ALBERT

Description: Long gamma-ray bursts (LGRBs) are associated with the death of massive stars. Their host galaxies therefore represent a unique class of objects tracing star formation across the observable Universe. Indeed, recently accumulated evidence shows that GRB hosts do not differ substantially from general population of galaxies at high ( z  〉 2) redshifts. However, it has been long recognized that the properties of z  〈 1.5 hosts, compared to general star-forming population, are unusual. To better understand the reasons for the supposed difference in LGRB hosts properties at z  〈 1.5, we obtained Very Large Telescope (VLT)/X-Shooter spectra of six hosts lying in the redshift range of 0.8 〈  z  〈 1.3. Some of these hosts have been observed before, yet we still lack well-constrained information on their characteristics such as metallicity, dust extinction and star formation rate (SFR). We search for emission lines in the VLT/X-Shooter spectra of the hosts and measure their fluxes. We perform a detailed analysis, estimating host average extinction, SFRs, metallicities and electron densities where possible. Measured quantities of our hosts are compared to a larger sample of previously observed GRB hosts at z  〈 2. SFRs and metallicities are measured for all the hosts analysed in this paper and metallicities are well determined for four hosts. The mass–metallicity relation, the fundamental metallicity relation and SFRs derived from our hosts occupy similar parameter space as other host galaxies investigated so far at the same redshift. We therefore conclude that GRB hosts in our sample support the found discrepancy between the properties of low-redshift GRB hosts and the general population of star-forming galaxies.

Description: We report the discovery and characterization of a deeply eclipsing AM CVn-system, Gaia14aae (=ASSASN-14cn). Gaia14aae was identified independently by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al.) and by the Gaia Science Alerts project, during two separate outbursts. A third outburst is seen in archival Pan-STARRS-1 (PS1; Schlafly et al.; Tonry et al.; Magnier et al.) and ASAS-SN data. Spectroscopy reveals a hot, hydrogen-deficient spectrum with clear double-peaked emission lines, consistent with an accreting double-degenerate classification. We use follow-up photometry to constrain the orbital parameters of the system. We find an orbital period of 49.71 min, which places Gaia14aae at the long period extremum of the outbursting AM CVn period distribution. Gaia14aae is dominated by the light from its accreting white dwarf (WD). Assuming an orbital inclination of 90° for the binary system, the contact phases of the WD lead to lower limits of 0.78 and 0.015 M on the masses of the accretor and donor, respectively, and a lower limit on the mass ratio of 0.019. Gaia14aae is only the third eclipsing AM CVn star known, and the first in which the WD is totally eclipsed. Using a helium WD model, we estimate the accretor's effective temperature to be 12 900 ± 200 K. The three outburst events occurred within four months of each other, while no other outburst activity is seen in the previous 8 yr of Catalina Real-time Transient Survey (CRTS; Drake et al.), Pan-STARRS-1 and ASAS-SN data. This suggests that these events might be rebrightenings of the first outburst rather than individual events.

Description: The first direct detection of gravitational waves was made in 2015 September with the Advanced LIGO detectors. By prior arrangement, a worldwide collaboration of electromagnetic follow-up observers were notified of candidate gravitational wave events during the first science run, and many facilities were engaged in the search for counterparts. Three alerts were issued to the electromagnetic collaboration over the course of the first science run, which lasted from 2015 September to 2016 January. Two of these alerts were associated with the gravitational wave events since named GW150914 and GW151226. In this paper we provide an overview of the Liverpool Telescope contribution to the follow-up campaign over this period. Given the hundreds of square degree uncertainty in the sky position of any gravitational wave event, efficient searching for candidate counterparts required survey telescopes with large (~degrees) fields of view. The role of the Liverpool Telescope was to provide follow-up classification spectroscopy of any candidates. We followed candidates associated with all three alerts, observing 1, 9 and 17 candidates respectively. We classify the majority of the transients we observed as supernovae. No counterparts were identified, which is in line with expectations given that the events were classified as black hole–black hole mergers. However these searches laid the foundation for similar follow-up campaigns in future gravitational wave detector science runs, in which the detection of neutron star merger events with observable electromagnetic counterparts is much more likely.

Description: We present a wide data set of gamma-ray, X-ray, UV/Opt/IR (UVOIR), and radio observations of the Swift GRB100814A. At the end of the slow decline phase of the X-ray and optical afterglow, this burst shows a sudden and prominent rebrightening in the optical band only, followed by a fast decay in both bands. The optical rebrightening also shows chromatic evolution. Such a puzzling behaviour cannot be explained by a single component model. We discuss other possible interpretations, and we find that a model that incorporates a long-lived reverse shock and forward shock fits the temporal and spectral properties of GRB100814 the best.

Description: We present broad-band observations and analysis of Swift gamma-ray burst (GRB) 120119A. Our early-time afterglow detections began under 15 s after the burst in the host frame (redshift z  = 1.73), and they yield constraints on the burst energetics and local environment. Late-time afterglow observations of the burst show evidence for a moderate column of dust ( A V 1.1 mag) similar to, but statistically distinct from, dust seen along Small Magellanic Cloud sightlines. Deep late-time observations reveal a dusty, rapidly star-forming host galaxy. Most notably, our early-time observations exhibit a significant red-to-blue colour change in the first ~200 s after the trigger at levels heretofore unseen in GRB afterglows. This colour change, which is coincident with the final phases of the prompt emission, is a hallmark prediction of the photodestruction of dust in GRB afterglows. We test whether dust-destruction signatures are significantly distinct from other sources of colour change, namely a change in the intrinsic spectral index β. We find that a time-varying power-law spectrum alone cannot adequately describe the observed colour change, and allowing for dust destruction (via a time-varying A V ) significantly improves the fit. While not definitively ruling out other possibilities, this event provides the best support yet for the direct detection of dust destruction in the local environment of a GRB.

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: After the initial burst of gamma-rays that defines a gamma-ray burst (GRB), expanding ejecta collide with the circumburst medium and begin to decelerate at the onset of the afterglow, during which a forward shock travels outwards and a reverse shock propagates backwards into the oncoming collimated flow, or 'jet'. Light from the reverse shock should be highly polarized if the jet's magnetic field is globally ordered and advected from the central engine, with a position angle that is predicted to remain stable in magnetized baryonic jet models or vary randomly with time if the field is produced locally by plasma or magnetohydrodynamic instabilities. Degrees of linear polarization of P approximately 10 per cent in the optical band have previously been detected in the early afterglow, but the lack of temporal measurements prevented definitive tests of competing jet models. Hours to days after the gamma-ray burst, polarization levels are low (P 〈 4 per cent), when emission from the shocked ambient medium dominates. Here we report the detection of P =28(+4)(-4) per cent in the immediate afterglow of Swift gamma-ray burst GRB 120308A, four minutes after its discovery in the gamma-ray band, decreasing to P = 16(+5)(-4) per cent over the subsequent ten minutes. The polarization position angle remains stable, changing by no more than 15 degrees over this time, with a possible trend suggesting gradual rotation and ruling out plasma or magnetohydrodynamic instabilities. Instead, the polarization properties show that GRBs contain magnetized baryonic jets with large-scale uniform fields that can survive long after the initial explosion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mundell, C G -- Kopac, D -- Arnold, D M -- Steele, I A -- Gomboc, A -- Kobayashi, S -- Harrison, R M -- Smith, R J -- Guidorzi, C -- Virgili, F J -- Melandri, A -- Japelj, J -- England -- Nature. 2013 Dec 5;504(7478):119-21. doi: 10.1038/nature12814.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24305162" 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: We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mundell, Carole G -- Steele, Iain A -- Smith, Robert J -- Kobayashi, Shiho -- Melandri, Andrea -- Guidorzi, Cristiano -- Gomboc, Andreja -- Mottram, Chris J -- Clarke, David -- Monfardini, Alessandro -- Carter, David -- Bersier, David -- New York, N.Y. -- Science. 2007 Mar 30;315(5820):1822-4. Epub 2007 Mar 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead, CH41 1LD, UK. cgm@astro.livjm.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17363631" target="_blank"〉PubMed〈/a〉

Description: Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ~ 3 x 10(53) ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the gamma-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maselli, A -- Melandri, A -- Nava, L -- Mundell, C G -- Kawai, N -- Campana, S -- Covino, S -- Cummings, J R -- Cusumano, G -- Evans, P A -- Ghirlanda, G -- Ghisellini, G -- Guidorzi, C -- Kobayashi, S -- Kuin, P -- La Parola, V -- Mangano, V -- Oates, S -- Sakamoto, T -- Serino, M -- Virgili, F -- Zhang, B-B -- Barthelmy, S -- Beardmore, A -- Bernardini, M G -- Bersier, D -- Burrows, D -- Calderone, G -- Capalbi, M -- Chiang, J -- D'Avanzo, P -- D'Elia, V -- De Pasquale, M -- Fugazza, D -- Gehrels, N -- Gomboc, A -- Harrison, R -- Hanayama, H -- Japelj, J -- Kennea, J -- Kopac, D -- Kouveliotou, C -- Kuroda, D -- Levan, A -- Malesani, D -- Marshall, F -- Nousek, J -- O'Brien, P -- Osborne, J P -- Pagani, C -- Page, K L -- Page, M -- Perri, M -- Pritchard, T -- Romano, P -- Saito, Y -- Sbarufatti, B -- Salvaterra, R -- Steele, I -- Tanvir, N -- Vianello, G -- Wiegand, B -- Wiersema, K -- Yatsu, Y -- Yoshii, T -- Tagliaferri, G -- New York, N.Y. -- Science. 2014 Jan 3;343(6166):48-51. doi: 10.1126/science.1242279. Epub 2013 Nov 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Istituto Nazionale di Astrofisica (INAF)-Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) Palermo, Via Ugo La Malfa 153 I-90146 Palermo, Italy.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24263134" target="_blank"〉PubMed〈/a〉