ALBERT

Description: We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duration Swift GRB 121024A at z  = 2.30, we give one of the most complete views of a GRB host/environment to date. We observe a strong damped Lyα absorber (DLA) with a hydrogen column density of log  $N({\rm H\,{\small I}})\,=\,21.88\pm 0.10$ , H 2 absorption in the Lyman–Werner bands (molecular fraction of log( f ) –1.4; fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular emission lines Hα, Hβ, [O ii ], [O iii ] and [N ii ], as well as metal absorption lines. We find a GRB host galaxy that is highly star forming (SFR ~ 40 M  yr –1 ), with a dust-corrected metallicity along the line of sight of [Zn/H] corr  = –0.6 ± 0.2 ([O/H] ~ –0.3 from emission lines), and a depletion factor [Zn/Fe] = 0.85 ± 0.04. The molecular gas is separated by 400 km s –1 (and 1–3 kpc) from the gas that is photoexcited by the GRB. This implies a fairly massive host, in agreement with the derived stellar mass of log( M * /M ) =  $9.9^{+0.2}_{-0.3}$ . We dissect the host galaxy by characterizing its molecular component, the excited gas, and the line-emitting star-forming regions. The extinction curve for the line of sight is found to be unusually flat ( R V  ~ 15). We discuss the possibility of an anomalous grain size distributions. We furthermore discuss the different metallicity determinations from both absorption and emission lines, which gives consistent results for the line of sight to GRB 121024A.

Description: The progenitors of superluminous supernovae (SLSNe) are still a mystery. Hydrogen-poor SLSN hosts are young, highly star-forming dwarf galaxies and the majority belongs to the class of ‘extreme emission line galaxies’. Here we present a resolved long-slit study of the host of the hydrogen-poor SLSN PTF12dam probing the kiloparsec environment of the SN site to determine the age of the progenitor. The SN occurred in a star-forming region in the head of a ‘tadpole’ galaxy with largely uniform properties. The galaxy experienced a recent starburst superimposed on an underlying old stellar population (SP). We determine a very young SP at the SN site of ~3 Myr and a metallicity of 12+log(O/H)=8.0 but do not observe any Wolf–Rayet features. The progenitor of PTF12dam was likely a massive star of 〉60 M and one of the first stars exploding as an SN in the most recent starburst episode.

Description: We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duration Swift GRB 121024A at z  = 2.30, we give one of the most complete views of a GRB host/environment to date. We observe a strong damped Lyα absorber (DLA) with a hydrogen column density of log  $N({\rm H\,{\small I}})\,=\,21.88\pm 0.10$ , H 2 absorption in the Lyman–Werner bands (molecular fraction of log( f ) –1.4; fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular emission lines Hα, Hβ, [O ii ], [O iii ] and [N ii ], as well as metal absorption lines. We find a GRB host galaxy that is highly star forming (SFR ~ 40 M  yr –1 ), with a dust-corrected metallicity along the line of sight of [Zn/H] corr  = –0.6 ± 0.2 ([O/H] ~ –0.3 from emission lines), and a depletion factor [Zn/Fe] = 0.85 ± 0.04. The molecular gas is separated by 400 km s –1 (and 1–3 kpc) from the gas that is photoexcited by the GRB. This implies a fairly massive host, in agreement with the derived stellar mass of log( M * /M ) =  $9.9^{+0.2}_{-0.3}$ . We dissect the host galaxy by characterizing its molecular component, the excited gas, and the line-emitting star-forming regions. The extinction curve for the line of sight is found to be unusually flat ( R V  ~ 15). We discuss the possibility of an anomalous grain size distributions. We furthermore discuss the different metallicity determinations from both absorption and emission lines, which gives consistent results for the line of sight to GRB 121024A.

Description: Blackbody-dominated (BBD) gamma-ray bursts (GRBs) are events characterized by long durations and the presence of a significant thermal component following the prompt emission, as well as by the absence of a typical afterglow. GRB 101225A is the most prominent member of this class. A plausible progenitor system for it and for BBD-GRBs is the merger a neutron star and a helium core of an evolved, massive star. Using relativistic hydrodynamic simulations we model the propagation of ultrarelativistic jets through the environments created by such mergers. In a previous paper we showed that the thermal emission in BBD-GRBs is linked to the interaction of an ultrarelativistic jet with the ejected envelope of the secondary star of the binary. Here we focus on explaining the emission properties of BBD-GRBs computing the whole radiative signature (both thermal and non-thermal) of the jet dynamical evolution. The non-thermal emission of the forward shock of the jet is dominant during the early phases of the evolution, when that shock is moderately relativistic. Our models do not produce a classical afterglow because the quick deceleration of the jet results primarily from the mass entrainment in the beam, and not from the process of plowing mass from the external medium in front of the GRB ejecta. The contribution of the reverse shock is of the same magnitude than that of the forward shock during the first 80 min after the GRB. Later, it quickly fades because the jet/environment interaction chocks the ultrarelativistic jet beam and effectively dumps the reverse shock. In agreement with observations, we obtain rather flat light curves during the first 2 d after the GRB, and a spectral evolution consistent with the observed reddening of the system.

Description: Superluminous supernovae (SLSNe) are very bright explosions that were only discovered recently and that show a preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES, focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen-poor) often (~50 per cent in our sample) occur in a class of galaxies that is known as Extreme Emission Line Galaxies (EELGs). The probability of this happening by chance is negligible and we therefore conclude that the extreme environmental conditions and the SLSN phenomenon are related. In contrast, SLSNe-II (hydrogen-rich) occur in more massive, more metal-rich galaxies with softer radiation fields. Therefore, if SLSNe-II constitute a uniform class, their progenitor systems are likely different from those of H-poor SLSNe. Gamma-ray bursts (GRBs) are, on average, not found in as extreme environments as H-poor SLSNe. We propose that H-poor SLSNe result from the very first stars exploding in a starburst, even earlier than GRBs. This might indicate a bottom-light initial mass function in these systems. SLSNe present a novel method of selecting candidate EELGs independent of their luminosity.

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: Magnetars are young neutron stars with very strong magnetic fields of the order of 10(14)-10(15) G. They are detected in our Galaxy either as soft gamma-ray repeaters or anomalous X-ray pulsars. Soft gamma-ray repeaters are a rare type of gamma-ray transient sources that are occasionally detected as bursters in the high-energy sky. No optical counterpart to the gamma-ray flares or the quiescent source has yet been identified. Here we report multi-wavelength observations of a puzzling source, SWIFT J195509+261406. We detected more than 40 flaring episodes in the optical band over a time span of three days, and a faint infrared flare 11 days later, after which the source returned to quiescence. Our radio observations confirm a Galactic nature and establish a lower distance limit of approximately 3.7 kpc. We suggest that SWIFT J195509+261406 could be an isolated magnetar whose bursting activity has been detected at optical wavelengths, and for which the long-term X-ray emission is short-lived. In this case, a new manifestation of magnetar activity has been recorded and we can consider SWIFT J195509+261406 to be a link between the 'persistent' soft gamma-ray repeaters/anomalous X-ray pulsars and dim isolated neutron stars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Castro-Tirado, A J -- de Ugarte Postigo, A -- Gorosabel, J -- Jelinek, M -- Fatkhullin, T A -- Sokolov, V V -- Ferrero, P -- Kann, D A -- Klose, S -- Sluse, D -- Bremer, M -- Winters, J M -- Nuernberger, D -- Perez-Ramirez, D -- Guerrero, M A -- French, J -- Melady, G -- Hanlon, L -- McBreen, B -- Leventis, K -- Markoff, S B -- Leon, S -- Kraus, A -- Aceituno, F J -- Cunniffe, R -- Kubanek, P -- Vitek, S -- Schulze, S -- Wilson, A C -- Hudec, R -- Durant, M -- Gonzalez-Perez, J M -- Shahbaz, T -- Guziy, S -- Pandey, S B -- Pavlenko, L -- Sonbas, E -- Trushkin, S A -- Bursov, N N -- Nizhelskij, N A -- Sanchez-Fernandez, C -- Sabau-Graziati, L -- England -- Nature. 2008 Sep 25;455(7212):506-9. doi: 10.1038/nature07328.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Astrofisica de Andalucia del Consejo Superior de Investigaciones Cientificas (IAA-CSIC), PO Box 03004, E-18080 Granada, Spain. ajct@iaa.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18818652" 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: We present GTC-10.4 m spectroscopy and multiband photometry of the faint ( r ~ 26) optical counterpart of the anomalous X-ray pulsar 4U 0142+61. The 5000–9000 Å spectrum – the first obtained for a magnetar – is featureless, allowing us to set an equivalent width upper limit EW 〈 25 Å to the presence of emission lines in the H α region. Multiband photometry in the g , r , i , z Sloan Digital Sky Survey (SDSS) bands obtained at different epochs over 12 yr shows no significant variability from minutes-to-years time-scales. The photometry has been calibrated, for the first time, against the SDSS itself, resulting in solid upper limits to variability ranging from ~0.2 mag in i (over 12 yr) to 0.05 mag in z (over 1.5 yr). The shape of the optical + near-infrared (literature values) spectral energy distribution is not well constrained due to the high extinction along the line of sight. Using a Markov Chain Monte Carlo analysis, we find that it can be described by a power law with a spectral index β = –0.7 ± 0.5 and E ( B – V ) = 1.5 ± 0.4. We also discuss on the implications of adding hard X-ray flux values from literature to the spectral fitting.