bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultra High Energy Cosmic Rays from Engine-driven Relativistic Supernovae
Authors: Chakraborti Sayan 
Published: September 2012

AbstractThe sources of the highest energy cosmic rays remain an enigma half a century after their discovery. Understanding their origin is a crucial step in probing new physics at energies unattainable by terrestrial accelerators. They must be accelerated in the local universe as otherwise interaction with cosmic background radiations would severely deplete the flux of protons and nuclei at energies above the Greisen-Zatsepin-Kuzmin (GZK) limit. Hypernovae, nearby GRBs, AGNs and their flares have all been suggested and debated in the literature as possible sources. Type Ibc supernovae have a local sub-population with mildly relativistic ejecta which are known to be sub-energetic GRBs or X-Ray Flashes for sometime and more recently as those with radio afterglows but without detected GRB counterparts, such as SN 2009bb. In this talk we present the size-magnetic field evolution, baryon loading and energetics of SN 2009bb using its radio spectra obtained with VLA and GMRT. We show that the engine-driven SNe lie above the Hillas line and they can explain the characteristics of post-GZK UHECRs.
Constraining gamma-ray burst progenitors
Authors: Levan Andrew 
Published: September 2012

AbstractThe past decade has seen great progress towards the unmasking of the progenitors of gamma-ray bursts, starting with the unambiguous detection of a supernova in the light of the long-GRB 030329 almost ten years ago, and the discovery of the first afterglows to short-GRBs in 2005. Here I review progress towards unveiling the progenitors of both long and short-duration GRBs. Furthermore, I examine the diverse broader population of GRBs and high energy transients, and suggest that a full consideration of this parameter space leads to the conclusion that additional progenitor models are likely to be needed, if we are to understand the complete view of GRBs and the transient high-energy sky.
Identifying Supernova Progenitors and Constraining the Explosion Channels
Authors: Van Dyk Schuyler D. 
Published: September 2012

AbstractConnecting the endpoints of massive star evolution with the various types of core-collapse supernovae (SNe) is ultimately the fundamental puzzle to be explored and solved. We can assemble clues indirectly, e.g., from information about the environments in which stars explode and establish constraints on the evolutionary phases of these stars. However, this is best accomplished through direct identification of the actual star that has exploded in pre-supernova imaging, preferably in more than one photometric band, where color and luminosity for the star can be precisely measured. We can then interpret the star's properties in light of expectations from the latest massive stellar evolutionary models, to attempt to assign an initial mass to the progenitor. So far, this has been done most successfully for SNe II-P, for which we now know that red supergiants in a relatively limited initial mass range are responsible. More recently, we have limited examples of the progenitors of SNe II-L, IIn, and IIb. The progenitors of SNe Ib and Ic, however, have been elusive so far; I will discuss the current status of our knowledge of this particular channel.
Spectropolarimetry of Type Ibc Supernovae
Authors: Tanaka Masaomi , Kawabata Koji S. , Hattori Takashi , Mazzali Paolo A. , Aoki Kentaro , Iye Masanori , Maeda Keiichi , Nomoto Ken'ichi , Pian Elena , Sasaki Toshiyuki , Yamanaka Masayuki 
Published: September 2012

AbstractStudying a multi-dimensional structure of supernovae (SNe) gives important constraints on the mechanism of the SN explosion. Polarization measurement is one of the most powerful methods to study the explosion geometry of extragalactic SNe. Especially, Type Ib/c SNe are the ideal targets because the core of the explosion is bare. We have performed spectropolarimetric observations of Type Ib/c SNe with the Subaru telescope. We detect a rotation of the polarization angle across the line, which is seen as a loop in the Q - U plane. This indicates that axisymmetry is broken in the SN ejecta. Adding our new data to the sample of stripped-envelope SNe with high-quality spectropolarimetric data, five SNe out of six show a loop in the Q - U plane. This implies that the SN explosion commonly has a non-axisymmetric, three-dimensional geometry.
Gravitational waves and gamma-ray bursts
Authors: Corsi Alessandra ,   for the LIGO Scientific Collaboration and Virgo collaboration
Published: September 2012

AbstractGamma-Ray Bursts are likely associated with a catastrophic energy release in stellar mass objects. Electromagnetic observations provide important, but indirect information on the progenitor. On the other hand, gravitational waves emitted from the central source, carry direct information on its nature. In this context, I give an overview of the multi-messenger study of gamma-ray bursts that can be carried out by using electromagnetic and gravitational wave observations. I also underline the importance of joint electromagnetic and gravitational wave searches, in the absence of a gamma-ray trigger. Finally, I discuss how multi-messenger observations may probe alternative gamma-ray burst progenitor models, such as the magnetar scenario.
Host Galaxies of Gamma-Ray Bursts
Authors: Levesque Emily M. 
Published: September 2012

AbstractHost galaxies are an excellent means of probing the natal environments that generate gamma-ray bursts (GRBs). Recent work on the host galaxies of short-duration GRBs has offered new insights into the parent stellar populations and ages of their enigmatic progenitors. Similarly, surveys of long-duration GRB (LGRB) host environments and their ISM properties have produced intriguing new results with important implications for long GRB progenitor models. These host studies are also critical in evaluating the utility of LGRBs as potential tracers of star formation and metallicity at high redshifts. I will summarize the latest research on LGRB host galaxies, and discuss the resulting impact on our understanding of these events' progenitors, energetics, and cosmological applications.
Type Ib/c Supernovae with and without Gamma-Ray Bursts
Authors: Modjaz Maryam 
Published: September 2012

AbstractWhile the connection between Long Gamma-Ray Bursts (GRBs) and Type Ib/c Supernovae (SNe Ib/c) from stripped stars has been well-established, one key outstanding question is what conditions and factors lead to each kind of explosion in massive stripped stars. One promising line of attack is to investigate what sets apart SNe Ib/c with GRBs from those without GRBs. Here, I briefly present two observational studies that probe the SN properties and the environmental metallicities of SNe Ib/c (specifically broad-lined SNe Ic) with and without GRBs. I present an analysis of expansion velocities based on published spectra and on the homogeneous spectroscopic CfA data set of over 70 SNe of Types IIb, Ib, Ic and Ic-bl, which triples the world supply of well-observed Stripped SNe. Moreover, I demonstrate that a meta-analysis of the three published SN 1b/c metallicity data sets when including only values at the SN positions to probe natal oxygen abundances, indicates at very high significance that indeed SNe Ic erupt from more metal-rich environments than SNe Ib, while SNe Ic-bl with GRBs still prefer, on average, more metal-poor sites than those without GRBs.
Magnetars and Gamma Ray Bursts
Authors: Bucciantini Niccolò 
Published: September 2012

AbstractIn the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I will review here the key aspects of the millisecond magnetar model for Long Duration Gamma Ray Bursts (LGRBs). I will briefly describe what constraints present observations put on any engine model, both in terms of energetics, outflow properties, and the relation with the associated Supernova (SN). For each of these I will show how the millisecond magnetar model satisfies the requirements, what are the limits of the model, how can it be further tested, and what observations might be used to discriminate against it. I will also discuss numerical results that show the importance of the confinement by the progenitor star in explaining the formation of a collimated outflow, how a detailed model for the evolution of the central engine can be built, and show that a wide variety of explosive events can be explained by different magnetar parameters. I will conclude with a suggestion that magnetars might be at the origin of the Extended Emission (EE) observed in a significant fraction of Short GRBs.
Super iron-rich gas towards GRB 080310: SN yields or dust destruction?
Authors: De Cia A. , Ledoux C. , Vreeswijk P. , Fox A. , Smette A. , Petitjean P. , Björnsson G. , Fynbo J. , Hjorth J. , Jakobsson P. 
Published: September 2012

AbstractWe performed Rapid-Response Mode (RRM) VLT/UVES high-resolution UV/ optical spectroscopy of the GRB 080310 afterglow, starting 13 min after the burst trigger, in order to investigate the ISM in the GRB host galaxy. The four spectra show remarkable features at zGRB, including a low log N(H i) = 18.7 and time-variable absorption from ground-state and excited levels of Fe ii and Fe iii, the latter being observed for the first time in a GRB afterglow. These observations indicate i) ongoing photo-ionization of the surrounding gas due to the GRB radiation and ii) Fe and Cr overabundances in the host galaxy ISM. We derive ionic column densities through a four-component Voigt-profile fit of the absorption lines and investigate the pre-burst ionization level of the gas with CLOUDY photo-ionization modelling. The resulting intrinsic [Si/Fe] = −1.4 ([C/H] = −1.3, [O/H] < −0.8, [Si/H] = −1.2, [Cr/H] = +0.7 and [Fe/H] = +0.2) for the whole line profile - and even more extreme for one of the absorption components - cannot be explained with current models of SN yields. Dust destruction may contribute to the marked iron overabundance, possibly induced by the burst. The overall high iron enhancement along the line-of-sight also suggests little recent star formation in the host galaxy.
The Luminous Type Ibc Supernova 2010as
Authors: Folatelli Gastón 
Published: September 2012

AbstractWe present photometric and spectroscopic follow-up observations of SN 2010as carried out by the MCSS and CSP. The SN appears to be of the transitional type Ibc (SN Ibc) and is spectroscopically similar to the peculiar SN 2005bf. Based on distance and extinction estimates, a bolometric luminosity light curve is constructed showing that this was a relatively luminous SN Ibc. He i line expansion velocities are remarkably low and remain nearly constant with time, similarly to SN~2005bf. A preliminary model is presented with a progenitor ZAMS mass of 15 M⊙ and a large yield of 0.35 M⊙ of 56Ni.
The Ultra-Fast Flash Observatory's space GRB mission and science
Authors: Lim H. , Ahmad S. , Barrillon P. , Blin-Bondil S. , Brandt S. , Budtz-Jørgensen C. , Castro-Tirado A. J. , Chen P. , Choi H. S. , Choi Y. J. , Connell P. , Dagoret-Campagne S. , De La Taille C. , Eyles C. , Grossan B. , Hermann I. , Huang M.-H. A. , Jeong S. , Jung A. , Kim J. E. , Kim S.-W. , Kim Y. W. , Lee J. , Linder E. V. , Liu T.-C. , Lund N. , Min K. W. , Na G. W. , Nam J. W. , Nam K. H. , Panasyuk M. I. , Park I. H. , Reglero V. , Řípa J. , Rodrigo J. M. , Smoot G. F. , Svetilov S. , Vedenkin N. , Yashin I. 
Published: September 2012

AbstractThe Ultra-Fast Flash Observatory (UFFO) is a space mission to detect the early moments of an explosion from Gamma-ray bursts (GRBs), thus enhancing our understanding of the GRB mechanism. It consists of the UFFO Burst & Trigger telescope (UBAT) for the recognition of GRB positions using hard X-ray from GRBs. It also contains the Slewing Mirror Telescope (SMT) for the fast detection of UV-optical photons from GRBs. It is designed to begin the UV-optical observations in less than a few seconds after the trigger. The UBAT is based on a coded-mask X-ray camera with a wide field of view (FOV) and is composed of the coded mask, a hopper and a detector module. The SMT has a fast rotatable mirror which allows a fast UV-optical detection after the trigger. The telescope is a modified Ritchey-Chrétien telescope with the aperture size of 10 cm diameter, and an image intensifier readout by CCD. The UFFO pathfinder is scheduled to launch into orbit on 2012 June by the Lomonosov spacecraft. It is a scaled-down version of UFFO in order to make the first systematic study of early UV/optical light curves, including the rise phase of GRBs. We expect UBAT to trigger ~44 GRBs/yr and expect SMT to detect ~10 GRBs/yr.
Exploding SNe with jets: time-scales
Authors: Papish Oded , Soker Noam 
Published: September 2012

AbstractWe perform hydrodynamical simulations of core collapse supernovae (CCSNe) with a cylindrically-symmetrical numerical code (FLASH) to study the inflation of bubbles and the initiation of the explosion within the frame of the jittering-jets model. We study the typical time-scale of the model and compare it to the typical time-scale of the delayed neutrino mechanism. Our analysis shows that the explosion energy of the delayed neutrino mechanism is an order of magnitude less than the required 1051 erg.
Observations of GRBs in the mm/submm range at the dawn of the ALMA era
Authors: de Ugarte Postigo A. , Lundgren A. , Martín S. , García-Appadoo D. , de Gregorio Monsalvo I. , Thöne C.C. , Gorosabel J. , Castro-Tirado A. J. , Sánchez-Ramírez R. , Tello J. C. 
Published: September 2012

AbstractGamma-ray bursts (GRBs) generate an afterglow with an emission peaking in the millimetre and submillimeter (mm/submm) range during the first hours to days, making the study in these wavelengths of great importance. Here we give an overview of the data that has been collected for GRB observations in this wavelengths until September 2011. The total sample includes 102 GRBs, of which 88 have afterglow observations, and the rest are only host galaxy searches. The 22 detections cover the redshift range between 0.168 and 8.2 and have peak luminosities that span 2.5 orders of magnitude. With the start of the operations at ALMA, the sensitivity with respect to previous facilities has already improved by over an order of magnitude. We estimate that, once completed, ALMA will be able to detect ~98 % of the afterglows.This proceeding is based on the work published by de Ugarte Postigo et al. (2012).
Spectral Evolutions Study of Gamma-Ray Burst Exponential Decays with Suzaku-WAM
Authors: Tashiro Makoto S. , Onda Kaori , Yamaoka Kazutaka , Ohno Masahiro , Sugita Satoshi , Uehara Takeshi , Seta Hiromi 
Published: September 2012

AbstractAn observational study is presented of the spectral evolution of gamma-ray burst (GRB) prompt emissions with the Suzaku Wide-band All-sky Monitor (WAM). We selected 6 bright GRBs exhibiting 7 well-separated fast-rise-exponential-decay (FRED) shaped light curves to investigate spectral changes by evaluating exponential decay time constants of the energy-resolved light curves. In addition, we carried out time-resolved spectroscopy of two of them which were located with accuracy sufficient to evaluate the time-resolved spectra with precise energy response matrices. The two imply different emission mechanisms; the one is well reproduced with a cooling blackbody radiation model with a power-law component, while the other prefers non-thermal emission model with a decaying turn over energy.
SVOM Visible Telescope: Performance and Data Process Scheme
Authors: Wu C. , Qiu Y. L. , Cai H. B. 
Published: September 2012

AbstractVT (Visible Telescope) is an instrument onboard SVOM (Space-based multi-band astronomical Variable Objects Monitor) satellite working in the visible band, which will play an important role in follow-up of two categories of GRBs: very distant events at higher redshift and faint/soft nearby events in SVOM mission. To fulfill these primary science requirements, decent sensitivity and wavelength coverage are fundamental for VT design. VT performance and data process strategy were successfully studied on its feasibility in Phase A, which is presented in this poster. Additionally, preliminary VT image simulator is also introduced here.
Development of a micro-satellite TSUBAME for X-ray polarimetry of GRBs
Authors: Yatsu Yoichi , Hayashi Mayumi , Kawakami Kousuke , Tokoyoda Kazuki , Enomoto Takahiro , Toizumi Takahiro , Kawai Nobuyuki , Ishizaka Kazuya , Muta Azusa , Morishita Hiroyuki , Matsunaga Saburo , Nakamori Takeshi , Kataoka Jun , Kubo Shin 
Published: September 2012

AbstractHard X-ray polarization is believed to be one of the most promising methods to investigate the physical processes just around the central engines by constraining the magnetic environment. For this purpose we are now developing a compact and highly sensitive hard X-ray polarimeter aboard a university class micro-satellite “TSUBAME”. We are now developing the flight model of the satellite aiming for the launch in late 2012 from Russia.
Bridging onshore and offshore present‐day kinematics of central and eastern Mediterranean: Implications for crustal dynamics and mantle flow
Authors: Pérouse Eugénie , Chamot‐Rooke Nicolas , Rabaute Alain , Briole Pierre , Jouanne François , Georgiev Ivan , Dimitrov Dimitar 
Published: September 2012

We present a new kinematic and strain model of an area encompassing the Calabrian and Hellenic subduction zones, western Anatolia and the Balkans. Using Haines and Holt's (1993) method, we derive continuous velocity and strain rate fields by interpolating geodetic velocities, including recent GPS data in the Balkans. Relative motion between stable Eurasia and the western Aegean Sea is gradually accommodated by distributed N‐S extension from Southern Balkans to the Eastern Corinth Gulf, so that the westward propagation of the North Anatolian Fault (NAF) throughout continental Greece or Peloponnesus is not required. We thus propose that the NAF terminates in north Aegean and that N‐S extension localized in the Corinth Gulf and distributed in Southern Balkans is due to the retreat of the Hellenic slab. The motion of the Hyblean plateau, Apulia Peninsula, south Adriatic Sea, Ionian Basin and Sirte plain can be minimized by a single rigid rotation around a pole located in the Sirte plain, compatible with the opening the Pelagian rifts (2–2.5 mm/yr) and seismotectonics in Libya. We interpret the trenchward ultraslow motion of the Calabrian arc (2–2.5 mm/yr) as pure collapse, the Calabrian subduction being now inactive. In the absolute plate motion reference frame, our modeled velocity field depicts two toroïdal crustal patterns located at both ends of the Hellenic subduction zone, clockwise in NW Greece and counter‐clockwise in western Anatolia. We suggest the NW Greece toroïdal pattern is the surface expression of a slab tear and consequent toroïdal asthenospheric flow.
Tearing mode velocity braking due to resonant magnetic perturbations
Authors: Frassinetti L. , Menmuir S. , Olofsson K.E.J. , Brunsell P.R. , Drake J.R. 
Published: September 2012

Abstract
The effect of resonant magnetic perturbations (RMPs) on the tearing mode (TM) velocity is studied in EXTRAP T2R. Experimental results show that the RMP produces TM braking until a new steady velocity or wall locking is reached. The braking is initially localized at the TM resonance and then spreads to the other TMs and to the rest of the plasma producing a global velocity reduction via the viscous torque. The process has been used to experimentally estimate the kinematic viscosity profile, in the range 2–40 m2 s−1, and the electromagnetic torque produced by the RMP, which is strongly localized at the TM resonance. Experimental results are then compared with a theoretical model which gives a reasonable qualitative explanation of the entire process.
The emerging problem of linezolid-resistant Staphylococcus
Authors: Gu Bing , Kelesidis Theodoros , Tsiodras Sotirios , Hindler Janet , Humphries Romney M. 
Published: September 2012

Abstract
The oxazolidinone antibiotic linezolid has demonstrated potent antimicrobial activity against Gram-positive bacterial pathogens, including methicillin-resistant staphylococci. This article systematically reviews the published literature for reports of linezolid-resistant Staphylococcus (LRS) infections to identify epidemiological, microbiological and clinical features for these infections. Linezolid remains active against &gt;98% of Staphylococcus, with resistance identified in 0.05% of Staphylococcus aureus and 1.4% of coagulase-negative Staphylococcus (CoNS). In all reported cases, patients were treated with linezolid prior to isolation of LRS, with mean times of 20.0 ± 47.0 months for S. aureus and 11.0 ± 8.0 days for CoNS. The most common mechanisms for linezolid resistance were mutation (G2576T) to the 23S rRNA (63.5% of LRSA and 60.2% of LRCoNS) or the presence of a transmissible cfr ribosomal methyltransferase (54.5% of LRSA and 15.9% of LRCoNS). The emergence of linezolid resistance in Staphylococcus poses significant challenges to the clinical treatment of infections caused by these organisms, and in particular CoNS.
Bioguided Fraction of Antioxidant Activity of Ethanol Extract from Tartary Buckwheat Bran
Authors: Guo Xu‐Dan , Wang Min , Gao Jin‐Ming , Shi Xin‐Wei 
Published: September 2012

ABSTRACTThis study describes the activity‐guided isolation of antioxidant agents from tartary buckwheat bran (TBB). The ethanol crude extract of oil‐free TBB was partitioned sequentially into ethyl acetate, n‐butanol, and residual aqueous fractions. The ethyl acetate fraction (EAF) had the highest phenolic and flavonoid contents and showed the strongest antioxidant activity. EAF was superior to rutin and inferior to vitamin C (Vc) in DPPH radical scavenging ability, had an advantage over rutin and Vc in ABTS radical scavenging ability, and again surpassed rutin and quercetin in reducing power. Then EAF was subjected to column chromatography, and isolated compounds were identified using nuclear magnetic resonance data by comparing with those reported in the literature. Finally, the bioassay‐guided fractionation of the crude ethanol extract of TBB afforded three known compounds (quercetin, p‐hydroxybenzoic acid, and daucosterol) responsible for antioxidant activity. p‐Hydroxybenzoic acid and daucosterol were isolated from buckwheat grain for the first time. Taken together, establishing of the three pure compounds is of paramount importance to the understanding of antioxidant activity of TBB, and there is an immense potential to process TBB or its EAF into value‐added functional foods and beverages.