ALBERT

Description: A key parameter in the study of magma evolution is the time scale on which magmatic processes occur. Using nanoscale secondary ion mass spectrometry (NanoSIMS), SIMS, and cathodoluminescence (CL) analyses, we have measured titanium (Ti) diffusion profiles in quartz phenocrysts from a Jurassic rhyolite of the El Quemado Complex (Patagonia, Argentina), providing new insights into the time scales of the associated volcanic processes. CL imaging of quartz phenocrysts reveals oscillatory magmatic zoning. We determined Ti concentrations with SIMS and acquired multiple NanoSIMS profiles across growth zones from core to rim. All transects show sharp changes in the 48 Ti/ 29 Si ratio, which correlate reasonably well with changes in CL intensity. Diffusion modeling of Ti in quartz yields a surprisingly short time scale for quartz crystallization of 5.6 ± 2.2 yr and a rapid crystal growth rate of 2.3 x 10 –12 m/s. Based on the observed quartz textures, we suggest that the rhyolite erupted shortly after initial onset of crystallization, followed by decompression-driven quartz dissolution during fast magma ascent. We further argue that the observed oscillatory zoning and the variation of the Ti concentration of the quartz phenocryst does not reflect temperature, pressure, or titanium activity (a Ti ) changes of the magmatic system, but rather is the result of growth kinetics, which has important implications for the Ti-in-quartz thermometry.

Description: Jellyfish blooms occur in many estuarine and coastal regions and may be increasing in their magnitude and extent worldwide. Voracious jellyfish predation impacts food webs by converting large quantities of carbon (C), fixed by primary producers and consumed by secondary producers, into gelatinous biomass, which restricts C transfer to higher trophic levels because jellyfish are not readily consumed by other predators. In addition, jellyfish release colloidal and dissolved organic matter (jelly-DOM), and could further influence the functioning of coastal systems by altering microbial nutrient and DOM pathways, yet the links between jellyfish and bacterioplankton metabolism and community structure are unknown. Here we report that jellyfish released substantial quantities of extremely labile C-rich DOM, relative to nitrogen (25.6 ± 31.6 C:1N), which was quickly metabolized by bacterioplankton at uptake rates two to six times that of bulk DOM pools. When jelly-DOM was consumed it was shunted toward bacterial respiration rather than production, significantly reducing bacterial growth efficiencies by 10% to 15%. Jelly-DOM also favored the rapid growth and dominance of specific bacterial phylogenetic groups (primarily γ-proteobacteria) that were rare in ambient waters, implying that jelly-DOM was channeled through a small component of the in situ microbial assemblage and thus induced large changes in community composition. Our findings suggest major shifts in microbial structure and function associated with jellyfish blooms, and a large detour of C toward bacterial CO2 production and away from higher trophic levels. These results further suggest fundamental transformations in the biogeochemical functioning and biological structure of food webs associated with jellyfish blooms.

Description: In order to improve understanding of how accessory garnet crystallizes in igneous rocks, and evaluate it as a mineral recorder of magma history, we analyzed d18O of garnets from the Hallowell and Togus plutons in south-central Maine (United States) by laser fluorination, and in situ by ion microprobe. Two types of garnet are recognized, magmatic and locally derived peritectic. Traverses of some single crystals show both gradual and abrupt changes of d18O(garnet), commonly 〉1‰, while other garnet grains are isotopically homogeneous. Rimward increase of d18O in many crystals indicates that garnet grew while high d18O metamorphic wall rocks were assimilated. Peritectic grains have a complementary record of the transfer of high d18O melts to the plutons. In some rocks, d18O varies among neighboring grains, evidence that crystals grew episodically or were juxtaposed from different sources during magma mixing. Garnet faithfully records changing magmatic d18O, and is a valuable tool to decipher magma petrogenesis.

Description: We report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri star LkCa 4 within the Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets (MaTYSSE) programme, involving ESPaDOnS at the Canada–France–Hawaii Telescope. Despite an age of only 2 Myr and a similarity with prototypical classical T Tauri stars, LkCa 4 shows no evidence for accretion and probes an interesting transition stage for star and planet formation. Large profile distortions and Zeeman signatures are detected in the unpolarized and circularly polarized lines of LkCa 4 using Least-Squares Deconvolution (LSD), indicating the presence of brightness inhomogeneities and magnetic fields at the surface of LkCa 4. Using tomographic imaging, we reconstruct brightness and magnetic maps of LkCa 4 from sets of unpolarized and circularly polarized LSD profiles. The large-scale field is strong and mainly axisymmetric, featuring a ~=2 kG poloidal component and a ~=1 kG toroidal component encircling the star at equatorial latitudes – the latter making LkCa 4 markedly different from classical T Tauri stars of similar mass and age. The brightness map includes a dark spot overlapping the magnetic pole and a bright region at mid-latitudes – providing a good match to the contemporaneous photometry. We also find that differential rotation at the surface of LkCa 4 is small, typically ~=5.5 times weaker than that of the Sun, and compatible with solid-body rotation. Using our tomographic modelling, we are able to filter out the activity jitter in the radial velocity curve of LkCa 4 (of full amplitude 4.3 km s –1 ) down to an rms precision of 0.055 km s –1 . Looking for hot Jupiters around young Sun-like stars thus appears feasible, even though we find no evidence for such planets around LkCa 4.

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: Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fermi LAT and Fermi GBM Collaborations -- Abdo, A A -- Ackermann, M -- Arimoto, M -- Asano, K -- Atwood, W B -- Axelsson, M -- Baldini, L -- Ballet, J -- Band, D L -- Barbiellini, G -- Baring, M G -- Bastieri, D -- Battelino, M -- Baughman, B M -- Bechtol, K -- Bellardi, F -- Bellazzini, R -- Berenji, B -- Bhat, P N -- Bissaldi, E -- Blandford, R D -- Bloom, E D -- Bogaert, G -- Bogart, J R -- Bonamente, E -- Bonnell, J -- Borgland, A W -- Bouvier, A -- Bregeon, J -- Brez, A -- Briggs, M S -- Brigida, M -- Bruel, P -- Burnett, T H -- Burrows, D -- Busetto, G -- Caliandro, G A -- Cameron, R A -- Caraveo, P A -- Casandjian, J M -- Ceccanti, M -- Cecchi, C -- Celotti, A -- Charles, E -- Chekhtman, A -- Cheung, C C -- Chiang, J -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Cominsky, L R -- Connaughton, V -- Conrad, J -- Costamante, L -- Cutini, S -- Deklotz, M -- 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 -- Edmonds, Y -- Evans, P A -- Fabiani, D -- Farnier, C -- Favuzzi, C -- Finke, J -- Fishman, G -- Focke, W B -- Frailis, M -- Fukazawa, Y -- Funk, S -- Fusco, P -- Gargano, F -- Gasparrini, D -- Gehrels, N -- Germani, S -- Giebels, B -- Giglietto, N -- Giommi, P -- Giordano, F -- Glanzman, T -- Godfrey, G -- Goldstein, A -- Granot, J -- Greiner, J -- Grenier, I A -- Grondin, M-H -- Grove, J E -- Guillemot, L -- Guiriec, S -- Haller, G -- Hanabata, Y -- Harding, A K -- Hayashida, M -- Hays, E -- Hernando Morat, J A -- Hoover, A -- Hughes, R E -- Johannesson, G -- Johnson, A S -- Johnson, R P -- Johnson, T J -- Johnson, W N -- Kamae, T -- Katagiri, H -- Kataoka, J -- Kavelaars, A -- Kawai, N -- Kelly, H -- Kennea, J -- Kerr, M -- Kippen, R M -- Knodlseder, J -- Kocevski, D -- Kocian, M L -- Komin, N -- Kouveliotou, C -- Kuehn, F -- Kuss, M -- Lande, J -- Landriu, D -- Larsson, S -- Latronico, L -- Lavalley, C -- Lee, B -- Lee, S-H -- Lemoine-Goumard, M -- Lichti, G G -- Longo, F -- Loparco, F -- Lott, B -- Lovellette, M N -- Lubrano, P -- Madejski, G M -- Makeev, A -- Marangelli, B -- Mazziotta, M N -- McBreen, S -- McEnery, J E -- McGlynn, S -- Meegan, C -- Meszaros, P -- Meurer, C -- Michelson, P F -- Minuti, M -- Mirizzi, N -- Mitthumsiri, W -- Mizuno, T -- Moiseev, A A -- Monte, C -- Monzani, M E -- Moretti, E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Nakamori, T -- Nelson, D -- Nolan, P L -- Norris, J P -- Nuss, E -- Ohno, M -- Ohsugi, T -- Okumura, A -- Omodei, N -- Orlando, E -- Ormes, J F -- Ozaki, M -- Paciesas, W S -- Paneque, D -- Panetta, J H -- Parent, D -- Pelassa, V -- Pepe, M -- Perri, M -- Pesce-Rollins, M -- Petrosian, V -- Pinchera, M -- Piron, F -- Porter, T A -- Preece, R -- Raino, S -- Ramirez-Ruiz, E -- Rando, R -- Rapposelli, E -- Razzano, M -- Razzaque, S -- Rea, N -- Reimer, A -- Reimer, O -- Reposeur, T -- Reyes, L C -- 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 -- Segal, K N -- Sgro, C -- Shimokawabe, T -- Siskind, E J -- Smith, D A -- Smith, P D -- Spandre, G -- Spinelli, P -- Stamatikos, M -- Starck, J-L -- Stecker, F W -- Steinle, H -- Stephens, T E -- Strickman, M S -- Suson, D J -- Tagliaferri, G -- Tajima, H -- Takahashi, H -- Takahashi, T -- Tanaka, T -- Tenze, A -- Thayer, J B -- Thayer, J G -- Thompson, D J -- Tibaldo, L -- Torres, D F -- Tosti, G -- Tramacere, A -- Turri, M -- Tuvi, S -- Usher, T L -- van der Horst, A J -- Vigiani, L -- Vilchez, N -- Vitale, V -- von Kienlin, A -- Waite, A P -- Williams, D A -- Wilson-Hodge, C -- Winer, B L -- Wood, K S -- Wu, X F -- Yamazaki, R -- Ylinen, T -- Ziegler, M -- New York, N.Y. -- Science. 2009 Mar 27;323(5922):1688-93. doi: 10.1126/science.1169101. Epub 2009 Feb 19.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19228997" target="_blank"〉PubMed〈/a〉

Description: Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here, we report the Fermi Large Area Telescope detection of variable gamma-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce pi(0) decay gamma-rays from proton-proton interactions. Emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fermi-LAT Collaboration -- Abdo, A A -- Ackermann, M -- Ajello, M -- Atwood, W B -- Baldini, L -- Ballet, J -- Barbiellini, G -- Bastieri, D -- Bechtol, K -- Bellazzini, R -- Berenji, B -- Blandford, R D -- Bloom, E D -- Bonamente, E -- Borgland, A W -- Bouvier, A -- Brandt, T J -- Bregeon, J -- Brez, A -- Brigida, M -- Bruel, P -- Buehler, R -- Burnett, T H -- Buson, S -- Caliandro, G A -- Cameron, R A -- Caraveo, P A -- Carrigan, S -- Casandjian, J M -- Cecchi, C -- Celik, O -- Charles, E -- Chaty, S -- Chekhtman, A -- Cheung, C C -- Chiang, J -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Conrad, J -- Corbel, S -- Corbet, R -- DeCesar, M E -- den Hartog, P R -- Dermer, C D -- de Palma, F -- Digel, S W -- Donato, D -- do Couto e Silva, E -- Drell, P S -- Dubois, R -- Dubus, G -- Dumora, D -- Favuzzi, C -- Fegan, S J -- Ferrara, E C -- Fortin, P -- Frailis, M -- Fuhrmann, L -- Fukazawa, Y -- Funk, S -- Fusco, P -- Gargano, F -- Gasparrini, D -- Gehrels, N -- Germani, S -- Giglietto, N -- Giordano, F -- Giroletti, M -- Glanzman, T -- Godfrey, G -- Grenier, I A -- Grondin, M-H -- Grove, J E -- Guiriec, S -- Hadasch, D -- Harding, A K -- Hayashida, M -- Hays, E -- Healey, S E -- Hill, A B -- Horan, D -- Hughes, R E -- Itoh, R -- Jean, P -- Johannesson, G -- Johnson, A S -- Johnson, R P -- Johnson, T J -- Johnson, W N -- Kamae, T -- Katagiri, H -- Kataoka, J -- Kerr, M -- Knodlseder, J -- Koerding, E -- Kuss, M -- Lande, J -- Latronico, L -- Lee, S-H -- Lemoine-Goumard, M -- Garde, M Llena -- Longo, F -- Loparco, F -- Lott, B -- Lovellette, M N -- Lubrano, P -- Makeev, A -- Mazziotta, M N -- McConville, W -- McEnery, J E -- Mehault, J -- Michelson, P F -- Mizuno, T -- Moiseev, A A -- Monte, C -- Monzani, M E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Nakamori, T -- Naumann-Godo, M -- Nestoras, I -- Nolan, P L -- Norris, J P -- Nuss, E -- Ohno, M -- Ohsugi, T -- Okumura, A -- Omodei, N -- Orlando, E -- Ormes, J F -- Ozaki, M -- Paneque, D -- Panetta, J H -- Parent, D -- Pelassa, V -- Pepe, M -- Pesce-Rollins, M -- Piron, F -- Porter, T A -- Raino, S -- Rando, R -- Ray, P S -- Razzano, M -- Razzaque, S -- Rea, N -- Reimer, A -- Reimer, O -- Reposeur, T -- Ripken, J -- Ritz, S -- Romani, R W -- Roth, M -- Sadrozinski, H F-W -- Sander, A -- Parkinson, P M Saz -- Scargle, J D -- Schinzel, F K -- Sgro, C -- Shaw, M S -- Siskind, E J -- Smith, D A -- Smith, P D -- Sokolovsky, K V -- Spandre, G -- Spinelli, P -- Stawarz, L -- Strickman, M S -- Suson, D J -- Takahashi, H -- Takahashi, T -- Tanaka, T -- Tanaka, Y -- Thayer, J B -- Thayer, J G -- Thompson, D J -- Tibaldo, L -- Torres, D F -- Tosti, G -- Tramacere, A -- Uchiyama, Y -- Usher, T L -- Vandenbroucke, J -- Vasileiou, V -- Vilchez, N -- Vitale, V -- Waite, A P -- Wallace, E -- Wang, P -- Winer, B L -- Wolff, M T -- Wood, K S -- Yang, Z -- Ylinen, T -- Ziegler, M -- Maehara, H -- Nishiyama, K -- Kabashima, F -- Bach, U -- Bower, G C -- Falcone, A -- Forster, J R -- Henden, A -- Kawabata, K S -- Koubsky, P -- Mukai, K -- Nelson, T -- Oates, S R -- Sakimoto, K -- Sasada, M -- Shenavrin, V I -- Shore, S N -- Skinner, G K -- Sokoloski, J -- Stroh, M -- Tatarnikov, A M -- Uemura, M -- Wahlgren, G M -- Yamanaka, M -- New York, N.Y. -- Science. 2010 Aug 13;329(5993):817-21. doi: 10.1126/science.1192537.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Space Science Division, Naval Research Laboratory, Washington, DC 20375, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20705855" target="_blank"〉PubMed〈/a〉

Description: A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 x 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abdo, A A -- Ackermann, M -- Ajello, M -- Allafort, A -- Baldini, L -- Ballet, J -- Barbiellini, G -- Bastieri, D -- Bechtol, K -- Bellazzini, R -- Berenji, B -- Blandford, R D -- Bloom, E D -- Bonamente, E -- Borgland, A W -- Bouvier, A -- Brandt, T J -- Bregeon, J -- Brez, A -- Brigida, M -- Bruel, P -- Buehler, R -- Buson, S -- Caliandro, G A -- Cameron, R A -- Cannon, A -- Caraveo, P A -- Casandjian, J M -- Celik, O -- Charles, E -- Chekhtman, A -- Cheung, C C -- Chiang, J -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Costamante, L -- Cutini, S -- D'Ammando, F -- Dermer, C D -- de Angelis, A -- de Luca, A -- de Palma, F -- Digel, S W -- do Couto e Silva, E -- Drell, P S -- Drlica-Wagner, A -- Dubois, R -- Dumora, D -- Favuzzi, C -- Fegan, S J -- Ferrara, E C -- Focke, W B -- Fortin, P -- Frailis, M -- Fukazawa, Y -- Funk, S -- Fusco, P -- Gargano, F -- Gasparrini, D -- Gehrels, N -- Germani, S -- Giglietto, N -- Giordano, F -- Giroletti, M -- Glanzman, T -- Godfrey, G -- Grenier, I A -- Grondin, M-H -- Grove, J E -- Guiriec, S -- Hadasch, D -- Hanabata, Y -- Harding, A K -- Hayashi, K -- Hayashida, M -- Hays, E -- Horan, D -- Itoh, R -- Johannesson, G -- Johnson, A S -- Johnson, T J -- Khangulyan, D -- Kamae, T -- Katagiri, H -- Kataoka, J -- Kerr, M -- Knodlseder, J -- Kuss, M -- Lande, J -- Latronico, L -- Lee, S-H -- Lemoine-Goumard, M -- Longo, F -- Loparco, F -- Lubrano, P -- Madejski, G M -- Makeev, A -- Marelli, M -- Mazziotta, M N -- McEnery, J E -- Michelson, P F -- Mitthumsiri, W -- Mizuno, T -- Moiseev, A A -- Monte, C -- Monzani, M E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Nakamori, T -- Naumann-Godo, M -- Nolan, P L -- Norris, J P -- Nuss, E -- Ohsugi, T -- Okumura, A -- Omodei, N -- Ormes, J F -- Ozaki, M -- Paneque, D -- Parent, D -- Pelassa, V -- Pepe, M -- Pesce-Rollins, M -- Pierbattista, M -- Piron, F -- Porter, T A -- Raino, S -- Rando, R -- Ray, P S -- Razzano, M -- Reimer, A -- Reimer, O -- Reposeur, T -- Ritz, S -- Romani, R W -- Sadrozinski, H F-W -- Sanchez, D -- Saz Parkinson, P M -- Scargle, J D -- Schalk, T L -- Sgro, C -- Siskind, E J -- Smith, P D -- Spandre, G -- Spinelli, P -- Strickman, M S -- Suson, D J -- Takahashi, H -- Takahashi, T -- Tanaka, T -- Thayer, J B -- Thompson, D J -- Tibaldo, L -- Torres, D F -- Tosti, G -- Tramacere, A -- Troja, E -- Uchiyama, Y -- Vandenbroucke, J -- Vasileiou, V -- Vianello, G -- Vitale, V -- Wang, P -- Wood, K S -- Yang, Z -- Ziegler, M -- New York, N.Y. -- Science. 2011 Feb 11;331(6018):739-42. doi: 10.1126/science.1199705. Epub 2011 Jan 6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21212321" target="_blank"〉PubMed〈/a〉

Description: We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉VERITAS Collaboration -- Aliu, E -- Arlen, T -- Aune, T -- Beilicke, M -- Benbow, W -- Bouvier, A -- Bradbury, S M -- Buckley, J H -- Bugaev, V -- Byrum, K -- Cannon, A -- Cesarini, A -- Christiansen, J L -- Ciupik, L -- Collins-Hughes, E -- Connolly, M P -- Cui, W -- Dickherber, R -- Duke, C -- Errando, M -- Falcone, A -- Finley, J P -- Finnegan, G -- Fortson, L -- Furniss, A -- Galante, N -- Gall, D -- Gibbs, K -- Gillanders, G H -- Godambe, S -- Griffin, S -- Grube, J -- Guenette, R -- Gyuk, G -- Hanna, D -- Holder, J -- Huan, H -- Hughes, G -- Hui, C M -- Humensky, T B -- Imran, A -- Kaaret, P -- Karlsson, N -- Kertzman, M -- Kieda, D -- Krawczynski, H -- Krennrich, F -- Lang, M J -- Lyutikov, M -- Madhavan, A S -- Maier, G -- Majumdar, P -- McArthur, S -- McCann, A -- McCutcheon, M -- Moriarty, P -- Mukherjee, R -- Nunez, P -- Ong, R A -- Orr, M -- Otte, A N -- Park, N -- Perkins, J S -- Pizlo, F -- Pohl, M -- Prokoph, H -- Quinn, J -- Ragan, K -- Reyes, L C -- Reynolds, P T -- Roache, E -- Rose, H J -- Ruppel, J -- Saxon, D B -- Schroedter, M -- Sembroski, G H -- Senturk, G D -- Smith, A W -- Staszak, D -- Tesic, G -- Theiling, M -- Thibadeau, S -- Tsurusaki, K -- Tyler, J -- Varlotta, A -- Vassiliev, V V -- Vincent, S -- Vivier, M -- Wakely, S P -- Ward, J E -- Weekes, T C -- Weinstein, A -- Weisgarber, T -- Williams, D A -- Zitzer, B -- New York, N.Y. -- Science. 2011 Oct 7;334(6052):69-72. doi: 10.1126/science.1208192.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21980105" target="_blank"〉PubMed〈/a〉

Description: The light emitted by stars and accreting compact objects through the history of the universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL is important to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are limited by galactic and other foreground emissions. Here, we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z approximately 1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to ultraviolet frequencies and allowed us to measure the EBL flux density in this frequency band.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ackermann, M -- Ajello, M -- Allafort, A -- Schady, P -- Baldini, L -- Ballet, J -- Barbiellini, G -- Bastieri, D -- Bellazzini, R -- Blandford, R D -- Bloom, E D -- Borgland, A W -- Bottacini, E -- Bouvier, A -- Bregeon, J -- Brigida, M -- Bruel, P -- Buehler, R -- Buson, S -- Caliandro, G A -- Cameron, R A -- Caraveo, P A -- Cavazzuti, E -- Cecchi, C -- Charles, E -- Chaves, R C G -- Chekhtman, A -- Cheung, C C -- Chiang, J -- Chiaro, G -- Ciprini, S -- Claus, R -- Cohen-Tanugi, J -- Conrad, J -- Cutini, S -- D'Ammando, F -- de Palma, F -- Dermer, C D -- Digel, S W -- do Couto e Silva, E -- Dominguez, A -- Drell, P S -- Drlica-Wagner, A -- Favuzzi, C -- Fegan, S J -- Focke, W B -- Franckowiak, A -- Fukazawa, Y -- Funk, S -- Fusco, P -- Gargano, F -- Gasparrini, D -- Gehrels, N -- Germani, S -- Giglietto, N -- Giordano, F -- Giroletti, M -- Glanzman, T -- Godfrey, G -- Grenier, I A -- Grove, J E -- Guiriec, S -- Gustafsson, M -- Hadasch, D -- Hayashida, M -- Hays, E -- Jackson, M S -- Jogler, T -- Kataoka, J -- Knodlseder, J -- Kuss, M -- Lande, J -- Larsson, S -- Latronico, L -- Longo, F -- Loparco, F -- Lovellette, M N -- Lubrano, P -- Mazziotta, M N -- McEnery, J E -- Mehault, J -- Michelson, P F -- Mizuno, T -- Monte, C -- Monzani, M E -- Morselli, A -- Moskalenko, I V -- Murgia, S -- Tramacere, A -- Nuss, E -- Greiner, J -- Ohno, M -- Ohsugi, T -- Omodei, N -- Orienti, M -- Orlando, E -- Ormes, J F -- Paneque, D -- Perkins, J S -- Pesce-Rollins, M -- Piron, F -- Pivato, G -- Porter, T A -- Raino, S -- Rando, R -- Razzano, M -- Razzaque, S -- Reimer, A -- Reimer, O -- Reyes, L C -- Ritz, S -- Rau, A -- Romoli, C -- Roth, M -- Sanchez-Conde, M -- Sanchez, D A -- Scargle, J D -- Sgro, C -- Siskind, E J -- Spandre, G -- Spinelli, P -- Stawarz, Lukasz -- Suson, D J -- Takahashi, H -- Tanaka, T -- Thayer, J G -- Thompson, D J -- Tibaldo, L -- Tinivella, M -- Torres, D F -- Tosti, G -- Troja, E -- Usher, T L -- Vandenbroucke, J -- Vasileiou, V -- Vianello, G -- Vitale, V -- Waite, A P -- Winer, B L -- Wood, K S -- Wood, M -- New York, N.Y. -- Science. 2012 Nov 30;338(6111):1190-2. doi: 10.1126/science.1227160. Epub 2012 Nov 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23118013" target="_blank"〉PubMed〈/a〉