GRBlog: A Database for Gamma-Ray Bursts

GRBlog is an on-line database providing researchers with quick access to all information reported in the GCN Circulars. Users of the GRBlog web site (grad40.as.utexas.edu/grblog.php) can search the circulars and produce afterglow light curve plots, or compile data tables. The site also offers advanced search capabilities to aide in statistical studies or comparative research. Most of the GCNs have already been entered into the GRBlog database, with the remainder to follow shortly.Comment: 4 pages, 2 figures. Proceedings for the 2003 GRB Conference (Santa Fe, NM, 2003 Sep 8-12

Does the threat of disqualification deter drivers from speeding?

Road Safety Research Report, number 96, is available from the National Archives: Department for Transport, and can be accessed from the link below.It has long been recognised that driving speeds that are excessive and inappropriate to the conditions are a major contributory factor in road accidents, and a major issue for road safety. Restraining driving speeds has proved to be a difficult task, given the improvements over the years in both vehicle performance and road design. Within the traditional ‘three Es’ countermeasures of engineering, education and enforcement, recent years have seen the introduction of a wide range of engineering measures designed to bring about speed reduction, but these tend to be restricted to specific parts of the road network. New technologies such as Intelligent Speed Adaptation (ISA) offer considerable promise, but mainly in the medium or longer term. Similarly, educative efforts to induce attitude and behaviour change in this context are bearing fruit, yet this is a long-term rather than short-term project. For the foreseeable future, enforcement will remain the principal means of influencing speed, by setting speed limits and imposing sanctions on drivers who are caught exceeding them. The number of licence endorsements has increased enormously in recent years. However, over the same period the number of disqualifications resulting from ‘totting-up’ points has decreased. This would seem to indicate that many drivers who accumulate up to 11 penalty points are either acting as if deterred by the threat of disqualification, or are avoiding disqualification in some other way. The extent to which penalty points act as a deterrent for the benefit of road safety in general is therefore an important issue, and this report describes work that has been carried out to study this issue by TRL and Brunel University, under contract to the Department for Transport

SN2008am: A Super-Luminous Type IIn Supernova

We present observations and interpretation of the Type IIn supernova SN 2008am discovered by the ROTSE Supernova Verification Project (RSVP). SN 2008am peaked at approximately -22.3 mag at a redshift of z=0.2338, giving it a peak luminosity of 3 x 10^{44}erg/s and making it one of the most luminous supernovae ever observed. The total radiated energy is ~ 2 x 10^{51} erg. Photometric observations in the ultraviolet, optical and infrared bands (J,H,Ks) constrain the SED evolution. We obtained six optical spectra of the supernova, five on the early decline from maximum light and a sixth nearly a year later plus a very late-time spectrum (~2 yr) of the host galaxy. The spectra of SN 2008am show strong Balmer-line and He I lambda 5876A emission with intermediate widths (~25A) in the first ~40 days after optical maximum. We examine a variety of models for the line wings and conclude that multiple scattering is most likely, implying that our spectra contain no specific information on the bulk flow velocity. We examine a variety of models for the ROTSE light curve subject to the rise time and the nature of the spectra, including radioactive decay, shocks in optically-thick and optically-thin circumstellar media (CSM) and a magnetar. The most successful model is one for which the CSM is optically-thick and in which diffusion of forward shock-deposited luminosity gives rise to the observed light curve. Diffusion of the shock-deposited energy from the forward shock is found to be important to account for the rising part of the light curve. Although there are differences in detail, SN 2008am appears to be closely related to other super-luminous Type IIn supernovae, SN 2006gy, SN 2006tf and perhaps SN 2008iy, that may represent the deaths of very massive LBV-type progenitors and for which the luminosity is powered by the interaction of the ejecta with a dense circumstellar medium.Comment: 58 pages, 14 figure

PTF 10bzf (SN 2010ah): A Broad-Line Ic Supernova Discovered by the Palomar Transient Factory

We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf (SN 2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SN distance is ≅218 Mpc, greater than GRB 980425/SN 1998bw and GRB 060218/SN 2006aj, but smaller than the other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we compare the properties of PTF 10bzf with those of SN 1998bw and other broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of ^(56)Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or radio counterpart to PTF 10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB 030329 or GRB 031203. Early-time radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB 030329 and GRB 031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf, we find that no GRB in the interplanetary network catalog could be associated with this SN

Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apd

We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift UV band (1928A) at -11days pre-maximum. Assuming an exponential form, we derived the rise time of 33days and the peak bolometric luminosity of 3x10^{44}ergs^-1. At maximum light, the estimated photospheric temperature and velocity are 17,000K and 14,000kms^-1 respectively. The inferred radiative and kinetic energy are roughly 1x10^{51} and 2x10^{52}erg. Gaia16apd is extremely UV luminous, emitting 50% of its total luminosity at 1000 - 2500A. Compared to the UV spectra (normalized at 3100A) of well studied SN1992A (Ia), SN2011fe(Ia), SN1999em (IIP) and SN1993J (IIb), it has orders of magnitude more far-UV emission. This excess is interpreted primarily as a result of weaker metal line blanketing due to much lower abundance of iron-group elements in the outer ejecta. Because these elements originate either from the natal metallicity of the star, or have been newly produced, our observation provides direct evidence that little of these freshly synthesized material, including 56Ni, was mixed into the outer ejecta, and the progenitor metallicity is likely sub-solar. This disfavors Pair-Instability Supernova (PISN) models with Helium core masses >=90Msun, where substantial 56Ni material is produced. Higher photospheric temperature of Gaia16apd than that of normal SNe may also contribute to the observed far-UV excess. We find some indication that UV luminous SLSNe-I like Gaia16apd could be common. Using the UV spectra, we show that WFIRST could detect SLSNe-I out to redshift of 8.Comment: 19 pages. Match with the version accepted in Ap

SN 2005hj: Evidence for Two Classes of Normal-Bright SNe Ia and Implications for Cosmology

HET Optical spectra covering the evolution from about 6 days before to about 5 weeks after maximum light and the ROTSE-IIIb unfiltered light curve of the "Branch-normal" Type Ia Supernova SN 2005hj are presented. The host galaxy shows HII region lines at redshift of z=0.0574, which puts the peak unfiltered absolute magnitude at a somewhat over-luminous -19.6. The spectra show weak and narrow SiII lines, and for a period of at least 10 days beginning around maximum light these profiles do not change in width or depth and they indicate a constant expansion velocity of ~10,600 km/s. We analyzed the observations based on detailed radiation dynamical models in the literature. Whereas delayed detonation and deflagration models have been used to explain the majority of SNe Ia, they do not predict a long velocity plateau in the SiII minimum with an unvarying line profile. Pulsating delayed detonations and merger scenarios form shell-like density structures with properties mostly related to the mass of the shell, M_shell, and we discuss how these models may explain the observed SiII line evolution; however, these models are based on spherical calculations and other possibilities may exist. SN 2005hj is consistent with respect to the onset, duration, and velocity of the plateau, the peak luminosity and, within the uncertainties, with the intrinsic colors for models with M_shell=0.2 M_sun. Our analysis suggests a distinct class of events hidden within the Branch-normal SNe Ia. If the predicted relations between observables are confirmed, they may provide a way to separate these two groups. We discuss the implications of two distinct progenitor classes on cosmological studies employing SNe Ia, including possible differences in the peak luminosity to light curve width relation.Comment: ApJ accepted, 31 page

Physiological effects of gonadotropin-releasing hormone immunocontraception on white-tailed deer

Before immunocontraceptives can be considered safe to use on wildlife species, potential health risks should be assessed. Gonadotropin-releasing hormone (GnRH) immunocontraceptive has successfully reduced fertility of white-tailed deer (Odocoileus virginianus); however, associated deer physiology has rarely been examined. We conducted gross necropsy examinations, histology, and blood chemistry comparisons on euthanized deer previously vaccinated with immunogenic GnRH (n = 18 females and n = 4 males), or left as untreated controls (n = 7 females and n = 6 males). Granulomas were found at injection sites of most deer, even 3 years post-treatment. There were no significant differences in ovary (F2,22= 0.31, P = 0.73), or pituitary weights (F2,22 = 0.30, P = 0.75) between treatment groups. Ovaries from control females had significantly more secondary follicles (F2,21 = 20.56, P ≤ 0.001), but not Graafi an follicles (F2,22= 2.22, P = 0.13). Immunized males had significantly lower mean testes weights, a number of morphologic abnormalities, and varying degrees of aspermatogenesis with fewer mature spermatozoa. We do not recommend treating male deer with anti-GnRH immunocontraceptive vaccines

Are Swift Long-Lag Gamma-Ray Bursts in the Local Supercluster?

A sample of 18 long-lag (tau_{lag} > 1 s) Gamma-Ray Bursts (GRBs) has been drawn from our catalog of all Swift long GRBs. Four different tests are done on this sample to test the prediction that a large fraction of long-lag GRBs are from our Local Supercluster. The results of these four tests come out that: (1) the distribution of these GRBs shows no tendency towards the Supergalactic plane; (2) the distribution shows no tendency towards the Virgo or Coma Cluster; (3) no associated bright host galaxies (m <=15) in the Local Supercluster are found for any of the 18 GRBs; (4) 17 of these 18 GRBs have redshifts of z>0.5, which are too far to be in the Local Supercluster. All these results disproved the hypothesis that any significant fraction of long-lag GRBs are from Local Supercluster. Hence these long-lag GRBs can not be counted in the calculation of LIGO detection rates. An explanation of why we can detect long-lag GRBs at high redshift is presented.Comment: 14 pages, 1 figure, ApJ accepte

Physiological effects of gonadotropin-releasing hormone immunocontraception on white-tailed deer

Before immunocontraceptives can be considered safe to use on wildlife species, potential health risks should be assessed. Gonadotropin-releasing hormone (GnRH) immunocontraceptive has successfully reduced fertility of white-tailed deer (Odocoileus virginianus); however, associated deer physiology has rarely been examined. We conducted gross necropsy examinations, histology, and blood chemistry comparisons on euthanized deer previously vaccinated with immunogenic GnRH (n = 18 females and n = 4 males), or left as untreated controls (n = 7 females and n = 6 males). Granulomas were found at injection sites of most deer, even 3 years post-treatment. There were no significant differences in ovary (F2,22= 0.31, P = 0.73), or pituitary weights (F2,22 = 0.30, P = 0.75) between treatment groups. Ovaries from control females had significantly more secondary follicles (F2,21 = 20.56, P ≤ 0.001), but not Graafi an follicles (F2,22= 2.22, P = 0.13). Immunized males had significantly lower mean testes weights, a number of morphologic abnormalities, and varying degrees of aspermatogenesis with fewer mature spermatozoa. We do not recommend treating male deer with anti-GnRH immunocontraceptive vaccines