey, G -- Granot, J -- Greiner, J -- Grenier, I A -- Grondin, M-H -- Grove, J E -- Grupe, D -- Guillemot, L -- Guiriec, S -- Hanabata, Y -- Harding, A K -- Hayashida, M -- Hays, E -- Hoversten, E A -- Hughes, R E -- Johannesson, G -- Johnson, A S -- Johnson, R P -- Johnson, W N -- Kamae, T -- Katagiri, H -- Kataoka, J -- Kawai, N -- Kerr, M -- Kippen, R M -- Knodlseder, J -- Kocevski, D -- Kouveliotou, C -- Kuehn, F -- Kuss, M -- Lande, J -- Latronico, L -- Lemoine-Goumard, M -- Longo, F -- Loparco, F -- Lott, B -- Lovellette, M N -- Lubrano, P -- Madejski, G M -- Makeev, A -- Mazziotta, M N -- McBreen, S -- McEnery, J E -- McGlynn, S -- Meszaros, P -- Meurer, C -- Michelson, P F -- Mitthumsiri, W -- Mizuno, T -- Moiseev, A A -- Monte, C -- Monzani, M E -- Moretti, E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Nakamori, T -- Nolan, P L -- Norris, J P -- Nuss, E -- Ohno, M -- Ohsugi, T -- Omodei, N -- Orlando, E -- Ormes, J F -- Ozaki, M -- Paciesas, W S -- Paneque, D -- Panetta, J H -- Parent, D -- Pelassa, V -- Pepe, M -- Pesce-Rollins, M -- Petrosian, V -- Piron, F -- Porter, T A -- Preece, R -- Raino, S -- Ramirez-Ruiz, E -- Rando, R -- Razzano, M -- Razzaque, S -- Reimer, A -- Reimer, O -- Reposeur, T -- Ritz, S -- Rochester, L S -- Rodriguez, A Y -- Roth, M -- Ryde, F -- Sadrozinski, H F-W -- Sanchez, D -- Sander, A -- Saz Parkinson, P M -- Scargle, J D -- Schalk, T L -- Sgro, C -- Siskind, E J -- Smith, D A -- Smith, P D -- Spandre, G -- Spinelli, P -- Stamatikos, M -- Stecker, F W -- Strickman, M S -- Suson, D J -- Tajima, H -- Takahashi, H -- Takahashi, T -- Tanaka, T -- Thayer, J B -- Thayer, J G -- Thompson, D J -- Tibaldo, L -- Toma, K -- Torres, D F -- Tosti, G -- Troja, E -- Uchiyama, Y -- Uehara, T -- Usher, T L -- van der Horst, A J -- Vasileiou, V -- Vilchez, N -- Vitale, V -- von Kienlin, A -- Waite, A P -- Wang, P -- Wilson-Hodge, C -- Winer, B L -- Wood, K S -- Wu, X F -- Yamazaki, R -- Ylinen, T -- Ziegler, M -- England -- Nature. 2009 Nov 19;462(7271):331-4. doi: 10.1038/nature08574. Epub 2009 Oct 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Space Science Division, Naval Research Laboratory, Washington, District of Columbia 20375, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19865083" target="_blank"〉PubMed〈/a〉

Description: Long duration gamma-ray bursts (GRBs) mark the explosive death of some massive stars and are a rare sub-class of type Ibc supernovae. They are distinguished by the production of an energetic and collimated relativistic outflow powered by a central engine (an accreting black hole or neutron star). Observationally, this outflow is manifested in the pulse of gamma-rays and a long-lived radio afterglow. Until now, central-engine-driven supernovae have been discovered exclusively through their gamma-ray emission, yet it is expected that a larger population goes undetected because of limited satellite sensitivity or beaming of the collimated emission away from our line of sight. In this framework, the recovery of undetected GRBs may be possible through radio searches for type Ibc supernovae with relativistic outflows. Here we report the discovery of luminous radio emission from the seemingly ordinary type Ibc SN 2009bb, which requires a substantial relativistic outflow powered by a central engine. A comparison with our radio survey of type Ibc supernovae reveals that the fraction harbouring central engines is low, about one per cent, measured independently from, but consistent with, the inferred rate of nearby GRBs. Independently, a second mildly relativistic supernova has been reported.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soderberg, A M -- Chakraborti, S -- Pignata, G -- Chevalier, R A -- Chandra, P -- Ray, A -- Wieringa, M H -- Copete, A -- Chaplin, V -- Connaughton, V -- Barthelmy, S D -- Bietenholz, M F -- Chugai, N -- Stritzinger, M D -- Hamuy, M -- Fransson, C -- Fox, O -- Levesque, E M -- Grindlay, J E -- Challis, P -- Foley, R J -- Kirshner, R P -- Milne, P A -- Torres, M A P -- England -- Nature. 2010 Jan 28;463(7280):513-5. doi: 10.1038/nature08714.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, Massachusetts 02138, USA. asoderberg@cfa.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20110995" target="_blank"〉PubMed〈/a〉