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Sample records for afterglow

  1. Chameleon induced atomic afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [CEA, IPhT, CNRS, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2010-09-15

    The chameleon is a scalar field whose mass depends on the density of its environment. Chameleons are necessarily coupled to matter particles and will excite transitions between atomic energy levels in an analogous manner to photons. When created inside an optical cavity by passing a laser beam through a constant magnetic field, chameleons are trapped between the cavity walls and form a standing wave. This effect will lead to an afterglow phenomenon even when the laser beam and the magnetic field have been turned off, and could be used to probe the interactions of the chameleon field with matter. (orig.)

  2. On the anomalous afterglow seen in a chameleon afterglow search

    International Nuclear Information System (INIS)

    We present data from our investigation of the anomalous orange-colored afterglow that was seen in the GammeV Chameleon Afterglow Search (CHASE). These data include information about the broadband color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to, and during the science operations of CHASE. While differing in several details, the generic properties of the afterglow from CHASE are similar to luminescence seen in some vacuum compounds. Contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectors and high intensity light sources in a cryogenic environment.

  3. On the anomalous afterglow seen in a chameleon afterglow search

    CERN Document Server

    Steffen, Jason H; Baumbaugh, Alan; Chou, Aaron S; Tomlin, Ray

    2012-01-01

    We present data from our investigation of the anomalous orange-colored afterglow that was seen in the GammeV Chameleon Afterglow Search (CHASE). These data includes information about the broad band color of the observed glow, the relationship between the glow and the temperature of the apparatus, and other data taken prior to and during the science operations of CHASE. While differing in several details, the generic properties of the afterglow from CHASE are similar to luminescence seen in some vacuum compounds. Contamination from this, or similar, luminescent signatures will likely impact the design of implementation of future experiments involving single photon detectors and high intensity light sources in a cryogenic environment.

  4. Investigations on afterglows of neon gas discharges

    International Nuclear Information System (INIS)

    Experimental and numerical investigations on afterglows of neon gas discharges are described. The investigated pressure range extends from 0.5 torr to 100 torr; the discharge currents lie between about 1 mA and 100 mA. The decay of the 1s atom densities has been determined experimentally as function of the time elapsed in the afterglow. From the measured decay of metastable 1s5 atom densities at gas pressure 5 atoms as well as the coefficinets of atomic collisional transfer between the 1s5 and 1s4 level are determined. To obtain more insight in the mutual influences of the various loss and production processes of 1s atoms and charge carriers in the afterglow a numerical model has been formed. The behaviour of the afterglow radiation intensity has been measured on discharges with a gas pressure of 1, 10, 20, 50 and 100 torr and a discharge current of 22, 24 and 50 mA. From the results the recombination distribution fractions of the 1s levels are determined and the electron densities at the start of the afterglow of 20, 50 and 100 torr discharges. With the help of the selective excitation spectroscopy the coefficients of atomic transfer between the 2p levels have been measured in the afterglow of discharge with a gas pressure of 1, 10, 20, 50 and 100 torr and a discharge current of 22 mA. From these results and the measured intensities of the various spectral lines in the afterglow the partial recombination coefficients for the 2p levels are calculated. (Auth. )

  5. Radio Observations of GRB Afterglows

    CERN Document Server

    Weiler, K W; Montes, M J; Weiler, Kurt W.; Panagia, Nino; Montes, Marcos J.

    2002-01-01

    Since 1997 the afterglow of gamma-ray bursting sources (GRBs) has occasionally been detected in the radio, as well in other wavelengths bands. In particular, the interesting and unusual gamma-ray burst GRB980425, thought to be related to the radio supernova SN1998bw, is a possible link between the two classes of objects. Analyzing the extensive radio emission data avaliable for SN1998bw, one can describe its time evolution within the well established framework available for the analysis of radio emission from supernovae. This then allows relatively detailed description of a number of physical properties of the object. The radio emission can best be explained as the interaction of a mildly relativistic shock with a dense preexplosion stellar wind-established circumstellar medium (CSM) that is highly structured both azimuthally, in clumps or filaments, and radially, with observed density enhancements. Because of its unusual characteristics for a Type Ib/c supernova, the relation of SN1998bw to GRB980425 is stre...

  6. Modeling the Afterglow of GW150914-GBM

    CERN Document Server

    Morsony, Brian J; Ryan, Dominic M

    2016-01-01

    We model the afterglow of the Fermi GBM event associated with LIGO detection GW150914, under the assumption that the gamma-ray are produced by a short GRB-like relativistic outflow. We model GW150914-GBM as both a weak, on-axis short GRB and normal short GRB seen far off axis. Given the large uncertainty in the position of GW150914, we determine that the best chance of finding the afterglow is with the MWA, with the flux from an off-axis short GRB reaching 0.1 - 10 mJy at 150 MHz by 1 - 12 months after the initial event. At low frequencies, the source would evolve from a hard to soft spectrum over several months. The radio afterglow would be detectable for several months to years after it peaks, meaning the afterglow may still be detectable and increasing in brightness NOW. With a localization from the MWA, the afterglow would be detectable at higher radio frequencies with the ATCA and in X-rays Chandra or XMM.

  7. Full auto optical afterglow searching system: MIKOTS

    International Nuclear Information System (INIS)

    Recently, to observe afterglow at various places has appeared necessary. To do so, we have set a fully automated afterglow searching system named MIKOTS. The aperture of our telescope, with a CCD camera, is 300 mm and the focal length is about 1000 mm. The CCD has 512 x 512 pixels size corresponding to a chip size of 10.2 mm x 10.2 mm. The field of view, resolution and lower limit magnitude are 37.0 x 37.0, 4.12 x 4.12 and 18.1, respectively. This system can start observation less than 15 seconds after receiving the data from GCN

  8. The Swift XRT: Observations of Early X-ray Afterglows

    International Nuclear Information System (INIS)

    During the first year of operations of the Swift observatory, the X-ray Telescope has made a number of discoveries concerning the nature of X-ray afterglows of both long and short GRBs. We highlight the key findings, which include rapid declines at early times, a standard template of afterglow light curve shapes, common flaring, and the discovery of the first short GRB afterglow

  9. Study of argon–oxygen flowing afterglow

    Science.gov (United States)

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon–oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon–oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  10. Beam profile indicator for swift heavy ions using phosphor afterglow

    Directory of Open Access Journals (Sweden)

    T. Z. Zhan

    2012-09-01

    Full Text Available In this letter, we report a beam profile indicator for swift heavy ions (SHIs which utilizes the afterglow of phosphors. Clear marks are left on SrAl2O4:Eu2+ and CaSrAl2Si2O8:Eu2+ samples by SHI irradiation through a permanent change of their afterglow intensity. The afterglow intensity of the SHI-irradiated areas has a Gaussian distribution. Moreover, afterglow intensity and irradiation fluence are linearly related, indicating that this type of indicator has good dose linearity. The results suggest that long-lasting phosphors are promising SHI beam profile indicators with high spatial resolution.

  11. Circular polarization in the optical afterglow of GRB 121024A

    DEFF Research Database (Denmark)

    Wiersema, K.; Covino, S.; Toma, K.;

    2014-01-01

    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 th...

  12. Very High Energy Afterglow from Gamma-ray Bursts

    CERN Document Server

    Fan, Yi-Zhong; Narayan, Ramesh; Wei, Da-Ming

    2007-01-01

    We present self-consistent calculations of the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron self-Compton (SSC) emission within the afterglow blast wave, and external inverse Compton (EIC) emission which occurs when flare photons (produced by an internal process) pass through the blast wave. We show that the high energy emission can be used to distinguish between different modifications of the standard afterglow model that have been considered in view of recent Swift observations. Our predictions can be tested with high energy observatories such as GLAST, Whipple, H.E.S.S., MAGIC and Kangaroo. Under favorable conditions we expect afterglow detections in all these detectors.

  13. Detectability of GRB optical afterglows with Gaia satellite

    CERN Document Server

    Japelj, J

    2011-01-01

    With the launch of Gaia satellite, detection of many different types of transient sources will be possible, one of them being optical afterglows of gamma-ray bursts (GRBs). Using the knowledge of the satellites dynamics and properties of GRB optical afterglows we performed a simulation in order to estimate an average GRB detection rate with Gaia. Here we present the simulation results for two types of GRB optical afterglows, differing in the observer's line-of-sight compared to a GRB jet axis: regular (on-axis) and orphan afterglows. Results show that for on-axis GRBs, less than 10 detections in five years of foreseen Gaia operational time are expected. The orphan afterglows simulation results are more promising, giving a more optimistic number of several tens of detections in five years.

  14. GRB 090902B: AFTERGLOW OBSERVATIONS AND IMPLICATIONS

    International Nuclear Information System (INIS)

    The optical-infrared afterglow of the Large Area Telescope (LAT)-detected long-duration burst, GRB 090902B, has been observed by several instruments. The earliest detection by ROTSE-IIIa occurred 80 minutes after detection by the Gamma-ray Burst Monitor instrument on board the Fermi Gamma-Ray Space Telescope, revealing a bright afterglow and a decay slope suggestive of a reverse shock origin. Subsequent optical-IR observations followed the light curve for 6.5 days. The temporal and spectral behavior at optical-infrared frequencies is consistent with synchrotron fireball model predictions; the cooling break lies between optical and XRT frequencies ∼1.9 days after the burst. The inferred electron energy index is p = 1.8 ± 0.2, which would however imply an X-ray decay slope flatter than observed. The XRT and LAT data have similar spectral indices and the observed steeper value of the LAT temporal index is marginally consistent with the predicted temporal decay in the radiative regime of the forward shock model. Absence of a jet break during the first 6 days implies a collimation-corrected γ-ray energy Eγ > 2.2 x 1052 erg, one of the highest ever seen in a long-duration gamma-ray bursts. More events combining GeV photon emission with multiwavelength observations will be required to constrain the nature of the central engine powering these energetic explosions and to explore the correlations between energetic quanta and afterglow emission.

  15. The synthesis and afterglow luminescence properties of a novel red afterglow phosphor: ZrO2:Sm3+,Sn4+

    International Nuclear Information System (INIS)

    A novel ZrO2:Sm3+,Sn4+ phosphor is synthesized by solid state reaction. The ZrO2:Sm3+ does not show afterglow. But, after doping Sn4+, intense red afterglow luminescence is firstly observed in ZrO2:Sm3+,Sn4+ and it can last more than 1000 s at maximum. The afterglow decay curves of ZrO2:Sm3+,Sn4+ are fitted by three exponential components and the decay process consists of initial fast, intermediate and slow decay. The thermoluminescence indicates that the Sn4+ ions induce suitable traps with the depth of 0.436 eV and result in efficient afterglow luminescence of ZrO2:Sm3+,Sn4+. The thermoluminescence filling and fading experiments further confirm the important role of the proper shallow traps induced by doping Sn4+ on the afterglow of ZrO2:Sm3+,Sn4+. - Highlights: ► We obtain a novel red afterglow phosphor ZrO2:Sm3+,Sn4+. ► The important role of Sn4+ on the afterglow is investigated. ► We give a feasible interpretation for the occurrence of afterglow in ZrO2:Sm3+,Sn4+.

  16. SRG/eROSITA prospects for detection of GRB afterglows

    CERN Document Server

    Khabibullin, I I; Sunyaev, R A

    2012-01-01

    We discuss the potential of the eROSITA telescope on board the \\emph{Spectrum-X-Gamma} observatory to detect gamma-ray burst (GRB) X-ray afterglows during its 4-year all-sky survey. The expected rate of afterglows associated with long-duration GRBs without any information on the bursts proper that can be identified by a characteristic power-law light curve in the eROSITA data is 4--8 events per year. An additional small number, $\\lesssim 2$ per year, of afterglows may be associated with short GRBs, ultra hard (GeV) GRBs and X-ray flashes. eROSITA can thus provide the first unbiased (unaffected by GRB triggering) sample of $\\lesssim 40$ X-ray afterglows, which can be used for statistical studies of GRB afterglows and for constraining the shape of the GRB $\\log N$--$\\log S$ distribution at its low-fluence end. The total number of afterglows detected by eROSITA may be yet higher due to orphan afterglows and failed GRBs. The actual detection rate could thus provide interesting constraints on the properties of rel...

  17. X-Ray Observations of Gamma-Ray Burst Afterglows

    OpenAIRE

    Frontera, Filippo

    2004-01-01

    The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long $\\gamma$-ray bursts. The 30 year mystery of the gamma-ray burst phenomenon is now on the way to solution. Here I rewiew the observationa...

  18. High Energy Afterglow from Gamma-ray Bursts

    OpenAIRE

    Fan, Yi-Zhong(Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, 210008, China); Piran, Tsvi; Narayan, Ramesh; Wei, Da-Ming

    2007-01-01

    We calculate the very high energy (sub-GeV to TeV) inverse Compton emission of GRB afterglows. We argue that this emission provides a powerful test of the currently accepted afterglow model. We focus on two processes: synchrotron self-Compton (SSC) emission within the afterglow blast wave, and external inverse Compton (EIC) emission which occurs when flare photons (produced by an internal process) pass through the blast wave. We show that if our current interpretations of the Swift XRT data a...

  19. Nonrelativistic phase in γ-ray burst afterglows

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The discovery of multiband afterglows definitely shows that most γ-ray bursts are of cosmological origin. γ-ray bursts are found to be one of the most violent explosive phenomena in the Universe, in which astonishing ultra-relativistic motions are involved.In this article, the multiband observational characteristics of γ-ray bursts and their afterglows are briefly reviewed. The standard model of γ-ray bursts, i.e. the fireball model, is described. Emphasis is then put on the importance of the nonrelativistic phase of afterglows. The concept of deep Newtonian phase is elaborated. A generic dynamical model applicable in both the relativistic and nonrelativistic phases is introduced. Based on these elaborations, the overall afterglow behaviors, from the very early stages to the very late stages, can be conveniently calculated.

  20. Biological decontamination using high and reduced pressure nitrogen afterglows

    OpenAIRE

    Sarrette, Jean-Philippe; Cousty, Sarah; Clement, Frank; Canal Barnils, Cristina; Ricard, André

    2012-01-01

    Typical results quantifying the antibacterial efficiencies of high and reduced pressure nitrogen afterglows are presented, using the same microbiological protocol. In parallel, the diffusion of the nitrogen atoms through different polymer membranes is studied. Peer Reviewed

  1. The Fabrication and Properties of a Blue Long Afterglow Phosphor

    Institute of Scientific and Technical Information of China (English)

    XiaoZhiguo; LuoXixian; LiuLifang; JinLei

    2004-01-01

    The Eu2+ and Dy3+ codoped St2 MgSi2 O7 : Eu2+ , Dy3+ blue emission long afterglow phosphor was synthesized and its photoluminescence properties were studied. It is known with the measurement method of X-ray diffraction pattern that the luminescent material is an akermanite crystal. It is shown with the decay curve that its afterglow properties are better than the traditional (Ca, Sr)S:Bi blue long afterglow phosphor. Its decay curve is in accordance with the calculated results of the formula lgl = A + B1 ×lgt + B2 x (lgt)2. Thermoluminescence spectra identified the existence of long afterglow luminescence. The excitation and emission spectra and microstructure of the phosphor were also investigated in detail.

  2. GRB 010921 Discovery of the First HETE Afterglow

    CERN Document Server

    Price, P A; Berger, E; Djorgovski, S G; Frail, D A; Mahabal, A A; Fox, D W; Harrison, F A; Bloom, J S; Yost, S A; Reichart, D E; Henden, A A; Ricker, G R; Van der Spek, R; Hurley, K; Atteia, J L; Kawai, N; Fenimore, E E; Graziani, C

    2003-01-01

    We report the discovery of the optical and radio afterglow of GRB 010921, the first gamma-ray burst afterglow to be found from a localization by the High Energy Transient Explorer (HETE) satellite. We present optical spectroscopy of the host galaxy which we find to be a dusty and apparently normal star-forming galaxy at z = 0.451. The unusually steep optical spectral slope of the afterglow can be explained by heavy extinction, A_V > 0.5 mag, along the line of sight to the GRB. Dust with similar A_V for the the host galaxy as a whole appears to be required by the measurement of a Balmer decrement in the spectrum of the host galaxy. Thanks to the low redshift, continued observations of the afterglow will enable the strongest constraints, to date, on the existence of a possible underlying supernova.

  3. The Radio Afterglows of Gamma-Ray Bursts

    CERN Document Server

    Frail, D A

    2003-01-01

    Radio afterglow studies have become an integral part of the study of gamma-ray bursts, providing complementary and sometimes unique diagnostics on GRB explosions, their progenitors, and their environments. This brief review consists of two parts. The first section is a summary of current search strategies and the main observational properties of radio afterglows. In the second section we highlight the key scientific contributions made by radio observations, either alone or as part of panchromatic studies.

  4. Influence on the long afterglow properties by the environmental temperature

    International Nuclear Information System (INIS)

    Sr2MgSi2O7:Eu2+, Dy3+ (SMED) and Ba2MgSi2O7:Eu2+, Dy3+ (BMED) were synthesized with the solid-state reaction. The SMED shows long afterglow while the afterglow of BMED is not visible at room temperature. When the environmental temperature is 150 deg. C, the afterglow of SMED is not obvious while the BMED shows the long afterglow. The decay curves measured at different temperatures conform to this phenomenon. It ascribes to the different trap depths of different samples. The thermoluminescence (TL) curves of SMED peaks at 80 deg. C. BMED has two TL peaks peaking at about 80 and 175 deg. C respectively. The low temperature peak is weak and its density is small. The high-temperature peak reveals that one trap of BMED is deeper than the one of SMED. The afterglows of the phosphors strongly depend on the environmental temperature since the lifetime of the trapping carriers is temperature-dependence. BMED is a potential optimum long afterglow phosphor for the purpose of high-temperature application.

  5. Influence on the long afterglow properties by the environmental temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wu Haoyi [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Hu Yihua, E-mail: huyh@gdut.edu.c [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Wang Yinhai; Mou Zhongfei [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2010-01-15

    Sr{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (SMED) and Ba{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+}, Dy{sup 3+} (BMED) were synthesized with the solid-state reaction. The SMED shows long afterglow while the afterglow of BMED is not visible at room temperature. When the environmental temperature is 150 deg. C, the afterglow of SMED is not obvious while the BMED shows the long afterglow. The decay curves measured at different temperatures conform to this phenomenon. It ascribes to the different trap depths of different samples. The thermoluminescence (TL) curves of SMED peaks at 80 deg. C. BMED has two TL peaks peaking at about 80 and 175 deg. C respectively. The low temperature peak is weak and its density is small. The high-temperature peak reveals that one trap of BMED is deeper than the one of SMED. The afterglows of the phosphors strongly depend on the environmental temperature since the lifetime of the trapping carriers is temperature-dependence. BMED is a potential optimum long afterglow phosphor for the purpose of high-temperature application.

  6. The ultra-long GRB 111209A. II. Prompt to afterglow and afterglow properties

    International Nuclear Information System (INIS)

    The 'ultra-long' gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of AV = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  7. The ultra-long GRB 111209A. II. Prompt to afterglow and afterglow properties

    Energy Technology Data Exchange (ETDEWEB)

    Stratta, G. [Osservatorio Astronomico di Roma (OAR/INAF), via Frascati 33, I-00040 Monte Porzio Catone (Italy); Gendre, B.; Boër, M. [ARTEMIS, UMR 7250 (CNRS/OCA/UNS), boulevard de l' Observatoire, BP 4229, F-06304 Nice Cedex (France); Atteia, J. L. [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Coward, D. M.; Howell, E. [School of Physics, University of Western Australia (UWA), Crawley, WA 6009 (Australia); De Pasquale, M.; Oates, S. [Mullard Space Science Laboratory (MSSL), University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom); Klotz, A. [IRAP, 14, avenue Edouard Belin, F-31400 Toulouse (France); Piro, L. [Istituto di Astrofisica e Planetologia Spaziali di Roma (IAPS/INAF), via fosso del cavaliere 100, I-00133 Roma (Italy)

    2013-12-10

    The 'ultra-long' gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of A{sub V} = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  8. The Broadband Afterglow of GRB980703

    CERN Document Server

    Frail, D A; Berger, E; Harrison, F A; Sari, R; Kulkarni, S R; Taylor, G B; Bloom, J S; Fox, D W; Moriarty-Schieven, G H; Price, P A

    2003-01-01

    We present radio observations of the afterglow of the bright gamma-ray burst GRB980703 made between one day and one year after the burst. These data are combined with published late-time radio measurements and existing optical, near-infrared (NIR) and X-ray observations to create a comprehensive broadband dataset for modeling the physical parameters of the outflow. While a wind-stratified medium cannot be ruled out statistically, it requires a high fraction of the shock energy in the electrons, and so is not favored on theoretical grounds. Instead, the data are consistent with a fireball model in which the ejecta are collimated and expanding into a constant density medium. The radio data cannot be fit with an isotropic shock but instead require a jet break at ~ 3.5 days, not seen at optical wavelengths due to the presence of a a bright host galaxy. The addition of the full radio dataset constrains the self-absorption frequency, giving an estimate of the circumburst density of n ~ 30 cm^-3, a value which diffe...

  9. Optical Photometry of the GRB 010222 Afterglow

    CERN Document Server

    Cowsik, R; Anupama, G C; Bhatt, B C; Sahu, D K; Ambika, S; Bhargavi, S G

    2001-01-01

    The optical afterglow of GRB 010222 was observed using the recently installed 2-m telescope at the Indian Astronomical Observatory Hanle and the telescopes at the Vainu Bappu Observatory, Kavalur, beginning ~0.6 day after the detection of the event. The results based on these photometric observations combined with others reported in the literature are presented in this paper. The R band light curve shows an initial decline of intensities proportional to t^{-0.608} which steepens, after 10.6 hours, to t^{-1.24}. Following the model of collimated outflow, the early break in the light curve implies a very narrow beam angle ~3 deg. The two decay rates are consistent with the standard jet model in a uniform density ambient medium, but require a hard spectrum of electron power density with ~1.5. The early spectral energy distribution derived using published fluxes in different bands and our R band light curve suggests that the ambient density is very low: n ~1 cm^-3. GRB 010222 is thus an example of a highly collim...

  10. MAGIC observation of the GRB080430 afterglow

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Backes, M; Baixeras, C; Balestra, S; Barrio, J A; Bastieri, D; González, J Becerra; Becker, J K; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Bock, R K; Bonnoli, G; Bordas, P; Tridon, D Borla; Bosch-Ramon, V; Bose, D; Braun, I; Bretz, T; Britzger, D; Camara, M; Carmona, E; Carosi, A; Colin, P; Commichau, S; Contreras, J L; Cortina, J; Costado, M T; Covino, S; Dazzi, F; De Angelis, A; del Pozo, E de Cea; Reyes, R De los; De Lotto, B; De Maria, M; De Sabata, F; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Elsaesser, D; Errando, M; Ferenc, D; Fernández, E; Firpo, R; Fonseca, M V; Font, L; Galante, N; López, R J García; Garczarczyk, M; Gaug, M; Godinovic, N; Goebel, F; Hadasch, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Hsu, C C; Jogler, T; Klepser, S; Krähenbühl, T; Kranich, D; La Barbera, A; Laille, A; Leonardo, E; Lindfors, E; Lombardi, S; Longo, F; López, M; Lorenz, E; Majumdar, P; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Miyamoto, H; Moldón, J; Moles, M; Moralejo, A; Nieto, D; Nilsson, K; Ninkovic, J; Orito, R; Oya, I; Paoletti, R; Paredes, J M; Pasanen, M; Pascoli, D; Pauss, F; Pegna, R G; Perez-Torres, M A; Persic, M; Peruzzo, L; Prada, F; Prandini, E; Puchades, N; Puljak, I; Reichardt, I; Rhode, W; Ribó, M; Rico, J; Rissi, M; Rügamer, S; Saggion, A; Saito, T Y; Salvati, M; Sánchez-Conde, M; Satalecka, K; Scalzotto, V; Scapin, V; Schweizer, T; Shayduk, M; Shore, S N; Sierpowska-Bartosik, A; Sillanpää, A; Sitarek, J; Sobczynska, D; Spanier, F; Spiro, S; Stamerra, A; Steinke, B; Strah, N; Struebig, J C; Suric, T; Takalo, L; Tavecchio, F; Temnikov, P; Tescaro, D; Teshima, M; Torres, D F; Turini, N; Vankov, H; Wagner, R M; Zabalza, V; Zandanel, F; Zanin, R; Zapatero, J; de Ugarte-Postigo, A

    2015-01-01

    Context: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. Aim: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at $\\sim 100$\\,GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. Me...

  11. The red optical afterglow of GRB 030725

    CERN Document Server

    Pugliese, G; Gorosabel, J; Jensen, B L; Fynbo, J P U; Hjorth, J; Jorgensen, S F; Monard, B; Vinter, C

    2005-01-01

    We present a photometric study of the optical counterpart of the long-duration Gamma Ray Burst (GRB) 030725, which triggered the HETE FREGATE and WXM instruments on July 25th, 2003, and lasted more than 160s. An optical counterpart was identified at the Bronberg Observatory in South Africa about 7 hours after the burst occurred. The optical afterglow (OA) was observed between 4 and 15 days after the burst with the 1.54m Danish telescope at La Silla in the V, Rc, and Ic bands. We fit a broken power law to the data and determine a break time in the light curve between 16 hours and 4.7 days after the first detection of the burst. The decay slope is alpha1 = -0.59 +0.59/-0.44 before and alpha2 = -1.43 +/- 0.06 after the break. A bump may be present in the light curve, only significant at the 2-sigma level, 13.9 days after the main burst. The spectral slope of the OA, measured 12 days after the burst, is -2.9 +/- 0.6 , i.e. it falls in the extreme red end of the distribution of previous OA spectral slopes. Observa...

  12. The Onset of Gamma-Ray Burst Afterglow

    Science.gov (United States)

    Kobayashi, Shiho; Zhang, Bing

    2007-02-01

    We discuss the reference time t0 of afterglow light curves in the context of the standard internal-external shock model. The decay index of early afterglow is very sensitive to the reference time one chooses. In order to understand the nature of early afterglow, it is essential to take a correct reference time. Our simple analytic model provides a framework for understanding special relativistic effects involved in early afterglow phase. We evaluate light curves of reverse shock emission as well as those of forward shock emission, based on full hydrodynamic calculations. We show that the reference time does not shift significantly even in the thick-shell case. For external shock emission components, measuring times from the beginning of the prompt emission is a good approximation and it does not cause an early steep decay. In the thin-shell case, the energy transfer time from fireball ejecta to ambient medium typically extends to thousands of seconds. This might be related to the shallow decay phases observed in early X-ray afterglow at least for some bursts.

  13. Fading and afterglow of practically available imaging plates

    International Nuclear Information System (INIS)

    In order to know fading behavior, it is needed to observe electron or hole trap center existing in a material, and the observation must be continued for a time of at least some hours after ceasing irradiation. Fading of the trap centers responsible for imaging plate (IP) is usually estimated by intensity of photo-stimulated luminescence (PSL). Therefore, effect of stimulating light intensity on fading curves must be considered when discussing on fading of IP. And, afterglow is caused by two kinds of origin, one of which is long-lived excited states caused by X-ray irradiation and the other is recombination among charge trapped centers through tunneling or thermal simulation. Afterglow of BaFBr:Eu reveals emission caused by excited state of Eu2+ with life time less than 1 micro second. Here was reported on properties of both fading and afterglow characterized by recombination luminescence, and on a close relationship between the fading and the afterglow. As a result, it was suggested that parameters deduced from afterglow decay curve could be available for analysis of fading properties of the IP. (G.K.)

  14. Radio rebrightening of the GRB afterglow by the accompanying supernova

    CERN Document Server

    Duran, Rodolfo Barniol

    2015-01-01

    The gamma-ray burst (GRB) jet powers the afterglow emission by shocking the surrounding medium, and radio afterglow can now be routinely observed to almost a year after the explosion. Long-duration GRBs are accompanied by supernovae (SNe) that typically contain much more energy than the GRB jet. Here we consider the fact that the SN blast wave will also produce its own afterglow, which will peak at much later time (since it is non-relativistic), when the SN blast wave transitions from a coasting phase to a decelerating Sedov-Taylor phase. We predict that this component will peak generally a few tens of years after the explosion and it will outshine the GRB powered afterglow well-before its peak emission. In the case of GRB 030329, where the external density is constrained by the $\\sim 10$-year coverage of the radio GRB afterglow, the radio emission is predicted to start rising over the next decade and to continue to increase for the following decades up to a level of $\\sim 0.5$ mJy. Detection of the SN-powere...

  15. Homogeneous gas phase models of relaxation kinetics in neon afterglow

    Directory of Open Access Journals (Sweden)

    Marković Vidosav Lj.

    2007-01-01

    Full Text Available The homogeneous gas phase models of relaxation kinetics (application of the gas phase effective coefficients to represent surface losses are applied for the study of charged and neutral active particles decay in neon afterglow. The experimental data obtained by the breakdown time delay measurements as a function of the relaxation time td (τ (memory curve is modeled in early, as well as in late afterglow. The number density decay of metastable states can explain neither the early, nor the late afterglow kinetics (memory effect, because their effective lifetimes are of the order of milliseconds and are determined by numerous collision quenching processes. The afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular neon Ne2 + and nitrogen ions N2 + (present as impurities and the approximate value of N2 + ambipolar diffusion coefficient is determined. After the charged particle decay, the secondary emitted electrons from the surface catalyzed excitation of nitrogen atoms on the cathode determine the breakdown time delay down to the cosmic rays and natural radioactivity level. Due to the neglecting of number density spatial profiles, the homogeneous gas phase models give only the approximate values of the corresponding coefficients, but reproduce correctly other characteristics of afterglow kinetics from simple fits to the experimental data.

  16. Radio rebrightening of the GRB afterglow by the accompanying supernova

    Science.gov (United States)

    Barniol Duran, R.; Giannios, D.

    2015-12-01

    The gamma-ray burst (GRB) jet powers the afterglow emission by shocking the surrounding medium, and radio afterglow can now be routinely observed to almost a year after the explosion. Long-duration GRBs are accompanied by supernovae (SNe) that typically contain much more energy than the GRB jet. Here we consider the fact that the SN blast wave will also produce its own afterglow (supernova remnant emission), which will peak at much later time (since it is non-relativistic), when the SN blast wave transitions from a coasting phase to a decelerating Sedov-Taylor phase. We predict that this component will peak generally a few tens of years after the explosion and it will outshine the GRB powered afterglow well-before its peak emission. In the case of GRB 030329, where the external density is constrained by the ˜10-year coverage of the radio GRB afterglow, the radio emission is predicted to start rising over the next decade and to continue to increase for the following decades up to a level of ˜ mJy. Detection of the SN-powered radio emission will greatly advance our knowledge of particle acceleration in ˜0.1c shocks.

  17. Circular polarization in the optical afterglow of GRB 121024A

    CERN Document Server

    Wiersema, K; 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; Alighieri, S di Serego; Tagliaferri, G; Vergani, S D; Elliott, J; Farina, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovski, V; Willingale, R

    2014-01-01

    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 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 burst in 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 negligable 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 blastwave. Here we report the detection of circularly polarized optical light in the afterglow of GRB 121024A, measured 0.1...

  18. The early high-energy afterglow emission from short GRBs

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We calculate the high energy afterglow emission from short Gamma-Ray Bursts(SGRBs) in the external shock model.There are two possible components contributing to the high energy afterglow:electron synchrotron emission and synchrotron self-Compton(SSC) emission.We find that for typical parameter values of SGRBs,the early high-energy afterglow emission in 10 MeV-10 GeV is dominated by synchrotron emission.For a burst occurring at redshift z = 0.1,the high-energy emission can be detectable by Fermi LAT if the blast wave has energy E ≥ 1051 ergs and the fraction of electron energy εe≥ 0.1.This provides a possible explanation for the high energy tail of SGRB 081024B.

  19. Altitudinal dependence of meteor radio afterglows measured via optical counterparts

    CERN Document Server

    Obenberger, K S; Dowell, J D; Schinzel, F K; Stovall, K; Sutton, E K; Taylor, G B

    2016-01-01

    Utilizing the all-sky imaging capabilities of the LWA1 radio telescope along with a host of all-sky optical cameras, we have now observed 44 optical meteor counterparts to radio afterglows. Combining these observations we have determined the geographic positions of all 44 afterglows. Comparing the number of radio detections as a function of altitude above sea level to the number of expected bright meteors we find a strong altitudinal dependence characterized by a cutoff below $\\sim$ 90 km, below which no radio emission occurs, despite the fact that many of the observed optical meteors penetrated well below this altitude. This cutoff suggests that wave damping from electron collisions is an important factor for the evolution of radio afterglows, which agrees with the hypothesis that the emission is the result of electron plasma wave emission.

  20. Swift GRBs: the early afterglow spectral energy distribution

    OpenAIRE

    Tagliaferri, G.; Malesani, D.; Vergani, S. D.; S. Campana; Chincarini, G.; Covino, S.; Guidorzi, C.; A. Moretti(Fermilab, Batavia, IL, USA); Romano, P; Antonelli, L.A.; Capalbi, M.; Conciatore, M. L.; Cusumano, G.; Giommi, P.; La Parola, V.

    2007-01-01

    We present the first results of a program to systematically study the optical-to-X-ray spectral energy distribution (SED) of Swift GRB afterglows with known redshift. The goal is to study the properties of the GRB explosion and of the intervening absorbing material. In this report we present the preliminary analysis on 23 afterglows. Thanks to Swift, we could build the SED at early times after the GRB (minutes to hours). We derived the Hydrogen column densities and the spectral slopes from th...

  1. Swift XRT Observations of the Afterglow of XRF 050416A

    OpenAIRE

    Mangano, Vanessa; La Parola, Valentina; Cusumano, Giancarlo; Mineo, Teresa; Malesani, Daniele; Dyks, Jaroslaw; Campana, Sergio; Capalbi, Milvia; Chincarini, Guido; Giommi, Paolo; Moretti, Alberto; Perri, Matteo; Romano, Patrizia; Tagliaferri, Gianpiero; Burrows, David N.

    2006-01-01

    Swift discovered XRF 050416A with the BAT and began observing it with its narrow field instruments only 64.5 s after the burst onset. Its very soft spectrum classifies this event as an X-ray flash. The afterglow X-ray emission was monitored up to 74 days after the burst. The X-ray light curve initially decays very fast, subsequently flattens and eventually steepens again, similar to many X-ray afterglows. The first and second phases end about 172 and 1450 s after the burst onset, respectively...

  2. Visualisation of Honeypot Data Using Graphviz and Afterglow

    Directory of Open Access Journals (Sweden)

    Craig Valli

    2009-06-01

    Full Text Available This research in progress paper explores the use of Graphviz and Afterglow for the analysis of data emanating from a honeypot system. Honeypot systems gather a wide range of data that is often difficult to readily search for patterns and trends using conventional log file analysis techniques. The data from the honeypots has been statically extracted and processed through Afterglow scripts to produce inputs suitable for use by the DOT graph based tools contained within Graphviz.  This paper explores some of the benefits and drawbacks of currently using this type of approach.

  3. Radiative Regimes in Gamma-Ray Bursts and Afterglows

    CERN Document Server

    Panaitescu, A

    1997-01-01

    We present numerical simulations of Gamma-Ray Bursts arising from external shocks in the impulsive and wind models, including a weak or a strong coupling between electrons and protons plus magnetic fields, and analyze the burst features in each scenario. The dynamics of the ejecta and external medium are followed into the late stages of deceleration, in order to study the hydrodynamics of the remnant and the temporal and spectral evolution of the afterglow. A brief comparison with the optical and radio afterglows of GRB 970228 and GRB 970508 is made.

  4. The Afterglows of Swift-era Gamma-Ray Bursts. II. Type I GRB versus Type II GRB Optical Afterglows

    Science.gov (United States)

    Kann, D. A.; Klose, S.; Zhang, B.; Covino, S.; Butler, N. R.; Malesani, D.; Nakar, E.; Wilson, A. C.; Antonelli, L. A.; Chincarini, G.; Cobb, B. E.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; Ferrero, P.; Fugazza, D.; Gorosabel, J.; Israel, G. L.; Mannucci, F.; Piranomonte, S.; Schulze, S.; Stella, L.; Tagliaferri, G.; Wiersema, K.

    2011-06-01

    Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" and "long/soft." The latter have been conclusively linked to the explosive deaths of massive stars, while the former are thought to result from the merger or collapse of compact objects. In recent years, indications have been accumulating that the short/hard versus long/soft division does not map directly onto what would be expected from the two classes of progenitors, leading to a new classification scheme called Type I and Type II which is based on multiple observational criteria. We use a large sample of GRB afterglow and prompt-emission data (adding further GRB afterglow observations in this work) to compare the optical afterglows (or the lack thereof) of Type I GRBs with those of Type II GRBs. In comparison to the afterglows of Type II GRBs, we find that those of Type I GRBs have a lower average luminosity and show an intrinsic spread of luminosities at least as wide. From late and deep upper limits on the optical transients, we establish limits on the maximum optical luminosity of any associated supernova (SN), confirming older works and adding new results. We use deep upper limits on Type I GRB optical afterglows to constrain the parameter space of possible mini-SN emission associated with a compact-object merger. Using the prompt-emission data, we search for correlations between the parameters of the prompt emission and the late optical afterglow luminosities. We find tentative correlations between the bolometric isotropic energy release and the optical afterglow luminosity at a fixed time after the trigger (positive), and between the host offset and the luminosity (negative), but no significant correlation between the isotropic energy release and the duration of the GRBs. We also discuss three anomalous GRBs, GRB 060505, GRB 060614, and GRB 060121, in light of their optical afterglow luminosities. Based in part

  5. The radio afterglow from the giant flare of SGR 1900+14: The same mechanism as afterglows from classic gamma-ray bursts?

    OpenAIRE

    Cheng, KS; Wang, XY

    2003-01-01

    A radio afterglow was detected following the 1998 August 27 giant flare from the soft gamma repeater (SGR) 1900+14. Its short-lived behavior is quite different from the radio nebula of SGR 1806-20, but very similar to radio afterglows from classic gamma-ray bursts (GRBs). Motivated by this, we attempt to explain it with the external shock model as invoked in the standard theory of GRB afterglows. We find that the light curve of this radio afterglow is not consistent with the forward shock emi...

  6. Circular polarization in the optical afterglow of GRB 121024A.

    Science.gov (United States)

    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; Götz, 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; Fariña, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovsky, V; Willingale, R

    2014-05-01

    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. PMID:24776800

  7. The Optical Afterglow of a Short Gamma-ray Burst

    Science.gov (United States)

    Hjorth, Jens; Watson, Darach; Flynbo, Johan P.U.; Price, Paul A.; Jensen, Brian L.; Jorgensen, Uffe G.; Kubas, Daniel; Gorosabel, Javier; Jakobssonk, Pall; Sollerman, Jesper

    2005-01-01

    It has long been known that there are two classes of gamma-ray bursts (GRBs), principally distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (greater than 2 seconds in duration), that ultimately linked them with energetic Type Ic supernovae, came about from the discovery of their long-lived X-ray and optical "afterglow", when precise and rapid localizations of the sources could finally be obtained. Recently, X-ray localizations have become available for short (less than 2 seconds in duration) GRBs, a hitherto elusive GRB population, that has evaded optical detection for more than thirty years. Here we report the discovery of transient optical emission (R approximately 23 mag) associated with a short GRB. This first short GRB afterglow is localized with sub-arcsecond accuracy onto the outskirts of a blue dwarf galaxy. Unless the optical and X-ray afterglow arise from different mechanisms our observations 33 h after the GRB suggest that, analogously to long GRBs, we observe synchrotron emission from ultrarelativistic ejecta (ZZZ CAN WE LIMIT GAMMA?). In contrast, we did not detect a bright supernova, as found in most nearby long GRB afterglows, which suggests a different origidstrongly constrain the nature of the short GRB progenitors.

  8. Circular polarization in the optical afterglow of GRB 121024A

    Science.gov (United States)

    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.; Götz, 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.; Fariña, C.; Hartoog, O. E.; Karjalainen, R.; Klose, S.; Knust, F.; Levan, A. J.; Schady, P.; Sudilovsky, V.; Willingale, R.

    2014-05-01

    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.

  9. The Afterglows and Host Galaxies of Short GRBs: An Overview

    CERN Document Server

    Berger, E

    2006-01-01

    Despite a rich diversity in observational properties, gamma-ray bursts (GRBs) can be divided into two broad categories based on their duration and spectral hardness -- the long-soft and the short-hard GRBs. The discovery of afterglows from long GRBs in 1997, and their localization to arcsecond accuracy, was a watershed event. The ensuing decade of intense study led to the realization that long-soft GRBs are located in star forming galaxies, produce about 10^51 erg in collimated relativistic ejecta, are accompanied by supernovae, and result from the death of massive stars. While theoretical arguments suggest that short GRBs have a different physical origin, the lack of detectable afterglows prevented definitive conclusions. The situation changed dramatically starting in May 2005 with the discovery of the first afterglows from short GRBs localized by Swift and HETE-2. Here I summarize the discovery of these afterglows and the underlying host galaxies, and draw initial conclusions about the nature of the progeni...

  10. Dust extinction for an unbiased sample of GRB afterglows

    CERN Document Server

    Covino, S; Salvaterra, R; Campana, S; Vergani, S D; Bernardini, M G; D'Avanzo, P; D'Elia, V; Fugazza, D; Ghirlanda, G; Ghisellini, G; Gomboc, A; Jin, Z P; Kruehler, T; Malesani, D; Nava, L; Sbarufatti, B; Tagliaferri, G

    2013-01-01

    In this paper we compute rest-frame extinctions for the afterglows of a sample of \\gamma-ray bursts complete in redshift. The selection criteria of the sample are based on observational high-energy parameters of the prompt emission and therefore our sample should not be biased against dusty sight-lines. It is therefore expected that our inferences hold for the general population of \\gamma-ray bursts. Our main result is that the optical/near-infrared extinction of \\gamma-ray burst afterglows in our sample does not follow a single distribution. 87% of the events are absorbed by less than 2 mag, and 50% suffer from less than 0.3-0.4 mag extinction. The remaining 13% of the afterglows are highly absorbed. The true percentage of \\gamma-ray burst afterglows showing high absorption could be even higher since a fair fraction of the events without reliable redshift measurement are probably part of this class. These events may be due to highly dusty molecular clouds/star forming regions associated with the \\gamma-ray b...

  11. The ultra-long GRB 111209A - II. Prompt to afterglow and afterglow properties

    CERN Document Server

    Stratta, G; Atteia, J L; Boër, M; Coward, D M; De Pasquale, M; Howell, E; Klotz, A; Oates, S; Piro, L

    2013-01-01

    The "ultra-long" Gamma Ray Burst GRB 111209A at redshift z=0.677, is so far the longest GRB ever observed, with rest frame prompt emission duration of ~4 hours. In order to explain the bursts exceptional longevity, a low metallicity blue supergiant progenitor has been invoked. In this work, we further investigate this peculiar burst by performing a multi-band temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus Wind, XMM-Newton, TAROT as well as from other ground based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: i) an unprecedented large optical delay of 410+/-50 s is measured between the peak epochs of a marked flare observed also in gamma-rays after about 2 ks from the first Swift/BAT trigger; ii) if the optical and X-ray/gamma-ray photons during the prompt emission share a common origin, as suggested by their similar tempor...

  12. A Late-Time Flattening of Afterglow Light Curves

    CERN Document Server

    Frail, D A; Berger, E; Kulkarni, S R; Yost, S A

    2004-01-01

    We present a sample of radio afterglow light curves with measured decay slopes which show evidence for a flattening at late times compared to optical and X-ray decay indices. The simplest origin for this behavior is that the change in slope is due to a jet-like outflow making a transition to sub-relativistic expansion. This can explain the late-time radio light curves for many but not all of the bursts in the sample. We investigate several possible modifications to the standard fireball model which can flatten late-time light curves. Changes to the shock microphysics which govern particle acceleration, or energy injection to the shock (either radially or azimuthally) can reproduce the observed behavior. Distinguishing between these different possibilities will require simultaneous optical/radio monitoring of afterglows at late times.

  13. VHE Gamma-ray Afterglow Emission from Nearby GRBs

    CERN Document Server

    Tam, P H; Wagner, S J; Behera, B; Fan, Y Z; Wei, D M

    2008-01-01

    Gamma-ray Bursts (GRBs) are among the potential extragalactic sources of very-high-energy (VHE) gamma-rays. We discuss the prospects of detecting VHE gamma-rays with current ground-based Cherenkov instruments during the afterglow phase. Using the fireball model, we calculate the synchrotron self-Compton (SSC) emission from forward-shock electrons. The modeled results are compared with the observational afterglow data taken with and/or the sensitivity level of ground-based VHE instruments (e.g. STACEE, H.E.S.S., MAGIC, VERITAS, and Whipple). We find that modeled SSC emission from bright and nearby bursts such as GRB 030329 are detectable by these instruments even with a delayed observation time of ~10 hours.

  14. Afterglows of Mildly Relativistic Supernovae: Baryon Loaded Blastwaves

    CERN Document Server

    Chakraborti, Sayan

    2011-01-01

    Relativistic supernovae have been discovered until recently only through their association with long duration Gamma Ray Bursts (GRB). As the ejecta mass is negligible in comparison to the swept up mass, the blastwaves of such explosions are well described by the Blandford-McKee (in the ultra relativistic regime) and Sedov-Taylor (in the non-relativistic regime) solutions during their afterglows. However, the recent discovery of the relativistic supernova SN 2009bb, without a detected GRB, has indicated the possibility of highly baryon loaded mildly relativistic outflows which remains in nearly free expansion phase during the radio afterglow. In this work, we consider the dynamics and emission from a massive, relativistic shell, launched by a Central Engine Driven EXplosion (CEDEX), decelerating adiabatically due to its collision with the pre-explosion circumstellar wind profile of the progenitor. We show that this model explains the observed radio evolution of the prototypical SN 2009bb and demonstrate that S...

  15. Estimation of the detectability of optical orphan afterglows

    CERN Document Server

    Zou, Y C; Dai, Z G

    2006-01-01

    Considering two main assumptions: no sideways expansion and the distribution of half-opening angle of jetted ejecta of gamma-ray bursts, we estimate the detectability of optical orphan afterglows. We show that the former assumption leads to more orphans to be detected while the latter greatly depresses the detectability compared with one single opening angle $\\theta_j=0.1$ model. We also consider the influence of other parameters, and find that the effects of ejecta energy $E_j$, post-jet-break temporal index $-\\alpha_2$ and the distribution of half-opening angle of the jet are important while the index of electron energy distribution $p$, electron energy equipartition factor $\\epsilon_e$ and environment density $n$ are insignificant. If the $E_j$ and $\\alpha_2$ are determined by other methods, one can constrain the distribution of half-opening angle of jets by observation of orphan afterglows.

  16. The CFHTLS Real Time Analysis System "Optically Selected GRB Afterglows"

    CERN Document Server

    Malacrino, F; Boër, M; Klotz, A; Veillet, C; Cuillandre, J C; Malacrino, Frederic; Atteia, Jean-Luc; Boer, Michel; Klotz, Alain; Veillet, Christian; Cuillandre, Jean-Charles

    2006-01-01

    We describe a wide and deep search for optical GRB afterglows on images taken with MegaCAM at the Canada France Hawaii Telescope, within the framework of the CFHT Legacy Survey. This search is performed in near real-time thanks to a Real Time Analysis System called "Optically Selected GRB Afterglows", which has been completely realized and installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images and extracts from them a list of astrometrically and photometrically variable objects which are displayed on a web page for validation by a member of the collaboration. In this paper, we comprehensively describe the RTAS process. We also present statistical results based on nearly one full year of operation, showing the quality of the images and the performance of the RTAS. Finally, we compare the efficiency of this study with similar searches, propose an ideal observational strategy using simulations, and discuss general considerations on the searches for GRB afterg...

  17. Simulation Study Of Early Afterglows Observed With Swift

    Science.gov (United States)

    Nishikawa, Ken-Ichi; Hededal, C.; Hardee, P.; Mizuno, Y.; Fishman, G. J.

    2006-09-01

    A 3-D relativistic particle-in-cell code has been used to simulate the dynamics of forward and reverse shocks with thin and thick shells within the parameter constraints provided by present Swift observations and the present models of GRB emission. Our 3-D RPIC simulations have provided the dynamics of collisionless shocks in electron-ion and electron-positron plasmas with and without initial ambient magnetic fields and revealed the importance of ``jitter radiation'' with prompt and afterglow spectra due to the inhomogeneous magnetic fields generated by the Weibel instability. It is different from synchrotron radiation, which is usually assumed to be the dominant radiation process. We have investigated gamma-ray burst emissions from prompt, early, and late afterglows considering microscopic processes. Based on our previous investigation of the Weibel instability for each stage of evolution of ejecta propagating in the ISM, we have incorporated the plasma conditions (relativistic jets) with the density and composition of the plasmas, the magnetic field strength ($\\sigma$-values (the ratio of the electromagnetic energy flux to the particle energy flux)) and its direction, and the Lorentz factor for the different stages in prompt and afterglows. Systematic simulation studies of the relativistic collisionless shocks, associated particle acceleration, magnetic field generation and self-consistent radiation provide insight into undetermined issues in prompt and afterglows observed by Swift. Self-consistently calculated lightcurves, spectra, spectral evolutions, and polarization as function of viewing angle will be done to light a shed on recent new observations by Swift, in particular, X-ray flares, early steep decay, and shallow decay.

  18. GRB afterglow light curves from realistic density profiles

    OpenAIRE

    Mimica, Petar; Giannios, Dimitrios

    2011-01-01

    The afterglow emission that follows gamma-ray bursts (GRBs) contains valuable information about the circumburst medium and, therefore, about the GRB progenitor. Theoretical studies of GRB blast waves, however, are often limited to simple density profiles for the external medium (mostly constant density and power-law R^{-k} ones). We argue that a large fraction of long-duration GRBs should take place in massive stellar clusters where the circumburst medium is much more complicated. As a case s...

  19. Effect of secondary emission on the argon plasma afterglow with large dust density

    International Nuclear Information System (INIS)

    A zero-dimensional, space-averaged model for argon plasma afterglow with large dust density is developed. In the model, three groups of electrons in the plasma afterglow are assumed: (i) thermal electrons with Maxwellian distribution, (ii) energetic electrons generated by metastable-metastable collisions (metastable pooling), and (iii) secondary electrons generated at collisions of ions with the electrodes, which have sufficiently large negative voltages in the afterglow. The model calculates the time-dependencies for electron densities in plasma afterglow based on experimental decay times for metastable density and electrode bias. The effect of secondary emission on electron density in the afterglow is estimated by varying secondary emission yields. It is found that this effect is less important than metastable pooling. The case of dust-free plasma afterglow is considered also, and it is found that in the afterglow the effect of secondary emission may be more important than metastable pooling. The secondary emission may increase thermal electron density ne in dust-free and dusty plasma afterglows on a few ten percentages. The calculated time dependencies for ne in dust-free and dusty plasma afterglows describe well the experimental results

  20. Effect of secondary emission on the afterglow of argon with negatively charged dust particles

    International Nuclear Information System (INIS)

    A theoretical model for an argon/dusty plasma afterglow in presence of nano-sized dust particles with large density is developed. According to the model, in the plasma afterglow the electrons are generated in metastable collisions and in the secondary emission by collisions of ions with electrodes. By using the model and experimental time-dependencies for metastable density and electrode bias, the time-dependencies for electron density in argon/dusty plasma afterglow are calculated. The effect of secondary emission on electron generation in argon/dusty plasma afterglow is analyzed.

  1. Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

    CERN Document Server

    Obenberger, K S; Hancock, P J; Holmes, J M; Pedersen, T R; Schinzel, F K; Taylor, G B

    2016-01-01

    Using the narrowband all-sky imager mode of the LWA1 we have now detected 30 transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only optically confirmed that 37 of these events are radio afterglows from meteors, evidence suggests that most, if not all, are. Using the beam-forming mode of the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz of four events. We compare the smooth, spectral components of these four events and fit the frequency dependent flux density to a power law, and find that the spectral index is time variable, with the spectrum steepening over time for each meteor afterglow. Using these spectral indices along with the narrow band flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the expected flux densities and rates for meteor afterglows potentially observable by other low frequency radio telescopes.

  2. The SEDs and Host Galaxies of the dustiest GRB afterglows

    CERN Document Server

    Krühler, T; Schady, P; Savaglio, S; Afonso, P M J; Clemens, C; Elliott, J; Filgas, R; Gruber, D; Kann, D A; Klose, S; Küpcü-Yoldas, A; McBreen, S; E., F Olivares; Pierini, D; Rau, A; Rossi, A; Nardini, M; Guelbenzu, A Nicuesa; Sudilovsky, V; Updike, A C

    2011-01-01

    (Abridged) Until recently the information inferred from gamma-ray burst follow-up observations was mostly limited to optically bright afterglows, biasing all demographic studies against sight-lines that contain large amounts of dust. Here, we present GRB afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction along the sight-line. This facilitates an investigation of the properties, geometry and location of the absorbing dust of these poorly-explored host galaxies, and a comparison to hosts from optically-selected samples. The hosts of the dustiest afterglows are diverse in their properties, but on average redder, more luminous and massive than the hosts of optically-bright events. We hence probe a different galaxy population, suggesting that previous host samples miss most of the massive, chemically-evolved and metal-rich members. This also indicates that the dust along the sight-line is often related to host properties, and thus p...

  3. Swift XRT Observations of the Afterglow of XRF 050416A

    CERN Document Server

    Mangano, V; Campana, S; Capalbi, M; Chincarini, G; Cusumano, G; Dyks, J; Giommi, P; Godet, O; Holland, S T; Kennea, J A; La Parola, V; Malesani, D; Mineo, T; Moretti, A; Page, K L; Perri, M; Racusin, J L; Romano, P; Roming, P W A; Tagliaferri, G; Zhang, B; Burrows, David N.; Campana, Sergio; Capalbi, Milvia; Chincarini, Guido; Cusumano, Giancarlo; Dyks, Jaroslaw; Giommi, Paolo; Godet, Olivier; Holland, Stephen T.; Kennea, Jamie A.; Malesani, Daniele; Mangano, Vanessa; Mineo, Teresa; Moretti, Alberto; Page, Kim L.; Parola, Valentina La; Perri, Matteo; Racusin, Judith L.; Romano, Patrizia; Roming, Peter W. A.; Tagliaferri, Gianpiero; Zhang, Bing

    2006-01-01

    Swift discovered XRF 050416A with the BAT and began observing it with its narrow field instruments only 64.5 s after the burst onset. Its very soft spectrum classifies this event as an X-ray flash. The afterglow X-ray emission was monitored up to 74 days after the burst. The X-ray light curve initially decays very fast, subsequently flattens and eventually steepens again, similar to many X-ray afterglows. The first and second phases end about 172 and 1450 s after the burst onset, respectively. We find evidence of spectral evolution from a softer emission with photon index $\\Gamma \\sim 3.0$ during the initial steep decay, to a harder emission with $\\Gamma \\sim 2.0$. The spectra show intrinsic absorption in the host galaxy. The consistency of the initial photon index with the high energy BAT photon index suggests that the initial phase of the X-ray afterglow may be the low-energy tail of the prompt emission. This also requires that the spectral peak energy of the burst decreased from the time of the BAT to the ...

  4. First hours of the GRB 030329 optical afterglow

    CERN Document Server

    Burenin, R A; Pavlinsky, M N; Denissenko, D V; Terekhov, O V; Tkachenko, A V; Aslan, Z; Khamitov, I; Uluc, K; Alpar, M A; Kiziloglu, U; Baykal, A; Bikmaev, I; Sakhibullin, N A; Suleymanov, V

    2003-01-01

    We present the first results of the observations of the extremely bright optical afterglow of gamma-ray burst (GRB) 030329 with the 1.5m Russian-Turkish telescope RTT150 (TUBITAK National Observatory, Bakyrlytepe, Turkey). RTT150 was one of the first 1.5m-class telescopes pointed to the afterglow. Observations were started approximately 6 hours after the burst. During the first 5 hours of our observations the afterglow faded exactly as a power law with index -1.19+-0.01 in each of the BVRI Bessel filters. After that, in all BVRI filters simultaneously we observe a steepening of the power law light curve. The power law decay index smoothly approaches the value ~= -1.9, observed by other observatories later. This power law break occurs at t-t_0 =0.57 days and lasts for +-0.1 days. We observe no variability above the gradual fading with the upper limits 10--1% on time scales 0.1--1000s. Spectral flux distribution in four BVRI filters corresponds to the power law spectrum with spectral index \\alpha=0.66+-0.01. Th...

  5. Radio Afterglows and Host Galaxies of Gamma-Ray Bursts

    CERN Document Server

    Li, Long-Biao; Huang, Yong-Feng; Wu, Xue-Feng; Kong, Si-Wei; Li, Di; Chang, Heon-Young; Choi, Chul-Sung

    2015-01-01

    Considering the contribution of the emission from the host galaxies of gamma-ray bursts (GRBs) to the radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of events, e.g. low-luminosity, standard and high-luminosity GRBs, it is found that a tight correlation exists between the ratio of the radio flux (RRF) of host galaxy to the total radio peak emission and the observational frequency. Especially, toward lower frequencies, the contribution from the host increases significantly. The correlation can be used to get a useful estimate for the radio brightness of those host galaxies which only have very limited radio afterglow data. Using this prediction, we re-considered the theoretical radio afterglow light curves for four kinds of events, i.e. high-luminosity, low-luminosity, standard and failed GRBs, taking into account the contribution from the host galaxies and aiming at exploring the detectability of these events by the Five-hundred-meter Aperture Sp...

  6. The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

    DEFF Research Database (Denmark)

    Castro-Tirado, A.J.; Sokolov, V.V.; Gorosabel, J.; Ceron, J.M.C.; Greiner, J.; Wijers, R.A.M.J.; Jensen, B.L.; Hjorth, J.; Toft, Søren; Pedersen, H.; Palazzi, E.; Pian, E.; Masetti, N.; Sagar, R.N.; Mohan, V.; Pandey, A.K.; Pandey, S.B.; Dodonov, S.N.; Fatkhullin, T.A.; Afanasiev, V.L.; Komarova, V.N.; Moiseev, A.V.; Hudec, R.; Simon, V.; Vreeswijk, P.; Rol, E.; Klose, S.; Stecklum, B.; Zapatero-Osorio, M.R.; Caon, N.; Blake, C.; Wall, J.; Heinlein, D.; Henden, A.; Benetti, S.; Magazzu, A.; Ghinassi, F.; Tommasi, L.; Bremer, M.; Kouveliotou, C.; Guziy, S.; Shlyapnikov, A.; Hopp, U.; Feulner, G.; Dreizler, S.; Hartmann, D.; Boehnhardt, H.; Paredes, J.M.; Marti, J.; Xanthopoulos, E.; Kristen, H.E.; Smoker, J.; Hurley, K.

    2001-01-01

    Broad-band optical observations of the extraordinarily bright optical afterglow of the intense gamma-rag burst GRB 991208 started similar to2.1 days after the event and continued until 4 Apr. 2000. The flux decay constant of the optic al afterglow in the R-band is -2.30 +/- 0.07 up to similar to5...

  7. The electromagnetic afterglows of gravitational waves as a test for Quantum Gravity

    CERN Document Server

    Abramowicz, M A; Ellis, G F R; Meissner, K A; Wielgus, M

    2016-01-01

    We argue that if particularly powerful electromagnetic afterglows of the gravitational waves bursts will be observed in the future, this could be used as a strong observational support for some suggested quantum alternatives for black holes (e.g., firewalls and gravastars). A universal absence of powerful afterglows should be taken as a suggestive argument against such hypothetical quantum-gravity objects.

  8. GRB off-axis afterglows and the emission from the accompanying supernovae

    CERN Document Server

    Kathirgamaraju, Adithan; Giannios, Dimitrios

    2016-01-01

    Gamma-Ray Burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long duration GRBs are also associated with powerful supernovae (SN). We consider the optical and radio afterglows of long GRBs for both blasts viewed along the jet axis ("on-axis" afterglows) and misaligned observes ("off-axis" afterglows). Comparing the optical emission from the afterglow with that of the accompanying SN, using SN 1998bw as an archetype, we find that only a few percent of afterglows viewed off-axis are brighter than the SN. For observable optical off-axis afterglows the viewing angle is at most twice the half-opening angle of the GRB jet. Radio off-axis afterglows should be detected with upcoming radio surveys within a few hundred Mpc. We propose that these surveys will act as "radio triggers," and that dedicated radio facilities should follow-up these sources. Follow-ups can unveil the presence of the radio supernova remnant, if present. In addition, they can ...

  9. The afterglow and complex environment of the optically dim burst GRB 980613

    DEFF Research Database (Denmark)

    Hjorth, J.; Thomsen, Bente; Nielsen, S.R.;

    2002-01-01

    We report the identification of the optical afterglow of GRB 980613 in R- and I-band images obtained between 16 and 48 hr after the gamma-ray burst. Early near-infrared (NIR) H and K' observations are also reported. The afterglow was optically faint (R approximate to 23) at discovery but did not...

  10. Optimal Coaddition of Imaging Data for Rapidly Fading Gamma-Ray Burst Afterglows

    CERN Document Server

    Morgan, A N; Roming, P W A; Nousek, J A; Koch, T S; Breeveld, A A; de Pasquale, M; Holland, S T; Kuin, N P M; Page, M J; Still, M

    2008-01-01

    We present a technique for optimal coaddition of image data for rapidly varying sources, with specific application to gamma-ray burst (GRB) afterglows. Unweighted coaddition of rapidly fading afterglow lightcurve data becomes counterproductive relatively quickly. It is better to stop coaddition of the data once noise dominates late exposures. A better alternative is to optimally weight each exposure to maximize the signal-to-noise ratio (S/N) of the final coadded image data. By using information about GRB lightcurves and image noise characteristics, optimal image coaddition increases the probability of afterglow detection and places the most stringent upper limits on non-detections. For a temporal power law flux decay typical of GRB afterglows, optimal coaddition has the greatest potential to improve the S/N of afterglow imaging data (relative to unweighted coaddition), when the decay rate is high, the source count rate is low, and the background rate is high. The optimal coaddition technique is demonstrated ...

  11. From Engine to Afterglow: Collapsars Naturally Produce Top-Heavy Jets and Early-Time Plateaus in Gamma Ray Burst Afterglows

    OpenAIRE

    Duffell, Paul C.; MacFadyen, Andrew I.

    2014-01-01

    We demonstrate that the steep decay and long plateau in the early phases of gamma ray burst (GRB) X-ray afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present two-dimensional axisymmetric hydrodynamical simulations which start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core which is highly relativistic af...

  12. Study of nitrogen flowing afterglow with mercury vapor injection

    International Nuclear Information System (INIS)

    The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems – the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254 nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 3P1), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N2(A3Σ+u) metastables to mercury atoms. However, the N2(A3Σ+u) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N2(A3Σ+u) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10−6 was determined from the experimental data. Also sensitivity analysis was applied for the analysis of kinetic model in order to reveal the main

  13. Study of nitrogen flowing afterglow with mercury vapor injection

    Energy Technology Data Exchange (ETDEWEB)

    Mazánková, V., E-mail: mazankova@fch.vutbr.cz; Krčma, F. [Institute of Physical and Applied Chemistry, Faculty of Chemistry, Brno University of Technology, Purkyňova 118, 612 00 Brno (Czech Republic); Trunec, D. [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno (Czech Republic)

    2014-10-21

    The reaction kinetics in nitrogen flowing afterglow with mercury vapor addition was studied by optical emission spectroscopy. The DC flowing post-discharge in pure nitrogen was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 130 W. The mercury vapors were added into the afterglow at the distance of 30 cm behind the active discharge. The optical emission spectra were measured along the flow tube. Three nitrogen spectral systems – the first positive, the second positive, and the first negative, and after the mercury vapor addition also the mercury resonance line at 254 nm in the spectrum of the second order were identified. The measurement of the spatial dependence of mercury line intensity showed very slow decay of its intensity and the decay rate did not depend on the mercury concentration. In order to explain this behavior, a kinetic model for the reaction in afterglow was developed. This model showed that the state Hg(6 {sup 3}P{sub 1}), which is the upper state of mercury UV resonance line at 254 nm, is produced by the excitation transfer from nitrogen N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables to mercury atoms. However, the N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastables are also produced by the reactions following the N atom recombination, and this limits the decay of N{sub 2}(A{sup 3}Σ{sup +}{sub u}) metastable concentration and results in very slow decay of mercury resonance line intensity. It was found that N atoms are the most important particles in this late nitrogen afterglow, their volume recombination starts a chain of reactions which produce excited states of molecular nitrogen. In order to explain the decrease of N atom concentration, it was also necessary to include the surface recombination of N atoms to the model. The surface recombination was considered as a first order reaction and wall recombination probability γ = (1.35 ± 0.04) × 10{sup −6} was determined from the experimental data. Also

  14. Delayed Energy Injection Model For Gamma-Ray Burst Afterglows

    CERN Document Server

    Geng, Jin Jun; Wu, Yong-Feng; Yu, Yong-Bo

    2013-01-01

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) is widely believed to be associated with the later activation of central engine. Some models of energy injection involve with a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving with a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time $\\sim t_{\\rm fb}$. Thus we propose a delayed energy injection model, the delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will "generate" a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can well explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy, this indicates GRBs accompanied with fall-back material ...

  15. Influence of dust particles on rf-discharge plasma afterglow

    International Nuclear Information System (INIS)

    In this paper we report about results of computer simulation by PIC/MCC method of the discharging of dust particles in the plasma afterglow and time dependence of plasma parameters in discharge gap after switching off the voltage. It is shown that discharging of dust particles in the afterglow plasma after switching off voltage of radiofrequency discharge occurs faster in the central part of the electrode gap due to the ion cloud forming and intense recombination of electrons in collisions with dust particles in this area. Moreover, the discharging rate is increasing with increasing of the dust particles density. In the initial stage after the switching off the voltage plasma has a positive potential relative to the electrodes. Eventually, when the electron and ion densities are significantly reduced, the charge of the plasma is determined by the amount of negative dust particles. In this case, the plasma potential is negative relative to the electrodes, which contributes to the effective diffusion of dust particles on the walls of the discharge chamber

  16. The distribution of equivalent widths in long GRB afterglow spectra

    CERN Document Server

    Postigo, A de Ugarte; Thoene, C C; Christensen, L; Gorosabel, J; Milvang-Jensen, B; Schulze, S; Jakobsson, P; Wiersema, K; Sanchez-Ramirez, R; Leloudas, G; Zafar, T; Malesani, D; Hjorth, J

    2012-01-01

    The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy. Using 69 low-resolution GRB afterglow spectra, we conduct a study of the rest-frame equivalent width (EW) distribution of features with an average rest-frame EW larger than 0.5 A. To compare an individual GRB with the sample, we develop EW diagrams as a graphical tool, and we give a catalogue with diagrams for the 69 spectra. We introduce a line strength parameter (LSP) that allows us to quantify the strength of the absorption features as compared to the sample by a single number. Using the distributions of EWs of single-species features, we derive the distribution of column densities by a curve of growth (CoG) fit. We find correlations between the LSP and the extinction of the GRB, the UV brightness of the host galaxies and the neutral hydrogen column density. However, we see no significant evolution of...

  17. The Interpretation and Implication of the Afterglow of GRB 060218

    CERN Document Server

    Fan, Y; Xu, D; Fan, Yizhong; Piran, Tsvi; Xu, Dong

    2006-01-01

    The nearby GRB 060216/SN 2006aj was an extremely long, weak and very soft GRB. While it was peculiar in many aspects its late ($>10^4$ sec) X-ray afterglow showed a canonical power law decay. Assuming that this component arises due to a relativistic blast wave decelerated by a circumburst matter we infer that the blast wave's kinetic energy was rather high, $5 \\times 10^{50}$ erg, close to what is seen in other GRBs. The lack of a "jet break" implies that the outflow was wide $\\theta_j \\sim 1$. The rather weak early optical emission rules out a dense circumburst wind profile. It also constrains the initial Lorentz factor to be significantly lower than usual, $\\Gamma_{\\rm ini}\\sim 15$. The observed afterglow suggests that the medium surrounding a massive star progenitor (up to distances of $\\sim 10^{17}-10^{18}$ cm) is not the expected dense stellar wind (a similar result was seen in many other bursts and in particular in GRB 030329). This implies that the progenitor's wind was weak during the last 100-1000 ye...

  18. GRB environment properties through X and optical afterglow observations

    International Nuclear Information System (INIS)

    We present the spectral analysis of 14 gamma-ray bursts (GRB) X-ray afterglows in order to investigate the properties of interstellar matter (ISM) along the line of sight of GRB. We carried out a simultaneous analysis of the NIR-optical and X-band for those afterglows with an optical counterpart too, in order to evaluate and strongly constrain the absorption effect on the spectral energy distribution due to dust extinction from GRB environment. We evaluated the equivalent hydrogen column density NH from X-ray spectroscopy and rest frame visual extinction Aν by assuming different type of ISM composition and dust grain size distribution. From our analysis we obtained a distribution of the GRB rest frame consistent with the one expected if GRB were embedded in a galactic-like molecular cloud. Moreover, values of the visual extinction estimated from the simultaneous analysis or NIR-to-X band favour an environment where small dust grains are destroyed by the interaction with the X-ray and UV photons from GRB

  19. GRB environment properties through X and optical afterglow observations

    CERN Document Server

    Conciatore, M L; Stratta, G; Fiore, F; Perna, R

    2005-01-01

    We present the spectral analysis of 14 gamma-ray bursts (GRB) X-ray afterglows in order to investigate the properties of interstellar matter (ISM) along the line of sight of GRB. We carried out a simultaneous analysis of the NIR-optical and X-band for those afterglows with an optical counterpart too, in order to evaluate and strongly constrain the absorption effect on the spectral energy distribution due to dust extinction from GRB environment. We evaluated the equivalent hydrogen column density Nh from X-ray spectroscopy and rest frame visual extinction Av by assuming different type of ISM composition and dust grain size distribution. From our analysis we obtained a distribution of the GRB rest frame consistent with the one expected if GRB were embedded in a Galactic-like molecular cloud. Moreover, values of the visual extinction estimated from the simultaneous analysis of NIR-to-X band favour an environment where small dust grain are destroyed by the interaction with the X-ray and UV photons from GRB.

  20. Jet simulations and Gamma-ray burst afterglow jet breaks

    CERN Document Server

    van Eerten, H J; Wijers, R A M J; Keppens, R

    2010-01-01

    The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on circumstances, the radio jet break may be postponed significantly. Using high-accuracy adaptive mesh fluid simulations in one dimension, coupled to a detailed synchrotron radiation code, we demonstrate that this is true even for the standard fireball model and hard-edged jets. We confirm these effects with a simulation in two dimensions. The frequency dependence of the jet break is a result of the angle dependence of the emission, the changing optical depth in the self-absorbed regime and the shape of the synchrotron spectrum in general. In the optically thin case the conventional analysis systematically overestimates the jet break time, leading to inferred opening angles that are underestimated by a factor 1.32 and explosion ...

  1. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    Science.gov (United States)

    Racusin, Judith L.; Oates, S. R.; Schady, P.; Burrows, D. N.; dePasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; Roming, P.; Sakamoto, T.; Swenson, C.; Troja, E.; Vasileiou, V.; Virgili, F.; Wanderman, D.; Zhang, B.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi -LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust dataset of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT detected GRBs and the well studied, fainter, less energetic GRBs detected by Swift -BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi -GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  2. On the afterglow and progenitor of FRB 150418

    CERN Document Server

    Zhang, Bing

    2016-01-01

    A radio afterglow was recently detected following FRB 150418, leading to the identification of an elliptical host galaxy at $z = 0.492 \\pm 0.008$ and the cosmological origin of at least some FRBs. We model the afterglow and constrain the isotropic energy of the explosion to be a few $10^{50}$ erg, comparable to that of a short duration GRB. The outflow may have a jet opening angle of $\\sim 0.22$ rad, so that the beaming-corrected energy is below $10^{49}$ erg. The results rule out most FRB progenitor models, but point towards either of the following two scenarios. The first scenario invokes a merger of an NS-NS binary, which produced a faint short GRB and a supra-massive neutron star, which subsequently collapsed into a black hole, probably 100s of seconds after the short GRB. The second scenario invokes the merger of a compact star binary (BH-BH, NS-NS, or BH-NS) with at least one member in the binary charged. The magnetospheric activity just before the merger made the FRB, and subsequently an undetected sho...

  3. Afterglows of Mildly Relativistic Supernovae: Baryon Loaded Blastwaves

    International Nuclear Information System (INIS)

    Relativistic supernovae have been discovered until recently only through their association with long duration Gamma Ray Bursts (GRB). As the ejecta mass is negligible in comparison to the swept up mass, the blastwaves of such explosions are well described by the Blandford-McKee (in the ultra relativistic regime) and Sedov-Taylor (in the non-relativistic regime) solutions during their afterglows. However, the recent discovery of the relativistic supernova SN 2009bb, without a detected GRB, has indicated the possibility of highly baryon loaded mildly relativistic outflows which remains in nearly free expansion phase during the radio afterglow. In this work, we consider the dynamics and emission from a massive, relativistic shell, launched by a Central Engine Driven EXplosion (CEDEX), decelerating adiabatically due to its collision with the pre-explosion circumstellar wind profile of the progenitor. We show that this model explains the observed radio evolution of the prototypical SN 2009bb and demonstrate that SN 2009bb had a highly baryon loaded, mildly relativistic outflow.

  4. When GRB afterglows get softer, hard components come into play

    International Nuclear Information System (INIS)

    We investigated the ability of simple spectral models to describe the early afterglow emission of GRBs. We found that four spectra, belonging to the GRB060502A, GRB060729, GRB060904B, GRB061H0A prompt-afterglow transition phase, can be modeled neither by a single power-law nor by the Band model. Instead we find that the data present high-energy (>3 keV, in the observer frame) statistically significant excesses with respect to these models In all four cases, the deviations can be modeled well by adding either a second power law or a blackbody component to the usual synchrotron power law spectrum. Although the data do not allow an unequivocal physical interpretation, the importance of this analysis consists in showing that a simple power-law model or a Band model is insufficient to describe the X-ray spectra of a small homogeneous sample of GRBs at the end of their prompt phase [1

  5. On the Afterglow and Progenitor of FRB 150418

    Science.gov (United States)

    Zhang, Bing

    2016-05-01

    Keane et al. recently detected a fading radio source following FRB 150418, leading to the identification of a putative host galaxy at z = 0.492 ± 0.008. Assuming that the fading source is the afterglow of FRB 150418, I model the afterglow and constrain the isotropic energy of the explosion to be a few 1050 erg, comparable to that of a short-duration gamma-ray burst (GRB). The outflow may have a jet opening angle of ˜0.22 rad, so that the beaming-corrected energy is below 1049 erg. The results rule out most fast radio burst (FRB) progenitor models for this FRB, but may be consistent with either of the following two scenarios. The first scenario invokes a merger of an NS-NS binary, which produced an undetected short GRB and a supra-massive neutron star, which subsequently collapsed into a black hole, probably hundreds of seconds after the short GRB. The second scenario invokes a merger of a compact star binary (BH-BH, NS-NS, or BH-NS) system whose pre-merger dynamical magnetospheric activities made the FRB, which is followed by an undetected short GRB-like transient. The gravitational-wave (GW) event GW 150914 would be a sister of FRB 150418 in this second scenario. In both cases, one expects an exciting prospect of GW/FRB/GRB associations.

  6. Swift XRT Observations of X-ray Flares in GRB Afterglows

    OpenAIRE

    Burrows, David N.; Romano, P; Godet, O.; Falcone, A; Pagani, C.; Cusumano, G.; Campana, S.; Chincarini, G.; Hill, J E; Giommi, P.; Goad, M. R.; Kennea, J. A.; Kobayashi, S; Meszaros, P.; Nousek, J. A.

    2005-01-01

    The Swift XRT has been observing GRB afterglows since December 23, 2004. Three-quarters of these observations begin within 300 s of the burst onset, providing an unprecendented look at the behavior of X-ray emission from GRB afterglows in the first few hours after the burst. While most of the early afterglows have smoothly declining lightcurves, a substantial fraction has large X-ray flares on short time-scales. We suggest that these flares provide support for models with extended central eng...

  7. The distribution of equivalent widths in long GRB afterglow spectra

    Science.gov (United States)

    de Ugarte Postigo, A.; Fynbo, J. P. U.; Thöne, C. C.; Christensen, L.; Gorosabel, J.; Milvang-Jensen, B.; Schulze, S.; Jakobsson, P.; Wiersema, K.; Sánchez-Ramírez, R.; Leloudas, G.; Zafar, T.; Malesani, D.; Hjorth, J.

    2012-12-01

    Context. The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy at almost any redshift. Aims: We describe the distribution of rest-frame equivalent widths (EWs) of the most prominent absorption features in GRB afterglow spectra, providing the means to compare individual spectra to the sample and identify its peculiarities. Methods: Using 69 low-resolution GRB afterglow spectra, we conduct a study of the rest-frame EWs distribution of features with an average rest-frame EW larger than 0.5 Å. To compare an individual GRB with the sample, we develop EW diagrams as a graphical tool, and we give a catalogue with diagrams for the 69 spectra. We introduce a line strength parameter (LSP) that allows us to quantify the strength of the absorption features in a GRB spectrum as compared to the sample by a single number. Using the distributions of EWs of single-species features, we derive the distribution of their column densities by a curve of growth (CoG) fit. Results: We find correlations between the LSP and the extinction of the GRB, the UV brightness of the host galaxies and the neutral hydrogen column density. However, we see no significant evolution of the LSP with the redshift. There is a weak correlation between the ionisation of the absorbers and the energy of the GRB, indicating that, either the GRB event is responsible for part of the ionisation, or that galaxies with high-ionisation media produce more energetic GRBs. Spectral features in GRB spectra are, on average, 2.5 times stronger than those seen in QSO intervening damped Lyman-α (DLA) systems and slightly more ionised. In particular we find a larger excess in the EW of C ivλλ1549 relative to QSO DLAs, which could be related to an excess of Wolf-Rayet stars in the environments of GRBs. From the CoG fitting we obtain an average number of components in the

  8. Optical and NIR observations of the afterglow of GRB 020813

    Science.gov (United States)

    Covino, S.; Malesani, D.; Tavecchio, F.; Antonelli, L. A.; Arkharov, A.; Di Paola, A.; Fugazza, D.; Ghisellini, G.; Larionov, V.; Lazzati, D.; Mannucci, F.; Masetti, N.; Barrena, R.; Benetti, S.; Castro-Tirado, A. J.; Di Serego Alighieri, S.; Fiore, F.; Frontera, F.; Fruchter, A.; Ghinassi, F.; Gladders, M.; Hall, P. B.; Israel, G. L.; Klose, S.; Magazzù, A.; Palazzi, E.; Pedani, M.; Pian, E.; Romano, P.; Stefanon, M.; Stella, L.

    2003-06-01

    We present optical and near-infrared (NIR) photometry of the bright afterglow of GRB 020813. Our data span from 3 hours to 4 days after the GRB event. A rather sharp achromatic break is present in the light curve, 14 hours after the trigger. In the framework of jetted fireballs, this break corresponds to a jet half-opening angle of 1.9degr +/-0.2degr , the smallest value ever inferred for a GRB. We discuss our results in the framework of currently available models, and find that they have problems in explaining the joint temporal and spectral properties, and in particular the slow decay before the break. Based on observations partly made with ESO telescopes at the Paranal Observatories under programme Id 69.D-0461 and with the Italian TNG telescope under programme TAC 8_01(47).

  9. Modelling extragalactic extinction through gamma-ray burst afterglows

    CERN Document Server

    Zonca, Alberto; Mulas, Giacomo; Casu, Silvia; Aresu, Giambattista

    2016-01-01

    We analyze extragalactic extinction pro?les derived through gamma-ray burst afterglows, using a dust model speci?cally constructed on the assumption that dust grains are not immutable but respond time-dependently to the local physics. Such a model includes core-mantle spherical particles of mixed chemical composition (silicate core, sp2 and sp3 carbonaceous layers), and an additional molecular component, in the form of free-flying polycyclic aromatic hydrocarbons. We fit most of the observed extinction pro?les. Failures occur for lines of sight presenting remarkable rises blueward the bump. We find a tendency in the carbon chemical structure to become more aliphatic with the galactic activity, and to some extent with increasing redshifts. Moreover, the contribution of the moleclar component to the total extinction is more important in younger objects. The results of the ?tting procedure (either successes and failures) may be naturally interpreted through an evolutionary prescription based on the carbon cycle ...

  10. Effect of Dust Extinction on Gamma-ray Burst Afterglows

    Science.gov (United States)

    Lŭ, Gu-Jing; Shao, Lang; Jin, Zhi-Ping; Wei, Da-Ming

    2011-10-01

    In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on the rigorous Mie theory and the latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters. Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity. However, the shape of the extinction curve is mainly determined by the size distribution of the dust grains. If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity. On the contrary, if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger amount of extinction. These results might provide an important insight into understanding the origin of the optically dark GRBs.

  11. Effect of Dust Extinction on Gamma-ray Burst Afterglows

    CERN Document Server

    Lv, Gu-Jing; Jin, Zhi-Ping; Wei, Da-Ming

    2011-01-01

    In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on rigorous Mie theory and latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters. Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity. However, the shape of the extinction curve is mainly determined by the size distribution of the dust grains. If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity. On the contrary, if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger amount of extinction. These results might provide an important insight into understanding the origin of the optically dark GRBs.

  12. The first Swift X-ray Flash: The faint afterglow of XRF 050215B

    CERN Document Server

    Levan, A J; Tanvir, N R; Page, K L; Rol, E; Zhang, B; Goad, M R; O'Brien, P T; Priddey, R S; Bersier, D; Burrows, D N; Chapman, R; Fruchter, A S; Giommi, P; Gehrels, N; Hughes, M A; Pak, S; Simpson, C; Tagliaferri, G; Vardoulaki, E

    2006-01-01

    We present the discovery of XRF 050215B and its afterglow. The burst was detected by the Swift BAT during the check-out phase and observations with the X-ray telescope began approximately 30 minutes after the burst. These observations found a faint, slowly fading X-ray afterglow near the centre of the error box as reported by the BAT. Infrared data, obtained at UKIRT after 10 hours also revealed a very faint K-band afterglow. The afterglow appear unusual since it is very faint, especially in the infrared with K>20 only 9 hours post burst. The X-ray and infrared lightcurves exhibit a slow, monotonic decay with alpha=0.8 and no evidence for steepening associated with the jet break to 10 days post burst. We discuss possible explanations for the faintness and slow decay in the context of present models for the production of X-ray Flashes.

  13. Shallow Decay of X-ray Afterglows in Short GRBs: Energy Injection from a Millisecond Magnetar?

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    With the successful launch of Swift satellite, more and more data of early X-ray afterglows from short gamma-ray bursts have been collected. Some interesting features such as unusual afterglow light curves and unexpected X-ray flares are revealed. Especially, in some cases, there is a flat segment in the X-ray afterglow light curve. Here we present a simplified model in which we believe that the flattening part is due to energy injection from the central engine. We assume that this energy injection arises from the magnetic dipole radiation of a millisecond pulsar formed after the merger of two neutron stars. We check this model with the short GRB 060313. Our numerical results suggest that energy injection from a millisecond magnetar could make part of the X-ray afterglow light curve flat.

  14. Trapping Effects in CdSiO3:In3+ Long Afterglow Phosphor

    Institute of Scientific and Technical Information of China (English)

    KUANG Jin-Yong; LIU Ying-Liang

    2006-01-01

    Trapping effects in CdSiO3:Jn3+ long afterglow phosphor based on photoluminescence (PL) and thermoluminescence (TL) curves are studied. The results of TL show that two intrinsic defects associated with peaks at 346 and 418 K appear in the undoped CdSiO3 phosphor; whereas only one strong cadmium vacancy V"Cd defect associated with peak at 348K appears in the Cd1-xInxSiO3 phosphor due to the chemical nonequivalent substitutions of Cd2+ ions by In3+ ions. This chemical nonequivalent substitution of In3+ ions into the CdSiO3 host produced the highly dense cadmium vacancy V"Cd trap level at 348K, which resulted in the origin of the long afterglow phenomenon. The findings has enlarged the family of non-rare-earth doped long afterglow phosphors available, and offers a promising approach for searching long afterglow phosphor.

  15. Hidden in the light: Magnetically induced afterglow from trapped chameleon fields

    Science.gov (United States)

    Gies, Holger; Mota, David F.; Shaw, Douglas J.

    2008-01-01

    We propose an afterglow phenomenon as a unique trace of chameleon fields in optical experiments. The vacuum interaction of a laser pulse with a magnetic field can lead to a production and subsequent trapping of chameleons in the vacuum chamber, owing to their mass dependence on the ambient matter density. Magnetically induced reconversion of the trapped chameleons into photons creates an afterglow over macroscopic timescales that can conveniently be searched for by current optical experiments. We show that the chameleon parameter range accessible to available laboratory technology is comparable to scales familiar from astrophysical stellar energy-loss arguments. We analyze quantitatively the afterglow properties for various experimental scenarios and discuss the role of potential background and systematic effects. We conclude that afterglow searches represent an ideal tool to aim at the production and detection of cosmologically relevant scalar fields in the laboratory.

  16. Multi-wavelength observations of afterglow of GRB 080319B and the modeling constraints

    CERN Document Server

    Pandey, S B; Jelínek, M; Kamble, Atish P; Gorosabel, J; Postigo, A de Ugarte; Prins, S; Oreiro, R; Chantry, V; Trushkin, S; Bremer, M; Winters, J M; Pozanenko, A; Krugly, Yu; Slyusarev, I; Kornienko, G; Erofeeva, A; Misra, K; Ramprakash, A N; Mohan, V; Bhattacharya, D; Volnova, A; Plá, J; Ibrahimov, M; Im, M; Volvach, A; Wijers, R A M J

    2009-01-01

    We present observations of the afterglow of GRB 080319B at optical, mm and radio frequencies from a few hours to 67 days after the burst. Present observations along with other published multi-wavelength data have been used to study the light-curves and spectral energy distributions of the burst afterglow. The nature of this brightest cosmic explosion has been explored based on the observed properties and it's comparison with the afterglow models. Our results show that the observed features of the afterglow fits equally good with the Inter Stellar Matter and the Stellar Wind density profiles of the circum-burst medium. In case of both density profiles, location of the maximum synchrotron frequency $\

  17. MAGIC upper limits on the GRB 090102 afterglow

    Science.gov (United States)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; de Almeida, U. Barres; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Fidalgo, D. Carreto; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Mendez, C. Delgado; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; López, R. J. García; Garczarczyk, M.; Terrats, D. Garrido; Gaug, M.; Giavitto, G.; Godinović, N.; Munoz, A. González; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Herrero, A.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Knoetig, M. L.; Krähenbühl, T.; Krause, J.; Kushida, J.; Barbera, A. La; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López-Coto, R.; López, M.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Masbou, J.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Prada, F.; Moroni, P. G. Prada; Prandini, E.; Preziuso, S.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Garcia, J. Rodriguez; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamatescu, V.; Stamerra, A.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zandanel, F.; Zanin, R.; Bouvier, A.; Hayashida, M.; Tajima, H.; Longo, F.

    2014-02-01

    Indications of a GeV component in the emission from gamma-ray bursts (GRBs) are known since the Energetic Gamma-Ray Experiment Telescope observations during the 1990s and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy (VHE) photons (E > 30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z = 1.547) field and Fermi Large Area Telescope data in the same time interval are analysed to derive upper limits of the GeV/TeV emission. We compare these results to the expected emissions evaluated for different processes in the framework of a relativistic blastwave model for the afterglow. Simultaneous upper limits with Fermi and a Cherenkov telescope have been derived for this GRB observation. The results we obtained are compatible with the expected emission although the difficulties in predicting the HE and VHE emission for the afterglow of this event makes it difficult to draw firmer conclusions. Nonetheless, MAGIC sensitivity in the energy range of overlap with space-based instruments (above about 40 GeV) is about one order of magnitude better with respect to Fermi. This makes evident the constraining power of ground-based observations and shows that the MAGIC telescope has reached the required performance to make possible GRB multiwavelength studies in the VHE range.

  18. Expected Number and Flux Distribution of Gamma-Ray-Burst Afterglows with High Redshifts

    OpenAIRE

    Ciardi, Benedetta; Loeb, Abraham

    2000-01-01

    If Gamma-Ray-Bursts (GRBs) occur at high redshifts, then their bright afterglow emission can be used to probe the ionization and metal enrichment histories of the intervening intergalactic medium during the epoch of reionization. In contrast to other sources, such as galaxies or quasars, which fade rapidly with increasing redshift, the observed infrared flux from a GRB afterglow at a fixed observed age is only a weak function of its redshift. This results from a combination of the spectral sl...

  19. Study of Dielectric Barrier Discharges in nitrogen and afterglows at atmospheric pressure

    International Nuclear Information System (INIS)

    This article is devoted to the study of Dielectric Barrier Discharges (DBD) and afterglows obtained at atmospheric pressure in nitrogen. Electrical and optical analysis of the DBD reactor are carried out in order to characterize specific activated gaseous species, which can travel with low energy dispersion for long distances in tubes. A hypothesis for the explanation of the presence of long-lived species in such afterglows is finally explained as related to a solitary wave effect.

  20. Study of Dielectric Barrier Discharges in nitrogen and afterglows at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Clement, F; Panousis, E; Lecoq, E; Loiseau, J-F; Held, B [Universite de Pau - LEGP, IPREM - 64000 Pau (France); Ricard, A [Universite Paul Sabatier - LAPLACE - 31000 Toulouse (France)

    2010-01-01

    This article is devoted to the study of Dielectric Barrier Discharges (DBD) and afterglows obtained at atmospheric pressure in nitrogen. Electrical and optical analysis of the DBD reactor are carried out in order to characterize specific activated gaseous species, which can travel with low energy dispersion for long distances in tubes. A hypothesis for the explanation of the presence of long-lived species in such afterglows is finally explained as related to a solitary wave effect.

  1. On the afterglow from the receding jet of gamma-ray burst

    OpenAIRE

    Xin WANG; Huang, Y.F.; Kong, Si-Wei

    2009-01-01

    According to popular progenitor models of gamma-ray bursts, twin jets should be launched by the central engine, with a forward jet moving toward the observer and a receding jet (or the counter jet) moving backwardly. However, in calculating the afterglows, usually only the emission from the forward jet is considered. Here we present a detailed numerical study on the afterglow from the receding jet. Our calculation is based on a generic dynamical description, and includes some delicate ingredi...

  2. Escherichia coli morphological changes and lipid A removal induced by reduced pressure nitrogen afterglow exposure.

    Directory of Open Access Journals (Sweden)

    Hayat Zerrouki

    Full Text Available Lipid A is a major hydrophobic component of lipopolysaccharides (endotoxin present in the membrane of most Gram-negative bacteria, and the major responsible for the bioactivity and toxicity of the endotoxin. Previous studies have demonstrated that the late afterglow region of flowing post-discharges at reduced pressure (1-20 Torr can be used for the sterilization of surfaces and of the reusable medical instrumentation. In the present paper, we show that the antibacterial activity of a pure nitrogen afterglow can essentially be attributed to the large concentrations of nitrogen atoms present in the treatment area and not to the UV radiation of the afterglow. In parallel, the time variation of the inactivation efficiency quantified by the log reduction of the initial Escherichia coli (E. coli population is correlated with morphologic changes observed on the bacteria by scanning electron microscopy (SEM for increasing afterglow exposure times. The effect of the afterglow exposure is also studied on pure lipid A and on lipid A extracted from exposed E. coli bacteria. We report that more than 60% of lipid A (pure or bacteria-extracted are lost with the used operating conditions (nitrogen flow QN2 = 1 standard liter per minute (slpm, pressure p = 5 Torr, microwave injected power PMW = 200 W, exposure time: 40 minutes. The afterglow exposure also results in a reduction of the lipid A proinflammatory activity, assessed by the net decrease of the redox-sensitive NFκB transcription factor nuclear translocation in murine aortic endothelial cells stimulated with control vs afterglow-treated (pure and extracted lipid A. Altogether these results point out the ability of reduced pressure nitrogen afterglows to neutralize the cytotoxic components in Gram-negative bacteria.

  3. A Possible Explanation of the Radio Afterglow of GRB980519: The Dense Medium Effect

    OpenAIRE

    X. Y. Wang; Dai, Z. G.; Lu, T.

    1999-01-01

    GRB{980519} is characterized by its rapidly declining optical and X-ray afterglows. Explanations of this behavior include models invoking a dense medium environment which makes the shock wave evolve quickly into the sub-relativistic phase, a jet-like outflow, and a wind-shaped circumburst medium environment. Recently, Frail {et al}. (1999a) found that the latter two cases are consistent with the radio afterglow of this burst. Here, by considering the trans-relativistic shock hydrodynamics, we...

  4. The Early Optical Afterglow of GRB 030418 and Progenitor Mass Loss

    CERN Document Server

    Rykoff, E S; Price, P A; Akerlof, C W; Ashley, M C B; Bizyaev, D V; Garradd, G J; McKay, T A; McNaught, R H; Phillips, A; Quimby, R; Schaefer, B; Schmidt, B; Vestrand, W T; Wheeler, J C; Wren, J

    2004-01-01

    The ROTSE-IIIa telescope and the SSO-40 inch telescope, both located at Siding Spring Observatory, imaged the early time afterglow of GRB 030418. In this report we present observations of the early afterglow, first detected by the ROTSE-IIIa telescope 211 s after the start of the burst, and only 76 s after the end of the gamma-ray activity. We detect optical emission that rises for ~600 s, slowly varies around R=17.3 mag for ~1400 s, and then fades as a power law of index alpha=-1.36. Additionally, the ROTSE-IIIb telescope, located at McDonald Observatory, imaged the early time afterglow of GRB 030723. The behavior of this light curve was qualitatively similar to that of GRB 030418, but two magnitudes dimmer. These two afterglows are dissimilar to other afterglows such as GRB 990123 and GRB 021211. We investigate whether the early afterglow can be attributed to a synchrotron break in a cooling synchrotron spectrum as it passes through the optical band, but find this model is unable to accurately describe the ...

  5. Observations of GRB 060526 Optical Afterglow with Russian-Turkish 1.5-m Telescope

    CERN Document Server

    Khamitov, I M; Bikmaev, I F; Sakhibullin, N A; Pavlinsky, M N; Sunyaev, R A; Aslan, Z

    2008-01-01

    We present the results of the photometric multicolor observations of GRB 060526 optical afterglow obtained with Russian-Turkish 1.5-m Telescope (RTT150, Mt. Bakirlitepe, Turkey). The detailed measurements of afterglow light curve, starting from about 5 hours after the GRB and during 5 consecutive nights were done. In addition, upper limits on the fast variability of the afterglow during the first night of observations were obtained and the history of afterglow color variations was measured in detail. In the time interval from 6 to 16 hours after the burst, there is a gradual flux decay, which can be described approximately as a power law with an index of -1.14+-0.02. After that the variability on the time scale \\delta t < t is observed and the afterglow started to decay faster. The color of the afterglow, V-R=~0.5, is approximately the same during all our observations. The variability is detected on time scales up to \\delta t/t =~ 0.0055 at \\Delta F_\

  6. Comprehensive multi-wavelength modelling of the afterglow of GRB050525A

    CERN Document Server

    Resmi, L; Jóhannesson, G; Castro-Tirado, A J; Gorosabel, J; Jelínek, M; Bhattacharya, D; Kubánek, P; Anupama, G C; Sota, A; Sahu, D K; Postigo, A de Ugarte; Pandey, S B; Sánchez-Ramírez, R; Bremer, M; Sagar, R

    2012-01-01

    The Swift era has posed a challenge to the standard blast-wave model of Gamma Ray Burst (GRB) afterglows. The key observational features expected within the model are rarely observed, such as the achromatic steepening (`jet-break') of the light curves. The observed afterglow light curves showcase additional complex features requiring modifications within the standard model. Here we present optical/NIR observations, millimeter upper limits and comprehensive broadband modelling of the afterglow of the bright GRB 0505025A, detected by Swift. This afterglow cannot be explained by the simplistic form of the standard blast-wave model. We attempt modelling the multi-wavelength light curves using (i) a forward-reverse shock model, (ii) a two-component outflow model and (iii) blast-wave model with a wind termination shock. The forward-reverse shock model cannot explain the evolution of the afterglow. The two component model is able to explain the average behaviour of the afterglow very well but cannot reproduce the fl...

  7. The Afterglows of Swift-era Gamma-ray Bursts. I. Comparing pre-Swift and Swift-era Long/Soft (Type II) GRB Optical Afterglows

    Science.gov (United States)

    Kann, D. A.; Klose, S.; Zhang, B.; Malesani, D.; Nakar, E.; Pozanenko, A.; Wilson, A. C.; Butler, N. R.; Jakobsson, P.; Schulze, S.; Andreev, M.; Antonelli, L. A.; Bikmaev, I. F.; Biryukov, V.; Böttcher, M.; Burenin, R. A.; Castro Cerón, J. M.; Castro-Tirado, A. J.; Chincarini, G.; Cobb, B. E.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; de Ugarte Postigo, A.; Efimov, Yu.; Ferrero, P.; Fugazza, D.; Fynbo, J. P. U.; Gålfalk, M.; Grundahl, F.; Gorosabel, J.; Gupta, S.; Guziy, S.; Hafizov, B.; Hjorth, J.; Holhjem, K.; Ibrahimov, M.; Im, M.; Israel, G. L.; Jeĺinek, M.; Jensen, B. L.; Karimov, R.; Khamitov, I. M.; Kiziloǧlu, Ü.; Klunko, E.; Kubánek, P.; Kutyrev, A. S.; Laursen, P.; Levan, A. J.; Mannucci, F.; Martin, C. M.; Mescheryakov, A.; Mirabal, N.; Norris, J. P.; Ovaldsen, J.-E.; Paraficz, D.; Pavlenko, E.; Piranomonte, S.; Rossi, A.; Rumyantsev, V.; Salinas, R.; Sergeev, A.; Sharapov, D.; Sollerman, J.; Stecklum, B.; Stella, L.; Tagliaferri, G.; Tanvir, N. R.; Telting, J.; Testa, V.; Updike, A. C.; Volnova, A.; Watson, D.; Wiersema, K.; Xu, D.

    2010-09-01

    We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowing us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature

  8. From Engine to Afterglow: Collapsars Naturally Produce Top-heavy Jets and Early-time Plateaus in Gamma-Ray Burst Afterglows

    Science.gov (United States)

    Duffell, Paul C.; MacFadyen, Andrew I.

    2015-06-01

    We demonstrate that the steep decay and long plateau in the early phases of gamma-ray burst X-ray afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present two-dimensional axisymmetric hydrodynamical simulations that start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core that is highly relativistic after breaking out of the star, but becomes baryon loaded after colliding with a massive outer shell, corresponding to mass from the stellar atmosphere of the progenitor star which became trapped in front of the jet core at breakout. The prompt emission produced before or during this collision would then have the signature of a high Lorentz factor jet, but the afterglow is produced by the amalgamated post-collision ejecta that has more inertia than the original highly relativistic jet core and thus has a delayed deceleration. This naturally explains the early light curve behavior discovered by Swift, including a steep decay and a long plateau, without invoking late-time energy injection from the central engine. The numerical simulation is performed continuously from engine to afterglow, covering a dynamic range of over 10 orders of magnitude in radius. Light curves calculated from the numerical output demonstrate that this mechanism reproduces basic features seen in early afterglow data. Initial steep decays are produced by internal shocks, and the plateau corresponds to the coasting phase of the outflow.

  9. Radio transient following FRB 150418: afterglow or coincident AGN flare?

    CERN Document Server

    Li, Ye

    2016-01-01

    Recently, Keane et al. reported the discovery of a fading radio transient following FRB 150418, and interpreted it as the afterglow of the FRB. Williams \\& Berger, on the other hand, suggested that the radio transient is analogous to a group of variable radio sources, so that it could be a coincident AGN flare in the observational beam of the FRB. A new observation with VLA showed a re-brightening, which is consistent with the AGN picture. Here, using the radio survey data of Ofek et al., we statistically examine the chance coincidence probability to produce an event like the FRB 150418 transient. We find that the probabilities to produce a variable radio transient with at least the same variability amplitude and signal-to-noise ratio as the FRB 150415 transient, without and with the VLA point, are $P_1 \\sim 6 \\times 10^{-4}$ and $P_1 \\sim 2 \\times 10^{-3}$, respectively. In addition, the chance probability to have a fading transient detected following a random time (FRB time) is less than $P_2 \\sim 10^{-...

  10. Gamma Ray Burst reverse shock emission in early radio afterglows

    CERN Document Server

    Resmi, Lekshmi

    2016-01-01

    Reverse shock (RS) emission from Gamma Ray Bursts is an important tool in investigating the nature of the ejecta from the central engine. If the ejecta magnetization is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would give important contribution to early afterglow light curves. In the radio band, synchrotron self-absorption may suppress early RS emission, and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band for different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both reverse and forward shocks. We calculate the ratio between the reverse to forward shock flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS e...

  11. Multi-Color Observations of the GRB000926 Afterglow

    CERN Document Server

    Price, P A; Galama, T J; Reichart, D E; Axelrod, T S; Busche, J; Cline, T; Diercks, A H; Djorgovski, S G; Frail, D A; Gal-Yam, A; Halpern, J; Hunt, J A H M; Hurley, K; Jacoby, B; Kimble, R A; Kulkarni, S R; Mirabal, N; Morrison, G; Pevunova, E O O; Sari, R; Schmidt, B P; Turnshek, D A; Yost, S; Bloom, S J

    2000-01-01

    We present multi-color light-curves of the optical afterglow of GRB 000926. Beginning 1.18 days after the burst, the light curves of this GRB steepen measurably. The existence of such achromatic breaks are usually taken to be an important observational signature that the ejecta are not expanding isotropically, but rather have a collimated jet-like geometry. If we interpret the data in this context, we derive an opening angle of 7 deg, which reduces the energy release compared to an isotropic model by a factor of 120, to 2.2 x 10^{51} erg. To fit the data with a simple jet model requires extinction along the line of sight. The derived A_V is in the range 0.91 -- 0.12 mag, depending on the adopted extinction law and whether the electrons giving rise to the optical emission are undergoing synchrotron cooling or not. Since this is in excess of the expected extinction from our Galaxy, we attribute this to the GRB host. We note that this extinction is typical of a galactic disk, and therefore the event likely took ...

  12. Testing GRB models with the strange afterglow of GRB 090102

    CERN Document Server

    Gendre, B; Palazzi, E; Kruhler, T; Covino, S; Afonso, P; Antonelli, L A; Atteia, J L; D'Avanzo, P; Boër, M; Greiner, J; Klose, S

    2009-01-01

    We present the observations of the afterglow of gamma-ray burst GRB 090102. We use optical data taken by the TAROT, REM, GROND, Palomar and NOT telescopes, and X-ray data taken by the XRT instrument on board the Swift spacecraft. This event features an unusual light curve. In X-rays, it presents a very monotonic decrease with no hint of temporal break from 0.005 to 6 days after the burst. In optical, the light curve presents a flattening after 1 ks. Before this break, the optical light curve is steeper than the X-ray one. In optical, no further break is observed up to 10 days after the burst. We tried to explain these observations in light of the standard fireball model, but we failed to do so. We then investigated several other models, like the cannonball model. We find that the explanation of the broad band data by any model requires a strong fine tuning when taking into account both optical and X-ray bands.

  13. Variable polarization in the optical afterglow of GRB 021004

    CERN Document Server

    Rol, E; Fynbo, J P U; Hjorth, J; Gorosabel, J; Egholm, M P; Castro-Cerón, J M; Castro-Tirado, A J; Kaper, L; Masetti, N; Palazzi, E; Pian, E; Tanvir, N R; Vreeswijk, P M; Kouveliotou, C; Møller, P; Pedersen, H; Fruchter, A S; Rhoads, J; Burud, I; Salamanca, I; Van den Heuvel, E P J

    2003-01-01

    We present polarimetric observations of the afterglow of gamma-ray burst (GRB) 021004, obtained with the Nordic Optical Telescope (NOT) and the Very Large Telescope (VLT) between 8 and 17 hours after the burst. Comparison among the observations shows a 45 degree change in the position angle from 9 hours after the burst to 16 hours after the burst, and comparison with published data from later epochs even shows a 90 degree change between 9 and 89 hours after the burst. The degree of linear polarization shows a marginal change, but is also consistent with being constant in time. In the context of currently available models for changes in the polarization of GRBs, a homogeneous jet with an early break time of t_b ~ 1 day provides a good explanation of our data. The break time is a factor 2 to 6 earlier than has been found from the analysis of the optical light curve. The change in the position angle of the polarization rules out a structured jet model for the GRB.

  14. GRB orphan afterglows in present and future radio transient surveys

    CERN Document Server

    Ghirlanda, G; Ghisellini, G; Salvaterra, R; Bernardini, M G; Campana, S; Covino, S; D'Avanzo, P; D'Elia, V; Melandri, A; Murphy, T; Nava, L; Vergani, S D; Tagliaferri, G

    2014-01-01

    Orphan Afterglows (OA) are slow transients produced by Gamma Ray Bursts seen off-axis that become visible on timescales of days/years at optical/NIR and radio frequencies, when the prompt emission at high energies (X and gamma rays) has already ceased. Given the typically estimated jet opening angle of GRBs theta_jet ~ 3 deg, for each burst pointing to the Earth there should be a factor ~ 700 more GRBs pointing in other directions. Despite this, no secure OAs have been detected so far. Through a population synthesis code we study the emission properties of the population of OA at radio frequencies. OAs reach their emission peak on year-timescales and they last for a comparable amount of time. The typical peak fluxes (which depend on the observing frequency) are of few micro Jy in the radio band with only a few OA reaching the mJy level. These values are consistent with the upper limits on the radio flux of SN Ib/c observed at late times. We find that the OA radio number count distribution has a typical slope ...

  15. AMRVAC and Relativistic Hydrodynamic simulations for GRB afterglow phases

    CERN Document Server

    Meliani, Z; Casse, F; Giannios, D

    2007-01-01

    We apply a novel adaptive mesh refinement code, AMRVAC, to numerically investigate the various evolutionary phases in the interaction of a relativistic shell with its surrounding cold Interstellar Medium (ISM). We do this for both 1D isotropic as well as full 2D jetlike fireball models. This is relevant for Gamma Ray Bursts, and we demonstrate that, thanks to the AMR strategy, we resolve the internal structure of the shocked shell-ISM matter, which will leave its imprint on the GRB afterglow. We determine the deceleration from an initial Lorentz factor $\\gamma=100$ up to the almost Newtonian $\\gamma\\sim{\\cal O}(2)$ phase of the flow. We present axisymmetric 2D shell evolutions, with the 2D extent characterized by their initial opening angle. In such jetlike GRB models, we discuss the differences with the 1D isotropic GRB equivalents. These are mainly due to thermally induced sideways expansions of both the shocked shell and shocked ISM regions. We found that the propagating 2D ultrarelativistic shell does not...

  16. How Bad or Good Are the External Forward Shock Afterglow Models of Gamma-Ray Bursts?

    Science.gov (United States)

    Wang, Xiang-Gao; Zhang, Bing; Liang, En-Wei; Gao, He; Li, Liang; Deng, Can-Min; Qin, Song-Mei; Tang, Qing-Wen; Kann, D. Alexander; Ryde, Felix; Kumar, Pawan

    2015-07-01

    The external forward shock models have been the standard paradigm to interpret the broadband afterglow data of gamma-ray bursts (GRBs). One prediction of the models is that some afterglow temporal breaks at different energy bands should be achromatic; that is, the break times should be the same in different frequencies. Multiwavelength observations in the Swift era have revealed chromatic afterglow behaviors at least in some GRBs, casting doubts on the external forward shock origin of GRB afterglows. In this paper, using a large sample of GRBs with both X-ray and optical afterglow data, we perform a systematic study to address the question: how bad or good are the external forward shock models? Our sample includes 85 GRBs up to 2014 March with well-monitored X-ray and optical light curves. Based on how well the data abide by the external forward shock models, we categorize them into five grades and three samples. The first two grades (Grade I and II) include 45 of 85 GRBs. They show evidence of, or are consistent with having, an achromatic break. The temporal and spectral behaviors in each afterglow segment are consistent with the predictions (the “closure relations”) of the forward shock models. These GRBs are included in the Gold sample. The next two grades (Grade III and IV) include 37 of 85 GRBs. They are also consistent with having an achromatic break, even though one or more afterglow segments do not comply with the closure relations. These GRBs are included in the Silver sample. Finally, Grade V (3/85) shows direct evidence of chromatic behaviors, suggesting that the external shock models are inconsistent with the data. These are included in the Bad sample. We further perform statistical analyses of various observational properties (temporal index α, spectral index β, break time tb) and model parameters (energy injection index q, electron spectral index p, jet opening angle {θ }j, radiative efficiency ηγ, and so on) of the GRBs in the Gold sample

  17. Discovery of a tight correlation for gamma ray burst afterglows with `canonical' light curves

    CERN Document Server

    Dainotti, M G; Capozziello, S; Cardone, V F; Ostrowski, M

    2010-01-01

    Gamma Ray Bursts (GRB) observed up to redshifts $z>8$ are fascinating objects to study due to their still unexplained relativistic outburst mechanisms and a possible use to test cosmological models. Our analysis of 77 GRB afterglows with known redshifts revealed a physical subsample of long GRBs with canonical {\\it plateau breaking to power-law} light curves with a significant {\\it luminosity $L^*_X$ - break time $T^*_a$} correlation in the GRB rest frame. This subsample forms approximately the {\\it upper envelope} of the studied distribution. We have also found a similar relation for a small sample of GRB afterglows that belong to the intermediate class (IC) between the short and the long ones. It proves that within the full sample of afterglows there exist physical subclasses revealed here by tight correlations of their afterglow properties. The afterglows with regular (`canonical') light curves obey not only a mentioned tight physical scaling, but -- for a given $T^*_a$ -- the more regular progenitor explo...

  18. Afterglow of a microwave microstrip plasma as an ion source for mass spectrometry

    International Nuclear Information System (INIS)

    A microwave-induced plasma that was previously used for optical emission spectrometry has been repurposed as an afterglow ion source for mass spectrometry. This compact microwave discharge, termed the microstrip plasma (MSP), is operated at 20–50 W and 2.45 GHz in helium at a flow of 300 mL/min. The primary background ions present in the afterglow are ionized and protonated water clusters. An exponential dilution chamber was used to introduce volatile organic compounds into the MSP afterglow and yielded limits of detection in the 40 ppb to 7 ppm range (v/v). A hydride-generation system was also utilized for detection of volatile hydride-forming elements (arsenic, antimony, tin) in the afterglow and produced limits of detection in the 10–100 ppb range in solution. The MSP afterglow was found capable of desorption and ionization of analyte species directly from a solid substrate, suggesting its use as an ion source for ambient desorption/ionization mass spectrometry

  19. The 7.67 Years Collection of Well-Monitored Fermi-LAT GRB Afterglows

    CERN Document Server

    Panaitescu, A

    2016-01-01

    We present the light-curves and spectra of 24 afterglows that have been monitored by Fermi-LAT at 0.1-100 GeV over more than a decade in time. All light-curves are consistent with a single power-law starting from their peaks, which occur, in most cases, before the burst end. The light-curves display a brightness-decay rate correlation, with all but one (130427) of the bright afterglows decaying faster than the dimmer afterglows. We attribute this dichotomy to a quick deposition of the relativistic ejecta energy in the external-shock for the former type and to an extended energy-injection in the afterglow shock for the latter. The spectra of 10 afterglows are better described with a broken power-law than a single power-law, indicating the existence of a hard component above a dip energy that ranges from 0.5 GeV to 5 GeV, and at a 1-3 sigma confidence level. We interpret those spectra as being synchrotron self-Compton emissions, and suggest that power-law photon spectra softer than dN/dE ~ E^{-2} are synchrotro...

  20. Polarization of prompt and afterglow emission of Gamma-Ray Bursts

    CERN Document Server

    Covino, Stefano

    2016-01-01

    Gamma-ray bursts and their afterglows are thought to be produced by an ultra-relativistic jet. One of the most important open questions is the outflow composition: the energy may be carried out from the central source either as kinetic energy (of baryons and/or pairs), or in electromagnetic form (Poynting flux). While the total observable flux may be indistinguishable in both cases, its polarization properties are expected to differ markedly. The prompt emission and afterglow polarization are also a powerful diagnostic of the jet geometry. Again, with subtle and hardly detectable differences in the output flux, we have distinct polarization predictions. In this review we briefly describe the theoretical scenarios that have been developed following the observations, and the now large observational datasets that for the prompt and the afterglow phases are available. Possible implications of polarimetric measurements for quantum gravity theory testing are discussed, and future perspectives for the field briefly ...

  1. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Surveys

    CERN Document Server

    Topinka, Martin

    2015-01-01

    Thanks to the advances in robotic telescopes, the time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. A special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques is used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the $g'-r'$, $r'-i'$ and $i'-z'$ colour indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of $\\gtrsim 90\\%$.

  2. The Early Time Properties of GRBs - Canonical Afterglows and the Importance of Prolonged Central Engine Activity

    International Nuclear Information System (INIS)

    Using a new, comprehensive multiwavelength survey of 63 Gamma Ray Bursts (GRBs) with unprecedented temporal coverage, we classify the observed afterglows into four main classes and discuss the underlying physics that can explain them. The presence or absence of temporal breaks in X-ray and optical bands is used to examine the emission in the context of the standard model; a number of GRBs are shown to deviate from the forward shock model even with the inclusion of energy injection or ambient density gradients. We show that additional emission in the early-time X-ray afterglow due to late-time central engine activity is key and may explain both GRBs whose afterglows do not fit the standard model and those GRBs that appear to be optically dark even at early times.

  3. Simulation and physical model based gamma-ray burst afterglow analysis

    CERN Document Server

    van Eerten, Hendrik

    2015-01-01

    Advances in our numerical and theoretical understanding of gamma-ray burst afterglow processes allow us to construct models capable of dealing with complex relativistic jet dynamics and non-thermal emission, that can be compared directly to data from instruments such as Swift. Because afterglow blast waves and power law spectra are intrinsically scale-invariant under changes of explosion energy and medium density, templates can be generated from large-scale hydrodynamics simulations. This allows for iterative template-based model fitting using the physical model parameters (quantifying the properties of the burster, emission and observer) directly as fit variables. Here I review how such an approach to afterglow analysis works in practice, paying special attention to the underlying model assumptions, possibilities, caveats and limitations of this type of analysis. Because some model parameters can be degenerate in certain regions of parameter space, or unconstrained if data in a limited number of a bands is a...

  4. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    Science.gov (United States)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  5. VizieR Online Data Catalog: Position catalogue of Swift XRT afterglows (Moretti+, 2006)

    Science.gov (United States)

    Moretti, A.; Perri, M.; Capalbi, M.; Angelini, L.; Hill, J. E.; Campana, S.; Burrows, D. N.; Osborne, J. P.; Tagliaferri, G.; Cusumano, G.; Giommi, P.; Romano, P.; Mineo, T.; Kennea, J.; Morris, D.; Nousek, J.; Pagani, C.; Racusin, J.; Abbey, A. F.; Beardmore, A. P.; Godet, O.; Goad, M. R.; Page, K. L.; Wells, A. A.; Chincarini, G.

    2006-02-01

    We present a catalogue of refined positions of 68 gamma ray burst (GRB) afterglows observed by the Swift X-ray Telescope (XRT) from the launch up to 2005 Oct. 16. This is a result of the refinement of the XRT boresight calibration. We tested this correction by means of a systematic study of a large sample of X-ray sources observed by XRT with well established optical counterparts. We found that we can reduce the systematic error radius of the measurements by a factor of two, from 6.5 to 3.2 (90% of confidence). We corrected all the positions of the afterglows observed by XRT in the first 11 months of the Swift mission. This is particularly important for the 37 X-ray afterglows without optical counterpart. Optical follow-up of dark GRBs, in fact, will be more efficient with the use of the more accurate XRT positions. (1 data file).

  6. Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

    International Nuclear Information System (INIS)

    Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

  7. Long afterglow properties of Eu2+/Mn2+ doped Zn2GeO4

    International Nuclear Information System (INIS)

    Zn2GeO4:Eu2+0.01 and Zn2GeO4:Mn2+0.01 long afterglow phosphors were synthesized via a high temperature solid state reaction. X-ray diffraction (XRD), afterglow spectra, decay curves and thermoluminescence curves were utilized to characterize the samples. The X-ray diffraction phases indicate that the doping of small amount of transition metal ions or rare earth ions has no significant influence on the crystal structure of Zn2GeO4. According to the afterglow spectra, we found that the Zn2GeO4:Eu2+0.01 exhibits a broad band emission with a peak at 474 nm, which could be ascribed to Eu2+ transition between 4f65d1 and 4f7 electron configurations. The Zn2GeO4:Mn2+0.01 shows a narrow band emission peaking at 532 nm corresponding to the characteristic transition of Mn2+(4T1→6A1). The thermoluminescence (TL) curves above room temperature are employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence. The results indicate that Zn2GeO4 may be an excellent host material for the rare earth ions or transition metal ions long afterglows. -- Highlights: • Zn2GeO4:Eu2+0.01 and Zn2GeO4:Mn2+0.01 long afterglow phosphors were synthesized. • Found that these phosphors possess a persistent luminescence property. • The long afterglow spectra were measured. • Found that these phosphors possess a trap level by thermoluminescence

  8. Dy3+:Ca2SnO4, a new yellow phosphor with afterglow behavior

    International Nuclear Information System (INIS)

    Highlights: • The photoluminescence and afterglow behavior of Dy3+:Ca2SnO4 was investigated. • PL spectra revealed the 4F9/2 → 6HJ (J = 15/2, 13/2, 11/2) energy transition of Dy3+ ions in Ca2SnO4. • CIE chromaticity coordinates results confirmed a yellow light emitting of the Dy3+:Ca2SnO4. • After the UV source was turned off, the Dy3+:Ca2SnO4 showed typical afterglow behavior. • The afterglow behavior of Dy3+:Ca2SnO4 was attributed to suitable electron and hole traps. - Abstract: This paper reports the photoluminescence and afterglow behavior of Dy3+ in Ca2SnO4 matrix (Dy3+:Ca2SnO4) prepared via a solid-state reaction. X-ray diffraction (XRD), photo luminescence spectroscope (PLS) and thermal luminescence spectroscope (TLS) were performed to investigate the physical properties of the phosphors. Typical 4F9/2 to 6Hj energy transition of Dy3+ ions was detected by PL spectra. CIE chromaticity coordinates of x = 0.4319, y = 4.456, calculated from the emission spectra, confirmed a yellow light emitting of the Dy3+:Ca2SnO4 phosphors. The Ca2SnO4 phosphors showed a typical afterglow behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Dy3+:Ca2SnO4 phosphors was generated by the suitable electron or hole traps which was resulted from the doping the Ca2SnO4 host with rare-earth ions (Dy3+)

  9. Degravitation, inflation and the cosmological constant as an afterglow

    International Nuclear Information System (INIS)

    In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation — where Netwon's constant is promoted to a scale dependent filter function — as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant 'afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale (L) in Planck units Λ ∼ l2pl/L2. We discuss circumstances through which this scenario reasonably yields the presently observed value for Λ ∼ O(10−120). We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale. We argue that different functional forms for the filter function will yield similar conclusions. In this way, we argue that although the degravitation models we study have the potential to explain why the cosmological constant is not large in

  10. The γ-ray afterglows of tidal disruption events

    Science.gov (United States)

    Chen, Xian; Gómez-Vargas, Germán Arturo; Guillochon, James

    2016-05-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such `tidal disruption event' (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can stream to a great distance, but so far there is no clear evidence that this `unbound debris stream' (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and an MC, which is likely to happen hundreds of years after a TDE. We focus on γ-ray emission (0.1-105 GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside an MC, the peak γ-ray luminosity, about 1039 erg s-1, is at least 100 times greater than that in the case without an MC (only with a smooth interstellar medium). The luminosity decays on a time-scale of decades, depending on the distance of the MC, and about a dozen of these `TDE afterglows' could be detected within a distance of about 16 Mpc by the future Cherenkov Telescope Array. Without careful discrimination, these sources potentially could contaminate the searches for starburst galaxies, galactic nuclei containing millisecond pulsars or dark matter annihilation signals.

  11. GRB Orphan Afterglows in Present and Future Radio Transient Surveys

    Science.gov (United States)

    Ghirlanda, G.; Burlon, D.; Ghisellini, G.; Salvaterra, R.; Bernardini, M. G.; Campana, S.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Melandri, A.; Murphy, T.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2014-05-01

    Orphan Afterglows (OA) are slow transients produced by Gamma Ray Bursts seen off-axis that become visible on timescales of days/years at optical/NIR and radio frequencies, when the prompt emission at high energies (X and γ rays) has already ceased. Given the typically estimated jet opening angle of GRBs θjet ~ 3°, for each burst pointing to the Earth there should be a factor ~ 700 more GRBs pointing in other directions. Despite this, no secure OAs have been detected so far. Through a population synthesis code we study the emission properties of the population of OA at radio frequencies. OAs reach their emission peak on year-timescales and they last for a comparable amount of time. The typical peak fluxes (which depend on the observing frequency) are of few μJy in the radio band with only a few OA reaching the mJy level. These values are consistent with the upper limits on the radio flux of SN Ib/c observed at late times. We find that the OA radio number count distribution has a typical slope - 1.7 at high fluxes and a flatter ( - 0.4) slope at low fluxes with a break at a frequency-dependent flux. Our predictions of the OA rates are consistent with the (upper) limits of recent radio surveys and archive searches for radio transients. Future radio surveys like VAST/ASKAP at 1.4 GHz should detect ~ 3 × 10- 3 OA deg- 2 yr- 1, MeerKAT and EVLA at 8.4 GHz should see ~ 3 × 10- 1 OA deg- 2 yr- 1. The SKA, reaching the μJy flux limit, could see up to ~ 0.2 - 1.5 OA deg- 2 yr- 1. These rates also depend on the duration of the OA above a certain flux limit and we discuss this effect with respect to the survey cadence.

  12. Early GRB Afterglows from Relativistic Blast Waves in General Radiative Regimes

    CERN Document Server

    Böttcher, M

    1999-01-01

    We present simple analytical expressions for the predicted spectral and temporal behavior of the early afterglow radiation from gamma-ray bursts in radiative regimes intermediate between the adiabatic and the fully radiative solutions of the blastwave hydrodynamic equations. Our expressions are valid as long as the relativistic electrons responsible for the observed synchrotron emission are in the fast cooling regime and the blast wave is relativistic. We show that even a slight deviation from a perfectly adiabatic evolution results in significant changes of the temporal characteristics of the afterglow emission.

  13. 10 Years of XRT light curves: a general view of the X-ray afterglow

    CERN Document Server

    Bardho, O; Gendre, B

    2015-01-01

    During the pre-Swift era, a clustering of light curves was observed in the X-ray, optical and infrared afterglow of gamma-ray bursts. We used a sample of 254 GRB X-ray afterglows to check this fact in the Swift era. We corrected fluxes for distance, time dilation and losses of energy due to cosmological effects. With all our data in hand, we faced with a problem: our data were scattered. We investigated 3 possibilities to explain this, namely: the clustering does not exist, there are problems during calibration of data, and there are instrumental problems. We finally confirm that our sample is consistent with Dainotti correlation.

  14. Afterglow emission from pair-loaded blast waves in gamma-ray bursts

    OpenAIRE

    Beloborodov, Andrei M.

    2005-01-01

    The MeV radiation front of gamma-ray bursts creates copious e+- pairs as it propagates through an ambient medium. The created pairs enrich the leptonic component of the medium by a large factor at distances R < R_load ~ 10^{16} cm from the burst center. The following blast wave sweeps up the pair-rich medium and then emits the observed afterglow radiation. We find that the afterglow has a "memory" of e+- loading outside R_load. The e+- pairs remain in the swept-up material and slowly cool dow...

  15. From Engine to Afterglow: Collapsars Naturally Produce Top-Heavy Jets and Early-Time Plateaus in Gamma Ray Burst Afterglows

    CERN Document Server

    Duffell, Paul C

    2014-01-01

    We demonstrate that the steep decay and long plateau in the early phases of gamma ray burst (GRB) afterglows are naturally produced in the collapsar model, by a means ultimately related to the dynamics of relativistic jet propagation through a massive star. We present hydrodynamical simulations which start from a collapsar engine and evolve all the way through the late afterglow phase. The resultant outflow includes a jet core which is highly relativistic after breaking out of the star, but becomes baryon-loaded and less relativistic after colliding with a massive outer shell, corresponding to mass from the stellar atmosphere of the progenitor star which became trapped in front of the jet core at breakout. The prompt emission produced before or during this collision would then have the signature of a high Lorentz factor jet, but the afterglow is produced by the amalgamated post-collision ejecta which has more inertia than the original highly relativistic jet core and thus has a delayed deceleration. This natu...

  16. Detailed optical and near-infrared polarimetry, spectroscopy and broadband photometry of the afterglow of GRB 091018: Polarisation evolution

    CERN Document Server

    Wiersema, K; Kruehler, T; Melandri, A; Rol, E; Starling, R L C; Tanvir, N R; van der Horst, A J; Covino, S; Fynbo, J P U; Goldoni, P; Gorosabel, J; Hjorth, J; Klose, S; Mundell, C G; O'Brien, P T; Palazzi, E; Wijers, R A M J; D'Elia, V; Evans, P A; Filgas, R; Gomboc, A; Greiner, J; Guidorzi, C; Kaper, L; Kobayashi, S; Kouveliotou, C; Levan, A J; Rossi, A; Rowlinson, A; Steele, I A; Postigo, A de Ugarte; Vergani, S D

    2012-01-01

    [Abridged] A number of phenomena have been observed in GRB afterglows that defy explanation by simple versions of the standard fireball model, leading to a variety of new models. Polarimetry can be a major independent diagnostic of afterglow physics, probing the magnetic field properties and internal structure of the GRB jets. In this paper we present the first high quality multi-night polarimetric light curve of a Swift GRB afterglow, aimed at providing a well calibrated dataset of a typical afterglow to serve as a benchmark system for modelling afterglow polarisation behaviour. In particular, our dataset of the afterglow of GRB 091018 (at redshift z=0.971) comprises optical linear polarimetry (R band, 0.13 - 2.3 days after burst); circular polarimetry (R band) and near-infrared linear polarimetry (Ks band). We add to that high quality optical and near-infrared broadband light curves and spectral energy distributions as well as afterglow spectroscopy. The linear polarisation varies between 0 and 3%, with bot...

  17. Erratum: The Late Afterglow and Host Galaxy of GRB 990712

    Science.gov (United States)

    Hjorth, J.; Holland, S.; Courbin, F.; Dar, A.; Olsen, L. F.; Scodeggio, M.

    2000-08-01

    In the Letter ``The Late Afterglow and Host Galaxy of GRB 990712'' by J. Hjorth, S. Holland, F. Courbin, A. Dar, L. F. Olsen, & M. Scodeggio (ApJ, 534, L147 [2000]), there was an error in the flux calibration of the spectrum. The y-axis scale of Figure 2 and the fluxes in the last column of Table 1 should be multiplied by a factor of 3.47 to read 2.25, 0.86, 1.61, and 3.79×10-16 ergs s-1 cm-2. The error affects the luminosities and star formation rates (SFRs) presented in the third and fourth paragraphs of § 5 as follows. In the third paragraph, the total SFR based on the continuum flux should be 0.91-1.41 Msolar yr-1 instead of 0.29-0.45 the [O II] luminosity should be L3727=1.5×1041 ergs s-1 instead of 6.3×1040 and the implied [O II] SFR should be 2.12+/-0.60 Msolar yr-1 instead of 0.88+/-0.25. Consequently, the last two sentences of this paragraph are revised to read ``The derived SFR (from the [O II] flux) is about half of the SFR found by Bloom et al. (1999b) for the host of GRB 990123 and 2-3 times that of the host of GRB 970508 (Bloom et al. 1998). The specific SFR per unit luminosity of the GRB 990712 host galaxy is comparable to that of the host galaxies of GRB 990123 and GRB 970508.'' In the fourth paragraph, the total V-band flux in the feature should be 0.405+/-0.004 μJy instead of 0.323+/-0.003 the power-law spectral index should be β=-2.57 instead of -2.93 and the SFR in the feature should be 0.11-0.17 Msolar instead of 0.03-0.05. The main results and conclusions of the original Letter are unaffected by the error. The authors thank P. M. Vreeswijk for bringing this error to their attention.

  18. The properties of the 2175AA extinction feature discovered in GRB afterglows

    CERN Document Server

    Zafar, Tayyaba; Eliasdottir, Ardis; Fynbo, Johan P U; Kruhler, Thomas; Schady, Patricia; Leloudas, Giorgos; Jakobsson, Pall; Thone, Christina C; Perley, Daniel A; Morgan, Adam N; Bloom, Joshua; Greiner, Jochen

    2012-01-01

    The unequivocal, spectroscopic detection of the 2175 bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two GRB afterglows (GRB 070802 and GRB 080607). In this work we analyse in detail the detections of the 2175 extinction bump in the optical spectra of the two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/NIR photometric, spectroscopic and X-ray data to construct multi-epoch SEDs for both GRB afterglows. We fit the SEDs with the Fitzpatrick & Massa (1990) model with a single or broken PL. We also fit a sample of 38 GRB afterglows, known to prefer a SMC-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single PL with a derived extinction of A_V = 0.52(+0.13 -0.16) and 0.50 (+0.13 -0.10), and 2.1(+0.7-0.6) and 1.5+/-0.2 respectively. While the slope of the extinction curve of GRB 080805 is not well-constrained, the extinction...

  19. The Afterglow of GRB 130427A from 1 to 10^16 GHz

    CERN Document Server

    Perley, D A; Corsi, A; Tanvir, N R; Levan, A J; Kann, D A; Sonbas, E; Wiersema, K; Zheng, W; Zhao, X -H; Bai, J -M; Chang, L; Clubb, K; Frail, D; Fruchter, A; Göğüş, E; Greiner, J; Güver, T; Horesh, A; Filippenko, A V; Klose, S; Mao, J; Morgan, A N; Schmidl, S; Stecklum, B; Tanga, M; Wang, J -G; Xin, Y -X

    2014-01-01

    We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst of the past 29 years. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z=0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300 s to 60 d after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies with no significant late-time flaring or rebrightening activity. The entire dataset from 1 GHz to 0.1 TeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observe...

  20. The mysterious optical afterglow spectrum of GRB140506A at z=0.889

    CERN Document Server

    Fynbo, J P U; Leighly, K; Ledoux, C; Vreeswijk, P M; Schulze, S; Noterdaeme, P; Watson, D; Wijers, R A M J; Bolmer, J; Cano, Z; Christensen, L; Covino, S; D'Elia, V; Flores, H; Friis, M; Goldoni, P; Greiner, J; Hammer, F; Hjorth, J; Jakobsson, P; Japelj, J; Kaper, L; Klose, S; Knust, F; Leloudas, G; Levan, A; Malesani, D; Milvang-Jensen, B; Møller, P; Guelbenzu, A Nicuesa; Oates, S; Pian, E; Schady, P; Sparre, M; Tagliaferri, G; Tanvir, N; Thöne, C C; Postigo, A de Ugarte; Vergani, S; Wiersema, K; Xu, D; Zafar, T

    2014-01-01

    Context. Gamma-ray burst (GRBs) afterglows probe sightlines to star-forming regions in distant star-forming galaxies. Here we present a study of the peculiar afterglow spectrum of the z = 0.889 Swift GRB 140506A. Aims. Our aim is to understand the origin of the very unusual properties of the absorption along the line-of-sight. Methods. We analyse spectroscopic observations obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs 8.8 h and 33 h after the burst as well as imaging from the GROND instrument. We also present imaging and spectroscopy of the host galaxy obtained with the Magellan telescope. Results. The underlying afterglow appears to be a typical afterglow of a long-duration GRB. However, the material along the line-of- sight has imprinted very unusual features on the spectrum. Firstly, there is a very broad and strong flux drop below 8000 AA (4000 AA in the rest frame), which seems to be variable between the two spectroscopic epochs. We can reproduce the flux-drops both as a g...

  1. Winds from massive stars: implications for the afterglows of γ-ray bursts

    Science.gov (United States)

    Ramirez-Ruiz, Enrico; Dray, Lynnette M.; Madau, Piero; Tout, Christopher A.

    2001-11-01

    Recent observations suggest that long-duration γ-ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in core-collapse explosions. The pre-explosive ambient medium provides a natural test for the most likely progenitors of GRBs. Those stars that shed their envelopes most readily have short jet crossing times and are more likely to produce a GRB. We construct a simple computational scheme to explore the expected contribution of the presupernova ejecta of single Wolf-Rayet (WR) stars to the circumstellar environment. Using detailed stellar tracks for the evolution of massive stars, we discuss the effects that the initial main-sequence mass, metallicity, rotation and membership in a binary system have on the ambient medium. We extend the theory of GRB afterglows in winds to consider the effect of the relativistic fireball propagating through the WR ejecta. Specific predictions are made for the interaction of the relativistic blast wave with the density bumps that arise when the progenitor star rapidly loses a large fraction of its initial mass or when the ejected wind interacts with the external medium and decelerates. A re-brightening of the afterglow with a spectrum redder than the typical synchrotron spectrum (as seen in GRB 970508, GRB 980326 and GRB 000911) is predicted. We also calculate the luminosity of the reflected echo that arises when circumstellar material Compton-scatters the prompt radiation, and examine the spectral signatures expected from the interaction of the GRB afterglow with the ejected medium.

  2. Dust extinction in high-z galaxies with gamma-ray burst afterglow spectroscopy

    DEFF Research Database (Denmark)

    Elíasdóttir, Á.; Fynbo, J. P. U.; Hjorth, J.;

    2009-01-01

    We report the clear detection of the 2175 Å dust absorption feature in the optical afterglow spectrum of the gamma-ray burst (GRB) GRB 070802 at a redshift of z = 2.45. This is the highest redshift for a detected 2175 Å dust bump to date, and it is the first clear detection of the 2175 Å bump in ...

  3. VLT/X-shooter spectroscopy of the GRB 090926A afterglow

    NARCIS (Netherlands)

    V. D'Elia; J.P.U. Fynbo; S. Covino; P. Goldoni; P. Jakobsson; F. Matteucci; S. Piranomonte; J. Sollerman; C.C. Thöne; S.D. Vergani; P.M. Vreeswijk; D.J. Watson; K. Wiersema; T. Zafar; A. de Ugarte Postigo; H. Flores; J. Hjorth; L. Kaper; A.J. Levan; D. Malesani; B. Milvang-Jensen; E. Pian; G. Tagliaferri; N.R. Tanvir

    2010-01-01

    Aims. The aim of this paper is to study the environment and intervening absorbers of the gamma-ray burst GRB090926A through analyzing optical spectra of its afterglow. Methods. We analyzed medium-resolution spectroscopic observations (R = 10 000, corresponding to 30 km s(-1), S/N = 15-30 and wavelen

  4. Radio Afterglow Rebrightening: Evidence for Multiple Active Phases in Gamma-Ray Burst Central Engines

    CERN Document Server

    Li, L B; Rice, J

    2015-01-01

    The rebrightening phenomenon is an interesting feature in some X-ray, optical, and radio afterglows of gamma-ray bursts (GRBs). Here, we propose a possible energy-supply assumption to explain the rebrightenings of radio afterglows, in which the central engine with multiple active phases can supply at least two GRB pulses in a typical GRB duration time. Considering the case of double pulses supplied by the central engine, the double pulses have separate physical parameters, except for the number density of the surrounding interstellar medium (ISM). Their independent radio afterglows are integrated by the ground detectors to form the rebrightening phenomenon. In this work, we firstly simulate diverse rebrightening light curves under consideration of different and independent physical parameters. Using this assumption, we also give our best fit to the radio afterglow of GRB 970508 at three frequencies of 1.43, 4.86, and 8.46 GHz. We suggest that the central engine may be active continuously at a timescale longer...

  5. GRB 110530A: Peculiar Broad Bump and Delayed Plateau in Early Optical Afterglows

    CERN Document Server

    Zhong, Shu-Qing; Liang, En-Wei; Wei, Jian-Yan; Urata, Yuji; Huang, Kui-Yun; Qiu, Yu-Lei; Deng, Can-Min; Wang, Yuan-Zhu; Deng, Jin-Song

    2016-01-01

    We report our very early optical observations of GRB 110530A and investigate its jet properties together with its X-ray afterglow data. A peculiar broad onset bump followed by a plateau is observed in its early R band afterglow lightcurve. The optical data in the other bands and the X-ray data are well consistent with the temporal feature of the R band lightcurve. Our joint spectral fits of the optical and X-ray data show that they are in the same regime, with a photon index of $\\sim 1.70$. The optical and X-ray afterglow lightcurves are well fitted with the standard external shock model by considering a delayed energy injection component. Based on our modeling results, we find that the radiative efficiency of the GRB jet is $\\sim 1\\%$ and the magnetization parameter of the afterglow jet is $<0.04$ with the derived extremely low $\\epsilon_B$ (the fraction of shock energy to magnetic field) of $(1.64\\pm 0.25)\\times 10^{-6}$. These results indicate that the jet may be matter dominated. Discussion on delayed ...

  6. Detailed afterglow modelling and host galaxy properties of the dark GRB 111215A

    DEFF Research Database (Denmark)

    Horst, A. J. van der; Levan, A. J.; Pooley, G. G.;

    2015-01-01

    Gamma-ray burst (GRB) 111215A was bright at X-ray and radio frequencies, but not detected in the optical or near-infrared (nIR) down to deep limits. We have observed the GRB afterglow with the Westerbork Synthesis Radio Telescope and Arcminute Microkelvin Imager at radio frequencies, with the Wil...

  7. The Afterglows, Redshifts, and Properties of Swift Gamma-Ray Bursts

    CERN Document Server

    Berger, E; Fox, D B; Soderberg, A M; Harrison, F A; Nakar, E; Kelson, D D; Gladders, M D; Mulchaey, J S; Oemler, A; Dressler, A; Cenko, S B; Price, P A; Schmidt, B P; Frail, D A; Morrell, N; González, S; Krzeminski, W; Sari, R; Gal-Yam, A; Moon, D S; Penprase, B E; Jayawardhana, R; Scholz, A; Rich, J; Peterson, B A; Anderson, G; McNaught, R; Minezaki, T; Yoshii, Y; Cowie, L L; Pimbblet, K A

    2005-01-01

    We present optical, near-IR, and radio follow up of sixteen Swift bursts, including our discovery of nine afterglows and a redshift determination for three. These observations, supplemented by data from the literature, provide an afterglow recovery rate of 60% in the optical/near-IR, much higher than in previous missions (BeppoSAX, HETE-2, INTEGRAL, and IPN). The optical/near-IR afterglows of Swift events are on average 1.7 mag fainter at t=12 hr than those of previous missions. The X-ray afterglows are similarly fainter compared to those of pre-Swift bursts. In the radio the limiting factor is the VLA threshold and the detection rate for Swift bursts is similar to that for past missions. The redshift distribution of pre-Swift bursts peaked at z~1, whereas the five Swift bursts with measured redshifts are distributed evenly between 1.3 and 3.2. From these results we conclude that (i) the pre-Swift distributions were biased in favor of bright events and low redshift events, (ii) the higher sensitivity and accu...

  8. Polarization Evolution of Early Optical Afterglows of Gamma-Ray Bursts

    Science.gov (United States)

    Lan, Mi-Xiang; Wu, Xue-Feng; Dai, Zi-Gao

    2016-01-01

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on the polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high (σ ≤ 1), so that the jet is mainly composed of baryons and leptons. We then calculate the light curves and polarization evolution of early optical afterglows and find that when the polarization position angle changes by 90° during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be nonzero for an aligned magnetic field. This result would be expected to provide a probe for the central engine of GRBs because an aligned field configuration could originate from a magnetar central engine and a toroidal field configuration could be produced from a black hole via the Blandford-Znajek mechanism. Finally, for such two kinds of magnetic field configurations, we fit the observed data of the early optical afterglow of GRB 120308A equally well.

  9. The complex light curve of the afterglow of GRB 071010A

    International Nuclear Information System (INIS)

    We present and discuss the results of an extensive observational campaign devoted to GRB 071010A, a long-duration gamma-ray burst detected by the Swift satellite. This event was followed for almost a month in the optical/near-infrared (NIR) with various telescopes starting from about 2 min after the high-energy event. Swift XRT observations started only later at about 0.4 d. The light-curve evolution allows us to single out an initial rising phase with a maximum at about 7 min, possibly the afterglow onset in the context of the standard fireball model, which is then followed by a smooth decay interrupted by a sharp re-brightening at about 0.6 d. The re-brightening was visible in both the optical/NIR and X-rays and can be interpreted as an episode of discrete energy injection, although various alternatives are possible. A steepening of the afterglow light curve is recorded at about 1 d. The entire evolution of the optical/NIR afterglow is consistent with being achromatic. This could be one of the few identified GRB afterglows with an achromatic break in the X-ray through the optical/NIR bands. Polarimetry was also obtained at about 1 d, just after the re-brightening and almost coincident with the steepening. This provided a fairly tight upper limit of 0.9 per cent for the polarized-flux fraction. (authors)

  10. The complex light curve of the afterglow of GRB 071010A

    Energy Technology Data Exchange (ETDEWEB)

    Covino, S.; D' Avanzo, P.; Campana, S.; Chincarini, G.; Guidorzi, C.; Tagliaferri, G.; Fugazza, D.; Molinari, E.; Moretti, A.; Romano, P.; Zerbi, F. [INAF Osservatorio Astron Brera, I-23807 Merate, LC, (Italy); D' Avanzo, P. [Univ Insubria, Dipartimento Matemat and Fis, I-22100 Como, (Italy); Klotz, A.; Boeer, M. [Observ Haute Provence, F-04870 St Michel L' observatoire, (France); Klotz, A. [Univ Toulouse, CESR, F-31400 Toulouse, (France); Perley, D.A.; Bloom, J.S.; Filippenko, A.V.; Foley, R.J.; Kocevksi, D.; Modjaz, M.; Poznanski, D.; Silverman, J.M. [Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 (United States); Amati, L.; Maiorano, E.; Masetti, N.; Palazzi, E. [Ist Astrofis Spaziale and Fis Cosm Bologna, INAF, I-40129 Bologna, (Italy); Chincarini, G.; Guidorzi, C. [Univ Milan, I-20126 Milan, (Italy); Cucchiara, A. [Penn State Univ, Dept Astron and Astrophys, University Pk, PA 16802 (United States); D' Elia, V.; Guetta, D.; Antonelli, L. A.; D' Alessio, F.; Piranomonte, S.; Stella, L.; Testa, V.; Vitali, F. [INAF Osservatorio Astron Roma, I-00040 Monte Porzio Catone, Roma, (Italy); Kann, D.A. [Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, (Germany); Yoldas, A. Kuepcue; Greiner, J.; Primak, N. [Max Planck Inst Extraterr Phys, D-85748 Garching, (Germany); Misra, K.; Pandey, S.B.; Roy, R. [Aryabhatta Res Inst Observat Sci ARIES, Naini Tal 263129, (India); Misra, K. [Inter Univ Ctr Astron and Astrophys, Pune 411007, Maharashtra, (India); Olofsson, G. [Stockholm Observ, S-10691 Stockholm, (Sweden); Berger, E. [Observ Carnegie Inst Washington, Pasadena, CA 91101 (United States); Della Valle, M. [INAF Osservatorio Astron Capodimonte, I-80131 Naples, (Italy); Della Valle, M. [Int Ctr Relativist Astrophys Network, Icranet, Pescara, (Italy); Della Valle, M. [European So Observ, D-8046 Garching, (Germany); Alighieri, S. di Serego [INAF Osservatorio Astrofis Arcetri, I-50125 Florence, (Italy)] [and others

    2008-07-01

    We present and discuss the results of an extensive observational campaign devoted to GRB 071010A, a long-duration gamma-ray burst detected by the Swift satellite. This event was followed for almost a month in the optical/near-infrared (NIR) with various telescopes starting from about 2 min after the high-energy event. Swift XRT observations started only later at about 0.4 d. The light-curve evolution allows us to single out an initial rising phase with a maximum at about 7 min, possibly the afterglow onset in the context of the standard fireball model, which is then followed by a smooth decay interrupted by a sharp re-brightening at about 0.6 d. The re-brightening was visible in both the optical/NIR and X-rays and can be interpreted as an episode of discrete energy injection, although various alternatives are possible. A steepening of the afterglow light curve is recorded at about 1 d. The entire evolution of the optical/NIR afterglow is consistent with being achromatic. This could be one of the few identified GRB afterglows with an achromatic break in the X-ray through the optical/NIR bands. Polarimetry was also obtained at about 1 d, just after the re-brightening and almost coincident with the steepening. This provided a fairly tight upper limit of 0.9 per cent for the polarized-flux fraction. (authors)

  11. Observations of GRB X-ray afterglows with SODART/SRG

    DEFF Research Database (Denmark)

    Brandt, Søren Kristian; Lund, Niels; Pedersen, Henrik;

    1998-01-01

    for detecting GRBs, and the powerful pointed SODART telescopes will be a unique tool for studying the long-term behavior of GRB afterglows. It is shown that SODART will be able to follow the temporal and spectral development of a GRB similar to the now famous GRB 970228 event for well over 20 days in order...

  12. Early afterglows from radially structured outflows and the application to X-ray shallow decays

    Institute of Scientific and Technical Information of China (English)

    Xue-Wen Liu; Xue-Feng WU; Yuan-Chuan Zou; Tan Lu

    2009-01-01

    In the fireball model, it is more physically realistic that gamma-ray burst (GRB) ejecta have a range of bulk Lorentz factors (assuming M ∝ Г-s), The low Lorentz factor part of the ejecta will catch up with the high Lorentz factor part when the latter is de-celerated by the surrounding medium to a comparable Lorentz factor. Such a process will develop a long-lasting weak reverse shock until the whole ejecta are shocked. Meanwhile, the forward shocked materials are gradually supplied with energy from the ejecta that are catching-up, and thus the temporal decay of the forward shock emission will be slower than that without an energy supply. However, the reverse shock may be strong. Here, we extend the standard reverse-forward shock model to the case of radially nonuniform ejecta. We show that this process can be classified into two cases: the thick shell case and the thin shell case. In the thin shell case, the reverse shock is weak and the temporal scaling law of the afterglow is the same as that in Sari & Mészáros (2000). However, in the thick shell case, the reverse shock is strong and thus its emission dominates the af-terglow in the high energy band. Our results also show slower decaying behavior of the afterglow due to the energy supply by low Lorentz factor materials, which may help the understanding of the plateau observed in the early optical and X-ray afterglows.

  13. Phenomenology of reverse-shock emission in the optical afterglows of gamma-ray bursts

    International Nuclear Information System (INIS)

    We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock (RS) emission and to determine which physical conditions lead to a prominent reverse-shock emission. We identify 10 GRBs with reverse-shock signatures: 990123, 021004, 021211, 060908, 061126, 080319B, 081007, 090102, 090424, and 130427A. By modeling their optical afterglows with reverse- and forward-shock analytic light curves and using Monte Carlo simulations, we estimate the parameter space of the physical quantities describing the ejecta and circumburst medium. We find that physical properties cover a wide parameter space and do not seem to cluster around any preferential values. Comparing the rest-frame optical, X-ray, and high-energy properties of the larger sample of non-RS-dominated GRBs, we show that the early-time (<1 ks) optical spectral luminosity, X-ray afterglow luminosity, and γ-ray energy output of our reverse-shock dominated sample do not differ significantly from the general population at early times. However, the GRBs with dominant reverse-shock emission have fainter than average optical forward-shock emission at late times (>10 ks). We find that GRBs with an identifiable reverse-shock component show a high magnetization parameter R B = εB,r/εB,f ∼ 2-104. Our results are in agreement with the mildly magnetized baryonic jet model of GRBs.

  14. Curvature Effect and the Spectral Softening Phenomenon Detected in GRB Afterglows

    Indian Academy of Sciences (India)

    Y.-P. Qin

    2011-03-01

    Detection of radiation from a relativistic fireball would be affected by the so-called curvature effect. I illustrate the expected temporal and spectral behaviours of this effect and show that it can well explain the observed spectral softening in the early GRB afterglows.

  15. The afterglow and complex environment of the optically dim burst GRB 980613

    DEFF Research Database (Denmark)

    Hjorth, J.; Thomsen, Bente; Nielsen, S.R.; Andersen, M.I.; Holland, S.T.; Fynbo, J.U.; Pedersen, H.; Jaunsen, A.O.; Halpern, J.P.; Fesen, R.; Gorosabel, J.; Castro-Tirado, A.; McMahon, R.G.; Hoenig, M.D.; Bjornsson, G.; Amati, L.; Tanvir, N.R.; Natarajan, P.

    2002-01-01

    of the optical afterglow was mainly due to the fairly at spectral shape rather than internal reddening in the host galaxy. We also present late-time Hubble Space Telescope/Space Telescope Imaging Spectrograph images of the field in which GRB 980613 occurred, obtained 799 days after the burst. These...

  16. Nanostructure deposition in the afterglow of a low power barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Sonnenfeld, Axel; Papageorgiou, Vasileios; Reichen, Patrick; Koerner, Lutz; Von Rohr, Philipp Rudolf, E-mail: sonnenfeld@ipe.mavt.ethz.ch, E-mail: vonrohr@ipe.mavt.ethz.ch [ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, 8092 Zurich (Switzerland)

    2011-02-23

    The precipitation of solid-state sphere-like nanostructures from an organosilicon precursor at atmospheric pressure is investigated with the prospect of improving powder flowability by the attachment of nanoscopic spacers to the powder particles' surfaces. Tetramethylsilane (TMS) is admixed to the afterglow of a low power (<0.5 W) barrier discharge (BD). The BD occurs in a single miniature flow channel, where Ar or He enriched with O{sub 2} is excited favouring homogeneous gas phase reactions of atomic oxygen and TMS in the afterglow. The chemical and morphological influence of Ar or He on the formation of nanostructures is explored at two positions in the afterglow by Fourier transform infrared spectroscopy and scanning electron microscopy. For the Ar-based BD, larger spherical nanostructures (100-1000 nm) of higher oxide content are obtained, while for He polymeric deposits with characteristic sizes below 100 nm are found. In addition, the processing capability of a BD device, consisting of a set of 64 miniature flow channels, is probed by means of the wettability improvement of polymer powder particles, conveyed through the BD afterglow zone of a multi-channel device. The treatment is shown to decrease the benzyl alcohol contact angle significantly with increasing oxygen feed.

  17. The Late-time Afterglow of the Extremely Energetic Short Burst GRB 090510 Revisited

    Science.gov (United States)

    Guelbenzu, A. Nicuesa; Klose, S.; Kruehler, T.; Greiner, J.; Rossi, A.; Kann, D. A.; Olivares, F.; Rau, A.; Afonso, P. M. J.; Elliott, J.; Filgas, R.; Yoldas, A. Kuepcue; McBreen, S.; Nardini, M.; Schady, P.; Schmidl, S.; Sudilovsky, V.; Updike, A. C.; Yoldas, A.

    2012-01-01

    Context. The Swift discovery of the short burst GRB 090510 has raised considerable attention mainly because of two reasons: first, it had a bright optical afterglow, and second it is among the most energetic events detected so far within the entire GRB population (long plus short). The afterglow of GRB 090510 was observed with Swift/UVOT and Swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. Aims. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to a (theoretically hard to understand) excess of optical flux at late times. We assess here the validity of this peculiar behavior. Methods. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. These additional g'r'i'z' data were then combined with the UVOT and XRT data to study the behavior of the afterglow at late times more stringently. Results. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. Conclusions. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times. The break seen in the optical light curve around 22 ks in combination with its missing counterpart in the X-ray band could be due to the passage of the

  18. Implications of the Early X-Ray Afterglow Light Curves of Swift GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Granot, Jonathan; /KIPAC, Menlo Park; Konigl, Arieh; /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Piran, Tsvi; /Hebrew U.

    2006-01-17

    According to current models, gamma-ray bursts (GRBs) are produced when the energy carried by a relativistic outflow is dissipated and converted into radiation. The efficiency of this process, {epsilon}{sub {gamma}}, is one of the critical factors in any GRB model. The X-ray afterglow light curves of Swift GRBs show an early stage of flattish decay. This has been interpreted as reflecting energy injection. When combined with previous estimates, which have concluded that the kinetic energy of the late ({approx}> 10 hr) afterglow is comparable to the energy emitted in {gamma}-rays, this interpretation implies very high values of {epsilon}{sub {gamma}}, corresponding to {approx}> 90% of the initial energy being converted into {gamma}-rays. Such a high efficiency is hard to reconcile with most models, including in particular the popular internal-shocks model. We re-analyze the derivation of the kinetic energy from the afterglow X-ray flux and re-examine the resulting estimates of the efficiency. We confirm that, if the flattish decay arises from energy injection and the pre-Swift broad-band estimates of the kinetic energy are correct, then {epsilon}{sub {gamma}} {approx}> 0.9. We discuss various issues related to this result, including an alternative interpretation of the light curve in terms of a two-component outflow model, which we apply to the X-ray observations of GRB 050315. We point out, however, that another interpretation of the flattish decay--a variable X-ray afterglow efficiency (e.g., due to a time dependence of afterglow shock microphysical parameters)--is possible. We also show that direct estimates of the kinetic energy from the late X-ray afterglow flux are sensitive to the assumed values of the shock microphysical parameters and suggest that broad-band afterglow fits might have underestimated the kinetic energy (e.g., by overestimating the fraction of electrons that are accelerated to relativistic energies). Either one of these possibilities implies a

  19. Parametric study of afterglows issued from Dielectric Barrier Discharges in nitrogen and air and applied on Aureobasidium fungi

    Energy Technology Data Exchange (ETDEWEB)

    Lecoq, E; Clement, F; Panousis, E [LEGP - IPREM - Universite de Pau, 64000 Pau (France); Leclaire, C; Orial, G [LRMH - 29 rue de Paris, 77420 Champs-sur-Marne (France); Ricard, A [LAPLACE - Universite Paul Sabatier, 31000 Toulouse (France)

    2010-01-01

    This article is devoted to the study of afterglows issued from two Dielectric Barrier Discharge reactors driven by two distinct High Voltage generators. The obtained afterglows are applied on Aureobasidium pullulans fungi in view of a curative treatment. In a first part, the electrical characteristics of the discharges obtained with both systems are studied and in a second part are presented the results of the fungi treatment efficiency.

  20. Parametric study of afterglows issued from Dielectric Barrier Discharges in nitrogen and air and applied on Aureobasidium fungi

    International Nuclear Information System (INIS)

    This article is devoted to the study of afterglows issued from two Dielectric Barrier Discharge reactors driven by two distinct High Voltage generators. The obtained afterglows are applied on Aureobasidium pullulans fungi in view of a curative treatment. In a first part, the electrical characteristics of the discharges obtained with both systems are studied and in a second part are presented the results of the fungi treatment efficiency.

  1. The very red afterglow of GRB 000418: Further evidence for dust extinction in a gamma-ray burst host galaxy

    DEFF Research Database (Denmark)

    Klose, S.; Stecklum, B.; Masetti, N.; Pian, E.; Palazzi, E.; Henden, A.A.; Vrba, F.J.; Hartmann, D.H.; Fischer, O.; Gorosabel, J.; Sanchéz-Fernandéz, C.; Butler, D.; Ott, Th.; Hippler, S.; Kasper, M.; Weiss, R.; Castro-Tirado, A.J.; Greiner, J.; Bartolini, C.; Guarnieri, A.; Piccioni, A.; Benetti, S.; Ghinassi, F.; Magazzú, A.; Hurley, K.; Cline, T.; Trombka, J.; McClanahan, T.; Starr, R.; Goldsten, J.; Gold, R.; Mazets, E.; Golenetskii, S.; Noeske, K.; Papaderos, P.; Vreeswijk, P.M.; Tanvir, N.; Oscoz, A.; Muñoz, J.A.; Sastro Cerón, J.M.

    2000-01-01

    be R = 23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K approximate to 4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long......) bursts are associated with events in star-forming regions....

  2. Investigation on luminescence enhancement and decay characteristics of long afterglow nanophosphors for dark-vision display applications

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis and structural characterization has been performed on long afterglow SrAl2O4:Eu2+, Dy3+ nanophosphor having afterglow time of ∼12 h. • Studied the effect of various fuels used for synthesis of nanophosphors on the decay and luminescence characteristics. Interestingly, afterglow times varied significantly with different fuels used for the synthesis of the nanophosphor. • Excitation by different illuminants has profound influence on the luminescence intensity and afterglow times of the synthesized nanophosphor. • Such studies could be guidelines for appropriate usage of nanophosphor under different lighting environment. - Abstract: Long afterglow SrAl2O4:Eu2+,Dy3+ nanophosphors were synthesized via a facile but effectual auto-combustion technique followed by post-annealing treatment at elevated temperatures. The influence of various fuels during synthesis and thereafter improvement in the luminescence decay characteristics under various illuminant irradiations of long afterglow nanophosphors have been reported. Extensive studies on structural, morphological and luminescent properties of the as-synthesized afterglow nanophosphors have been presented. Powder X-ray diffraction studies confirm the presence of high-purity, single-phase monoclinic nanophosphors. HRTEM investigations confirm the formation of nanophosphors of particle size less than 50 nm. Photoluminescence emission is attributed to the characteristic d–f transition (4f65d1→4f7) of Eu2+ ions and was positioned at 512 nm. As-synthesized nanophosphors exhibit considerable confinement effects resulting into blue shift in emission maxima as compared to their bulk counterparts. The mechanism underlined for long afterglow has been discussed using trapping–detrapping model. The nanophosphor being multifunctional finds many interesting applications including dark-vision display, energy storage, fingerprint detection, in vivo and in vitro biological

  3. The behaviour of negative oxygen ions in the afterglow of a reactive HiPIMS discharge

    International Nuclear Information System (INIS)

    Using a single Langmuir probe, the temporal evolution of the oxygen negative ion, n−, and electron, ne, densities in the afterglow of a reactive HiPIMS discharge operating in argon–oxygen gas mixtures have been determined. The magnetron was equipped with a titanium target and operated in ‘poisoned’ mode at a frequency of 100 Hz with a pulse width of 100 µs for a range of oxygen partial pressures, pO2/ptotal=0.0-0.5. In the initial afterglow, the density of the principle negative ion in the discharge (O−) was of the order of 1016 m−3 for all conditions. The O− concentration was found to decay slowly with characteristic decay times between 585 µs and 1.2 ms over the oxygen partial pressure range. Electron densities were observed to fall more rapidly, resulting in long-lived highly electronegative afterglow plasmas where the ratio, α = n−/ne, was found to reach values up to 672 (±100) for the highest O2 partial pressure. By comparing results to a simple plasma-chemical model, we speculate that with increased pO2/ptotal ratio, more O− ions are formed in the afterglow via dissociative electron attachment to highly excited metastable oxygen molecules, with the latter being formed during the active phase of the discharge. After approximately 2.5 ms into the off-time, the afterglow degenerates into an ion–ion plasma and negative ions are free to impinge upon the chamber walls and grounded substrates with flux densities of the order of 1018 m−2 s−1, which is around 10% of the positive ion flux measured during the on-time. This illustrates the potential importance of the long afterglow in reactive HiPIMS, which can act as a steady source of low energy O− ions to a growing thin film at the substrate during periods of reduced positive ion bombardment. (paper)

  4. Characterization of the flowing afterglows of an N2 O2 reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NOβ UV intensity variation with the N and O atom densities

    Science.gov (United States)

    Boudam, M. K.; Saoudi, B.; Moisan, M.; Ricard, A.

    2007-03-01

    The flowing afterglow of an N2-O2 discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N_{2}^{+} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N2(B) state, indicating a reduced contribution from the early afterglow N2 metastable species. We have studied the influence of operating conditions (pressure, O2 content in the N2-O2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O2 and then decreases, while the O atom density increases regularly with the O2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using

  5. The properties of a novel green long afterglow phosphor Zn2GeO4:Mn2+, Pr3+

    Science.gov (United States)

    Wan, Minhua; Wang, Yinhai; Wang, Xiansheng; Zhao, Hui; Hu, Zhengfa

    2014-01-01

    Novel Zn2GeO4:Mn2+, Pr3+ long afterglow phosphor was successfully synthesized by the high temperature solid state reaction. Long afterglow properties of the sample has been investigated in detail by measuring the X-ray diffraction (XRD), excitation spectrum, emission spectrum, afterglow spectrum, decay curve and thermoluminescence curve. The X-ray diffraction phases indicate that the co-doped Mn2+, Pr3+ have little influence on the crystal structure of Zn2GeO4. According to the emission spectra, we found that the Zn2GeO4:Mn2+, Pr3+ exhibit a narrow band emission with the peak at 532 nm, which could be ascribed to Mn2+ transition between 4T1 and 6A1 electron configurations. The green long afterglow of Zn2GeO4:Mn2+, Pr3+ could be observed for three hours by naked eyes at room temperature under 254 nm UV excitation. The thermoluminescence (TL) curve is employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence. The results suggest that Zn2GeO4 may be an excellent host material for Mn2+-based long afterglow. Furthermore, the function of co-doped Pr3+ ions is confirmed as trap center, which can greatly postpone the afterglow emission properties of Mn2+.

  6. Evidence for the Connection between Prompt and X-ray Afterglow emission of Swift-Detected Gamma-Ray Bursts

    CERN Document Server

    Grupe, Dirk; Verres, Peter; Zhang, Binbin; Gehrels, Neil

    2013-01-01

    When a massive star explodes as a Gamma Ray Burst information about this explosion is retained in the properties of the prompt and afterglow emission. We report on tight relationships between the prompt and X-ray afterglow emission of Swift-detected Gamma Ray Bursts found from BAT and XRT data between 2004 December and 2013 March. These relations suggest that the prompt and afterglow emission are closely linked. In particular, we find very strong correlations between the BAT 15-150keV T90 and the break times before and after the plateau phase in the X-ray 0.3-10keV afterglow light curves. We also find a strong anti-correlation between the photon index of the GRB prompt emission and the X-ray spectral slope of the afterglow. Further, anti-correlations exist between the rest frame peak energy in the prompt emission, E_ peak, and the X-ray afterglow decay slope during the plateau phase and the break times after the plateau phase. The rest-frame break times before and after the plateau phase are also anti-correla...

  7. The potential for detecting gamma-ray burst afterglows from population III stars with the next generation of infrared telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Macpherson, D. [ICRAR, University of Western Australia, Crawley, WA 6009 (Australia); Coward, D. M. [School of Physics, University of Western Australia, Crawley, WA 6009 (Australia); Zadnik, M. G., E-mail: damien.macpherson@icrar.org [Department of Imaging and Applied Physics, Curtin University, Perth, WA 6845 (Australia)

    2013-12-10

    We investigate the detectability of a proposed population of gamma-ray bursts (GRBs) from the collapse of Population III (Pop III) stars. The James Webb Space Telescope (JWST) and Space Infrared Telescope for Cosmology and Astrophysics (SPICA) will be able to observe the late time infrared afterglows. We have developed a new method to calculate their detectability, which takes into account the fundamental initial mass function and formation rates of Pop III stars, from which we find the temporal variability of the afterglows and ultimately the length of time JWST and SPICA can detect them. In the range of plausible Pop III GRB parameters, the afterglows are always detectable by these instruments during the isotropic emission, for a minimum of 55 days and a maximum of 3.7 yr. The average number of detectable afterglows will be 2.96× 10{sup –5} per SPICA field of view (FOV) and 2.78× 10{sup –6} per JWST FOV. These are lower limits, using a pessimistic estimate of Pop III star formation. An optimal observing strategy with SPICA could identify a candidate orphan afterglow in ∼1.3 yr, with a 90% probability of confirmation with further detailed observations. A beamed GRB will align with the FOV of the planned GRB detector Energetic X-ray Imaging Survey Telescope once every 9 yr. Pop III GRBs will be more easily detected by their isotropic emissions (i.e., orphan afterglows) rather than by their prompt emissions.

  8. Optical Properties of Afterglow Nanoparticles Sr2MgSi2O7: Eu2+, Dy3+ Capped with Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Fumitaka Yoshimura

    2012-01-01

    Full Text Available The optical properties of afterglow nanoparticles were successfully improved by the addition of polyethylene glycol (PEG to an afterglow colloidal solution. Afterglow nanoparticles—Sr2MgSi2O7: Eu2+, Dy3+—were prepared by laser ablation in liquid. The quantum yields and the decay curves were measured by a fluorescence spectrophotometer. An increase in the amount of PEG added to the solution increased the quantum yield of the nanoparticles and improved the afterglow property in the initial portion of the decay curve. However, the afterglow property did not change after a substantial amount of time had passed. The afterglow nanoparticles were capped with PEG molecules, and surface defects of the nanoparticles were passivated, which decreased the optical properties.

  9. Constraining chameleon field theories using the GammeV afterglow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Upadhye, A.; /Chicago U., EFI /KICP, Chicago; Steffen, J.H.; /Fermilab; Weltman, A.; /Cambridge U., DAMTP /Cape Town U.

    2009-11-01

    The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here we present a detailed calculation of the chameleon afterglow rate underlying these constraints. The dependence of GammeV constraints on various assumptions in the calculation is studied. We discuss GammeV-CHASE, a second-generation GammeV experiment, which will improve upon GammeV in several major ways. Using our calculation of the chameleon afterglow rate, we forecast model-independent constraints achievable by GammeV-CHASE. We then apply these constraints to a variety of chameleon models, including quartic chameleons and chameleon dark energy models. The new experiment will be able to probe a large region of parameter space that is beyond the reach of current tests, such as fifth force searches, constraints on the dimming of distant astrophysical objects, and bounds on the variation of the fine structure constant.

  10. Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924

    CERN Document Server

    Huang, K Y; Filippenko, A V; Hu, J H; Ip, W H; Kuo, P H; Li, W; Lin, H C; Lin, Z Y; Makishima, K; Onda, K; Qiu, Y; Tamagawa, T

    2005-01-01

    The 1-m telescope at Lulin Observatory and the 0.76-m Katzman Automatic Imaging Telescope at Lick Observatory were used to observe the optical afterglow of the short-duration (1.2--1.5 s) gamma-ray burst (GRB) 040924. This object has a soft high-energy spectrum, thus making it an exceptional case, perhaps actually belonging to the short-duration tail of the long-duration GRBs. Our data, combined with other reported measurements, show that the early R-band light curve can be described by two power laws with index alpha = -0.7 (at t = 16-50 min) and alpha = -1.06 (at later times). The rather small difference in the spectral indices can be more easily explained by an afterglow model invoking a cooling break rather than a jet break.

  11. A Search for Correlations between Gamma-Ray Burst Variability and Afterglow Onset

    CERN Document Server

    Yost, S A

    2015-01-01

    We compared the time (or time limit) of onset for optical afterglow emission to the gamma-ray variability V in 76 GRBs with redshifts. In the subset (25 cases) with the rise evident in the data, we fit the shape of the onset peak as well and compared the rising and decaying indices to V. We did not find any evidence for any patterns between these properties and there is no statistical support for any correlations. This indicates a lack of connection between irregularities of the prompt gamma-ray emission and the establishment of the afterglow phase. In the ordinary prompt internal shocks interpretation, this would indicate a lack of relationship between V and the bulk Lorentz factor of the event.

  12. Long afterglow properties of Zn2GeO4:Mn2+, Cr3+ phosphor

    Science.gov (United States)

    Cong, Yan; He, Yangyang; Dong, Bin; Xiao, Yu; Wang, Limei

    2015-04-01

    Zn2GeO4:Mn2+, Cr3+ phosphors were prepared by conventional solid state reaction and the photoluminescence properties were investigated. The Mn2+ activated Zn2GeO4 phosphors exhibited green emission at 533 nm due to the 4T1(4G) → 6A1(6S) transition of Mn2+ ions. With Cr3+ co-doping in Zn2GeO4 host, long afterglow characteristics were found from the same transition of Mn2+. The TL results revealed the presence of same traps in the phosphor, and the doping of Cr3+ ions deepened the VGe traps. The native defect VGe as a hole traps is responsible for the long afterglow emission in Zn2GeO4:Mn2+, Cr3+ phosphor. The possible mechanism of this phosphor has also been discussed.

  13. Afterglow from GRB 070610/Swift J195509.6+261406:An explanation using the fireball model

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    GRB 070610,which is also named Swift J195509.6+261406,is a peculiar Galactic transient with significant variability on short timescales in both X-ray and optical light curves.One possible explanation is that GRB 070610/Swift J195509.6 + 261406 is a soft gamma-ray repeater(SGR) in our Galaxy.Here,we use the fireball model,which is usually recognized as the standard model of gamma-ray burst(GRB) afterglows,and the energy injection hypothesis to interpret the X-ray and optical afterglow light curves of GRB 070610/Swift J195509.6 + 261406.It is found that the model is generally consistent with observations.

  14. Erosion of a-C:H in the afterglow of ammonia plasma

    Science.gov (United States)

    Drenik, Aleksander; Mourkas, Angelos; Zaplotnik, Rok; Primc, Gregor; Mozetič, Miran; Panjan, Peter; Alegre, Daniel; Tabarés, Francisco L.

    2016-07-01

    Amorphous hydrogenated carbon (a-C:H) deposits were eroded in the afterglow of a NH3 plasma, created with an inductively coupled RF generator in pure NH3 at the gas pressure of 50 Pa. The plasma system was characterised by optical emission spectroscopy and mass spectrometry, and the erosion process was monitored in-situ with a laser interferometry system. Based on the mass spectrometry measurements, the degree of dissociation of the NH3 molecules was estimated at 90% at the highest generator forward power in the discharge region, however the densities of N and H atoms were significantly smaller at the location of the sample holder. The erosion rates were found to increase with surface temperature and forward generator power. In the high dissociation regime, the composition of the afterglow and the reaction products highlight the role of N atoms in the erosion process.

  15. The early afterglow and magnetized ejecta present in GRB 110731A

    CERN Document Server

    Fraija, Nissim

    2015-01-01

    One of the most energetic gamma-ray bursts GRB 110731A, was observed from optical to GeV energy range by Fermi and Swift Observatories, and by the MOA and GROND optical telescopes. The multiwavelength observations over different epochs (from trigger time to more than 800 s) showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind to describe the multiwavelength light curves observations. In particular, the origin of the LAT emission is explained through the superposition of synchrotron radiation from the forward shock and synchrotron self-Compton emission from the reverse shock. The bulk Lorentz factor required in this model is $\\Gamma\\simeq520$ and the result suggests that the ejecta must be magnetized.

  16. The Early X-ray Afterglows of Optically Bright and Dark Gamma-Ray Bursts

    Institute of Scientific and Technical Information of China (English)

    Yi-Qing Lin

    2006-01-01

    A systematic study on the early X-ray afterglows of both optically bright and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift is presented. Our sample includes 25 GRBs of which 13 are B-GRBs and 12 are D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes (Fx), the gamma-ray fluxes (Sγ), and the ratio (Rγ,X) are similar for the two kinds of GRBs, that any observed differences should be simply statistical fluctuation. These results indicate that the progenitors of the two kinds of GRBs are of the same population with comparable total energies of explosion. The suppression of optical emission in the D-GRBs should result from circumburst but not from their central engine.

  17. Constraining chameleon field theories using the GammeV afterglow experiments

    International Nuclear Information System (INIS)

    The GammeV experiment has constrained the couplings of chameleon scalar fields to matter and photons. Here we present a detailed calculation of the chameleon afterglow rate underlying these constraints. The dependence of GammeV constraints on various assumptions in the calculation is studied. We discuss GammeV-CHASE, a second-generation GammeV experiment, which will improve upon GammeV in several major ways. Using our calculation of the chameleon afterglow rate, we forecast model-independent constraints achievable by GammeV-CHASE. We then apply these constraints to a variety of chameleon models, including quartic chameleons and chameleon dark energy models. The new experiment will be able to probe a large region of parameter space that is beyond the reach of current tests, such as fifth force searches, constraints on the dimming of distant astrophysical objects, and bounds on the variation of the fine structure constant.

  18. X-ray spectral components observed in the afterglow of GRB 130925A

    DEFF Research Database (Denmark)

    Bellm, Eric C.; Barrière, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn Erland; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Reynolds, Stephen P.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between...... Fermi/Large Area Telescope.......We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at >4σ significance, and its spectral shape varies between...

  19. Diverse Features of the Multi-wavelength Afterglows of Gamma-ray Bursts: Natural or Special?

    CERN Document Server

    Geng, J J

    2016-01-01

    The detection of optical re-brightenings and X-ray plateaus in the afterglows of gamma-ray bursts (GRBs) challenges the generic external shock model. Recently, we have developed a numerical method to calculate the dynamic of the system consisting of a forward shock and a reverse shock. Here, we briefly review the applications of this method in the afterglow theory. By relating these diverse features to the central engines of GRBs, we find that the steep optical re-brightenings would be caused by the fall-back accretion of black holes, while the shallow optical re-brightenings are the consequence of the injection of the electron-positron-pair wind from the central magnetar. These studies provide useful ways to probe the characteristics of GRB central engines.

  20. Neutrino emission from a GRB afterglow shock during an inner supernova shock breakout

    CERN Document Server

    Yu, Yun-Wei; Zheng, Xiao-Ping

    2008-01-01

    The observations of a nearby low-luminosity gamma-ray burst (GRB) 060218 associated with supernova SN 2006aj may imply an interesting astronomical picture where a supernova shock breakout locates behind a relativistic GRB jet. Based on this picture, we study neutrino emission for early afterglows of GRB 060218-like GRBs, where neutrinos are expected to be produced from photopion interactions in a GRB blast wave that propagates into a dense wind. Relativistic protons for the interactions are accelerated by an external shock, while target photons are basically provided by the incoming thermal emission from the shock breakout and its inverse-Compton scattered component. Because of a high estimated event rate of low-luminosity GRBs, we would have more opportunities to detect afterglow neutrinos from a single nearby GRB event of this type by IceCube. Such a possible detection could provide evidence for the picture described above.

  1. Gamma-ray burst afterglows from decelerating material: Blast waves and plasmoids

    International Nuclear Information System (INIS)

    We examine the dynamics and emitted radiation from material with a large initial bulk Lorentz factor which decelerates as it sweeps up ambient matter. The bulk kinetic energy of the material is converted into non-thermal energy of electrons which radiate isotropically in the locally co-moving frame. Self-consistent solutions for the dynamics of the material are computed which account for changes in its bulk relativistic inertia due to accretion and the emitted radiation. Fully radiative and non-radiative solutions are shown to be limiting cases agreeing with standard solutions for spherically expanding blast waves. We have calculated the afterglow synchrotron emission for a variety of parameters and geometries, and we compare a fiducial example to the afterglow behavior observed from recent gamma-ray burst X-ray and optical counterparts

  2. The afterglow of GRB 130427A from 1 to 1016 GHz

    International Nuclear Information System (INIS)

    We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst (GRB) of the past 29 yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z = 0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300 s to 130 days after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies, with no significant late-time flaring or rebrightening activity. The entire data set from 1 GHz to 10 GeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observed to last for minutes to hours following other very bright GRBs. A tenuous, wind-stratified circumburst density profile is required by the observations, suggesting a massive-star progenitor with a low mass-loss rate, perhaps due to low metallicity. GRBs similar in nature to GRB 130427A, inhabiting low-density media and exhibiting strong reverse shocks, are probably not uncommon but may have been difficult to recognize in the past owing to their relatively faint late-time radio emission; more such events should be found in abundance by the new generation of sensitive radio and millimeter instruments.

  3. The afterglow of GRB 130427A from 1 to 10{sup 16} GHz

    Energy Technology Data Exchange (ETDEWEB)

    Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd, Pasadena, CA 91125 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Corsi, A. [Physics Department, George Washington University, 725 21st St, NW Washington, DC 20052 (United States); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom); Levan, A. J. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Kann, D. A.; Greiner, J. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85748 Garching (Germany); Sonbas, E. [Department of Physics, University of Adiyaman, 02040 Adiyaman (Turkey); Zheng, W.; Clubb, K. I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Zhao, X.-H.; Bai, J.-M.; Chang, L. [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China); Bremer, M. [Institute de Radioastronomie Millimètrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d' Hères (France); Castro-Tirado, A. J. [Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Frail, D. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Fruchter, A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Göğüş, E. [Sabancı University, Orhanlı- Tuzla, İstanbul 34956 (Turkey); Güver, T., E-mail: dperley@astro.caltech.edu [Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul (Turkey); and others

    2014-01-20

    We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst (GRB) of the past 29 yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z = 0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300 s to 130 days after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies, with no significant late-time flaring or rebrightening activity. The entire data set from 1 GHz to 10 GeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observed to last for minutes to hours following other very bright GRBs. A tenuous, wind-stratified circumburst density profile is required by the observations, suggesting a massive-star progenitor with a low mass-loss rate, perhaps due to low metallicity. GRBs similar in nature to GRB 130427A, inhabiting low-density media and exhibiting strong reverse shocks, are probably not uncommon but may have been difficult to recognize in the past owing to their relatively faint late-time radio emission; more such events should be found in abundance by the new generation of sensitive radio and millimeter instruments.

  4. Afterglow chemistry of atmospheric-pressure helium–oxygen plasmas with humid air impurity

    International Nuclear Information System (INIS)

    The formation of reactive species in the afterglow of a radio-frequency-driven atmospheric-pressure plasma in a fixed helium–oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means of an extensive global plasma chemical kinetics model. As an original objective, we explore the effects of humid air impurity on the biologically relevant reactive species in an oxygen-dependent system. After a few milliseconds in the afterglow environment, the densities of atomic oxygen (O) decreases from 1015 to 1013 cm−3 and singlet delta molecular oxygen (O2(1D)) of the order of 1015 cm−3 decreases by a factor of two, while the ozone (O3) density increases from 1014 to 1015 cm−3. Electrons and oxygen ionic species, initially of the order of 1011 cm−3, recombine much faster on the time scale of some microseconds. The formation of atomic hydrogen (H), hydroxyl radical (OH), hydroperoxyl (HO2), hydrogen peroxide (H2O2), nitric oxide (NO) and nitric acid (HNO3) resulting from the humid air impurity as well as the influence on the afterglow chemistry is clarified with particular emphasis on the formation of dominant reactive oxygen species (ROS). The model suggests that the reactive species predominantly formed in the afterglow are major ROS O2(1D) and O3 (of the order of 1015 cm−3) and rather minor hydrogen- and nitrogen-based reactive species OH, H2O2, HNO3 and NO2/NO3, of which densities are comparable to the O-atom density (of the order of 1013 cm−3). Furthermore, the model quantitatively reproduces the experimental results of independent O and O3 density measurements. (paper)

  5. Polarization Evolution of Early Optical Afterglows of Gamma-Ray Bursts

    OpenAIRE

    Lan, Mi-Xiang; Wu, Xue-Feng; Dai, Zi-Gao

    2015-01-01

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock re...

  6. Electron attachment coefficients determined using a flowing afterglow/langmuir probe (FALP) apparatus

    International Nuclear Information System (INIS)

    The attachment of thermal electrons to SF6, CCl4, CCl3F, CCl2F2, CHCl3 and Cl2 has been studied over the temperature range 200-600K using a flowing afterglow/Langmuir probe apparatus. Results were obtained for the electron attachment coefficients as a function of temperature, and the activation energies for electron attachment reactions of CCl3F, CCl2F2, CHCl3 and Cl2 have been derived. (Authors)

  7. Color indices of optical afterglows of long GRBs in the Swift era

    Czech Academy of Sciences Publication Activity Database

    Šimon, Vojtěch; Pizzichini, G.; Hudec, René

    Les Ulis : EDP Sciences, 2013, s. 271-273. ISBN 9782759810024. ISSN 1633-4760. - (EAS Publications Series. 61). [Fall Gamma Ray Burst Symposium on 15 years of Gamma-Ray Bursts afterglows. Malaga (ES), 08.10.2012-12.10.2012] R&D Projects: GA ČR GA205/08/1207 Institutional support: RVO:67985815 Keywords : gamma-ray bursts * evolution Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  8. Afterglow mode and the new Micro Pulsed Beam mode applied to an ECR Ion Source

    OpenAIRE

    Maunoury, Laurent; Adoui, Lamri; Grandin, Jean-Pierre; Huber, Bernd; Lamour, Emily; Leherissier, Patrick; Noury, Fabien; Pacquet, Jean-Yves; Prigent, Christophe; Rozet, Jean-Pierre; Vernhet, Dominique

    2008-01-01

    An increasing number of experiments in the field of low energy ion physics ( µA) a pulsed beam chopper, installed downstream to the analyzing dipole, is used. For low-intensity beams (< 100 nA) the ion intensity delivered during the pulse may be increased by operating the ECR discharge in the afterglow mode [1]. This method gives satisfactory results (ie average current during the beam pulse is h...

  9. Studies on Self-Luminous Material and Coating with Long Persistent Yellow-Green Afterglow

    Institute of Scientific and Technical Information of China (English)

    邱关明; 孙彦彬; 陈永杰; 张明

    2003-01-01

    The preparation, properties, expression and luminescent mechanism of self-luminous material (SrAl2O4∶Eu2+, Dy3+) were discussed. The long afterglow luminescent coating was prepared by adding proper luminescent powders SrAl2O4∶Eu2+, Dy3+ and other aids into styrene/acrylic emulsion. The best prescription of the coating was defined. The properties of luminescent coating were determined. The primary factors which affect the coating properties were discussed.

  10. Multicolor observations of the afterglow of the short/hard GRB 050724

    CERN Document Server

    Malesani, D; D'Avanzo, P; D'Elia, V; Fugazza, D; Piranomonte, S; Ballo, L; Campana, S; Stella, L; Tagliaferri, G; Antonelli, L A; Chincarini, G; Della Valle, M; Goldoni, P; Guidorzi, C; Israel, G L; Lazzati, D; Melandri, A; Romano, P; Stratta, G; Vergani, S D

    2007-01-01

    New information on short/hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, in turn drawing some inferences on the global short GRB population. We present optical observations of the afterglow of GRB 050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements in the literature. Including X-ray data, we study the afterglow light curve and spectrum. We also present observations of the host galaxy. The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet eff...

  11. The Afterglow and ULIRG Host Galaxy of the Dark Short GRB 120804A

    CERN Document Server

    Berger, E; Levan, A; Margutti, R; Laskar, T; Fong, W; Mangano, V; Fox, D B; Tunnicliffe, R L; Chornock, R; Tanvir, N R; Menten, K M; Hjorth, J; Roth, K; Dupuy, T J

    2012-01-01

    We present the optical discovery and sub-arcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with Swift/XRT, Chandra, and XMM-Newton to ~19 d reveal a single power law decline. The optical afterglow is faint, and comparison to the X-ray flux indicates that GRB 120804A is "dark", with a rest-frame extinction of A_V~2.5 mag (at z~1.3). The intrinsic neutral hydrogen column density inferred from the X-ray spectrum, N_H~2x10^22 cm^-2, is commensurate with the large extinction. The host galaxy exhibits red optical/near-IR colors. Equally important, JVLA observations at 0.9-11 d reveal a constant 5.8 GHz flux density and an optically-thin spectrum, unprecedented for GRB afterglows, but suggestive instead of emission from the host galaxy. The optical/near-IR and radio fluxes are well fit with the scaled spectral energy distribution of the local ultra-luminous infrared galaxy (ULIRG) Arp 220 at z~1...

  12. Spectrophotometric analysis of GRB afterglow extinction curves with X-shooter

    CERN Document Server

    Japelj, J; Gomboc, A; Vergani, S D; Goldoni, P; Selsing, J; Cano, Z; D'Elia, V; Flores, H; Fynbo, J P U; Hammer, F; Hjorth, J; Jakobsson, P; Kaper, L; Kopač, D; Krühler, T; Melandri, A; Piranomonte, S; Sánchez-Ramírez, R; Tagliaferri, G; Tanvir, N R; Postigo, A de Ugarte; Watson, D; Wijers, R A M J

    2015-01-01

    In this work we use gamma-ray burst (GRB) afterglow spectra observed with the VLT/X-shooter spectrograph to measure rest-frame extinction in GRB lines-of-sight by modeling the broadband near-infrared (NIR) to X-ray afterglow spectral energy distributions (SEDs). Our sample consists of nine Swift GRBs, eight of them belonging to the long-duration and one to the short-duration class. Dust is modeled using the average extinction curves of the Milky Way and the two Magellanic Clouds. We derive the rest-frame extinction of the entire sample, which fall in the range $0 \\lesssim {\\it A}_{\\rm V} \\lesssim 1.2$. Moreover, the SMC extinction curve is the preferred extinction curve template for the majority of our sample, a result which is in agreement with those commonly observed in GRB lines-of-sights. In one analysed case (GRB 120119A), the common extinction curve templates fail to reproduce the observed extinction. To illustrate the advantage of using the high-quality X-shooter afterglow SEDs over the photometric SED...

  13. Afterglow Population Studies from Swift Follow-Up Observations of Fermi LAT GRBs

    Science.gov (United States)

    Racusin, Judith L.; Oates, S. R.; McEnery, J.; Vasileiou, V.; Troja, E.; Gehrels, N.

    2010-01-01

    The small population of Fermi LAT detected GRBs discovered over the last year has been providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 5 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into other components of GRB emission structure. We explore the new ability to utilize both of these observatories to study the same GRBs over 10 orders of magnitude in energy, although not always concurrently. Almost all LAT GRBs that have been followed-up by Swift within 1-day have been clearly detected and carefully observed. We will present the context of the lower-energy afterglows of this special subset of GRBs that has > 100 MeV emission compared to the hundreds in the Swift database that may or may not have been observed by LAT, and theorize upon the relationship between these properties and the origin of the high energy gamma-ray emission.

  14. The host-galaxy response to the afterglow of GRB 100901A

    CERN Document Server

    Hartoog, Olga E; Vreeswijk, Paul M; Kaper, Lex; Tanvir, Nial R; Savaglio, Sandra; Berger, Edo; Chornock, Ryan; Covino, Stefano; D'Elia, Valerio; Flores, Hector; Fynbo, Johan P U; Goldoni, Paolo; Gomboc, Andreja; Melandri, Andrea; Pozanenko, Alexei; Schaye, Joop; Postigo, Antonio de Ugarte; Wijers, Ralph A M J

    2013-01-01

    For Gamma-Ray Burst 100901A, we have obtained Gemini-North and Very Large Telescope optical afterglow spectra at four epochs: one hour, one day, three days and one week after the burst, thanks to the afterglow remaining unusually bright at late times. Apart from a wealth of metal resonance lines, we also detect lines arising from fine-structure levels of the ground state of Fe II, and from metastable levels of Fe II and Ni II at the host redshift (z = 1.4084). These lines are found to vary significantly in time. The combination of the data and modelling results shows that we detect the fall of the Ni II 4 F9/2 metastable level population, which to date has not been observed. Assuming that the population of the excited states is due to the UV-radiation of the afterglow, we estimate an absorber distance of a few hundred pc. This appears to be a typical value when compared to similar studies. We detect two intervening absorbers (z = 1.3147, 1.3179). Despite the wide temporal range of the data, we do not see sign...

  15. Luminescence of divalent europium activated spinels synthesized by combustion and the enhanced afterglow by dysprosium incorporation

    Science.gov (United States)

    Wu, Haoyi; Jin, Yahong

    2016-05-01

    Herein we report a luminescent phenomenon of Eu2+ in the spinel MgAl2O4 and ZnAl2O4 samples which are successfully synthesized via a combustion method. The XRD shows cubic spinel structure is obtained from the prepared samples. The mean crystal sizes estimated from XRD data are 30 and 10 nm for MgAl2O4 and ZnAl2O4 respectively, and the large grain particles are the agglomeration of crystallites. The Eu2+ ions show a blue emission at around 480 nm and an afterglow phenomenon is observed after the removal of excitation. The afterglow spectrum of MgAl2O4: Eu2+, Dy3+ shows two emissions at 480 and 520 nm while only one at 480 nm is observed in ZnAl2O4: Eu2+, Dy3+. The afterglow intensity and the persisting duration can be substantially enhanced by the Dy3+ incorporation because the trapping ability of the electron traps is reinforced. This is confirmed by the TL curves of the samples.

  16. Estimates for Lorentz factors of gamma-ray bursts from early optical afterglow observations

    International Nuclear Information System (INIS)

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Γ of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Γ. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Γ and the burst luminosity L γ does not hold. However, the data clearly show a lower bound Γmin that increases with L γ. We suggest an explanation for this feature: explosions with large jet luminosities and Γ < Γmin suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation, we examine the effect of adiabatic cooling on the GRB location in the L γ – Γ plane using a Monte Carlo simulation of the GRB population. Our results predict detectable on-axis 'orphan' afterglows. We also derive upper limits on the density of the ambient medium that decelerates the explosion ejecta. We find that the density in many cases is smaller than expected for stellar winds from normal Wolf-Rayet progenitors. The burst progenitors may be peculiar massive stars with weaker winds, or there might exist a mechanism that reduces the stellar wind a few years before the explosion.

  17. Luminosity--time and luminosity--luminosity correlations for GRB prompt and afterglow plateau emissions

    CERN Document Server

    Dainotti, M G; Willingale, R; Brien, P O'; Ostrowski, M; Nagataki, S

    2015-01-01

    We present an analysis of 123 Gamma-ray bursts (GRBs) with known redshifts possessing an afterglow plateau phase. We reveal that $L_a-T^{*}_a$ correlation between the X-ray luminosity $L_a$ at the end of the plateau phase and the plateau duration, $T^*_a$, in the GRB rest frame has a power law slope different, within more than 2 $\\sigma$, from the slope of the prompt $L_{f}-T^{*}_{f}$ correlation between the isotropic pulse peak luminosity, $L_{f}$, and the pulse duration, $T^{*}_{f}$, from the time since the GRB ejection. Analogously, we show differences between the prompt and plateau phases in the energy-duration distributions with the afterglow emitted energy being on average $10\\%$ of the prompt emission. Moreover, the distribution of prompt pulse versus afterglow spectral indexes do not show any correlation. In the further analysis we demonstrate that the $L_{peak}-L_a$ distribution, where $L_{peak}$ is the peak luminosity from the start of the burst, is characterized with a considerably higher Spearman ...

  18. Afterglow emission from pair-loaded blast waves in gamma-ray bursts

    CERN Document Server

    Beloborodov, A M

    2005-01-01

    The MeV radiation front of gamma-ray bursts creates copious e+- pairs as it propagates through an ambient medium. The created pairs enrich the leptonic component of the medium by a large factor at distances R < R_load ~ 10^{16} cm from the burst center. The following blast wave sweeps up the pair-rich medium and then emits the observed afterglow radiation. We find that the afterglow has a "memory" of e+- loading outside R_load. The e+- pairs remain in the swept-up material and slowly cool down by emitting synchrotron radiation. They are likely to dominate the blast-wave emission in IR, optical, and UV bands during the first minutes of the observed afterglow. The expected e+- radiation is described by a simple formula, which is derived analytically and checked by numerical integration of synchrotron emission over the blast material; a suitable Lagrangian formalism is developed for such calculations. The main signature of e+- radiation is its flat ("white") spectrum in a broad range of frequencies from IR to...

  19. X-ray Emission Lines in GRB Afterglows: Evidence for a Two-component Jet Model

    Institute of Scientific and Technical Information of China (English)

    Wei-Hong Gao; Da-Ming Wei

    2005-01-01

    X-ray emission lines have been observed in X-ray afterglows of several γ-ray bursts (GRBs). It is a major breakthrough for understanding the nature of the progenitors. It has been proposed that the X-ray emission lines can be well explained by the Geometry-Dominated models, but in these models the illuminating angle is much larger than that of the collimated jet of the GRB. For GRB 011211, we have obtained an illuminating angle of about θ~ 45°, while the angle of the GRB jet is only 3.6°. So we propose that the outflow of GRBs with emission lines should have two distinct components: a wide component that illuminates the reprocessing material and produces the emission lines and a narrow one that produces the GRB. Observations show the energy for producing the emission lines is higher than that of the GRB. In this case, when the wide component dominates the afterglows, a bump should appear in the GRB afterglow. For GRB 011211,the bump should occur within 0.05 days of the GRB, which is obviously too early for the observation to catch it. Alongside the X-ray emission lines there should also be a bright emission component between the UV and the soft X-rays. These features can be tested by the Swift satellite in the near future.

  20. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    International Nuclear Information System (INIS)

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay (∞ t-a with 3 ∼1 ∼2 ∼3 ∼break,1 ∼3 s ∼break,2 ∼4 s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (tbreak,1) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a2) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (tbreak,2). This energy injection increases the energy of the afterglow shock by at least a factor of f ∼> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission

  1. Extremely Soft X-Ray Flash as the Indicator of Off-axis Orphan GRB Afterglow

    Science.gov (United States)

    Urata, Yuji; Huang, Kuiyun; Yamazaki, Ryo; Sakamoto, Takanori

    2015-06-01

    We verified the off-axis jet model of X-ray flashes (XRFs) and examined a discovery of off-axis orphan gamma-ray burst (GRB) afterglows. The XRF sample was selected on the basis of the following three factors: (1) a constraint on the lower peak energy of the prompt spectrum {E}{obs}{src}, (2) redshift measurements, and (3) multicolor observations of an earlier (or brightening) phase. XRF 020903 was the only sample selected on the basis of these criteria. A complete optical multicolor afterglow light curve of XRF 020903 obtained from archived data and photometric results in the literature showed an achromatic brightening around 0.7 days. An off-axis jet model with a large observing angle (0.21 rad, which is twice the jet opening half-angle, {θ }{jet}) can naturally describe the achromatic brightening and the prompt X-ray spectral properties. This result indicates the existence of off-axis orphan GRB afterglow light curves. Events with a larger viewing angle (\\gt ∼ 2{θ }{jet}) could be discovered using an 8 m class telescope with wide-field imagers such as the Subaru Hyper-Suprime-Cam and the Large Synoptic Survey Telescope.

  2. Extremely Soft X-ray Flash as the indicator of off-axis orphan GRB afterglow

    CERN Document Server

    Urata, Yuji; Yamazaki, Ryo; Sakamoto, Takanori

    2015-01-01

    We verified the off-axis jet model of X-ray flashes (XRFs) and examined a discovery of off-axis orphan gamma-ray burst (GRBs) afterglows. The XRF sample was selected on the basis of the following three factors: (1) a constraint on the lower peak energy of the prompt spectrum $E^{src}_{obs}$, (2) redshift measurements, and (3) multi-color observations of an earlier (or brightening) phase. XRF020903 was the only sample selected basis of these criteria. A complete optical multi-color afterglow light curve of XRF020903 obtained from archived data and photometric results in literature showed an achromatic brightening around 0.7 days. An off-axis jet model with a large observing angle (0.21 rad, which is twice the jet opening half-angle, $\\theta_{jet}$) can naturally describe the achromatic brightening and the prompt X-ray spectral properties. This result indicates the existence of off-axis orphan GRB afterglow light curves. Events with a larger viewing angle ($>\\sim2\\theta_{jet}$) could be discovered using an 8-m ...

  3. Estimates for Lorentz factors of gamma-ray bursts from early optical afterglow observations

    Energy Technology Data Exchange (ETDEWEB)

    Hascoët, Romain; Beloborodov, Andrei M. [Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States); Daigne, Frédéric; Mochkovitch, Robert, E-mail: hascoet@astro.columbia.edu [Institut d' Astrophysique de Paris, UMR 7095 Université Pierre et Marie Curie-CNRS, 98 bis boulevard Arago, F-75014 Paris (France)

    2014-02-10

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Γ of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Γ. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Γ and the burst luminosity L {sub γ} does not hold. However, the data clearly show a lower bound Γ{sub min} that increases with L {sub γ}. We suggest an explanation for this feature: explosions with large jet luminosities and Γ < Γ{sub min} suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation, we examine the effect of adiabatic cooling on the GRB location in the L {sub γ} – Γ plane using a Monte Carlo simulation of the GRB population. Our results predict detectable on-axis 'orphan' afterglows. We also derive upper limits on the density of the ambient medium that decelerates the explosion ejecta. We find that the density in many cases is smaller than expected for stellar winds from normal Wolf-Rayet progenitors. The burst progenitors may be peculiar massive stars with weaker winds, or there might exist a mechanism that reduces the stellar wind a few years before the explosion.

  4. Robust photometric redshift determinations of gamma-ray burst afterglows at z ≳ 2

    Science.gov (United States)

    Curran, P. A.; Wijers, R. A. M. J.; Heemskerk, M. H. M.; Starling, R. L. C.; Wiersema, K.; van der Horst, A. J.

    2008-11-01

    Context: Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts, z, greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Aims: Here we introduce our code, GRBz, a method of simultaneous multi-parameter fitting of GRB afterglow optical and near infrared, spectral energy distributions. It allows for early determinations of the photometric redshift, spectral index and host extinction to be made. Methods: We assume that GRB afterglow spectra are well represented by a power-law decay and model the effects of absorption due to the Lyman forest and host extinction. We use a genetic algorithm-based routine to simultaneously fit the parameters of interest, and a Monte Carlo error analysis. Results: We use GRBs of previously determined spectroscopic redshifts to prove our method, while also introducing new near infrared data of GRB 990510 which further constrains the value of the host extinction. Conclusions: Our method is effective in estimating the photometric redshift of GRBs, relatively unbiased by assumptions of the afterglow spectral index or the host galaxy extinction. Monte Carlo error analysis is required as the method of error estimate based on the optimum population of the genetic algorithm underestimates errors significantly.

  5. Novel methods for measuring afterglow in developmental scintillators for X-ray and neutron detection

    International Nuclear Information System (INIS)

    In this paper we discuss two novel methods of measuring afterglow in scintillators. One method is designed for X-ray detection and the other for neutron detection applications. In the first method a commercial fan-beam scanner of basic design similar to those seen at airports is used to deliver a typically 12 ms long X-ray pulse to a scintillator by passing the test equipment through the scanner on the conveyor belt. In the second method the thermal neutron beam from a research reactor is incident on the scintillator. The beam is cut-off in about 1 ms using a 10B impregnated aluminum pneumatic shutter, and the afterglow is recorded on a dual range storage oscilloscope to capture both the steady state intensity and the weak decay. We describe these measurement methods and the results obtained for a range of developmental ceramic and glass scintillators, as well as some standard scintillators such as NaI(Tl), LiI(Eu) and the plastic scintillator NE102A. Preliminary modeling of the afterglow is presented.

  6. GRB 110731A: Early afterglow in stellar wind powered by a magnetized outflow

    CERN Document Server

    Fraija, Nissim

    2015-01-01

    One of the most energetic gamma-ray burst GRB 110731A was observed from optical to GeV energy range. Previous analysis on the prompt phase revealed similarities with the Large Area Telescope (LAT) bursts observed by Fermi: i) a delayed onset of the high-energy emission ($> 100$ MeV), ii) a short-lasting bright peak at later times and iii) a temporally extended component from this phase and lasting hundreds of seconds. Additionally to the prompt phase, multiwavelength observations over different epochs showed that the spectral energy distribution was better fitted by a wind afterglow model. We present a leptonic model based on an early afterglow that evolves in a stellar wind of its progenitor. We apply this model to interpret the temporally extended LAT emission and the brightest LAT peak exhibited by the prompt phase of GRB 110731A. Additionally, using the same set of parameters, we describe the multiwavelength afterglow observations. The origin of the temporally extended LAT, X-ray and optical flux is expla...

  7. Afterglow in bulk AlN single crystals under β-irradiation

    International Nuclear Information System (INIS)

    Regularities of afterglow at room temperature and of thermoluminescence at further heating up to 673 K have been studied in bulk aluminum nitride single crystals. It has been established that after exposure to β-irradiation luminescence decay at RT may be described by superposition of two exponential components: fast (59 s) and slow (606 s) ones, caused by defects of the anion crystal sublattice ON- and VN-centers, respectively. The afterglow spectrum is shown to be characterized by the 3.43 eV band with FWHM=0.61 eV that dominates also in the thermoluminescence under study. From analysis of the TL curves in terms of the general order formalism it has been concluded that variation of the activation energy observed within the 0.46–0.85 eV range with increasing storage of the samples from 5 min to 3 days may be caused by energy distribution of traps on the basis of oxygen-related centers. For the first time the compensation effect has been found, and phenomenologically interpreted for the TL processes of the AlN single crystals. Isokinetic temperature has been estimated within the framework of empiric and non-empiric relations. - Highlights: ► Analysis of afterglow curves and emission spectra in irradiated bulk AlN crystals. ► Evaluation of kinetic and thermodynamic parameters of thermoluminescence. ► Observation of compensation effect in TL processes for AlN in the first time.

  8. Polarization Evolution of Early Optical Afterglows of Gamma-Ray Bursts

    CERN Document Server

    Lan, Mi-Xiang; Dai, Zi-Gao

    2015-01-01

    The central engine and jet composition of gamma-ray bursts (GRBs) remain mysterious. Here we suggest that observations on polarization evolution of early optical afterglows may shed light on these questions. We first study the dynamics of a reverse shock and a forward shock that are generated during the interaction of a relativistic jet and its ambient medium. The jet is likely magnetized with a globally large-scale magnetic field from the central engine. The existence of the reverse shock requires that the magnetization degree of the jet should not be high ($\\sigma\\leq 1$), so that the jet is mainly composed of baryons and leptons. We then calculate the light curve and polarization evolution of an early optical afterglow, and find that when the polarization position angle changes by $90^\\circ$ during the early afterglow, the polarization degree is zero for a toroidal magnetic field but is very likely to be non-zero for an aligned magnetic field. This result would be expected to provide a probe for the centra...

  9. GAMMA-RAY BURST AFTERGLOW SCALING RELATIONS FOR THE FULL BLAST WAVE EVOLUTION

    International Nuclear Information System (INIS)

    We demonstrate that gamma-ray burst afterglow spectra and light curves can be calculated for arbitrary explosion and radiation parameters by scaling the peak flux and the critical frequencies connecting different spectral regimes. Only one baseline calculation needs to be done for each jet opening angle and observer angle. These calculations are done numerically using high-resolution relativistic hydrodynamical afterglow blast wave simulations which include the two-dimensional dynamical features of expanding and decelerating afterglow blast waves. Any light curve can then be generated by applying scaling relations to the baseline calculations. As a result, it is now possible to fully fit for the shape of the jet break, e.g., at early-time X-ray and optical frequencies. In addition, late-time radio calorimetry can be improved since the general shape of the transition into the Sedov-Taylor regime is now known for arbitrary explosion parameters so the exact moment when the Sedov-Taylor asymptote is reached in the light curve is no longer relevant. When calculating the baselines, we find that the synchrotron critical frequency νm and the cooling break frequency νc are strongly affected by the jet break. The νm temporal slope quickly drops to the steep late-time Sedov-Taylor slope, while the cooling break νc first steepens and then rises to meet the level of its shallow late-time asymptote.

  10. Klein-Nishina effects on the high-energy afterglow emission of gamma-ray bursts

    CERN Document Server

    Wang, Xiang-Yu; Li, Zhuo; Wu, Xue-Feng; Dai, Zi-Gao

    2009-01-01

    Extended high-energy(>100MeV) gamma-ray emission that lasts much longer than the prompt sub-MeV emission has been detected from quite a few gamma-ray bursts (GRBs) by Fermi Large Area Telescope (LAT) recently. A plausible scenario is that this emission is the afterglow synchrotron emission produced by electrons accelerated in the forward shocks. In this scenario, the electrons that produce synchrotron high-energy emission also undergo inverse-Compton (IC) loss and the IC scattering with the synchrotron photons should be in the Klein-Nishina regime. Here we study effects of the Klein-Nishina scattering on the high-energy synchrotron afterglow emission. We find that, at early times the Klein-Nishina suppression effect on those electrons that produce the high-energy emission is usually strong and therefore their inverse-Compton loss is small with a Compton parameter Y < a few for a wide range of parameter space. This leads to a relatively bright synchrotron afterglow at high energies that can be detected by F...

  11. The puzzling case of GRB 990123: prompt emission and broad-band afterglow modeling

    CERN Document Server

    Corsi, A; Kuulkers, E; Amati, L; Antonelli, L A; Costa, E; Feroci, M; Frontera, F; Guidorzi, C; Heise, J; Zand, J; Maiorano, E; Montanari, E; Nicastro, L; Pian, E; Soffitta, P

    2005-01-01

    We report on BeppoSAX simultaneous X- and gamma-ray observations of the bright GRB 990123. We present the broad-band spectrum of the prompt emission, including optical, X- and gamma-rays, confirming the suggestion that the emission mechanisms at low and high frequencies must have different physical origins. In the framework of the standard fireball model, we discuss the X-ray afterglow observed by the NFIs and its hard X-ray emission up to 60 keV several hours after the burst, detected for about 20 ks by the PDS. Considering the 2-10 keV and optical light curves, the 0.1-60 keV spectrum during the 20 ks in which the PDS signal was present and the 8.46 GHz upper limits, we find that the multi-wavelength observations cannot be readily accommodated by basic afterglow models. While the temporal and spectral behavior of the optical afterglow is possibly explained by a synchrotron cooling frequency between the optical and the X-ray energy band during the NFIs observations, in X-rays this assumption only accounts fo...

  12. Electrical characterization of the flowing afterglow of N2 and N2/O2 microwave plasmas at reduced pressure

    International Nuclear Information System (INIS)

    A cylindrical Langmuir probe was used to analyze the spatial distribution of the number density of positive ions and electrons as well as the electron energy distribution function (EEDF) in the flowing afterglow of a 6 Torr N2 and N2/O2 plasma sustained by a propagating electromagnetic surface wave in the microwave regime. In pure N2 discharges, ion densities were in the mid 1014 m−3 in the pink afterglow and in the mid 1012 m−3 early in the late afterglow. In both pink and late afterglows, the ion population was much higher than the electron population, indicating non-macroscopically neutral media. The EEDF was close to a Maxwellian with an electron temperature of 0.5 ± 0.1 eV, except in the pink afterglow where the temperature rose to 1.1 ± 0.2 eV. This latter behavior is ascribed to N2 vibration-vibration pumping in the pink afterglow that increases the concentration of high N2 vibrational states and thus rises the electron temperature by vibration-electron collisions. After addition of small amounts of O2 in the nominally pure N2 discharge, the charged particles densities and average electron energy first strongly increased and then decreased with increasing O2 concentration. Based on these data and the evolution of the N2+(B) band emission intensities, it is concluded that a significant change in the positive ion composition of the flowing afterglow occurs, going from N2+ in nominally pure N2 discharges to NO+ after addition of trace amounts of O2 in N2

  13. Spectroscopic Study of Recombination in the Early Afterglow of a Helium Plasma

    International Nuclear Information System (INIS)

    Some properties of a decaying helium plasma have been studied using time resolved spectroscopy and probe diagnostics. The plasma was produced in a pulsed, repetitive, hot cathode discharge in helium at a pressure 11 torr , and the light emitted in the afterglow of the discharge was measured by means of a spectrometer-photomultiplier combination. Single photoelectrons were counted on a scaler during a preset gate time of each discharge cycle, and after a preset number of cycles recorded on punched tape. The spectrometer was calibrated for absolute intensity measurements of the spectral lines of atomic helium. The overall conductance of the positive column was determined by measuring the voltage difference between two probes inserted into the plasma, passing a very small current pulse between the anode and cathode in the afterglow. Heavier current pulses were used to heat the free electrons selectively, thus providing so-called 'afterglow quenching'. From the measured absolute intensities of the helium lines, the number densities of the excited states of helium were calculated. All levels with principal quantum number n ≥ 8 were found to be in near Saha equilibrium with the free electrons at a temperature 1,275 deg K in the early afterglow (15-35 μs after end of the discharge). By measuring the absolute intensities of some of the molecular helium bands, an estimate of the rate of conversion of atomic helium ions into molecular helium ions was obtained. The atomic line radiation, as well as the molecular band radiation, was assumed to result from collisional-radiative recombination of atomic and molecular helium ions, respectively. The rate of recombination down to the metastable level n = 2 was obtained from the measured line intensities. By adding the rate of ambipolar diffusion, calculated from known literature data, quite good agreement with the measured decay rate for the electron density was found. The measured line intensities were also used to calculate the

  14. Reddish orange long afterglow phosphor Ca{sub 2}SnO{sub 4}:Sm{sup 3+}prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Ju Zhenghua [Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Tianshui south road 222, Lanzhou 730000 (China); Zhang Shuihe [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Gao Xiuping [Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Tianshui south road 222, Lanzhou 730000 (China); School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Tang Xiaoliang [Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Tianshui south road 222, Lanzhou 730000 (China); Liu Weisheng, E-mail: liuws@lzu.edu.cn [Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Tianshui south road 222, Lanzhou 730000 (China)

    2011-08-04

    Highlights: > A promising reddish orange emissive long afterglow phosphor Ca{sub 2}SnO{sub 4}:Sm{sup 3+} prepared by sol-gel method was firstly reported. > The optics properties of Ca{sub 2}SnO{sub 4}:Sm{sup 3+} were discussed. > Very useful tool, thermoluminscent technique was chosen to investigate the traps in the material. The results of thermoluminscent spectra indicating that the depth and number of traps are critical factors in determining their performance. > Furthermore, the phosphorescence mechanism was discussed successfully. > This work provides a potential approach to develop reddish orange light emitting long afterglow phosphor. - Abstract: A reddish orange light emissive long afterglow phosphor, Ca{sub 2}SnO{sub 4}:Sm{sup 3+} was prepared by sol-gel method at lower temperature. The synthesized phosphors were characterized by X-ray diffraction, scanning electron micrograph images, photoluminescence spectra, afterglow decay curves and thermoluminescence spectra. Three emission peaks locate at 565 nm, 609 nm and 655 nm corresponding to CIE chromaticity coordinates of x = 0.53 and y = 0.47, which indicates the reddish orange light emitting. The fluorescent intensity and the afterglow characteristic depends on the concentration of Sm{sup 3+} and the optimized concentration is 1.5 mol%. The afterglow decay curves are well fitted with triple-exponential decay models. The thermoluminescence glow curves show that the Sm{sup 3+} induces suitable trap depth and result in the long afterglow phenomenon, and the corresponding increase or decrease in afterglow is associated with trap concentration, nearly no change in trap depth. The 1.5 mol% Sm{sup 3+}-doped Ca{sub 2}SnO{sub 4} sample has the biggest trap concentration and exhibit the best afterglow characteristic, its' afterglow time is about 1 h. The phosphorescence mechanism of this long afterglow phosphor was discussed.

  15. Discovery of the Very Red Near-Infrared and Optical Afterglow of the Short-Duration GRB 070724A

    CERN Document Server

    Berger, E; Fox, D B; Cucchiara, A

    2009-01-01

    [Abridged] We report the discovery of the near-infrared and optical afterglow of the short-duration gamma-ray burst GRB070724A. The afterglow is detected in i,J,H,K observations starting 2.3 hr after the burst with K=19.59+/-0.16 mag and i=23.79+/-0.07 mag, but is absent in images obtained 1.3 years later. Fading is also detected in the K-band between 2.8 and 3.7 hr at a 4-sigma significance level. The optical/near-IR spectral index, beta_{O,NIR}=-2, is much redder than expected in the standard afterglow model, pointing to either significant dust extinction, A_{V,host}~2 mag, or a non-afterglow origin for the near-IR emission. The case for extinction is supported by a shallow optical to X-ray spectral index, consistent with the definition for ``dark bursts'', and a normal near-IR to X-ray spectral index. Moreover, a comparison to the optical discovery magnitudes of all short GRBs with optical afterglows indicates that the near-IR counterpart of GRB070724A is one of the brightest to date, while its observed op...

  16. In search of progenitors for supernova-less GRBs 060505 and 060614: re-examination of their afterglows

    CERN Document Server

    Xu, D; Fynbo, J P U; Sollerman, J; Yost, S; Watson, D; Foley, S; O'Brien, P T; Hjorth, J

    2008-01-01

    GRB060505 and GRB060614 are nearby long-duration gamma-ray bursts (LGRBs) without accompanying supernovae (SNe) down to very strict limits. They thereby challenge the conventional LGRB-SN connection and naturally give rise to the question: are there other peculiar features in their afterglows which would help shed light on their progenitors? To answer this question, we combine new observational data with published data and investigate the multi-band temporal and spectral properties of the two afterglows. We find that both afterglows can be well interpreted within the framework of the jetted standard external shock wave model, and that the afterglow parameters for both bursts fall well within the range observed for other LGRBs. Hence, from the properties of the afterglows there is nothing to suggest that these bursts should have another progenitor than other LGRBs. Recently, GRB080503 has been found to be a spike + tail burst similar to GRB060614. We analyse the prompt emission of this burst and find that this...

  17. Discovery and redshift of an optical afterglow in 71 square degrees iPTF13bxl and GRB 130702A

    CERN Document Server

    Singer, Leo P; Kasliwal, Mansi M; Perley, Daniel A; Ofek, Eran O; Brown, Duncan A; Nugent, Peter E; Kulkarni, S R; Corsi, Alessandra; Frail, Dale A; Bellm, Eric; Mulchaey, John; Arcavi, Iair; Barlow, Tom; Bloom, Joshua S; Cao, Yi; Gehrels, Neil; Horesh, Assaf; Masci, Frank J; McEnery, Julie; Rau, Arne; Surace, Jason A; Yaron, Ofer

    2013-01-01

    We report the discovery of the optical afterglow of the gamma-ray burst (GRB) 130702A, identified upon searching 71 square degrees surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory (iPTF), iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the VLA confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200-inch telescopes showed the afterglow to be at a redshift of z=0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt gamma-ray energy release and afterglow luminosity are intermediate between typical cosmological...

  18. LOOKING INTO THE FIREBALL: ROTSE-III AND SWIFT OBSERVATIONS OF EARLY GAMMA-RAY BURST AFTERGLOWS

    International Nuclear Information System (INIS)

    We report on a complete set of early optical afterglows of gamma-ray bursts (GRBs) obtained with the Robotic Optical Transient Search Experiment (ROTSE-III) telescope network from 2005 March through 2007 June. This set is comprised of 12 afterglows with early optical and Swift/X-Ray Telescope observations, with a median ROTSE-III response time of 45 s after the start of γ-ray emission (8 s after the GCN notice time). These afterglows span 4 orders of magnitude in optical luminosity, and the contemporaneous X-ray detections allow multi-wavelength spectral analysis. Excluding X-ray flares, the broadband synchrotron spectra show that the optical and X-ray emission originate in a common region, consistent with predictions of the external forward shock in the fireball model. However, the fireball model is inadequate to predict the temporal decay indices of the early afterglows, even after accounting for possible long-duration continuous energy injection. We find that the optical afterglow is a clean tracer of the forward shock, and we use the peak time of the forward shock to estimate the initial bulk Lorentz factor of the GRB outflow, and find 100 ∼0 ∼< 1000, consistent with expectations.

  19. Synthesis of ZnS:Ag,Co water-soluble blue afterglow nanoparticles and application in photodynamic activation.

    Science.gov (United States)

    Ma, Lun; Zou, Xiaoju; Hossu, Marius; Chen, Wei

    2016-08-01

    Silver and cobalt co-doped ZnS (ZnS:Ag,Co) water-soluble afterglow nanoparticles were synthesized using a wet chemistry method followed by aging at room temperature. The nanoparticles had a cubic zinc blende structure with average sizes of approximately 4 nm and emitted a blue fluorescence emission centered at 441 nm due to radiative transitions from surface defects to Ag(+) luminescent centers. Intense afterglow emission peaking at 475 nm from the obtained nanoparticles was observed and was red-shifted compared to the fluorescence emission peak. X-ray photoelectron spectroscopy revealed a large increase of O/S ratio, indicating a surface oxidation process during aging. The S vacancies produced accordingly may contribute to form more electron traps and enhance afterglow. The ZnS:Ag,Co afterglow nanoparticles have a very low dark-toxicity and are applied as a light source for photodynamic therapy activation by conjugating with protoporphyrin together. Our preliminary study has shown that the ZnS:Ag,Co afterglow nanoparticles can significantly reduce the x-ray dosage used in activation and thus may be a very promising candidate for future x-ray excited photodynamic therapy in deep cancer treatment. PMID:27345100

  20. Densities of active species in N2 and N2–H2 RF pink afterglow

    International Nuclear Information System (INIS)

    The transverse distribution of N2 radiative states has been analyzed in the early afterglow of RF N2 flowing discharge with the introduction of a few H2 molecules (10−5–10−3) in the discharge. The transverse distributions of N2, 1st (580 nm), 2nd pos (316 nm) and N2+,1st neg (391.4 nm) band intensities have a sharp profile in pure N2. As more H2 was introduced into N2, a sharper profile for the N2+,1st neg was observed, and inversely a broader profile for the N2, 1st pos. With the introduction of H2 into N2 the early afterglow was changed from a sharp pink to a broad late afterglow where the N + N recombination is the dominant process. After NO titration of N-atom density in pure N2 late afterglow, the variation of N-atom and N2(A) density in the N2–H2 early afterglow is deduced. The N2(X, v > 13) density is also estimated. (paper)

  1. Modelling the Multi-band Afterglow of GRB 091127: Evidence of a Hard Electron Energy Spectrum with an Injection Break

    CERN Document Server

    Zhang, Qiang; Zong, Hong-Shi

    2016-01-01

    The afterglow of GRBs is believed to originate from the synchrotron emission of shock-accelerated electrons produced by the interaction between the outflow and the external medium. The accelerated electrons are usually assumed to follow a power law energy distribution with an index of $p$. Observationally, although most GRB afterglows have a $p$ larger than 2, there are still a few GRBs suggestive of a hard ($p<2$) electron spectrum. GRB 091127, with well-sampled broad-band afterglow data, shows evidence of a hard electron spectrum and strong spectral evolution, with a spectral break moving from high to lower energies. The spectral break evolves very fast and cannot be explained by the cooling break in the standard afterglow model, unless evolving microphysical parameters are assumed. Besides, the multi-band afterglow light curves show an achromatic break at around 33 ks. Based on the model of a hard electron spectrum with an injection break, we interpret the observed spectral break as the synchrotron freq...

  2. Synthesis of ZnS:Ag,Co water-soluble blue afterglow nanoparticles and application in photodynamic activation

    Science.gov (United States)

    Ma, Lun; Zou, Xiaoju; Hossu, Marius; Chen, Wei

    2016-08-01

    Silver and cobalt co-doped ZnS (ZnS:Ag,Co) water-soluble afterglow nanoparticles were synthesized using a wet chemistry method followed by aging at room temperature. The nanoparticles had a cubic zinc blende structure with average sizes of approximately 4 nm and emitted a blue fluorescence emission centered at 441 nm due to radiative transitions from surface defects to Ag+ luminescent centers. Intense afterglow emission peaking at 475 nm from the obtained nanoparticles was observed and was red-shifted compared to the fluorescence emission peak. X-ray photoelectron spectroscopy revealed a large increase of O/S ratio, indicating a surface oxidation process during aging. The S vacancies produced accordingly may contribute to form more electron traps and enhance afterglow. The ZnS:Ag,Co afterglow nanoparticles have a very low dark-toxicity and are applied as a light source for photodynamic therapy activation by conjugating with protoporphyrin together. Our preliminary study has shown that the ZnS:Ag,Co afterglow nanoparticles can significantly reduce the x-ray dosage used in activation and thus may be a very promising candidate for future x-ray excited photodynamic therapy in deep cancer treatment.

  3. The synchrotron-self-Compton radiation accompanying shallow decaying X-ray afterglow: the case of GRB 940217

    CERN Document Server

    Wei, Da-Ming

    2008-01-01

    High energy emission (> tens MeV) of Gamma-Ray Bursts (GRBs) provides an important clue to understand the physical processes involved in GRBs, which may be correlated with the GRB early afterglow. A shallow decline phase has been well detected in about half {\\it Swift} Gamma-ray Burst X-ray afterglows. The widely considered interpretation involves a significant energy injection and possibly time-evolving shock parameter(s). This work we calculate the synchrotron-self-Compton (SSC) radiation of such an external forward shock and show that it could explain the well-known long term high energy (i.e., tens MeV to GeV) afterglow of GRB 940217. We propose that the cooperation of Swift and GLAST will help to reveal the nature of GRBs.

  4. Electromagnetic Afterglows Associated with Gamma-Ray Emission Coincident with Binary Black Hole Merger Event GW150914

    CERN Document Server

    Yamazaki, Ryo; Ohira, Yutaka

    2016-01-01

    Fermi Gamma-ray Burst Monitor detected gamma-ray emission 0.4 sec after a binary black-hole merger event, GW150914. We show that the gamma-ray emission is caused by a relativistic outflow with Lorentz factor larger than 10. Subsequently debris outflow pushes ambient gas to form a shock, which is responsible for the afterglow synchrotron emission. We find that the fluxes of radio and optical afterglows increase from about $10^7$ sec to at least $\\sim10$ yr after the burst trigger. Further follow-up observations in the radio and optical/infrared bands are encouraged. Detection of afterglows will localize the sky position of the gravitational-wave and the gamma-ray emissions and it will support the physical association between them.

  5. The Synchrotron-self-Compton Radiation Accompanying Shallow Decaying X-Ray Afterglow: the Case of GRB 940217

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    High energy emission (> tens MeV) of Gamma-Ray Bursts (GRBs) provides an important clue on the physical processes occurring in GRBs that may be correlated with the GRB early afterglow. A shallow decline phase has been well identified in about half of Swift Gamma-ray Burst X-ray afterglows. The widely considered interpretation involves a significant energy injection and possibly time-evolving shock parameter(s). We calculate the synchrotron-self-Compton (SSC) radiation of such an external forward shock and show that it could explain the well-known long term high energy (i.e., tens MeV to GeV) afterglow of GRB 940217. We propose that cooperation of Swift and GLAST will help to reveal the nature of GRBs.

  6. Multicolor observations of the afterglow of the short/hard GRB 050724

    Science.gov (United States)

    Malesani, D.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Piranomonte, S.; Ballo, L.; Campana, S.; Stella, L.; Tagliaferri, G.; Antonelli, L. A.; Chincarini, G.; Della Valle, M.; Goldoni, P.; Guidorzi, C.; Israel, G. L.; Lazzati, D.; Melandri, A.; Pellizza, L. J.; Romano, P.; Stratta, G.; Vergani, S. D.

    2007-10-01

    Context: New information on short/hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. Aims: We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, and make some inferences on the global short GRB population. Methods: We present optical observations of the afterglow of GRB 050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements from the literature. We study the afterglow light curve and spectrum including X-ray data. We also present observations of the host galaxy. Results: The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet effect. Available data are indeed consistent with low collimation, in turn implying a large energy release, comparable to that of long GRBs. The flare properties also constrain the internal shock mechanism, requiring a large Lorentz factor contrast between the colliding shells. This implies that the central engine was active at late times, rather than ejecting all shells simultaneously. The host galaxy has red colors and no ongoing star formation, consistent with previous findings on this GRB. However, it is not a pure elliptical, and has some faint spiral structure. Conclusions: GRB 050724 provides the most compelling case for association between a short burst and a galaxy with old stellar population. It thus plays a pivotal role in constraining progenitors models, which should allow for long delays between birth and explosion. Based on observations carried out at ESO telescopes under programmes Id 075.D-0787, 075.D-0468 and 078.D-0809.

  7. A High Signal-to-noise Ratio Composite Spectrum of Gamma-ray Burst Afterglows

    Science.gov (United States)

    Christensen, L.; Fynbo, J. P. U.; Prochaska, J. X.; Thöne, C. C.; de Ugarte Postigo, A.; Jakobsson, P.

    2011-02-01

    We present a composite spectrum of 60 long duration gamma-ray burst (GRB) afterglows with redshifts in the range 0.35 composite spectrum covers the wavelength range 700-6600 Å in the rest frame and has a mean signal-to-noise ratio of 150 per 1 Å pixel and reaches a maximum of ~300 in the range 2500-3500 Å. Equivalent widths are measured from metal absorption lines from the Lyα line to ~5200 Å, and associated metal and hydrogen lines are identified between the Lyman break and Lyα line. The average transmission within the Lyman forest is consistent with that found along quasar lines of sight. We find a temporal variation in fine-structure lines when dividing the sample into bursts observed within 2 hr from their trigger and those observed later. Other lines in the predominantly neutral gas show variations too, but this is most likely a random effect caused by weighting of individual strong absorption lines and which mimics a temporal variation. Bursts characterized with high- or low-prompt GRB energy release produce afterglows with similar absorption line strengths, and likewise for bursts with bright or faint optical afterglows. Bursts defined as dark from their optical to X-ray spectral index have stronger absorption lines relative to the optically bright bursts. The composite spectrum has strong Ca II and Mg II absorption lines as commonly found in dusty galaxies, however, we find no evidence for dust or a significant molecular content based on the non-detection of diffuse interstellar bands. Compared to starburst galaxy spectra, the GRB composite has much stronger fine-structure lines, while metal absorption lines are weaker.

  8. The origin of the plateau and late rebrightening in the afterglow of GRB 120326A

    International Nuclear Information System (INIS)

    GRB 120326A is an unusual gamma-ray burst (GRB) that has a long plateau and a very late rebrightening in both X-ray and optical bands. The similar behavior of the optical and X-ray light curves suggests that they may share a common origin. The long plateau starts at several hundred seconds and ends at tens of thousands of seconds, and the peak time of the late rebrightening is about 30,000 s. We analyze the energy injection model by means of numerical and analytical solutions, considering both the wind environment and the interstellar medium environment for GRB afterglows. We particularly study the influence of the injection starting time, ending time, stellar wind density (or density of the circumburst environment), and injection luminosity on the shape of the afterglow light curves, respectively. In the wind model, we find that the light curve is largely affected by the parameters and that there is a 'bump' in the late stage. In the wind environment, we found that the longer the energy is injected, the more obvious the rebrightening will be. We also find that the peak time of the bump is determined by the stellar wind density. We use the late continuous injection model to interpret the unusual afterglow of GRB 120326A. The model fits the observational data well; however, we find that the timescale of the injection must be higher than 10,000 s, which implies that the timescale of the central engine activity must also be more than 10,000 s. This information can give useful constraints on the central engines of GRBs—we consider a newborn millisecond pulsar with a strong magnetic field to be the central engine. On the other hand, our results suggest that the circumburst environment of GRB 120326A is very likely a stellar wind.

  9. The supercritical pile gamma-ray burst model: The GRB afterglow steep decline and plateau phase

    Energy Technology Data Exchange (ETDEWEB)

    Sultana, J. [Mathematics Department, Faculty of Science, University of Malta, Msida MSD2080 (Malta); Kazanas, D. [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mastichiadis, A., E-mail: joseph.sultana@um.edu.mt [Department of Physics, University of Athens, Panepistimiopolis, GR 15783 Zografos (Greece)

    2013-12-10

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the 'supercritical pile' GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E {sub pk} ∼ m{sub e}c {sup 2}. We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Γ to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (∼25%) decrease in Γ at a radius that is smaller (depending on conditions) than the deceleration radius R{sub D} . Because of this reduction, the kinematic criticality criterion of the 'supercritical pile' is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by ∼m{sub p} /m{sub e} than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R{sub D} , the RBW internal energy continues to drive the RBW expansion at a constant (new) Γ and its X-ray luminosity remains constant until R{sub D} is reached, at which point it resumes its more conventional decay, thereby completing the 'unexpected' XRT light curve phase. If this transition occurs at R ≅ R{sub D} , the steep decline is followed by a flux decrease instead of a 'plateau,' consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R ≅ R{sub D} , thus providing novel insights into GRB phenomenology.

  10. The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

    Science.gov (United States)

    Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

    2013-01-01

    We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

  11. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    Science.gov (United States)

    Holland, Stephen T.; De Pasquale, Massimiliano; Mao, Jirong; Sakamoto, Takanori; Schady, Patricia; Covino, Stefano; Fan, Yi-Zhong; Jin, Zhi-Ping; D'Avanzo, Paolo; Antonelli, Angelo; D'Elia, Valerio; Ohincarini, Guido; Fiore, Fabrizio; Pandey, Shashi Bhushan; Cobb, Bethany E.

    2012-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift Ultra Violet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a detailed data set extending from 86 s to approx.100,000 s after the BAT trigger. Our data covers a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18,000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.injection

  12. The plateau phase of gamma-ray burst afterglows in the thick-shell scenario

    Science.gov (United States)

    Leventis, K.; Wijers, R. A. M. J.; van der Horst, A. J.

    2014-01-01

    We present analytic calculations of synchrotron radiation from the forward and the reverse shock of gamma-ray burst blast waves, in the thick-shell scenario (i.e. when the reverse shock is relativistic). We show that this scenario can naturally account for the plateau phase, observed early in the afterglows of about half the bursts detected by Swift. We generalize our approach to include power-law luminosity of the central engine and show that when radiation from both regions (forward and reverse shock) is taken into account, a wide range of possibilities emerge, including chromatic and achromatic breaks, frequency-dependent spectral evolution during the injection break and widely varying decay indices in different bands. For both the forward and the reverse shock, we derive formulas for the spectral parameters and the observed flux in different power-law segments of the spectrum, as a function of observer time. We explore the Fb-tb relation (between the observed time of the end of the plateau phase and the flux at that point) in the framework of the presented model and show that model predictions favour the reverse shock as the dominant source of emission in both optical and X-rays. As case studies, we present simultaneous fits to X-ray and optical/IR afterglow data of GRB 080928 and GRB 090423. We identify the end of the plateau phase with the cessation of energy injection and infer the corresponding upper limits to central-engine activity, which are about 1 h for the former and 1.5 h for the latter. We conclude that smooth energy injection through the reverse shock is a plausible explanation for the plateau phase of gamma-ray burst afterglows. During that phase, radiation from the reverse shock is likely to be important, or even dominant, and should be taken into account when fitting model parameters to observations.

  13. Multicolor observations of the afterglow of the short/hard GRB050724

    International Nuclear Information System (INIS)

    Context. New information on short/ hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. Aims. We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, and make some inferences on the global short GRB population. Methods. We present optical observations of the afterglow of GRB050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements from the literature. We study the afterglow light curve and spectrum including X-ray data. We also present observations of the host galaxy. Results. The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet effect. Available data are indeed consistent with low collimation, in turn implying a large energy release, comparable to that of long GRBs. The flare properties also constrain the internal shock mechanism, requiring a large Lorentz factor contrast between the colliding shells. This implies that the central engine was active at late times, rather than ejecting all shells simultaneously. The host galaxy has red colors and no ongoing star formation, consistent with previous findings on this GRB. However, it is not a pure elliptical, and has some faint spiral structure. Conclusions. GRB 050724 provides the most compelling case for association between a short burst and a galaxy with old stellar population. It thus plays a pivotal role in constraining progenitors models, which should allow for long delays between birth and explosion. (authors)

  14. Multicolor observations of the afterglow of the short/hard GRB050724

    Energy Technology Data Exchange (ETDEWEB)

    Malesani, D. [Univ Copenhagen, Niels Bohr Inst, Dark Cosmol Ctr, DK-2100 Copenhagen 0, (Denmark); Covino, S.; D' Avanzo, P.; Fugazza, D.; Campana, S.; Tagliaferri, G.; Chincarini, G.; Guidorzi, C.; Romano, P. [Osser Astron Brera, INAF, I-23807 Merate (Italy); D' Avanzo, P. [Univ Insubria, Dipartimento Matemat and Fis, I-23807 Merate, LC, (Italy); D' Elia, V.; Piranomonte, S.; Stella, L.; Antonelli, L.A.; Israel, G.L.; Melandri, A. [Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, (Italy); Fugazza, D.; Chincarini, G.; Guidorzi, C.; Romano, P. [Univ Milano Bicocca, Dipartimento Fis, I-20126 Milan, (Italy); Ballo, L. [ESA, European Space Astron Ctr, Madrid 28691, (Spain); Antonelli, L.A.; Stratta, G. [ASI Sci Data Ctr, I-00044 Frascati, (Italy); Della Valle, M. [Osserv Astrofis Arcetri, INAF, I-50125 Florence, (Italy); Della Valle, M. [Univ Calif Santa Barbara, Kavli Inst Theoret Phys, Santa Barbara, CA 93106 (United States); Goldoni, P. [Lab Astrparticule and Cosmol, F-75205 Paris 13, (France); Goldoni, P. [CEA Saclay, DSM, DAPNIA SAp, Serv Astrophys, F-91191 Gif Sur Yvette, (France)] (and others)

    2007-07-01

    Context. New information on short/ hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. Aims. We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, and make some inferences on the global short GRB population. Methods. We present optical observations of the afterglow of GRB050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements from the literature. We study the afterglow light curve and spectrum including X-ray data. We also present observations of the host galaxy. Results. The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet effect. Available data are indeed consistent with low collimation, in turn implying a large energy release, comparable to that of long GRBs. The flare properties also constrain the internal shock mechanism, requiring a large Lorentz factor contrast between the colliding shells. This implies that the central engine was active at late times, rather than ejecting all shells simultaneously. The host galaxy has red colors and no ongoing star formation, consistent with previous findings on this GRB. However, it is not a pure elliptical, and has some faint spiral structure. Conclusions. GRB 050724 provides the most compelling case for association between a short burst and a galaxy with old stellar population. It thus plays a pivotal role in constraining progenitors models, which should allow for long delays between birth and explosion. (authors)

  15. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    Energy Technology Data Exchange (ETDEWEB)

    Nousek, J.A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S.K.; Burrows, D.N.; Mangano, V.; Barthelmy, S.; Beardmore, A.P.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Falcone, A.D.; Gehrels, N.; Giommi, P.; Goad, M.; Godet, O.; Hurkett, C.; /Penn State U., Astron. Astrophys. /NASA, Marshall /Leicester

    2005-08-17

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay ({infinity} t{sup -a} with 3 {approx}< a{sub 1} {approx}< 5) , followed by (2) a very shallow decay (0.2 {approx}< a{sub 2} {approx}< 0.8), and finally (3) a somewhat steeper decay (1 {approx}< a{sub 3} {approx}< 1.5). These power law segments are separated by two corresponding break times, 300 s {approx}< t{sub break,1} {approx}< 500 s and 10{sup 3} s {approx}< t{sub break,2} {approx}< 10{sup 4} s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (t{sub break,1}) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a{sub 2}) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (t{sub break,2}). This energy injection increases the energy of the afterglow shock by at least a factor of f {approx}> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  16. The origin of the plateau and late rebrightening in the afterglow of GRB 120326A

    Energy Technology Data Exchange (ETDEWEB)

    Hou, S. J.; Lu, J. F. [Department of Astronomy and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, Fujian 361005 (China); Geng, J. J.; Wang, K.; Huang, Y. F.; Dai, Z. G. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: xfwu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2014-04-20

    GRB 120326A is an unusual gamma-ray burst (GRB) that has a long plateau and a very late rebrightening in both X-ray and optical bands. The similar behavior of the optical and X-ray light curves suggests that they may share a common origin. The long plateau starts at several hundred seconds and ends at tens of thousands of seconds, and the peak time of the late rebrightening is about 30,000 s. We analyze the energy injection model by means of numerical and analytical solutions, considering both the wind environment and the interstellar medium environment for GRB afterglows. We particularly study the influence of the injection starting time, ending time, stellar wind density (or density of the circumburst environment), and injection luminosity on the shape of the afterglow light curves, respectively. In the wind model, we find that the light curve is largely affected by the parameters and that there is a 'bump' in the late stage. In the wind environment, we found that the longer the energy is injected, the more obvious the rebrightening will be. We also find that the peak time of the bump is determined by the stellar wind density. We use the late continuous injection model to interpret the unusual afterglow of GRB 120326A. The model fits the observational data well; however, we find that the timescale of the injection must be higher than 10,000 s, which implies that the timescale of the central engine activity must also be more than 10,000 s. This information can give useful constraints on the central engines of GRBs—we consider a newborn millisecond pulsar with a strong magnetic field to be the central engine. On the other hand, our results suggest that the circumburst environment of GRB 120326A is very likely a stellar wind.

  17. Nitric oxide kinetics in the afterglow of a diffuse plasma filament

    Science.gov (United States)

    Burnette, D.; Montello, A.; Adamovich, I. V.; Lempert, W. R.

    2014-08-01

    A suite of laser diagnostics is used to study kinetics of vibrational energy transfer and plasma chemical reactions in a nanosecond pulse, diffuse filament electric discharge and afterglow in N2 and dry air at 100 Torr. Laser-induced fluorescence of NO and two-photon absorption laser-induced fluorescence of O and N atoms are used to measure absolute, time-resolved number densities of these species after the discharge pulse, and picosecond coherent anti-Stokes Raman spectroscopy is used to measure time-resolved rotational temperature and ground electronic state N2(v = 0-4) vibrational level populations. The plasma filament diameter, determined from plasma emission and NO planar laser-induced fluorescence images, remains nearly constant after the discharge pulse, over a few hundred microseconds, and does not exhibit expansion on microsecond time scale. Peak temperature in the discharge and the afterglow is low, T ≈ 370 K, in spite of significant vibrational nonequilibrium, with peak N2 vibrational temperature of Tv ≈ 2000 K. Significant vibrational temperature rise in the afterglow is likely caused by the downward N2-N2 vibration-vibration (V-V) energy transfer. Simple kinetic modeling of time-resolved N, O, and NO number densities in the afterglow, on the time scale longer compared to relaxation and quenching time of excited species generated in the plasma, is in good agreement with the data. In nitrogen, the N atom density after the discharge pulse is controlled by three-body recombination and radial diffusion. In air, N, NO and O concentrations are dominated by the reverse Zel'dovich reaction, N + NO → N2 + O, and ozone formation reaction, O + O2 + M → O3 + M, respectively. The effect of vibrationally excited nitrogen molecules and excited N atoms on NO formation kinetics is estimated to be negligible. The results suggest that NO formation in the nanosecond pulse discharge is dominated by reactions of excited electronic states of nitrogen, occurring on

  18. Delayed X-Ray Afterglows from Obscured Gamma-Ray Bursts in Star-Forming Regions

    OpenAIRE

    Meszaros, P.; Gruzinov, A.

    2000-01-01

    For Gamma-Ray Bursts occurring in dense star-forming regions, the X-ray afterglow behavior minutes to days after the trigger may be dominated by the small-angle scattering of the prompt X-ray emission off dust grains. We give a simple illustrative model for the X-ray light curves at different X-ray energies, and discuss possible implications. A bump followed by a steeper decay in soft X-rays is predicted for bursts which are heavily obscured in the optical.

  19. Self-organized criticality in X-ray flares of gamma-ray burst afterglows

    OpenAIRE

    Wang, F.Y.; Dai, Z. G.

    2013-01-01

    X-ray flares detected in nearly half of gamma-ray burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues to the nature of the central engines of GRBs, an...

  20. Direct and bulk-scattered forward-shock emissions: sources of X-ray afterglow diversity

    OpenAIRE

    Panaitescu, A.

    2008-01-01

    I describe the modifications to the standard forward-shock model required to account for the X-ray light-curve features discovered by Swift in the early afterglow emission and propose that a delayed, pair-enriched, and highly relativistic outflow, which bulk-scatters the forward-shock synchrotron emission, yields sometimes a brighter X-ray emission, producing short-lived X-ray flares, X-ray light-curve plateaus ending with chromatic breaks, and fast post-plateau X-ray decays.

  1. Plastic damping of Alfv\\'en waves in magnetar flares and delayed afterglow emission

    CERN Document Server

    Li, Xinyu

    2015-01-01

    Magnetar flares generate Alfv\\'en waves bouncing in the closed magnetosphere with energy up to $\\sim 10^{46}$ erg. We show that on a 10-ms timescale the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  2. Iron lines in the X-ray afterglows of Gamma-ray bursts

    Science.gov (United States)

    Piro, L.

    1998-12-01

    X-ray measurements of iron lines can provide a powerful diagnostics of the environment of Gamma-ray bursts, thus enlightening the still misterious nature of the central engine powering these phenomena. Furthermore, they would allow a direct measurement of the distance of the GRB, bypassing completely the long chain of steps that, from the Gamma and X-ray localization, brings to the optical determination of the redshift. In this contribution we will present the results of a search of this feature in the BeppoSAX X-ray afterglows of GRB. We will discuss their implication for near future missions, as AXAF and XMM.

  3. Optical-infrared flares and radio afterglows from the tidal disruption of Jovian planets by their host star

    CERN Document Server

    Yamazaki, Ryo; Loeb, Abraham

    2015-01-01

    When a Jovian planet gets sufficiently close to its host star to be tidally disrupted, its debris stream deposits energy on the star's surface, producing an expanding bubble of hot plasma. We study the radiation from the bubble and show that it includes optical-infrared prompt emission and a subsequent radio afterglow. The prompt emission from M31 and Large Magellanic Cloud is detectable by optical-near infrared transient surveys with a large field of view at an event rate of a few events per year. The subsequent radio afterglows are detectable for $10^{3-4}$~years.

  4. Failed Gamma-Ray Bursts: Thermal UV/Soft X-ray Emission Accompanied by Peculiar Afterglows

    CERN Document Server

    Xu, M; Huang, Y -F; Lee, S -H

    2011-01-01

    We show that the photospheres of "failed" Gamma-Ray Bursts (GRBs), whose bulk Lorentz factors are much lower than 100, can be outside of internal shocks. The resulting radiation from the photospheres is thermal and bright in UV/Soft X-ray band. The photospheric emission lasts for about one thousand seconds with luminosity about several times 10^46 erg/s. These events can be observed by current and future satellites. It is also shown that the afterglows of failed GRBs are peculiar at the early stage, which makes it possible to distinguish failed GRBs from ordinary GRBs and beaming-induced orphan afterglows.

  5. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    Science.gov (United States)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

  6. Study of GRB light curve decay indices in the afterglow phase

    CERN Document Server

    Del Vecchio, Roberta; Ostrowski, Michał

    2016-01-01

    In this work we study the distribution of temporal power-law decay indices, $\\alpha$, in the Gamma Ray Burst (GRB) afterglow phase, fitted for $176$ GRBs (139 long GRBs, 12 short GRBs {\\it with extended emission} and 25 X-Ray Flashes (XRFs)) with known redshifts. These indices are compared to the values of characteristic afterglow luminosity, $L_a$, the time, $T_a^*$, and the decay index, $\\alpha_W$, derived with global light curve fitting using the \\cite{willingale07} model. This model fitting yields similar distributions of $\\alpha_W$ to the fitted $\\alpha$, but for individual bursts a difference can be significant. Analysis of the ($\\alpha$, $L_a$) distribution reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB $\\alpha$ values along the $L_a$ versus $T_a^*$ (LT) distribution, with systematic variation of $\\alpha$ parameter distribution with luminosity for any selected $T_a^*$. We analyze this systematics with respect to the fitted LT co...

  7. GRB 070125 and the environments of spectral-line poor afterglow absorbers

    CERN Document Server

    De Cia, A; Wiersema, K; van der Horst, A J; Vreeswijk, P M; Björnsson, G; Postigo, A de Ugarte; Jakobsson, P; Levan, A J; Rol, E; Schulze, S; Tanvir, N R

    2011-01-01

    GRB 070125 is among the most energetic bursts detected and the most extensively observed so far. Nevertheless, unresolved issues are still open in the literature on the physics of the afterglow and on the GRB environment. In particular, GRB 070125 was claimed to have exploded in a galactic halo environment, based on the uniqueness of the optical spectrum and the non-detection of an underlying host galaxy. In this work we collect all publicly available data and address these issues by modelling the NIR-to-X-ray spectral energy distribution (SED) and studying the high signal-to-noise VLT/FORS afterglow spectrum in comparison with a larger sample of GRB absorbers. The SED reveals a synchrotron cooling break in the UV, low equivalent hydrogen column density and little reddening caused by a LMC- or SMC-type extinction curve. From the weak MgII absorption at z=1.5477 in the spectrum, we derived logN(MgII)=12.96+0.13-0.18 and upper limits on the ionic column density of several metals. These suggest that the GRB abso...

  8. Discovery and identification of the very high redshift afterglow of GRB 050904

    CERN Document Server

    Haislip, J; Reichart, D; Levan, A; Tanvir, N; Cenko, S; Fox, D; Price, P; Castro-Tirado, A J; Gorosabel, J; Evans, C; Figueredo, E; MacLeod, C; Kirschbrown, J; Jelinek, M; Guziy, S; De Postigo, A U; Cypriano, E S; La Cluyze, A; Graham, J; Priddey, R; Chapman, R; Rhoads, J; Fruchter, A; Lamb, D; Kouveliotou, C; Wijers, R A M J; Schmidt, B; Soderberg, A M; Kulkarni, S; Harrison, F; Moon, D; Gal-Yam, A; Kasliwal, M; Hudec, R; Vítek, S; Kubánek, P; Crain, J; Foster, A; Bayliss, M; Clemens, J; Bartelme, J

    2005-01-01

    In 2000, Lamb and Reichart predicted that gamma-ray bursts (GRBs) and their afterglows occur in sufficient numbers and at sufficient brightnesses at very high redshifts (z > 5) to eventually replace quasars as the preferred probe of element formation and reionization in the early universe and to be used to characterize the star-formation history of the early universe, perhaps back to when the first stars formed. Here we report the discovery of the afterglow of GRB 050904 and the identification of GRB 050904 as the first very high redshift GRB. We measure its redshift to be 6.39(+0.11,-0.12), which is consistent with the reported spectroscopic redshift (6.29 +/- 0.01). Furthermore, just redward of Ly-alpha the flux is suppressed by a factor of three on the first night, but returns to expected levels by the fourth night. We propose that this is due to absorption by molecular hydrogen that was excited to rovibrational states by the GRB's prompt emission, but was then overtaken by the jet. Now that very high reds...

  9. Winds from massive stars implications for the afterglows of gamma-ray bursts

    CERN Document Server

    Ramirez-Ruiz, E; Madau, P; Tout, C A; Ramirez-Ruiz, Enrico; Dray, Lynnette M.; Madau, Piero; Tout, Christopher A.

    2001-01-01

    Recent observations suggest that long-duration gamma-ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in core-collapse explosions. The pre-explosive ambient medium provides a natural test for the most likely progenitors of GRBs. Those stars that shed their envelopes most readily have short jet crossing times and are more likely to produce a GRB. We construct a simple computational scheme to explore the expected contribution of the presupernova ejecta of single Wolf-Rayet (WR) stars to the circumstellar environment. Using detailed stellar tracks for the evolution of massive stars, we discuss the effects that the initial main sequence mass, metallicity, rotation and membership in a binary system have on the ambient medium. We extend the theory of GRB afterglows in winds to consider the effect of the relativistic fireball propagating through the WR ejecta. We make specific predictions for the interaction of the relativistic blast wave with the density bumps that arise when ...

  10. The unusual radio afterglow of the ultra-long gamma-ray burst GRB 130925A

    CERN Document Server

    Horesh, Assaf; Perley, Daniel A; Kulkarni, S R; Hallinan, Gregg; Bellm, Eric

    2015-01-01

    GRB 130925A is one of the recent additions to the growing family of ultra-long GRBs (T90$ \\gtrsim 1000$ s). While the X-ray emission of ultra-long GRBs have been studied extensively in the past, no comprehensive radio dataset has been obtained so far. We report here the early discovery of an unusual radio afterglow associated with the ultra-long GRB 130925A. The radio emission peaks at low-frequencies ($\\sim 7$ GHz) at early times, only $2.2$ days after the burst occurred. More notably, the radio spectrum at frequencies above $10$ GHz exhibits a rather steep cut-off, compared to other long GRB radio afterglows. This cut-off can be explained if the emitting electrons are either mono-energetic or originate from a rather steep, $dN/dE \\propto E^{-4}$, power-law energy distribution. An alternative electron acceleration mechanism may be required to produce such an electron energy distribution. Furthermore, the radio spectrum exhibits a secondary underlying and slowly varying component. This may hint that the radio...

  11. REMIR: The REM infrared camera to follow up the early phases of GRBs afterglows

    Science.gov (United States)

    Calzoletti, L.; Melandri, A.; Testa, V.; Antonelli, L. A.; Vitali, F.; D'Alessio, F.; di Paola, A.; Zerbi, F. M.; Chincarini, G.; Cunniffe, R.; Jordan, B.; Rodonò, M.; Conconi, P.; Covino, S.; Cutispoto, G.; Molinari, E.; Tosti, G.; Ross/Rem Team

    2005-07-01

    REMIR is a near-infrared camera, covering the 0.95-2.3 μm range with 5 filters (z,J,H,Ks and H2), mounted at one of the Nasmyth foci of the REM (Rapid Eye Mount) telescope. REM is a fully robotic fast-slewing 60 cm telescope, primarily designed to follow-up the early phases of the afterglow of GRBs detected by dedicated instruments onboard satellites (like SWIFT, a satellite entirely dedicated to GRBs science launched the 12 November 2004). Moreover REM hosts a slitless spectrograph covering the range 0.45-0.95 μm, with 30 sample points and with the possibility to perform broad-band V,R,I photometry (ROSS, REM Optical Slitless Spectrograph). The main task of REMIR is to perform realtime NIR observations of GRBs detected by gamma-ray monitors onboard satellites, looking for any possible infrared transient source. As soon as a transient source is detected in the IR images, larger telescopes are promptly alerted to perform early spectroscopy of the afterglow. All the above operations are performed in a fully automatic way and without any human supervision. We present the results of on-site tests that have been done to characterize the REMIR camera and the performances of the dedicated reduction pipeline AQuA (Automatic Quick Analysis), suited for fast transients detection.

  12. Very early multi-color observations of the plateau phase of GRB 041006 afterglow

    CERN Document Server

    Urata, Y; Qiu, Y L; Hu, J; Kuo, P H; Tamagawa, T; Ip, W H; Kinoshita, D; Fukushi, H; Isogai, M; Miyata, T; Nakada, Y; Aoki, T; Soyano, T; Tarusawa, K; Mito, H; Onda, K; Ibrahimov, M; Pozanenko, A; Makishima, K

    2006-01-01

    Observations of the optical afterglow of GRB 041006 with the Kiso Observatory 1.05 m Schmidt telescope, the Lulin Observatory 1.0 m telescope and the Xinglong Observatory 0.6 m telescope. Three-bands (B, V and R) of photometric data points were obtained on 2004 October 6, 0.025-0.329 days after the burst. These very early multi band light curves imply the existence of a color dependent plateau phase. The B-band light curve shows a clear plateau at around 0.03 days after the burst. The R band light curve shows the hint of a plateau, or a possible slope change, at around 0.1 days after the burst. The overall behavior of these multi-band light curves may be interpreted in terms of the sum of two separate components, one showing a monotonic decay the other exhibiting a rising and a falling phase, as described by the standard afterglow model.

  13. Swift and Suzaku Observations of the X-Ray Afterglow from the GRB 060105

    CERN Document Server

    Tashiro, M S; Angelini, L; Barthelmy, S; Gehrels, N; Ishikawa, N; Kaluzienski, L J; Kawai, N; Kelley, R L; Kinugasa, K; Kodaira, H; Kohmura, T; Kubota, K; Maeda, Y; Maeno, S; Murakami, H; Murakami, T; Nakagawa, Y E; Nakazawa, K; Nousek, J; Okuno, S; Onda, K; Reeves, J N; Ricker, G; Sato, G; Sonoda, E; Suzuki, M; Takahashi, T; Tamagawa, T; Torii, K; Ueda, Y; Urata, Y; Yamaoka, K; Yamauchi, M; Yonetoku, D; Yoshida, A; Yoshinari, S

    2006-01-01

    Results are presented of early X-ray afterglow observations of GRB 060105 by Swift and Suzaku. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope (BAT) at 06:49:28 on 5 January 2006. The Suzaku team commenced a pre-planned target of opportunity observation at 19 ks (5.3 hr) after the Swift trigger. Following the prompt emission and successive very steep decay, a shallow decay was observed from T_0+187 s to T_0+1287 s. After an observation gap during T_0 +(1.5-3) ks, an extremely early steep decay was observed in T_0+(4-30) ks. The lightcurve flattened again at T_0+30 ks, and another steep decay followed from T_0+50 ks to the end of observations. Both steep decays exhibited decay indices of 2.3 - 2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below 1 degree. The unique Suzaku/XIS data allow us to set very tight upper limits on line emission or absorption in thi...

  14. REMIR: the REM infrared camera to follow up the early phases of GRBs afterglows

    International Nuclear Information System (INIS)

    REMIR is a near-infrared camera, covering the 0.95-2.3 μm range with 5 filters (z, J, H, Ks and H2), mounted at one of the Nasmyth foci of the REM (Rapid Eye Mount) telescope. REM is a fully robotic fast-slewing 60 cm telescope, primarily designed to follow-up the early phases of the afterglow of GRBs detected by dedicated instruments onboard satellites (like SWIFT, a satellite entirely dedicated to GRBs science launched the 12 November 2004). Moreover REM hosts a slitless spectrograph covering the range 0.45-0.95 μm, with 30 sample points and with the possibility to perform broad-band V, R, I photometry (ROSS, REM Optical Slitless Spectrograph). The main task of REMIR is to perform realtime NIR observations of GRBs, detected by gamma-ray monitors onboard satellites, looking for any possible infrared transient source. As soon as a transient source is detected in the IR images, larger telescope are promptly alerted to perform early spectroscopy of the afterglow. All the above operations are performed in a fully automatic way and without any human supervision. We present the results of on-site tests that have been done to characterize the REMIR camera and the performances of the dedicated reduction pipeline AQuA (Automatic Quick Analysis), suited for fast transients detection

  15. Applying an accurate spherical model to gamma-ray burst afterglow observations

    Science.gov (United States)

    Leventis, K.; van der Horst, A. J.; van Eerten, H. J.; Wijers, R. A. M. J.

    2013-05-01

    We present results of model fits to afterglow data sets of GRB 970508, GRB 980703 and GRB 070125, characterized by long and broad-band coverage. The model assumes synchrotron radiation (including self-absorption) from a spherical adiabatic blast wave and consists of analytic flux prescriptions based on numerical results. For the first time it combines the accuracy of hydrodynamic simulations through different stages of the outflow dynamics with the flexibility of simple heuristic formulas. The prescriptions are especially geared towards accurate description of the dynamical transition of the outflow from relativistic to Newtonian velocities in an arbitrary power-law density environment. We show that the spherical model can accurately describe the data only in the case of GRB 970508, for which we find a circumburst medium density n ∝ r-2. We investigate in detail the implied spectra and physical parameters of that burst. For the microphysics we show evidence for equipartition between the fraction of energy density carried by relativistic electrons and magnetic field. We also find that for the blast wave to be adiabatic, the fraction of electrons accelerated at the shock has to be smaller than 1. We present best-fitting parameters for the afterglows of all three bursts, including uncertainties in the parameters of GRB 970508, and compare the inferred values to those obtained by different authors.

  16. Multiwavelength Observations of GRB 110731A: GeV Emission from Onset to Afterglow

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Asano, K.; Baldini, L.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bellazzini, R.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Knödlseder, J.; Kocevski, D.; 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.; Mészáros, P.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romoli, C.; Roth, M.; Ryde, F.; Sanchez, D. A.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spinelli, P.; Stamatikos, M.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Gruber, D.; Bhat, P. N.; Bissaldi, E.; Briggs, M. S.; Burgess, J. M.; Connaughton, V.; Foley, S.; Kippen, R. M.; Kouveliotou, C.; McBreen, S.; McGlynn, S.; Paciesas, W. S.; Pelassa, V.; Preece, R.; Rau, A.; van der Horst, A. J.; von Kienlin, A.; Kann, D. A.; Filgas, R.; Klose, S.; Krühler, T.; Fukui, A.; Sako, T.; Tristram, P. J.; Oates, S. R.; Ukwatta, T. N.; Littlejohns, O.

    2013-02-01

    We report on the multiwavelength observations of the bright, long gamma-ray burst GRB 110731A, by the Fermi and Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that GRB 110731A shares many features with bright Large Area Telescope bursts observed by Fermi during the first three years on-orbit: a light curve with short time variability across the whole energy range during the prompt phase, delayed onset of the emission above 100 MeV, extra power-law component and temporally extended high-energy emission. In addition, this is the first GRB for which simultaneous GeV, X-ray, and optical data are available over multiple epochs beginning just after the trigger time and extending for more than 800 s, allowing temporal and spectral analysis in different epochs that favor emission from the forward shock in a wind-type medium. The observed temporally extended GeV emission is most likely part of the high-energy end of the afterglow emission. Both the single-zone pair transparency constraint for the prompt signal and the spectral and temporal analysis of the forward-shock afterglow emission independently lead to an estimate of the bulk Lorentz factor of the jet Γ ~ 500-550.

  17. A possible Macronova in the late afterglow of the `long-short' burst GRB 060614

    CERN Document Server

    Yang, Bin; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-01-01

    GRB 060614 was a unique burst straddling both long and short duration gamma-ray bursts and its physical origin is still debated. Here we re-examine the afterglow data of GRB 060614 and find a significant F814W-band excess at $t\\sim 13.6$ day after the burst observed by the {\\it Hubble Space Telescope (HST)}. This corresponds to an extremely-low luminosity $\\sim 3\\times 10^{40}~{\\rm erg~s^{-1}}$. The excess component has a very red spectrum and a rapid decline, both unexpected within the present theoretical framework of afterglow. We examine two possible sources of this signal$-$a very weak supernova and a Li-Paczynski Macronova/kilonova. We find that the observed signal is incompatible with a weak supernova. However, it is compatible with the ejection of $\\sim 0.03-0.1~M_\\odot$ of $r-$process material. If this interpretation is correct GRB 060614 arose from a compact binary (most likely a black hole$-$neutron star but also possibly a double neutron star) merger.

  18. Signature of gravitational radiation in afterglow of short Gamma-Ray Bursts?

    CERN Document Server

    Fan, Yi-Zhong; Wei, Da-Ming

    2013-01-01

    Short Gamma-Ray Bursts (GRBs) are brief intense emission of $\\gamma-$rays characterized by a duration shorter than 2 seconds and some, if not all of them, are likely powered by the coalescence of binary neutron stars. Sometimes the remnants may be supramassive highly-magnetized neutron stars (magnetars) with a typical rotational period $P_0 \\sim 1$ ms and the rapid rotation prevents the gravitational collapse until a good fraction of the rotational energy has been lost. Plausible observational evidence for the short-living magnetar central engine reported in the literature is the X-ray plateaus followed by an abrupt decline identified in some short GRB afterglow. We however find that with a moderate/high radiation efficiency favored by the very dim optical afterglow emission, the observed duration of some X-ray plateaus are significantly shorter than that expected in the dipole radiation model (i.e., the magnetar collapsed considerably earlier than the prediction of the pure dipole radiation). We suggest that...

  19. Evidence for Supernova-Synthesised Dust from the Rising Afterglow of GRB 071025 at z~5

    CERN Document Server

    Perley, Daniel A; Klein, C R; Covino, S; Minezaki, T; Wozniak, P; Vestrand, W T; Williams, G G; Milne, P; Butler, N R; Updike, A C; Krühler, T; Afonso, P; Antonelli, A; Cowie, L; Ferrero, P; Greiner, J; Kakazu, Y; Yoldas, A Küpcü; Morgan, A N; Price, P A; Prochaska, J X; Yoshii, Y

    2009-01-01

    We present observations and analysis of the broadband afterglow of Swift GRB 071025. Using optical and infrared (RIYJHK) photometry, we derive a photometric redshift of 4.4 < z < 5.2; at this redshift our simultaneous multicolour observations begin at ~30 s after the GRB trigger in the host frame and during the initial rising phase of the afterglow. We associate the light curve peak at 580 s in the observer frame with the formation of the forward shock, giving an estimate of the initial Lorentz factor Gamma_0 ~ 200. The red spectral energy distribution (even in regions not affected by the Lyman-alpha break) provides secure evidence of a large dust column. However, the inferred extinction curve shows a prominent flat component between 2000-3000 Angstroms in the rest-frame, inconsistent with any locally observed template but well-fit by models of dust formed by supernovae. Time-dependent fits to the extinction profile reveal no evidence of dust destruction and limit the decrease in the extinction column t...

  20. Discovery of the optical afterglow of XRF 040812: VLT and Chandra observations

    CERN Document Server

    D'Avanzo, P; Campana, S; Covino, S; Moretti, A; Tagliaferri, G; Chincarini, G

    2006-01-01

    We present Chandra and VLT observations of the X-Ray Flash XRF 040812. The X-ray analysis reveals with high precision the position of a hard, fading source. A careful analysis of our I-band VLT images taken starting 17 hours after the burst led to the discovery of the optical afterglow superimposed to a bright (I=21.5) host galaxy. The optical afterglow is seen decaying with an index of 1.1. We do not detect any jet break and supernova rebrightening in the optical light curve. The bright apparent luminosity of the host galaxy allows us to get a rough estimate of the redshift, comparing with a set of GRB/XRF host galaxies with known luminosity and redshift. Such comparison suggests a redshift of XRF 040812 in the range 0.3

  1. Correlated optical and X-ray flares in the afterglow of XRF 071031

    CERN Document Server

    Krühler, T; McBreen, S; Klose, S; Rossi, A; Afonso, P; Clemens, C; Filgas, R; Yoldas, A Küpcü; Szokoly, G P; Yoldas, A

    2009-01-01

    We present a densely sampled early light curve of the optical/near-infrared (NIR) afterglow of the X-Ray Flash (XRF) 071031 at z=2.692. Simultaneous and continuous observations in seven photometric bands from g' to K with GROND at the 2.2 m MPI/ESO telescope on LaSilla were performed between 4 minutes and 7 hours after the burst. The light curve consists of 547 individual points which allows us to study the early evolution of the optical transient associated with XRF 071031 in great detail. The optical/NIR light curve is dominated by an early increase in brightness which can be attributed to the apparent onset of the forward shock emission. There are several bumps which are superimposed onto the overall rise and decay. Significant flaring is also visible in the Swift X-Ray Telescope (XRT) light curve from early to late times. The availability of high quality, broadband data enables detailed studies of the connection between the X-ray and optical/NIR afterglow and its colour evolution during the first night po...

  2. VLT/X-shooter spectroscopy of the GRB 120327A afterglow

    CERN Document Server

    D'Elia, V; Goldoni, P; Covino, S; Postigo, A de Ugarte; Ledoux, C; Calura, F; Gorosabel, J; Malesani, D; Sanchez-Ramirez, F Matteucci R; Savaglio, S; Castro-Tirado, A J; Hartoog, O E; Kaper, L; Munoz-Darias, T; Pian, E; Piranomonte, S; Tagliaferri, G; Tanvir, N; Vergani, S D; Watson, D J; Xu, D

    2014-01-01

    We present a study of the environment of the Swift long gamma-ray burst GRB 120327A at z ~2.8 through optical spectroscopy of its afterglow. We analyzed medium-resolution, multi-epoch spectroscopic observations (~7000 - 12000, corresponding to ~ 15 - 23 km/s, S/N = 15- 30 and wavelength range 3000-25000AA) of the optical afterglow of GRB 120327A, taken with X-shooter at the VLT 2.13 and 27.65 hr after the GRB trigger. The first epoch spectrum shows that the ISM in the GRB host galaxy at z = 2.8145 is extremely rich in absorption features, with three components contributing to the line profiles. The hydrogen column density associated with GRB 120327A has log NH / cm^(-2) = 22.01 +/- 0.09, and the metallicity of the host galaxy is in the range [X/H] = -1.3 to -1.1. In addition to the ground state lines, we detect absorption features associated with excited states of CII, OI, SiII, FeII, and NiII, which we used to derive information on the distance between the host absorbing gas and the site of the GRB explosion...

  3. Emission and afterglow properties of an expanding RF plasma with nonuniform neutral gas density

    Science.gov (United States)

    Chaplin, Vernon H.; Bellan, Paul M.

    2016-08-01

    We describe some notable aspects of the light emission and afterglow properties in pulsed, high-density ( 1018-1020 m-3 ) argon inductively coupled discharges initiated following fast gas injection. The plasma was created in a long, narrow discharge tube and then expanded downstream of the radiofrequency (RF) antenna into a large chamber. Fast camera images of the expanding plasma revealed a multi-phase time-dependent emission pattern that did not follow the ion density distribution. Dramatic differences in visible brightness were observed between discharges with and without an externally applied magnetic field. These phenomena were studied by tracking excited state populations using passive emission spectroscopy and are discussed in terms of the distinction between ionizing and recombining phase plasmas. Additionally, a method is presented for inferring the unknown neutral gas pressure in the discharge tube from the time-dependent visible and infrared emission measured by a simple photodiode placed near the antenna. In magnetized discharges created with fast gas injection, the downstream ion density rose by Δni˜1018 m-3 in the first ˜100 μs after the RF power was turned off. The conditions conducive to this afterglow density rise are investigated in detail, and the effect is tentatively attributed to pooling ionization.

  4. Study of a Population of Gamma-ray Bursts with Low-Luminosity Afterglows

    CERN Document Server

    Dereli, Hüsne

    2015-01-01

    Gamma-ray bursts (GRB) are extreme events. They are crudely classified into two groups based on their duration, namely the short and long bursts. Such a classification has proven to be useful to determine their progenitors: the merger of two compact objects for short bursts and the explosion of a massive star for long bursts. Further classifying the long GRBs might give tighter constraints on their progenitor and on the emission mechanism(s). In my thesis, I present evidence for the existence of a sub-class of long GRBs, based on their faint afterglow emission. These bursts were named low-luminosity afterglow (LLA) GRBs. I discuss the data analysis and the selection method, and their main properties are described. Their link to supernova is strong as 64% of all the bursts firmly associated to SNe are LLA GRBs. Finally, I present additional properties of LLA GRBs: the study of their rate density, which seems to indicate a new distinct third class of events, the properties of their host galaxies, which show tha...

  5. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    Science.gov (United States)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

  6. The Afterglow and Host Galaxy of the Energetic Short-Hard Gamma-Ray Burst 051221

    CERN Document Server

    Soderberg, A M; Cenko, S B; Fox, D B; Frail, D A; Gal-Yam, A; Kasliwal, M; Kulkarni, S R; Price, P A; Roth, K C; Schmidt, B P

    2006-01-01

    We present detailed optical, X-ray and radio observations of the bright afterglow of the short GRB051221 and an optical spectrum from which we measure the redshift of the burst, z=0.5459. The isotropic-equivalent prompt energy release was about 2.4 x 10^51 erg, and using the standard afterglow synchrotron model we find that the blastwave kinetic energy is similar, E_{KE,iso}~1.4 x 10^51 erg. The lack of an observed jet break to t~13 days indicates that the opening angle is > 13 deg and the total beaming-corrected energy is > 1 x 10^50 erg, at least an order of magnitude larger than for previous short GRBs. We further show that the burst experienced an episode of energy injection by a factor of 3.4 between t=1.4 and 3.4 hours, which was accompanied by reverse shock emission in the radio band. This result provides continued evidence that the central engines of short GRBs may be active significantly longer than the duration of the burst and/or produce a wide range of Lorentz factors. Finally, we show that the ho...

  7. Off-Axis Afterglow Light Curves from High-Resolution Hydrodynamical Jet Simulations

    CERN Document Server

    van Eerten, H J; Zhang, W

    2011-01-01

    Numerical jet simulations serve a valuable role in calculating gamma-ray burst afterglow emission beyond analytical approximations. Here we present the results of high resolution 2D simulations of decelerating relativistic jets performed using the RAM adaptive mesh refinement relativistic hydrodynamics code. We have applied a separate synchrotron radiation code to the simulation results in order to calculate light curves at frequencies varying from radio to X-ray for observers at various angles from the jet axis. We provide a confirmation from radio light curves from simulations rather than from a simplified jet model for earlier results in the literature finding that only a very small number of local Ibc supernovae can possibly harbor an orphan afterglow. Also, recent studies have noted an unexpected lack of observed jet breaks in the Swift sample. Using a jet simulation with physical parameters representative for an average Swift sample burst, such as a jet half opening angle of 0.1 rad and a source redshif...

  8. Estimates for Lorentz factors of gamma-ray bursts from early optical afterglow observations

    CERN Document Server

    Hascoet, R; Daigne, F; Mochkovitch, R

    2013-01-01

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Gamma of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Gamma. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Gamma and the burst luminosity L_gamma does not hold. However, the data clearly shows a lower bound Gamma_min which increases with L_gamma. We suggest an explanation for this feature: explosions with large jet luminosities and Gamma < Gamma_min suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation we examine the effect of adiabatic cooling on the GRB location in the L_gamma - Gamma plane using a Monte Carlo simulation of the GRB population. Our results predict detectable...

  9. Robust photometric redshift determinations of gamma-ray burst afterglows at z > 2

    CERN Document Server

    Curran, P A; Heemskerk, M H M; Starling, R L C; Wiersema, K; Van der Horst, A J

    2008-01-01

    Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Here we introduce our code, GRBz, a method of simultaneous multi-parameter fitting of GRB afterglow optical and near infrared, spectral energy distributions. It allows for early determinations of the photometric redshift, spectral index and host extinction to be made. We assume that GRB afterglow spectra are well represented by a power-law decay and model the effects of absorption due to the Lyman forest and host extinction. We use a genetic algorithm-based routine to simultaneously fit the parameters of interest, and a Monte Carlo error analysis. We use GRBs of previously determined spectroscopic redshifts to prove our method, while also introducing new near infrared data of GRB 990510 which further constrains the value of the host extinction. Our method is effective in estimating the photome...

  10. The nature of HI absorbers in GRB afterglows: clues from hydrodynamic simulations

    CERN Document Server

    Pontzen, Andrew; Governato, Fabio; Pettini, Max; Wadsley, James; Quinn, Thomas; Brooks, Alyson; Bellovary, Jillian; Fynbo, Johan

    2009-01-01

    In recent work, we have shown that it is possible to link quantitatively many aspects of damped Lyman alpha (DLA) absorbers in the spectra of quasars to high resolution simulations of galaxy formation. Using runs from the same series of hydrodynamic numerical studies, we consider the expected properties of Lyman alpha absorbers seen in the spectra of high redshift (z>2) gamma ray burst afterglows (GRB-DLAs). If GRBs are associated with the death of massive stars, their afterglows provide insights into otherwise unprobed regions of protogalactic objects, but detailed physical interpretations are currently embryonic. We find that median impact parameters (measured from the potential minimum) are approximately 1 kpc for GRBs compared with 4 kpc for QSO-DLAs. However, an equally important difference is that GRB-DLAs are predominantly associated with halos of mass 10^1010^19 cm^-2, but they somewhat underpredict the incidence of low column densities N_HI<10^19 cm^-2. Line-of-sight neutral gas metallicities pred...

  11. Optical observations of GRB 060124 afterglow: A case for an injection break

    CERN Document Server

    Misra, K; Sahu, D K; Sagar, R; Anupama, G C; Castro-Tirado, A J; Guziy, S S; Bhatt, B C; Misra, Kuntal; Sagar, Ram

    2007-01-01

    We present broad band optical afterglow observations of a long duration GRB 060124 using the 1.04-m Sampurnanand Telescope at ARIES, Nainital and the 2.01-m HCT at IAO, Hanle, including the earliest ground based observations in R band for this GRB. We determine the decay slope of the light curve at different bands and examine the reality of a proposed jet break. We use data from our observations as well as others reported in the literature to construct light curves in different bands and make power law fits to them. The spectral slope of the afterglow emission in the optical band is estimated. Our first R-band observations were taken $\\sim 0.038$~d after burst. We find that all available optical data after this epoch are well fit by a single power law, with a temporal flux decay index $\\alpha\\sim 0.94$. We do not find any evidence of a jet break within our data, which extend till $\\sim 2$~d after the burst. The X-ray light curve, however, shows a distinct break around 0.6 day. We attribute this break to a ste...

  12. Metastable atomic species in the N{sub 2} flowing afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Levaton, J. [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol - CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil); Amorim, J., E-mail: jayr.amorim@bioetanol.org.br [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol - CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, Sao Paulo (Brazil)

    2012-03-13

    Graphical abstract: Calculated N({sup 4}S), N({sup 2}D) and N({sup 2}P) absolute densities as a function of the afterglow time. Highlights: Black-Right-Pointing-Pointer Nitrogen flowing post-discharge. Black-Right-Pointing-Pointer N({sup 4}S) and N({sup 2}D) densities. Black-Right-Pointing-Pointer Kinetic numerical model of the nitrogen afterglow. - Abstract: We have studied by optical emission spectroscopy the post-discharge of a pure N{sub 2} DC flowing discharge in such experimental conditions that the pink afterglow and the Lewis-Rayleigh afterglow occur. The emission profiles originated from the N{sub 2}(B{sup 3}{Pi}{sub g}), N{sub 2}(C{sup 3}{Pi}{sub u}) and N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}) states and the N{sub 2}(B{sup 3}{Pi}{sub g},6{<=}v{<=}12) and N{sub 2}(C{sup 3}{Pi}{sub u},0{<=}v{<=}4) vibrational distributions were obtained in the post-discharge region. With basis on the works of Bockel et al. [S. Bockel, A.M. Diamy, A. Ricard, Surf. Coat. Tech. 74 (1995) 474] and Amorim and Kiohara [J. Amorim, V. Kiohara, Chem. Phys. Lett. 385 (2004) 268], we have obtained the experimental N({sup 4}S) and N({sup 2}D) relative densities along the post-discharge. A numerical model, previously developed to describe the neutral atomic, molecular and ionic species in the afterglow, was improved to include the kinetics of N({sup 2}D) and N({sup 2}P) states. Several kinetic mechanisms leading to the production of N({sup 2}D) in the post-discharge have been studied in order to explain the experimental data. We have determined that the dominant one is the reaction N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +},v>8)+N({sup 4}S){yields}N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +})+N({sup 2}D) with an estimated rate constant of 7 Multiplication-Sign 10{sup -14} cm{sup 3} s{sup -1}. Also, the fit of the numerical density profiles of N{sub 2}(C{sup 3}{Pi}{sub u}) and N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}) to the experimental ones has provided the rate constant for reaction

  13. Discovery of an extra hard spectral component in the high-energy afterglow emission of GRB 130427A

    CERN Document Server

    Tam, Pak-Hin Thomas; Hou, Shujing; Liu, Ruo-Yu; Wang, Xiang-Yu

    2013-01-01

    The extended high-energy gamma-ray (>100 MeV) emission occurred after the prompt gamma-ray bursts is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. The afterglow inverse-Compton emission has long been predicted to be able to produce a high-energy component as well, but previous observations have not revealed such a signature clearly, probably due to the small number of >10 GeV photons even for the brightest GRBs known so far. In this Letter, we report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV emission from the very bright and nearby GRB 130427A. We characterize the time-resolved spectra of the GeV emission from the GRB onset to the afterglow phase. Based on detection of about a dozen >10 GeV photons from GRB 130427A, we found a strong evidence of an extra hard spectral component that exists in the extended high-energy emission of this GRB. We argue that this hard component may arise from the afterglow inverse Co...

  14. Gamma-ray burst radio afterglows from Population III stars: Simulation methods and detection prospects with SKA precursors

    CERN Document Server

    Macpherson, Damien

    2015-01-01

    We investigate the prospects of detecting radio afterglows from long Gamma-Ray Bursts (GRBs) from Population III (Pop III) progenitors using the SKA precursor instruments WMA (Murchison Widefield Array) and ASKAP (Australian SKA Pathfinder). We derive a realistic model of GRB afterglows that encompasses the widest range of plausible physical parameters and observation angles. We define the best case scenario of Pop III GRB energy and redshift distributions. Using probability distribution functions fitted to the observed microphysical parameters of long GRBs, we simulate a large number of Pop III GRB afterglows to find the global probability of detection. We find that ASKAP may be able to detect 35% of Pop III GRB afterglows in the optimistic case, and 27% in the pessimistic case. A negligible number will be detectable by MWA in either case. Detections per image for ASKAP, found by incorporating intrinsic rates with detectable timescales, are as high as $\\sim$ 6000 and as low as $\\sim$ 11, which shows the opti...

  15. Production of Highly Charged Heavy Ions by Means of a Hybrid Source in DC Mode and in Afterglow Mode

    Czech Academy of Sciences Publication Activity Database

    Gammino, S.; Ciavola, G.; Torrisi, L.; Celona, L.; Andó, L.; Manciagli, S.; Consoli, F.; Galatá, A.; Picciotto, A.; Mezzasalma, A. M.; Krása, Josef; Láska, Leoš; Pfeifer, Miroslav; Rohlena, Karel; Wolowski, J.; Woryna, E.; Parys, P.; Shirkov, G. D.; Hitz, D.

    2005-01-01

    Roč. 2, č. 6 (2005), s. 458-463. ISSN 1612-8850 R&D Projects: GA MŠk(CZ) ME 238 Institutional research plan: CEZ:AV0Z10100523 Keywords : afterglow plasma processes * electron cyclotron resonance (ECR) * ion beams * laser ablation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.846, year: 2005

  16. VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50

    DEFF Research Database (Denmark)

    Andersen, M. I.; Hjorth, J.; Pedersen, H.;

    2000-01-01

    We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent prec...

  17. The Potential for Detecting Gamma-Ray Burst Afterglows from Population III Stars with the Next Generation of Infrared Telescopes

    CERN Document Server

    Macpherson, Damien; Zadnik, M G

    2013-01-01

    We investigate the detectability of a proposed population of Gamma-Ray Bursts (GRBs) from the collapse of Population III (Pop III) stars. The James Webb Space Telescope (JWST) and Space Infrared telescope for Cosmology and Astrophysics (SPICA) will be able to observe the late time infrared afterglows. We have developed a new method to calculate their detectability, which takes into account the fundamental initial mass function (IMF) and formation rates of Pop III stars, from which we find the temporal variability of the afterglows and ultimately the length of time JWST and SPICA can detect them. In the range of plausible Pop III GRB parameters, the afterglows are always detectable by these instruments during the isotropic emission, for a minimum of 55 days and a maximum of 3.7 years. The average number of detectable afterglows will be 2.96$\\times 10^{-5}$ per SPICA field of view (FOV) and 2.78$\\times 10^{-6}$ per JWST FOV. These are lower limits, using a pessimistic estimate of Pop III star formation. An opti...

  18. On the Late-Time Spectral Softening Found in X-ray Afterglows of Gamma-Ray Bursts

    CERN Document Server

    Wang, Yuan-Zhu; Shao, Lang; Liang, En-Wei; Lu, Zu-Jia

    2016-01-01

    Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around circum-burst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening, we now systematically search the X-ray afterglows detected by X-Ray Telescope (XRT) of Swift and collect twelve GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal and spectral features. For some well observed bursts with high-quality data, their time-resolved spectra could be well produced within the scattering scenario by taking into account the X-ray absorption from circum-burst medium. We also find that during spectral softening the power-law index in the high energy end of the spectra does not vary much....

  19. A catalog of optical/near-infrared data on GRB afterglows in the pre-Swift era. I. Light curve information

    OpenAIRE

    Kann, D. A.; Zeh, A.; Klose, S.

    2005-01-01

    The present catalog is the result of our attempts to collect all published photometric data on GRB afterglows observed in the pre-Swift era by the end of 2004 in order to gain statistical insight on the phenomenology of GRB afterglows. Part I contains all published data on GRB afterglows in filters we used in Zeh, Klose, & Kann (2005) to create reference light curves and derive light curve parameters (mostly R band, but a few bursts have better data in other colors) including the correspondin...

  20. X-ray plateaus followed by sharp drops in GRBs 060413, 060522,060607A and 080330: Further evidences for central engine afterglow from gamma-ray bursts

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui Zhang

    2009-01-01

    The X-ray afterglows of GRBs 060413, 060522, 060607A and 080330 are characterized by a plateau followed by a very sharp drop. The plateau could be explained within the framework of the external forward shock model but the sharp drop can not.We interpret the plateau as the afterglows of magnetized central engines, plausibly magnetars. In this model, the X-ray afterglows are powered by the internal magnetic energy dissipation and the sudden drop is caused by the collapse of the magnetar. Accordingly,the X-ray plateau photons should have a high linear polarization, which can be tested by future X-ray polarimetry.

  1. Afterglow Light Curves of Jetted Gamma-ray Burst Ejecta in Stellar Winds

    Institute of Scientific and Technical Information of China (English)

    Xue-Feng Wu; Zi-Gao Dai; Yong-Feng Huang; Hai-Tao Ma

    2004-01-01

    Optical and radio afterglows arising from shocks by relativistic conical ejecta running into pre-burst massive stellar winds are revisited. Under the homogeneous thin-shell approximation and a realistic treatment for the lateral expansion of jets, our results show that a notable break exists in the optical light curve in most cases we calculated in which the physical parameters are varied within reasonable ranges. For a relatively tenuous wind which cannot decelerate the relativistic jet to cause a light curve break within days, the wind termination shock due to the ram pressure of the surrounding medium occurs at a small radius, namely, a few times 1017 cm. In such a structured wind environment, the jet will pass through the wind within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallower drop after the jet encounters the uniform medium, and then declines deeply, triggered by runaway lateral expansion.

  2. THE AFTERGLOW AND ULIRG HOST GALAXY OF THE DARK SHORT GRB 120804A

    Energy Technology Data Exchange (ETDEWEB)

    Berger, E.; Zauderer, B. A.; Margutti, R.; Laskar, T.; Fong, W.; Chornock, R.; Dupuy, T. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Levan, A.; Tunnicliffe, R. L. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Mangano, V. [INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Via U. La Malfa 153, I-90146 Palermo (Italy); Fox, D. B. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Menten, K. M. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany); Hjorth, J. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Roth, K. [Gemini Observatory, 670 North Aohoku Place, Hilo, HI 96720 (United States)

    2013-03-10

    We present the optical discovery and subarcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with Swift/XRT, Chandra, and XMM-Newton extending to {delta}t Almost-Equal-To 19 days reveal a single power-law decline. The optical afterglow is faint, and comparison to the X-ray flux indicates that GRB 120804A is ''dark'', with a rest-frame extinction of A {sup host}{sub V} Almost-Equal-To 2.5 mag (at z = 1.3). The intrinsic neutral hydrogen column density inferred from the X-ray spectrum, N{sub H,{sub int}}(z = 1.3) Almost-Equal-To 2 Multiplication-Sign 10{sup 22} cm{sup -2}, is commensurate with the large extinction. The host galaxy exhibits red optical/near-IR colors. Equally important, JVLA observations at Almost-Equal-To 0.9-11 days reveal a constant flux density of F{sub {nu}}(5.8 GHz) = 35 {+-} 4 {mu}Jy and an optically thin spectrum, unprecedented for GRB afterglows, but suggestive instead of emission from the host galaxy. The optical/near-IR and radio fluxes are well fit with the scaled spectral energy distribution of the local ultraluminous infrared galaxy (ULIRG) Arp 220 at z Almost-Equal-To 1.3, with a resulting star formation rate of x Almost-Equal-To 300 M{sub Sun} yr{sup -1}. The inferred extinction and small projected offset (2.2 {+-} 1.2 kpc) are also consistent with the ULIRG scenario, as is the presence of a companion galaxy at the same redshift and with a separation of about 11 kpc. The limits on radio afterglow emission, in conjunction with the observed X-ray and optical emission, require a circumburst density of n {approx} 10{sup -3} cm{sup -3}, an isotropic-equivalent energy scale of E{sub {gamma},{sub iso}} Almost-Equal-To E{sub K,{sub iso}} Almost-Equal-To 7 Multiplication-Sign 10{sup 51} erg, and a jet opening angle of {theta}{sub j} {approx}> 11 Degree-Sign . The expected fraction of luminous infrared

  3. Coulomb fission of a charged dust cloud in an afterglow plasma

    Science.gov (United States)

    Merlino, Robert; Meyer, John

    2015-11-01

    A dust cloud of 1 micron diameter silica microspheres was confined in a DC glow discharge dusty plasma in argon at a pressure of 100 mTorr (13 Pa). Laser sheet illumination and a fast video camera (2000 frames/s) was used to record the dynamics of this cloud following the switch-off of the plasma and confining forces. Due to the rapid decay of the plasma, and the substantial residual charge on the particles in the plasma afterglow, the cloud evolved under the mutual Coulomb repulsion forces. A variety of dynamic evolutions were observed with different clouds and under different conditions including, Coulomb explosion and expansion. In one case, the cloud underwent a Coulomb fission process, fragmenting into two clouds. Observations and analysis of this Coulomb fission event will be presented. Work supported by DOE.

  4. Self Organized Criticality in an one dimensional magnetized grid. Application to GRB X-ray afterglows

    CERN Document Server

    Harko, Tiberiu; Stroia, Nicoleta

    2015-01-01

    A simplified one dimensional grid is used to model the evolution of magnetized plasma flow. We implement diffusion laws similar to those so-far used to model magnetic reconnection with Cellular Automata. As a novelty, we also explicitly superimpose a background flow. The aim is to numerically investigate the possibility that Self-Organized Criticality appears in a one dimensional magnetized flow. The cellular automaton's cells store information about the parameter relevant to the evolution of the system being modelled. Under the assumption that this parameter stands for the magnetic field, the magnetic energy released by one volume during one individual relaxation event is also computed. Our results show that indeed in this system Self-Organized Criticality is established. The possible applications of this model to the study of the X-ray afterglows of GRBs is also briefly considered.

  5. The rapid decay phase of the afterglow as the signature of the Blandford-Znajek mechanism

    Science.gov (United States)

    Nathanail, A.; Strantzalis, A.; Contopoulos, I.

    2016-02-01

    Gamma-ray bursts (GRBs) are believed to be powered by the electromagnetic extraction of spin energy from a black hole endowed with a magnetic field supported by electric currents in a surrounding disc (Blandford & Znajek). A generic feature of this mechanism is that, under certain fairly general assumptions, the energy loss rate decays exponentially. In this work, we are looking precisely for such exponential decay in the light curves of long-duration GRBs observed with the X-ray telescope (XRT) instrument on the Swift satellite. We found out that almost 30 per cent of XRT light curves show such behaviour before they reach the afterglow plateau. According to Blandford & Znajek, the duration of the burst depends on the magnetic flux accumulated on the event horizon. This allows us to estimate the surface magnetic field of a possible progenitor. Our estimations are consistent with magnetic fields observed in Wolf-Rayet stars.

  6. The Giant Flare From SGR 1806-20 And Its Radio Afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, G.B.; /New Mexico U. /NRAO, Socorro; Granot, J.; /KIPAC, Menlo Park

    2006-09-26

    The multi-wavelength observations of the 2004 December 27 Giant Flare (GF) from SGR 1806-20 and its long-lived radio afterglow are briefly reviewed. The GF appears to have been produced by a dramatic reconfiguration of the magnetic field near the surface of the neutron star, possibly accompanied by fractures in the crust. The explosive release of over 10{sup 46} erg (isotropic equivalent) powered a one-sided mildly relativistic outflow. The outflow produced a new expanding radio nebula, that is still visible over a year after the GF. Also considered are the constraints on the total energy in the GF, the energy and mass in the outflow, and on the external density, as well as possible implications for short {gamma}-ray bursts and potential signatures in high energy neutrinos, photons, or cosmic rays. Some possible future observations of this and other GFs are briefly discussed.

  7. Experimental and numerical studies on Xe2* VUV emission in fast electric discharge afterglow

    International Nuclear Information System (INIS)

    Optical and electrical properties of a fast (∼50 ns) discharge in pure Xe were studied experimentally and simulated numerically. Afterglow vacuum ultraviolet (VUV) emission was revealed lasting for a few microseconds. Its duration depended on the Xe gas pressure. The length of the discharge was 42 cm. Operation of the discharge was limited in gas pressure by the development of instability. The highest pressure of pure Xe for a stable discharge run was 0.9 bars. A detailed kinetic model of discharge plasma was developed, which calculated self-consistently the electron energy distribution function and excited states including dimer population dynamics. VUV emission dynamics observed experimentally can be explained theoretically only in a model with an essentially increased number of electronic states taken into account. Calculated discharge voltage history and VUV emission dynamics agree satisfactorily with measurements

  8. Constraining cosmological parameters by Gamma Ray Burst X - ray afterglow lightcurves

    CERN Document Server

    Cardone, V F; Capozziello, S; Willingale, R

    2010-01-01

    We present the Hubble diagram (HD) of 66 Gamma Ray Bursts (GRBs) derived using only data from their X - ray afterglow lightcurve. To this end, we use the recently updated L_X - T_a correlation between the break time T_a and the X - ray luminosity L_X measured at T_a calibrated from a sample of Swift GRBs with lightcurves well fitted by the Willingale et al. (2007) model. We then investigate the use of this HD to constrain cosmological parameters when used alone or in combination with other data showing that the use of GRBs leads to constraints in agreement with previous results in literature. We finally argue that a larger sample of high luminosity GRBs can provide a valuable information in the search for the correct cosmological model.

  9. Fast radio bursts and their possible "afterglows" as Kerr-Newman black hole binaries

    CERN Document Server

    Liu, Tong; Liu, Mo-Lin; Li, Ang

    2016-01-01

    Fast radio bursts (FRBs) are radio transients lasting only about a few milliseconds. They seem to occur at cosmological distances. We propose that these events can be originated in the collapse of the magnetosphere of Kerr-Newman black holes (KNBHs). We show that the closed orbits of charged particles in the magnetosphere of these objects are unstable. After examining their dependences on the mass, charge, and angular momentum of the particle and the spin of the KNBH, we conclude that the resulting timescale and radiation mechanism fit well with the extant observations of FRBs. Furthermore, we argue that the merger of a KNBH binary is one of the plausible central engines for potential gamma-ray or radio "afterglow" following a certain FRBs, and can also account for gravitational wave (GW) events like GW 150914. Our model leads to predictions that can be tested by combined multi-wavelength electromagnetic and GW observations.

  10. Nanostructures design by plasma afterglow-assisted oxidation of iron-copper thin films

    Science.gov (United States)

    Imam, A.; Boileau, A.; Gries, T.; Ghanbaja, J.; Mangin, D.; Hussein, K.; Sezen, H.; Amati, M.; Belmonte, T.

    2016-05-01

    Oxidizing thin films made of Fe-Cu alloy with an Ar-O2 micro-afterglow operated at atmospheric pressure shows remarkable growth processes. The presence of iron in copper up to about 50% leads to the synthesis of CuO nanostructures (nanowalls, nanotowers and nanowires). Nanotowers show the presence of an amorphous phase trapped between crystalline domains. Beyond 50%, Fe2O3 iron nanoblades are also found. CuO nanowires as small as 5 nm in diameter can be synthesized. Thanks to the presence of patterned domains induced by buckling, it was possible to show that the stress level decreases when the iron content in the alloy increases. Iron blades grow from the inner Fe2O3 layer through the overlying CuO if it is thin enough.

  11. Effect of Dust Extinction on the Gamma-ray Burst Afterglows

    Science.gov (United States)

    Lv, G. J.; Shao, L.; Jin, Z. P.; Wei, D. M.

    2011-05-01

    In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on rigorous Mie theory and latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters. Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity, however, the shape of the extinction curve is mainly determined by the size distribution of the dust grains. If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity; on the contrary, if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger extinction quantity. These results might provide an important insight into understanding the origin of the optically dark GRBs.

  12. Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra

    CERN Document Server

    Campana, S; Braito, V; Cusumano, G; D'Avanzo, P; D'Elia, V; Ghirlanda, G; Ghisellini, G; Melandri, A; Salvaterra, R; Tagliaferri, G; Vergani, S D

    2014-01-01

    We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of Gamma Ray Burst (GRB) afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power law shape with index 2.4. However, for real instruments, this value depends on their low energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 10^5-10^6 counts in the 0.3-10 keV band are needed to constrain the redshift with 10% accuracy. As a test case we discuss the XMM-Newton observation of GRB 090618 at z=0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

  13. Polymer etching in the oxygen afterglow - Increased etch rates with increased reactor loading

    Science.gov (United States)

    Lerner, N. R.; Wydeven, T.

    1989-01-01

    Reactor loading has an effect on the etch rate (rate of decrease of film thickness) of films of polyvinylfluoride (Tedlar) and polyethylene exposed in the afterglow of an RF discharge in oxygen. The etch rate is found to increase with the total surface area of the polymer exposed in the reactor. The etch rates of polypyromellitimide (Kapton H) and polystyrene under these conditions are very low. However, the etch rate of these polymers is greatly enhanced by adding either Tedlar or polyethylene to the reactor. A kinetic model is proposed based on the premise that the oxygen atoms produced by the RF discharge react with Tedlar or polyethylene to produce a much more reactive species, which dominates the etching of the polymers studied.

  14. Modeling the early afterglow in the short and hard GRB 090510

    CERN Document Server

    Fraija, Nissim; Veres, Peter; Duran, Rodolfo Barniol

    2016-01-01

    The bright, short and hard GRB 090510 was detected by all instruments aboard Fermi and Swift satellites. The multiwavelength observations of this burst presented similar features with the Fermi-LAT-detected gamma-ray bursts. In the framework of the external shock model of early afterglow, a leptonic scenario that evolves in a homogeneous medium is proposed to revisit GRB 090510 and explain the multiwavelength light curve observations presented in this burst. These observations are consistent with the evolution of a jet before and after the jet break. The long-lasting LAT, X-ray and optical fluxes are explained in the synchrotron emission from the adiabatic forward shock. Synchrotron self-Compton emission from the reverse shock is consistent with the bright LAT peak provided that progenitor environment is entrained with strong magnetic fields. It could provide compelling evidence of magnetic field amplification in the neutron star merger.

  15. Evidence of a two-component jet in the afterglow of GRB 070419A

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A two-component jet model is proposed to explain the unusual afterglow of GRB 070419A.Regarding the optical light curve,a wide "jet" with an opening angle of >30-40 degrees is assumed to produce the late shallow decay,while the three early power-law segments must be caused by a narrow jet with an opening angle of-2-4 degrees.Additional energy injections to both components are required.Late X-ray emission may come from either the wide jet or the narrow one.If the latter is correct,the jets may run into an ISM environment and the temporal index of the late energy injection may be q-0.65.

  16. The unusual X-ray light-curve of GRB 080307: the onset of the afterglow?

    CERN Document Server

    Page, K L; O'Brien, P T; Tanvir, N R; Osborne, J P; Zhang, B; Holland, S T; Levan, A J; Melandri, A; Starling, R L C; Bersier, D; Burrows, D N; Geach, J E; Maxted, P

    2009-01-01

    Swift-detected GRB 080307 showed an unusual smooth rise in its X-ray light-curve around 100 seconds after the burst, at the start of which the emission briefly softened. This `hump' has a longer duration than is normal for a flare at early times and does not demonstrate a typical flare profile. Using a two component power-law-to-exponential model, the rising emission can be modelled as the onset of the afterglow, something which is very rarely seen in Swift-X-ray light-curves. We cannot, however, rule out that the hump is a particularly slow early-time flare, or that it is caused by upscattered reverse shock electrons.

  17. Wide field x-ray telescopes: Detecting x-ray transients/afterglows related to GRBs

    International Nuclear Information System (INIS)

    The recent discovery of X-ray afterglows of GRBs opens the possibility of analyses of GRBs by their X-ray detections. However, imaging X-ray telescopes in current use mostly have limited fields of view. Alternative X-ray optics geometries achieving very large fields of view have been theoretically suggested in the 70's but not constructed and used so far. We review the geometries and basic properties of the wide-field X-ray optical systems based on one- and two-dimensional lobster-eye geometry and suggest technologies for their development and construction. First results of the development of double replicated X-ray reflecting flats for use in one-dimensional X-ray optics of lobster-eye type are presented and discussed. The optimum strategy for locating GRBs upon their X-ray counterparts is also presented and discussed

  18. The rapid decay phase of the afterglow as the signature of the Blandford-Znajek mechanism

    CERN Document Server

    Nathanail, Antonios; Contopoulos, Ioannis

    2015-01-01

    Gamma-ray bursts (GRBs) are believed to be powered by the electromagnetic extraction of spin energy from a black hole endowed with a magnetic field supported by electric currents in a surrounding disk (Blandford & Znajek 1977). A generic feature of this mechanism is that, under certain fairly general assumptions, the energy loss rate decays exponentially. In this work, we are looking precisely for such exponential decay in the lightcurves of long duration GRBs observed with the XRT instrument on the Swift satellite. We found out that almost 30 % of XRT lightcurves show such behavior before they reach the afterglow plateau. According to Blandford & Znajek, the duration of the burst depends on the magnetic flux accumulated on the event horizon. This allows us to estimate the surface magnetic field of a possible progenitor. Our estimations are consistent with magnetic fields observed in Wolf-Rayet stars.

  19. Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra

    Science.gov (United States)

    Campana, S.; Bernardini, M. G.; Braito, V.; Cusumano, G.; D'Avanzo, P.; D'Elia, V.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Salvaterra, R.; Tagliaferri, G.; Vergani, S. D.

    2014-07-01

    We investigate the scaling relation between the observed amount of absorption in the X-ray spectra of gamma-ray burst afterglows and the absorber redshift. Through dedicated numerical simulations of an ideal instrument, we establish that this dependence has a power-law shape with index 2.4. However, for real instruments, this value depends on their low-energy cut-off, spectral resolution and on the detector spectral response in general. We thus provide appropriate scaling laws for specific instruments. Finally, we discuss the possibility to measure the absorber redshift from X-ray data alone. We find that 105-106 counts in the 0.3-10 keV band are needed to constrain the redshift with 10 per cent accuracy. As a test case, we discuss the XMM-Newton observation of GRB 090618 at z = 0.54. We are able to recover the correct redshift of this burst with the expected accuracy.

  20. Gamma-Ray Burst Afterglows with Energy Injection: Homogeneous VersusWind External Media

    Institute of Scientific and Technical Information of China (English)

    王伟; 戴子高

    2001-01-01

    Assuming an adiabatic evolution of a gamma-ray burst (GRB) fireball interacting with an external medium,we calculate the hydrodynamics of the fireball with an energy injection from a strongly magnetic millisecond pulsar through magnetic dipole radiation, and obtain the light curve of the optical afterglow from the fireball by synchrotron radiation. The results are given both for an homogeneous external medium and for a wind ejected by GRB progenitor. Our calculations are also available in both ultra-relativistic and non-relativistic phases.Furthermore, the observed R-band light curve of GRB000301C can be well fitted in our model, which might provide a probe of the properties of GRB progenitors.

  1. Detailed afterglow modelling and host galaxy properties of the dark GRB 111215A

    Science.gov (United States)

    van der Horst, A. J.; Levan, A. J.; Pooley, G. G.; Wiersema, K.; Krühler, T.; Perley, D. A.; Starling, R. L. C.; Curran, P. A.; Tanvir, N. R.; Wijers, R. A. M. J.; Strom, R. G.; Kouveliotou, C.; Hartoog, O. E.; Xu, D.; Fynbo, J. P. U.; Jakobsson, P.

    2015-02-01

    Gamma-ray burst (GRB) 111215A was bright at X-ray and radio frequencies, but not detected in the optical or near-infrared (nIR) down to deep limits. We have observed the GRB afterglow with the Westerbork Synthesis Radio Telescope and Arcminute Microkelvin Imager at radio frequencies, with the William Herschel Telescope and Nordic Optical Telescope in the nIR/optical, and with the Chandra X-ray Observatory. We have combined our data with the Swift X-Ray Telescope monitoring, and radio and millimetre observations from the literature to perform broad-band modelling, and determined the macro- and microphysical parameters of the GRB blast wave. By combining the broad-band modelling results with our nIR upper limits we have put constraints on the extinction in the host galaxy. This is consistent with the optical extinction we have derived from the excess X-ray absorption, and higher than in other dark bursts for which similar modelling work has been performed. We also present deep imaging of the host galaxy with the Keck I telescope, Spitzer Space Telescope, and Hubble Space Telescope (HST), which resulted in a well-constrained photometric redshift, giving credence to the tentative spectroscopic redshift we obtained with the Keck II telescope, and estimates for the stellar mass and star formation rate of the host. Finally, our high-resolution HST images of the host galaxy show that the GRB afterglow position is offset from the brightest regions of the host galaxy, in contrast to studies of optically bright GRBs.

  2. Recombination rates and excited state formation and collisional destruction in plasma-afterglows

    International Nuclear Information System (INIS)

    The dissociative recombination process for heavy diatomic molecular ions capturing electrons, Hg2+ + e- reversible arrows (Hg2/sup *>)/sub r/ → Hg/sup */+ Hg, has been studied using a plasma/afterglow method. Microwave techniques are employed to generate the plasma, measure the electron density decay and control the electron temperature. Optical spectrometric observations of afterglow radiation are also performed. The recombination coefficient, α(Hg2+) and the excited states of mercury produced by this process are determined as a function of electron temperature. We also measured the two-body collisional destruction rates and partial recombination rates for the argon excited states, 5p12, 5p23, 6s12, 4d12, 4d01, 4d00, 4d33, 4d34, 5d33, 5d34, 4p00/sup prime/, and 4p00, produced by dissociative recombination of Ar2+ ions by measuring the variation of the intensity of radiation from these states with argon pressure. (Production and destruction of a few xenon excited states were also studied qualitatively in this respect.) The collisional destruction (quenching) rate coefficients for the argon states range from approx. 2 x 10-11cm3/sec to approx. 2 x 10-10 cm3/s The quenching rates for the states lying above the ground state of Ar2+ provide an upper bound on the associative ionization rates for these states. The states which have large collisional destruction rates (approx. 2 x 10-10cm3/s) are found to have large partial recombination coefficients

  3. PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

    International Nuclear Information System (INIS)

    We present a comprehensive analysis of a bright, long-duration (T90 ∼ 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the γ-ray band, with optical light curve showing correlation with γ-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to γ-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (∼1100 s), a bright (R = 14.0) optical emission hump with very steep rise (α ∼ 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (RGRB ∼ 3 × 1013 cm), initial Lorentz factor of the outflow (Γ0 ∼ 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.

  4. Fast gas heating in nitrogenoxygen discharge plasma: II. Energy exchange in the afterglow of a volume nanosecond discharge at moderate pressures

    OpenAIRE

    Mintoussov, E I; Pendleton, S J; Gerbault, F; Popov, N. A.; Starikovskaia, S M

    2011-01-01

    Abstract gas heating in nitrogen?oxygen discharge plasma. II. Energy exchange in the afterglow of a volume nanosecond discharge at moderate pressures. Abstract. The process of fast gas heating in air in the near afterglow of a pulsed nanosecond spatially uniform discharge has been investigated experimentally and numerically at moderate (3?9 mbar) pressures and high (200?400 Td) reduced electric fields. The temporal behavior of discharge current, deposited energy, electric field and tempera...

  5. Dy{sup 3+}:Ca{sub 2}SnO{sub 4}, a new yellow phosphor with afterglow behavior

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Mingming; Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Chang, Chengkang

    2015-08-05

    Highlights: • The photoluminescence and afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was investigated. • PL spectra revealed the {sup 4}F{sub 9/2} → {sup 6}H{sub J} (J = 15/2, 13/2, 11/2) energy transition of Dy{sup 3+} ions in Ca{sub 2}SnO{sub 4}. • CIE chromaticity coordinates results confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4}. • After the UV source was turned off, the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} showed typical afterglow behavior. • The afterglow behavior of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} was attributed to suitable electron and hole traps. - Abstract: This paper reports the photoluminescence and afterglow behavior of Dy{sup 3+} in Ca{sub 2}SnO{sub 4} matrix (Dy{sup 3+}:Ca{sub 2}SnO{sub 4}) prepared via a solid-state reaction. X-ray diffraction (XRD), photo luminescence spectroscope (PLS) and thermal luminescence spectroscope (TLS) were performed to investigate the physical properties of the phosphors. Typical {sup 4}F{sub 9/2} to {sup 6}H{sub j} energy transition of Dy{sup 3+} ions was detected by PL spectra. CIE chromaticity coordinates of x = 0.4319, y = 4.456, calculated from the emission spectra, confirmed a yellow light emitting of the Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors. The Ca{sub 2}SnO{sub 4} phosphors showed a typical afterglow behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Dy{sup 3+}:Ca{sub 2}SnO{sub 4} phosphors was generated by the suitable electron or hole traps which was resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Dy{sup 3+})

  6. Transition from interpulse to afterglow plasmas driven by repetitive short-pulse microwaves in a multicusp magnetic field

    International Nuclear Information System (INIS)

    In the power-off phase, plasmas generated by repetitive short-pulse microwaves in a multicusp magnetic field show a transitive nature from interpulse to afterglow as a function of pulse duration tw = 20–200 μs. The ionized medium can be driven from a highly non equilibrium to an equilibrium state inside the pulses, thereby dictating the behavior of the plasma in the power-off phase. Compared to afterglows, interpulse plasmas observed for tw 4 s−1) of the electron temperature, as corroborated by optical measurements. The associated electron energy probability function indicates depletion in low energy electrons which appear at higher energies just after the end of the pulse. The transition occurs at tw ∼ 50 μs as confirmed by time evolution of integrated electron numbers densities obtained from the distribution function.

  7. Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

    Science.gov (United States)

    Lauck, Ronald; Brandis, Michal; Bromberger, Benjamin; Dangendorf, Volker; Goldberg, Mark B.; Mor, Ilan; Tittelmeier, Kai; Vartsky, David

    2009-06-01

    For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specific TCSPC method and discuss the results.

  8. Trapping mechanism in the afterglow process of the rare-earth activated Y2O2S phosphors

    International Nuclear Information System (INIS)

    Phosphorescence properties are investigated in Y2O2S phosphors doped with rare-earth (lanthanoid, Ln) ions. Luminescence afterglow with a decay time of several ten milliseconds is observed at room temperature in the phosphors activated by Nd, Sm, Eu, Dy, Ho, Tm, Er, and Yb. The depths (thermal activation energies) of the traps causing the afterglow are measured with the transient luminescence method. It is concluded that the excited electron and the hole in the conduction and valence bands are trapped separately in the states (impurity levels) located in the vicinity of the Ln3+ ion. The trapping depths of the level range from 0.3 to 1.1 eV and are dependent on the electron affinity of the Ln3+ ion estimated from the energy difference between the 4fn+1 and the 4fn configurations in the 4f shell of the ion

  9. Synthesis of Long Afterglow SrAl2O4 :Eu2+, Dy3+ Phosphor by Microemulsion Method

    Institute of Scientific and Technical Information of China (English)

    Chen Yongjie; Qiu Guanming; Geng Xiujuan; Xiao Linjiu; Tian Yiguang; Sun Yanbin

    2004-01-01

    Long afterglow SrAl2 O4: Eu2+, Dy3+ phosphor was synthesized by microemulsion method. The synthesized phosphor was characterized by XRD. XRD pattern indicates that the phosphor has monoclinic SrAl2 O4 crystal structre.The microstructure of the phosphor was investigated by SEM and TEM. The excitation spectrum, emission spectrum and afterglow decay curve were measured, the wide range of excitation wavelength indicated that the luminescent material could be excited by the light from ultraviolet ray to visible light, and the emission maximum was found to peak mainly at λem of 525 nm. The sample excited by ultraviolet visible light could emit bright green light.

  10. Shallow Decay Phase of the Early X-Ray Afterglow from External Shock in a Wind Environment

    Institute of Scientific and Technical Information of China (English)

    雷海东; 汪九洲; 吕静; 邹远川

    2011-01-01

    We investigate the shallow decay phase of an early x-ray afterglow in gamma-ray bursts discovered by Swift, and suggest that both the shallow decay phase and the normal phase are from external shock in a wind environment, while the transferring time is the deceleration time. We apply this model to GRBs 050319 and 081008, and find that they can be explained by choosing a proper set of parameters.%We investigate the shallow decay phase of an early x-ray afterglow in gamma-ray bursts discovered by Swift,and suggest that both the shallow decay phase and the normal phase are from external shock in a wind environment,while the transferring time is the deceleration time.We apply this model to GRBs 050319 and 081008,and find that they can be explained by choosing a proper set of parameters.

  11. Simulations of GRB Jets in a Stratified External Medium: Dynamics, Afterglow Lightcurves, Jet Breaks and Radio Calorimetry

    CERN Document Server

    De Colle, Fabio; Granot, Jonathan; Lopez-Camara, Diego

    2011-01-01

    The dynamics of GRB jets during the afterglow phase is most reliably and accurately modelled using hydrodynamic simulations. All published simulations, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with $\\rho \\propto r^{-k}$ for k = 0, 1, 2. The simulations are performed in 2D using the special relativistic version of the Mezcal code. The dynamics for stratified external media are broadly similar to those derived for expansion into a uniform external medium. The jet half-opening angle start increasing logarithmically with time once the Lorentz factor drops below 1/theta_0. For larger k values the lateral expansion is faster at early times and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timesc...

  12. Off-Axis Gamma-Ray Burst Afterglow Modeling Based On A Two-Dimensional Axisymmetric Hydrodynamics Simulation

    CERN Document Server

    van Eerten, Hendrik; MacFadyen, Andrew

    2010-01-01

    Starting as highly relativistic collimated jets, gamma-ray burst outflows gradually decelerate and become non-relativistic spherical blast waves. Although detailed analytical solutions describing the afterglow emission received by an on-axis observer during both the early and late phases of the outflow evolution exist, a calculation of the received flux during the intermediate phase and for an off-axis observer requires either a more simplified analytical model or direct numerical simulations of the outflow dynamics. In this paper we present light curves for off-axis observers covering the long-term evolution of the blast wave calculated from a high resolution two-dimensional relativistic hydrodynamics simulation using a synchrotron radiation model. We compare our results to earlier analytical work and calculate the consequence of the observer angle with respect to the jet axis both for the detection of orphan afterglows and for jet break fits to the observational data. We find that observable jet breaks can ...

  13. Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

    CERN Document Server

    Lauck, Ronald; Bromberger, Benjamin; Dangendorf, Volker; Goldberg, Mark B; Mor, Ilan; Tittelmeier, Kai; Vartsky, David

    2009-01-01

    For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specif...

  14. Toward finding gravitational-wave signals from progenitors of short hard gamma-ray bursts and orphaned afterglows

    CERN Document Server

    Ghosh, Shaon

    2013-01-01

    With multiple observatories and missions being planned for detecting orphaned afterglows associated with gamma-ray bursts (GRBs) we emphasize the importance of developing data analysis strategies for searching their possible counterpart signals in the data of gravitational wave (GW) detectors in the advanced detector era. This is especially attractive since short hard gamma-ray bursts (SGRBs) may have compact binary coalescences involving neutron stars (CBCNSs) as their progenitors, which emit gravitational waves. Joint electromagnetic (EM) and GW observations of these objects will enrich our understanding of their beaming, energetics, galactic environment, and shed light on a host of other outstanding questions related to them. Here we recognize some of the astrophysical factors that determine what fraction of CBCNS sources can generate orphaned afterglows. Pipelines already exist that target the sky-position and time of occurrence of SGRBs, known from EM observations, to search for their counterparts in GW ...

  15. An inverse Compton origin for the 55 GeV photon in the late afterglow of GRB 130907A

    CERN Document Server

    Tang, Qing-Wen; Wang, Xiang-Yu

    2014-01-01

    The extended high-energy gamma-ray (>100 MeV) emission which occurs well after the prompt gamma-ray bursts (GRBs) is usually explained as the afterglow synchrotron radiation. Here we report the analysis of the Fermi Large Area Telescope observations of GRB 130907A. A 55 GeV photon compatible with the position of the burst was found at about 5 hours after the prompt phase. The probability that this photon is associated with GRB 130907A is higher than 99.96%. The energy of this photon exceeds the maximum synchrotron photon energy at this time and its occurrence thus challenges the synchrotron mechanism as the origin for the extended high-energy >10 GeV emission. Modeling of the broad-band spectral energy distribution suggests that such high energy photons can be produced by the synchrotron self-Compton emission of the afterglow.

  16. Observation of visible emission from the molecular helium ion in the afterglow of a dense helium Z-pinch plasma

    International Nuclear Information System (INIS)

    The authors present the results of axial and radial time resolved visible emission spectroscopy from the afterglow of a dense helium Z-pinch. These results show that the visible emissions in the pinch afterglow are dominated by line emissions from molecular helium and He II. Axial spectroscopy measurements show the occurrence of several absorption bands which cannot be identified as molecular or atomic helium nor impurities from the discharge chamber materials. The authors believe that these absorption bands are attributable to the molecular helium ion which is present in the discharge. The molecular ion has been observed by others in low pressure and temperature helium discharges directly by means of mass spectrometry and indirectly by the presence of helium atoms in the 2/sup 3/S state, (the He 2/sup 3/S state is believed to result from molecular helium ion recombination). However, the molecular helium ion has not previously been observed spectroscopically

  17. Ratio of Balmer line to spectrally adjacent emission, from the afterglow of a Z-pinch discharge in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Jones, W.M.; Healy, M.C.; McCulloch, G.L.

    1987-08-01

    Measurements of line to continuum ratios have been made for the Hsub(..beta..), Hsub(..gamma..), Hsub(delta) and Hsub(epsilon) lines, at different times in the afterglow of a Z-pinch discharge in hydrogen. The contributions of Stark broadening of the lines and atom-electron interaction continuum, to the observed continuum signal, are considered. The electron temperature is estimated with an uncertainty of about +- 10%.

  18. A model for the dissociation pulse, afterglow, and laser pulse in the Cu/CuCl double pulse laser

    OpenAIRE

    Kushner, M J; Culick, F. E. C.

    1980-01-01

    A model which completely describes the Cu/CuCl double pulse laser is presented. The dissociation discharge pulse and afterglow are simulated and the results are used as initial conditions for an analysis of the pumping discharge pulse and laser pulse. Experimental behavior including the minimum, optimum, and maximum delays between pulses, and the dependence of laser pulse energy on dissociation energy are satisfactorily reproduced. An optimum tube temperature is calculated, and the dependence...

  19. A model for the dissociation pulse, afterglow, and laser pulse in the Cu/CuCI double pulse laser

    OpenAIRE

    Kushner, M J; Culick, F. E. C.

    1980-01-01

    A model which completely describes the Cu/CuCI double pulse laser is presented. The dissociation discharge pulse and afterglow are simulated and the results are used as initial conditions for an analysis of the pumping discharge pulse and laser pulse. Experimental behavior including the minimum, optimum, and maximum delays between pulses, and the dependence of laser pulse energy on dissociation energy are satisfactorily reproduced. An optimum tube temperature is calculated, and the depende...

  20. Luminescent Afterglow Behavior in the M2Si5N8: Eu Family (M = Ca, Sr, Ba

    Directory of Open Access Journals (Sweden)

    Koen Van den Eeckhout

    2011-05-01

    Full Text Available Persistent luminescent materials are able to emit light for hours after being excited. The majority of persistent phosphors emit in the blue or green region of the visible spectrum. Orange- or red-emitting phosphors, strongly desired for emergency signage and medical imaging, are scarce. We prepared the nitrido-silicates Ca2Si5N8:Eu (orange, Sr2Si5N8:Eu (reddish, Ba2Si5N8:Eu (yellowish orange, and their rare-earth codoped variants (R = Nd, Dy, Sm, Tm through a solid state reaction, and investigated their luminescence and afterglow properties. In this paper, we describe how the persistent luminescence is affected by the type of codopant and the choice and ratio of the starting products. All the materials exhibit some form of persistent luminescence, but for Sr2Si5N8:Eu,R this is very weak. In Ba2Si5N8:Eu the afterglow remains visible for about 400 s, and Ca2Si5N8:Eu,Tm shows the brightest and longest afterglow, lasting about 2,500 s. For optimal persistent luminescence, the dopant and codopant should be added in their fluoride form, in concentrations below 1 mol%. A Ca3N2 deficiency of about 5% triples the afterglow intensity. Our results show that Ba2Si5N8:Eu(,R and Ca2Si5N8:Eu(,R are promising persistent phosphors for applications requiring orange or red light.

  1. The Needle in the 100 deg2 Haystack: Uncovering Afterglows of Fermi GRBs with the Palomar Transient Factory

    CERN Document Server

    Singer, Leo P; Cenko, S Bradley; Perley, Daniel A; Anderson, Gemma E; Anupama, G C; Arcavi, Iair; Bhalerao, Varun; Bue, Brian D; Cao, Yi; Connaughton, Valerie; Corsi, Alessandra; Cucchiara, Antonino; Fender, Rob P; Fox, Derek B; Gehrels, Neil; Goldstein, Adam; Gorosabel, J; Horesh, Assaf; Hurley, Kevin; Johansson, Joel; Kann, D A; Kouveliotou, Chryssa; Huang, Kuiyun; Kulkarni, S R; Masci, Frank; Nugent, Peter; Rau, Arne; Rebbapragada, Umaa D; Staley, Tim D; Svinkin, Dmitry; Thöne, C C; Postigo, A de Ugarte; Urata, Yuji; Weinstein, Alan

    2015-01-01

    The Fermi Gamma-Ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi Gamma-ray Burst Monitor (GBM) instrument have posed a formidable obstacle to locating the bursts' host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target of opportunity mode for the intermediate Palomar Transient Factory (iPTF) in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: eight afterglow discoveries, two of which (GRBs 130702A and 140606B) were at low redshift (z=0.145 and 0.384 respectively) and had spectroscopically confirmed broad-line type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samp...

  2. Soft X-ray absorption excess in gamma-ray burst afterglow spectra: Absorption by turbulent ISM

    CERN Document Server

    Tanga, M; Gatto, A; Greiner, J; Krause, M G H; Diehl, R; Savaglio, S; Walch, S

    2016-01-01

    Two-thirds of long duration gamma-ray bursts (GRBs) show soft X-ray absorption in excess of the Milky Way. The column densities of metals inferred from UV and optical spectra differ from those derived from soft X-ray spectra, at times by an order of magnitude, with the latter being higher. The origin of the soft X-ray absorption excess observed in GRB X-ray afterglow spectra remains a heavily debated issue, which has resulted in numerous investigations on the effect of hot material both internal and external to the GRB host galaxy on our X-ray afterglow observations. Nevertheless, all models proposed so far have either only been able to account for a subset of our observations (i.e. at z > 2), or they have required fairly extreme conditions to be present within the absorbing material. In this paper, we investigate the absorption of the GRB afterglow by a collisionally ionised and turbulent interstellar medium (ISM). We find that a dense (3 per cubic centimeters) collisionally ionised ISM could produce UV/opti...

  3. Discovery of Smoothly Evolving Blackbodies in the Early Afterglow of GRB 090618 : An Evidence for a Spine-Sheath Jet?

    CERN Document Server

    Basak, Rupal

    2014-01-01

    GRB~090618 is a bright GRB with multiple pulses. It shows evidence of a thermal emission in the initial pulses as well as in the early afterglow phase. We investigate the shape and evolution of the thermal component in the early afterglow/ late prompt emission phase using data from Swift/BAT, Swift/XRT, and Fermi/GBM detectors. An independent fit to the BAT and the XRT data reveals two correlated blackbodies with monotonically decreasing temperatures. Hence we investigated the combined data with a model consisting of two blackbodies and a power-law (2BBPL), a model suggested for several bright GRBs. We elicit the following interesting features of the 2BBPL model: a) the same model is applicable from the peak of the last pulse in the prompt emission to the afterglow emission, b) the ratio of temperatures and the fluxes of the two black bodies remain constant throughout the observations, c) the black body temperatures and fluxes show a monotonic decrease with time, with the fluxes dropping about a factor of two...

  4. Radio afterglows of a complete sample of bright Swift GRBs: predictions from present days to the SKA era

    CERN Document Server

    Ghirlanda, G; Burlon, D; Campana, S; Melandri, A; Bernardini, M G; Covino, S; D'Avanzo, P; D'Elia, V; Ghisellini, G; Nava, L; Prandoni, I; Sironi, L; Tagliaferri, G; Vergani, S D; Wolter, A

    2013-01-01

    Radio observations of Gamma Ray Bursts afterglows are fundamental in providing insights into their physics and environment, and in constraining the true energetics of these sources. Nonetheless, radio observations of GRB afterglows are presently sparse in the time/frequency domain. Starting from a complete sample of 58 bright Swift long bursts (BAT6), we constructed a homogeneous sub-sample of 38 radio detections/upper limits which preserves all the properties of the parent sample. One half of the bursts have detections between 1 and 5 days after the explosion with typical fluxes F>100 muJy at 8.4 GHz. Through a Population SYnthesis Code coupled with the standard afterglow Hydrodynamical Emission model (PSYCHE) we reproduce the radio flux distribution of the radio sub-sample. Based on these results we study the detectability in the time/frequency domain of the entire long GRB population by present and future radio facilities. We find that the GRBs that typically trigger Swift can be detected at 8.4 GHz by JVL...

  5. Connecting Prompt and Afterglow GRB emission I. Investigating the impact of optical selection effects in the Epi - Eiso plane

    CERN Document Server

    Turpin, D; Dezalay, J -P; Atteia, J-L; Klotz, A; Dornic, D

    2015-01-01

    Measuring GRB properties in their rest-frame is crucial to understand the physics at work in gamma-ray bursts. This can only be done for GRBs with known redshift. Since redshifts are usually measured from the optical spectrum of the afterglow, correlations between prompt and afterglow emissions may introduce biases in the distribution of rest-frame properties of the prompt emission, especially considering that we measure the redshift of only one third of Swift GRBs. In this paper we study the brightness of optical GRB afterglows and the role of optical selection effects in the distribution of various intrinsic properties of GRBs and on the Epi - Eiso relation discovered by Amati et al. (2002). Our analysis is based on a sample of 85 GRBs with good optical follow-up and well measured prompt emission. 71 of them have a measure of redshift and 14 have no redshift. We discuss the connection between the location of GRBs in the Epi-Eiso plane and their optical brightness measured two hours after the trigger in the ...

  6. iPTF14yb: The First Discovery of a GRB Afterglow Independent of a High-Energy Trigger

    CERN Document Server

    Cenko, S Bradley; Perley, Daniel A; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B; Cao, Yi; Kasliwal, Mansi M; Lien, Amy; Arcavi, Iair; Bloom, Joshua S; Butler, Nat R; Cucchiara, Antonino; de Diego, Jose A; Filippenko, Alexei V; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Gonzalez, J Jesus; Graham, John F; Greiner, Jochen; Kann, D Alexander; Klein, Christopher R; Knust, Fabian; Kulkarni, S R; Kutyrev, Alexander; Laher, Russ; Lee, William H; Nugent, Peter E; Prochaska, J Xavier; Ramirez-Ruiz, Enrico; Richer, Michael G; Rubin, Adam; Urata, Yuji; Varela, Karla; Watson, Alan M; Wozniak, Przemek R

    2015-01-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous ($M_{r}\\approx-27.8$ mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferring an all-sky value of $\\Re_{\\mathrm{rel}}=610$ yr$^{-1}$ (68% confidence interval of 110-2000 yr$^{-1}$). Our derived rate is consistent (within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we briefly discuss the implications of the nondetection to date of bona fide "orphan" afterglows (i.e., those lackin...

  7. The detection efficiency of on-axis short gamma ray burst optical afterglows triggered by aLIGO/Virgo

    CERN Document Server

    Coward, David; Howell, Eric; Lasky, Paul; Boer, Michel

    2014-01-01

    Assuming neutron star (NS) or neutron star/stellar-mass black hole (BH) mergers as progenitors of the short gamma ray bursts, we derive and demonstrate a simple analysis tool for modelling the efficiency of recovering on-axis optical afterglows triggered by a candidate gravitational wave event detected by the Advanced LIGO and Virgo network. The coincident detection effiency has been evaluated for different classes of operating telescopes using observations of gamma ray bursts. We show how the efficiency depends on the luminosity distribution of the optical afterglows, the telescope features, and the sky localisation of gravitational wave triggers. We estimate a plausible optical afterglow and gravitational wave coincidence rate of $1$ yr$^{-1}$ ($0.1$ yr$^{-1}$) for NS-NS (NS-BH), and how this rate is scaled down in detection efficiency by the time it takes to image the gravitational wave sky localization and the limiting magnitude of the telescopes. For NS-NS (NS-BH) we find maximum detection efficiencies o...

  8. Imprints of Electron-positron Winds on the Multi-wavelength Afterglows of Gamma-ray Bursts

    CERN Document Server

    Geng, J J; Huang, Y F; Li, L; Dai, Z G

    2016-01-01

    Optical re-brightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical re-brightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron-positron pairs through some magnetic dissipation processes. As proposed by Dai (2004), this wind will catch up with the GRB outflow and a long-lasting reverse shock would form. By applying this scenario to GRB afterglows, we find that the reverse shock propagating back into the electron-positron wind can lead to an observable optical re-brightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs, i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A, of which the optical afterglows are well observed and show clear re-bright...

  9. Afterglow Light Curves from Jetted Gamma-ray Burst Ejecta in Stellar Winds

    CERN Document Server

    Wu, X F; Huang, Y F; Ma, H T

    2003-01-01

    We revisit optical and radio afterglows arising from the shocks by relativistic conical ejecta running into pre-burst massive stellar winds. Under the homogeneous thin-shell approximation and the realistic treatment for lateral expansion of jets, our results show that a notable break of optical light curve within one decade in time indeed exists in most cases of our calculations by varying physical parameters within reasonable ranges. We rectify the conclusions of previous works on the jet+wind model, which claimed that there was no sharp break as the transition time lasts for two decades. Even for a relatively tenuous wind which cannot decelerate the relativistic jet to cause a sharp break within days, the wind termination shock due to the ram pressure balance by surrounding medium occurs at a small radius, i.e. several times $10^{17}$ cm. The jet will pass through the wind environment within several hours and run into the outer uniform dense medium. The resulting optical light curve flattens with a shallowe...

  10. The energy budget of GRBs based on updated prompt \\& afterglow observations

    CERN Document Server

    Wygoda, Nahliel; Mandich, Marc-Adrien; Waxman, Eli

    2015-01-01

    We compare the isotropic equivalent 15-2000 keV gamma-ray energy, E_gamma, emitted by a sample of 91 swift Gamma-Ray Bursts (GRBs) with known redshifts, with the isotropic equivalent fireball energy, E_fb, as estimated within the fireball model framework from X-ray afterglow observations of these bursts. The uncertainty in E_gamma, which spans the range of ~10^51 erg to ~10^53.5 erg, is approximately 25% on average, due mainly to the extrapolation from the BAT detector band to the 15-2000 keV band. The uncertainty in E_fb is approximately a factor of 2, due mainly to the X-ray measurements' scatter. We find E_gamma and E_fb to be tightly correlated. The average(std) of {\\eta}^11hr_gamma is approximately log_10(E_gamma/(3{\\epsilon} _eE^11hr_fb)) are -0.34(0.60), and the upper limit on the intrinsic spread of {\\eta}_gamma is approximately 0.5 ({\\epsilon}_e is the fraction of shocked plasma energy carried by electrons and E^x hr_fb is inferred from the X-ray flux at x hours). We also find that E_fb inferred from...

  11. The Dust Scattering Model Can Not Explain The Shallow X-ray Decay in GRB Afterglows

    CERN Document Server

    Shen, Rong-Feng; Kumar, Pawan; O'Brien, Paul T; Evans, Phil A

    2008-01-01

    A dust scattering model was recently proposed to explain the shallow X-ray decay (plateau) observed prevalently in Gamma-Ray Burst (GRB) early afterglows. In this model the plateau is the scattered prompt X-ray emission by the dust located close (about 10 to a few hundred pc) to the GRB site. In this paper we carefully investigate the model and find that the scattered emission undergoes strong spectral softening with time, due to the model's essential ingredient that harder X-ray photons have smaller scattering angle thus arrive earlier, while softer photons suffer larger angle scattering and arrive later. The model predicts a significant change, i.e., $\\Delta \\beta \\sim 2 - 3$, in the X-ray spectral index from the beginning of the plateau toward the end of the plateau, while the observed data shows close to zero softening during the plateau and the plateau-to-normal transition phase. The scattering model predicts a big difference between the harder X-ray light curve and the softer X-ray light curve, i.e., th...

  12. Self-organized criticality in X-ray flares of gamma-ray burst afterglows

    CERN Document Server

    Wang, F Y

    2013-01-01

    X-ray flares detected in nearly half of gamma-ray burst (GRB) afterglows are one of the most intriguing phenomena in high-energy astrophysics. All the observations indicate that the central engines of bursts, after the gamma-ray emission has ended, still have long periods of activity, during which energetic explosions eject relativistic materials, leading to late-time X-ray emission. It is thus expected that X-ray flares provide important clues to the nature of the central engines of GRBs, and more importantly, unveil the physical mechanism of the flares themselves, which has so far remained mysterious. Here we report statistical results of X-ray flares of GRBs with known redshifts, and show that X-ray flares and solar flares share three statistical properties: power-law frequency distributions for energies, durations, and waiting times. All of the distributions can be well understood within the physical framework of a self-organized criticality (SOC) system. The statistical properties of X-ray flares of GRBs...

  13. A High Signal-to-Noise Ratio Composite Spectrum of Gamma-ray Burst Afterglows

    CERN Document Server

    Christensen, L; Prochaska, J X; Thoene, C C; Postigo, A de Ugarte; Jakobsson, P

    2010-01-01

    We present a composite spectrum of 60 long duration gamma-ray burst (GRB) afterglows with redshifts in the range 0.35

  14. Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical Afterglow

    CERN Document Server

    Huang, K Y; Kuo, P H; Ip, W H; Ioka, K; Aoki, T; Chen, C W; Chen, W P; Isogai, M; Lin, H C; Makishima, K; Mito, H; Miyata, T; Nakada, Y; Nishiura, S; Onda, K; Qiu, Y; Soyano, T; Tamagawa, T; Tarusawa, K; Tashiro, M; Yoshioka, T

    2006-01-01

    Multi-wavelength B, V, R, I observations of the optical afterglow of GRB 050319 were performed by the 1.05-m telescope at Kiso Observatory and the 1.0-m telescope at Lulin Observatory from 1.31 hours to 9.92 hours after the burst. Our R band lightcurves, combined with other published data, can be described by the smooth broken power-law function, with $\\alpha_1$ = -0.84 $\\pm$0.02 to $\\alpha_2$ = -0.48$\\pm$0.03, 0.04 days after the GRB. The optical lightcurves are characterized by shallow decays-- as was also observed in the X-rays-- which may have a similar origin, related to energy injection. However, our observations indicate that there is still a puzzle concerning the chromatic breaks in the R band lightcurve (at 0.04 days) and the X-ray lightcurve (at 0.004 days) that remains to be solved.

  15. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    Science.gov (United States)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  16. Luminescence properties and afterglow in spinel crystals doped with trivalent Tb ions

    International Nuclear Information System (INIS)

    Luminescence properties of Tb3+-doped spinel crystals have been investigated at various temperatures between 8 and 300 K under excitation in the Tb3+ absorption bands and in the intrinsic absorption region. Two Tb3+ absorption bands are observed at 5.3 and 6.3 eV in the intrinsic absorption edge region. With excitation in these bands, two series of sharp luminescence bands appear in the region between 1.8 and 3.5 eV, which are to be well established as those due to the series transitions from the 5D3 and 5D4 excited states to the 7DJ (J=6, 5, 4, 3,2) ground states, with radiative lifetimes of 1.5 and 2.0 ms, respectively. The same luminescence spectrum is produced with excitation in the intrinsic absorption region above 7 eV. In this case, prominent slow rise and afterglow components of luminescence are observed which last for up to an hour depending on the temperature. The origins of the slow components of luminescence are connected to the presence of oxygen vacancies as electron trapping centers and Tb4+ ions as hole trapping centers. Optically created electrons and holes would be trapped at the above-mentioned centers and released thermally to activate Tb3+ ions giving rise to the slow luminescence components. Discussion will be made on the dynamical processes of electrons and holes in the excited states

  17. Simulation of Relativistic Shocks and Associated Self-Consistent Radiation for GRB Prompt Emission and Afterglows

    Science.gov (United States)

    Nishikawa, Ken-Ichi; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Guiriec, S.; Fishman, G. J.

    2010-01-01

    Plasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. This simulation corresponds to a case for gamma-ray burst afterglows. We will simulate colliding shells as an internal shock model for prompt emission. Turbulent magnetic fields generated by a slower shell will be collided by a faster shell. These magnetic fields contribute to the electron s transverse deflection behind the shock. We calculate the radiation from deflected electrons in the turbulent magnetic fields. The properties of this radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts

  18. The First Swift Ultra-Violet/Optical Telescope GRB Afterglow Catalog

    CERN Document Server

    Roming, P W A; Oates, S R; Porterfield, B L; Berk, D E Vanden; Boyd, P T; Holland, S T; Hoversten, E A; Immler, S; Marshall, F E; Page, M J; Racusin, J L; Schneider, D P; Breeveld, A A; Brown, P J; Chester, M M; Cucchiara, A; De Pasquale, M; Gronwall, C; Hunsberger, S D; Kuin, N P M; Landsman, W B; Schady, P; Still, M

    2008-01-01

    We present the first Swift Ultra-Violet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog. The catalog contains data from over 64,000 independent UVOT image observations of 229 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), and the Interplanetary Network (IPN). The catalog covers GRBs occurring during the period from 2005 Jan 17 to 2007 Jun 16 and includes ~86% of the bursts detected by the Swift Burst Alert Telescope (BAT). The catalog provides detailed burst positional, temporal, and photometric information extracted from each of the UVOT images. Positions for bursts detected at the 3-sigma-level are provided with a nominal accuracy, relative to the USNO-B1 catalog, of ~0.25 arcseconds. Photometry for each burst is given in three UV bands, three optical bands, and a 'white' or open filter. Upper limits for magnitudes are reported for sources detected below 3-sigma. General properties of the burst samp...

  19. Ambient magnetic field amplification in shock fronts of relativistic jets: an application to GRB afterglows

    CERN Document Server

    da Silva, G Rocha; Kowal, G; Pino, E M de Gouveia Dal

    2014-01-01

    Strong downstream magnetic fields of order of $\\sim 1$G, with large correlation lengths, are believed to cause the large synchrotron emission at the afterglow phase of gamma ray bursts (GRBs). Despite of the recent theoretical efforts, models have failed to fully explain the amplification of the magnetic field, particularly in a matter dominated scenario. We revisit the problem by considering the synchrotron emission to occur at the expanding shock front of a weakly magnetized relativistic jet over a magnetized surrounding medium. Analytical estimates and a number of high resolution 2D relativistic magneto-hydrodynamical (RMHD) simulations are provided. Jet opening angles of $\\theta = 0^{\\circ} - 20^{\\circ}$, and ambient to jet density ratios of $10^{-4} - 10^2$ were considered. We found that most of the amplification is due to compression of the ambient magnetic field at the contact discontinuity between the reverse and forward shocks at the jet head, with substantial pile-up of the magnetic field lines as t...

  20. GAMMA-RAY BURST AFTERGLOW BROADBAND FITTING BASED DIRECTLY ON HYDRODYNAMICS SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Van Eerten, Hendrik; MacFadyen, Andrew [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States); Van der Horst, Alexander [Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States)

    2012-04-10

    We present a powerful new tool for fitting broadband gamma-ray burst afterglow data, which can be used to determine the burst explosion parameters and the synchrotron radiation parameters. By making use of scale invariance between relativistic jets of different energies and different circumburst medium densities, and by capturing the output of high-resolution two-dimensional relativistic hydrodynamical (RHD) jet simulations in a concise summary, the jet dynamics are generated quickly. Our method calculates the full light curves and spectra using linear radiative transfer sufficiently fast to allow for a direct iterative fit of RHD simulations to the data. The fit properly accounts for jet features that so far have not been successfully modeled analytically, such as jet decollimation, inhomogeneity along the shock front, and the transitory phase between the early-time relativistic and late-time non-relativistic outflow. As a first application of the model we simultaneously fit the radio, X-ray, and optical data of GRB 990510. We find not only noticeable differences between our findings for the explosion and radiation parameters and those of earlier authors, but also an improved model fit when we include the observer angle in the data fit. The fit method will be made freely available on request and online at http://cosmo.nyu.edu/afterglowlibrary. In addition to data fitting, the software tools can also be used to quickly generate a light curve or spectrum for arbitrary observer position, jet, and radiation parameters.

  1. Shocked by the Very Bright Radio Flare and Afterglow of GRB 130427A

    Science.gov (United States)

    van der Horst, Alexander J.

    2014-01-01

    Gamma-ray burst (GRB) 130427A was extremely bright across the electromagnetic spectrum, with emission spanning 16 orders of magnitude in observing frequency, from almost 100 GeV gamma-rays down to the GHz radio regime. While the intrinsic luminosity of this GRB was not extreme compared to other GRBs, it displayed the largest measured fluence of the last three decades due to its proximity with a redshift of 0.34. One of the most notable characteristics of this GRB was its bright radio emission, in particular the radio flare which has been observed only a few times in other GRBs and is usually attributed to the reverse shock moving back into the GRB jet. Here we present radio observations with unprecedented temporal coverage at three observing frequencies obtained with the Westerbork Synthesis Radio Telescope (WSRT) and the Arcminute Microkelvin Imager (AMI). AMI had the earliest radio detection at 8 hours after the initial flash of gamma-rays, catching the radio flare on the rise. The 12-hour WSRT observations in the first few days enabled a detailed study of the short time-scale behavior at radio wavelengths. Besides our observations of the radio flare and afterglow up to three months after the gamma-ray trigger, we present our results for modeling the radio light curves together with the broadband data set in various other wavelength regimes, enabling us to determine physical parameters of both the reverse and forward shock of this enigmatic GRB.

  2. Dynamics and Afterglow Light Curves of GRB Blast Waves with a Long-lived Reverse Shock

    CERN Document Server

    Uhm, Z Lucas; Hascoet, Romain; Daigne, Frederic; Mochkovitch, Robert; Park, Il H

    2012-01-01

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS makes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the "mechanical model" that correctly incorporates the energy conservation for such blast waves with a long-lived RS, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. In particul...

  3. The "Supercritical Pile" GRB Model: Afterglows and GRB, XRR, XRF Unification

    CERN Document Server

    Kazanas, D; Georganopoulos, M; Kazanas, Demosthenes; Mastichiadis, Apostolos; Georganopoulos, Markos

    2006-01-01

    We present the general notions and observational consequences of the "Supercritical Pile" GRB model; the fundamental feature of this model is a detailed process for the conversion of the energy stored in relativistic protons in the GRB Relativistic Blast Waves (RBW) into relativistic electrons and then into radiation. The conversion is effected through the $p \\gamma \\to p e^+e^-$ reaction, whose kinematic threshold is imprinted on the GRB spectra to provide a peak of their emitted luminosity at energy \\Ep $\\sim 1$ MeV in the lab frame. We extend this model to include, in addition to the (quasi--)thermal relativistic post-shock protons an accelerated component of power law form. This component guarantees the production of $e^+e^- -$pairs even after the RBW has slowed down to the point that its (quasi--)thermal protons cannot fulfill the threshold of the above reaction. We suggest that this last condition marks the transition from the prompt to the afterglow GRB phase. We also discuss conditions under which thi...

  4. The 'Supercritical Pile' GRB Model: Afterglows and GRB, XRR, XRF Unification

    Science.gov (United States)

    Kazanas, D.

    2007-01-01

    We present the general notions and observational consequences of the "Supercritical Pile" GRB model; the fundamental feature of this model is a detailed process for the conversion of the energy stored in relativistic protons in the GRB Relativistic Blast Waves (RBW) into relativistic electrons and then into radiation. The conversion is effected through the $p \\, \\gamma \\rightarrow p \\, e circumflex + e circumflex -$ reaction, whose kinematic threshold is imprinted on the GRB spectra to provide a peak of their emitted luminosity at energy \\Ep $\\sim 1$ MeV in the lab frame. We extend this model to include, in addition to the (quasi--)thermal relativistic post-shock protons an accelerated component of power law form. This component guarantees the production of $e circumflex +e circumflex- - $pairs even after the RBW has slowed down to the point that its (quasi-) thermal protons cannot fulfill the threshold of the above reaction. We suggest that this last condition marks the transition from the prompt to the afterglow GRB phase. We also discuss conditions under which this transition is accompanied by a significant drop in the flux and could thus account for several puzzling, recent observations. Finally, we indicate that the same mechanism applied to the late stages of the GRB evolution leads to a decrease in \\Ep $\\propto \\Gamma circumflex 2(t)\\propto t circumflex {-3/4}$, a feature amenable to future observational tests.

  5. NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

    International Nuclear Information System (INIS)

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied

  6. Shedding light on the prompt high efficiency paradox - self consistent modeling of GRB afterglows

    CERN Document Server

    Beniamini, Paz; Duran, Rodolfo Barniol; Piran, Tsvi

    2015-01-01

    We examine GRBs with both Fermi-LAT and X-ray afterglow data. Assuming that the 100MeV (LAT) emission is radiation from cooled electrons accelerated by external shocks, we show that the kinetic energy of the blast wave estimated from the 100MeV flux is 50 times larger than the one estimated from the X-ray flux. This can be explained if either: i) electrons radiating at X-rays are significantly cooled by SSC (suppressing the synchrotron flux above the cooling frequency) or ii) if the X-ray emitting electrons, unlike those emitting at 100MeV energies, are in the slow cooling regime. In both cases the X-ray flux is no longer an immediate proxy of the blast wave kinetic energy. We model the LAT, X-ray and optical data and show that in general these possibilities are consistent with the data, and explain the apparent disagreement between X-ray and LAT observations. All possible solutions require weak magnetic fields: $10^{-6}< \\epsilon_B < 10^{-3}$ (where $\\epsilon_B$ is the fraction of shocked plasma energy...

  7. Detection of the optical afterglow of GRB 000630: Implications for dark bursts

    DEFF Research Database (Denmark)

    Fynbo, J.U.; Jensen, B.L.; Gorosabel, J.;

    2001-01-01

    a power-law decline characterized by a decay slope of alpha = -1.035 +/- 0.097. A deep image obtained 25 days after the burst shows no indication of a contribution from a supernova or a host galaxy at the position of the transient. The closest detected galaxy is a R = 324.68 +/- 0.15 galaxy 2......We present the discovery of the optical transient of the long-duration gamma-ray burst GRB 000630. The optical transient was detected with the Nordic Optical Telescope 21.1 hours after the burst. At the time of discovery the magnitude of the transient was R = 23.04 +/- 0.08. The transient displayed...... conclude that i) based on the gamma-ray: properties of the current sample we cannot conclude that GRBs with no detected OTs belong to another class of GRBs than GRBs with detected OTs and ii) the majority (greater than or similar to 75%) of GRBs for which searches for optical afterglow have been...

  8. Detailed Afterglow Modeling and Host Galaxy Properties of the Dark GRB 111215A

    CERN Document Server

    van der Horst, A J; Pooley, G G; Wiersema, K; Kruhler, T; Perley, D A; Starling, R L C; Curran, P A; Tanvir, N R; Wijers, R A M J; Strom, R G; Kouveliotou, C; Hartoog, O E; Xu, D; Fynbo, J P U; Jakobsson, P

    2014-01-01

    Gamma-ray burst (GRB) 111215A was bright at X-ray and radio frequencies, but not detected in the optical or near-infrared (nIR) down to deep limits. We have observed the GRB afterglow with the Westerbork Synthesis Radio Telescope and Arcminute Microkelvin Imager at radio frequencies, with the William Herschel Telescope and Nordic Optical Telescope in the nIR/optical, and with the Chandra X-ray Observatory. We have combined our data with the Swift X-Ray Telescope monitoring, and radio and millimeter observations from the literature to perform broadband modeling, and determined the macro- and microphysical parameters of the GRB blast wave. By combining the broadband modeling results with our nIR upper limits we have put constraints on the extinction in the host galaxy. This is consistent with the optical extinction we have derived from the excess X-ray absorption, and higher than in other dark bursts for which similar modeling work has been performed. We also present deep imaging of the host galaxy with the Kec...

  9. GRB 080503 late afterglow re-brightening: signature of a magnetar powered merger-nova

    CERN Document Server

    Gao, He; Wu, Xue-Feng; Dai, Zi-Gao; Zhang, Bing

    2015-01-01

    GRB 080503 is a short gamma-ray burst (GRB) detected by \\emph{Swift} and has been classified as a compact-star-merger-origin GRB. The soft extended emission and the simultaneous late re-brightening in both the X-ray and optical afterglow lightcurves raise interesting questions regarding its physical origin. We show that the broad-band data of GRB 080503 can be well explained within the framework of the double neutron star merger model, provided that the merger remnant is a rapidly-rotating massive neutron star with an extremely high magnetic field (i.e. a millisecond magnetar). We show that the late optical re-brightening is consistent with the emission from a magnetar-powered "merger-nova". This adds one more case to the growing sample of merger-novae associated with short GRBs. The soft extended emission and the late X-ray excess emission are well connected through a magnetar dipole spin-down luminosity evolution function, suggesting that direct magnetic dissipation is the mechanism to produce these X-rays....

  10. Effect of humidity on gas temperature in the afterglow of pulsed positive corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Ryo; Teramoto, Yoshiyuki [Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 227-8568 (Japan); Oda, Tetsuji [Department of Electrical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)], E-mail: ryo-ono@k.u-tokyo.ac.jp

    2010-01-15

    The effects of humidity on gas temperature in the afterglow of a pulsed positive corona discharge are studied. The gas temperature is measured using the laser-induced fluorescence (LIF) of NO molecules. The discharge occurs in a 13 mm point-to-plane gap under atmospheric pressure. When the water vapor concentration in air is increased from 0.5% to 2.4%, the temperature increases from 550 to 850 K near the anode tip, and from 350 to 650 K at a position 2.5 mm from the anode tip. The gas heating in the humid environment is due to the fast vibration-to-vibration processes of the O{sub 2}-H{sub 2}O and N{sub 2}-H{sub 2}O systems and the extremely rapid vibration-to-translation process of the H{sub 2}O-H{sub 2}O system. These processes accelerate the transfer of energy from O{sub 2}(v) and N{sub 2}(v) to translational energy. Measurements of the LIF of O{sub 2}(v = 6) show that the decay rate of O{sub 2}(v) density is increased by humidification.

  11. Measurement of gas temperature and OH density in the afterglow of pulsed positive corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Ryo [High Temperature Plasma Center, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 227-8568 (Japan); Oda, Tetsuji [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)

    2008-02-07

    The gas temperature and OH density in the afterglow of pulsed positive corona discharge are measured using the laser-induced predissociation fluorescence (LIPF) of OH radicals. Discharge occurs in a 13 mm point-to-plane gap in an atmospheric-pressure H{sub 2}O(2.8%)/O{sub 2}(2.0%)/N{sub 2} mixture. The temperature measurement shows that (i) the temperature increases after discharge and (ii) the temperature near the anode tip (within 1 mm from the anode tip) is much higher than that of the rest of the discharge volume. Near the anode tip, the temperature increases from 500 K (t = 0 {mu}s) to 1100 K (t = 20 {mu}s), where t is the postdischarge time, while it increases from 400 K (t = 0 {mu}s) to 700 K (t = 100 {mu}s) in the rest of the discharge volume away from the anode tip. This temperature difference between the two volumes (near and far from the anode tip) causes a difference in the decay rate of OH density: OH density near the anode tip decays approximately 10 times slower than that far from the tip. The spatial distribution of OH density shows good agreement with that of the secondary streamer luminous intensity. This shows that OH radicals are mainly produced in the secondary streamer, not in the primary one.

  12. Measurement of gas temperature and OH density in the afterglow of pulsed positive corona discharge

    International Nuclear Information System (INIS)

    The gas temperature and OH density in the afterglow of pulsed positive corona discharge are measured using the laser-induced predissociation fluorescence (LIPF) of OH radicals. Discharge occurs in a 13 mm point-to-plane gap in an atmospheric-pressure H2O(2.8%)/O2(2.0%)/N2 mixture. The temperature measurement shows that (i) the temperature increases after discharge and (ii) the temperature near the anode tip (within 1 mm from the anode tip) is much higher than that of the rest of the discharge volume. Near the anode tip, the temperature increases from 500 K (t = 0 μs) to 1100 K (t = 20 μs), where t is the postdischarge time, while it increases from 400 K (t = 0 μs) to 700 K (t = 100 μs) in the rest of the discharge volume away from the anode tip. This temperature difference between the two volumes (near and far from the anode tip) causes a difference in the decay rate of OH density: OH density near the anode tip decays approximately 10 times slower than that far from the tip. The spatial distribution of OH density shows good agreement with that of the secondary streamer luminous intensity. This shows that OH radicals are mainly produced in the secondary streamer, not in the primary one

  13. The effect of a direct current field on the microparticle charge in the plasma afterglow

    Energy Technology Data Exchange (ETDEWEB)

    Wörner, L. [Max Planck Institute for extraterrestrial Physics, P.O. Box 1312, Giessenbachstr., 85741 Garching (Germany); Groupe de Recherches sur l' Energétique des Milieux Ionisés, UMR7344, CNRS, Univ. Orléans, F-45067 Orléans (France); Ivlev, A. V.; Huber, P.; Hagl, T.; Thomas, H. M.; Morfill, G. E. [Max Planck Institute for extraterrestrial Physics, P.O. Box 1312, Giessenbachstr., 85741 Garching (Germany); Couëdel, L. [Centre National de la Recherche Scientifique, Aix-Marseille-Université, Laboiratoire de Physique des Intéractions Ioniques et Moléculaires, UMR 7345, 13397 Marseille cedex 20 (France); Schwabe, M. [Max Planck Institute for extraterrestrial Physics, P.O. Box 1312, Giessenbachstr., 85741 Garching (Germany); Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720 (United States); Mikikian, M.; Boufendi, L. [Groupe de Recherches sur l' Energétique des Milieux Ionisés, UMR7344, CNRS, Univ. Orléans, F-45067 Orléans (France); Skvortsov, A. [Yuri Gagarin Cosmonauts Training Center, RU-141160 Star City (Russian Federation); Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, RU-125412 Moscow (Russian Federation)

    2013-12-15

    Residual charges of individual microparticles forming dense clouds were measured in a RF discharge afterglow. Experiments were performed under microgravity conditions on board the International Space Station, which ensured particle levitation inside the gas volume after the plasma switch-off. The distribution of residual charges as well as the spatial distribution of charged particles across the cloud were analyzed by applying a low-frequency voltage to the electrodes and measuring amplitudes of the resulting particle oscillations. Upon “free decharging” conditions, the charge distribution had a sharp peak at zero and was rather symmetric (with charges concentrated between −10e and +10e), yet positively and negatively charged particles were homogeneously distributed over the cloud. However, when decharging evolved in the presence of an external DC field (applied shortly before the plasma switch-off) practically all residual charges were positive. In this case, the overall charge distribution had a sharp peak at about +15e and was highly asymmetric, while the spatial distribution exhibited a significant charge gradient along the direction of the applied DC field.

  14. Breakdown and afterglow physics of pulsed 13.56MHz capacitive discharges in Ar

    Science.gov (United States)

    Booth, J. P.; Cunge, G.; Sadeghi, N.; Boswell, R.; Braithwaite, N. St J.

    1996-10-01

    The breakdown and afterglow phases of rapidly modulated 13.56MHz parallel plate discharges in 50mTorr Ar were studied, using powered electrode voltage probe, planar ion flux probe, microwave interferometer and optical emission techniques. The RF risetime is determined by the generator and match box. At low repetition rates this is often faster than the time taken to establish the DC bias, leading to a symmetric discharge localised between the powered electrode and the nearest wall. For several μs the plasma is weakly ionised but highly energetic. As the plasma increases in density and fills more of the reactor, the blocking capacitor charges (rate determined by the Bohm-limited ion flux to the grounded reactor walls) and the plasma becomes asymmetric, approaching the steady state in 10's of μs. On plasma extinction, the electrons cool rapidly (3μs timescale), as seen by the rapid drop in optical emission intensity and ion flux, in excellent agreement with a simple diffusional cooling model. The DC bias is mostly discharged within 10μs. At longer times (100μs) the plasma density drops due to ambipolar diffusion.

  15. Weibel Filament Decay and Thermalization in Collisionless Shocks and Gamma-Ray Burst Afterglows

    CERN Document Server

    Milosavljevic, M; Milosavljevic, Milos; Nakar, Ehud

    2006-01-01

    Models for the synchrotron emission of gamma-ray burst afterglows suggest that the magnetic field is generated in the shock wave that forms as relativistic ejecta plow through the circum-burst medium. Transverse Weibel instability efficiently generates magnetic fields near equipartition with the post-shock energy density. The detailed saturated state of the instability, as seen in particle-in-cell simulations, consists of magnetically self-pinched current filaments. The filaments are parallel to the direction of propagation of the shock and are about a plasma skin depth in radius, forming a quasi--two-dimensional structure. We use a rudimentary analytical model to argue that the Weibel filaments are unstable to a kink-like mode, which destroys their quasi--two-dimensional structure. For wavelengths longer than than the skin depth, the instability grows at the rate equal to the speed of light divided by the wavelength. We calculate the transport of collisionless test particles in the filaments experiencing the...

  16. REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

    International Nuclear Information System (INIS)

    Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ0. We aim to provide a direct measure of Γ0. Methods. The early-time afterglow light curve carries information about Γ0, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB060418 and GRB060607A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Γ0 similar to 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R-dec approximate to 1017 cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB. (authors)

  17. REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, E.; Covino, S.; D' Avanzo, P.; Chincarini, G.; Zerbi, F.M.; Conconi, P.; Malaspina, G.; Campana, S.; Rizzuto, D.; Tagliaferri, G. [Osserv Astron Brera, INAF, I-23807 Merate, LC, (Italy); Vergani, S.D.; Meurs, E.J.A.; Ward, P.A. [DIAS, Dunsink Observ, Dublin 15, (Ireland); Vergani, S.D.; Norci, L. [Dublin City Univ, Sch Phys Sci, NCPST, Dublin 9, (Ireland); Malesani, D. [SISSA, ISAS, I-34014 Trieste, (Italy); Malesani, D. [Univ Copenhagen, Niels Bohr Inst, Dark Cosmol Ctr, DK-2100 Copenhagen, (Denmark); D' Avanzo, P. [Univ Insubria, Dipartimento Matemat and Fis, I-22100 Como, (Italy); Chincarini, G.; Rizzuto, D. [Univ Milan, I-20126 Milan, (Italy); Antonelli, L.A.; Testa, V.; Vitali, F.; D' Alessio, F.; Guetta, D.; Piranomonte, S.; Stella, L. [Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, (Italy); Tosti, G. [Univ Perugia, Dipartimento Fis, Osservatorio Astron, I-06123 Perugia, (Italy); Nicastro, L.; Palazzi, E.; Masetti, N. [IASF Bologna, INAF, I-40129 Bologna, (Italy); Goldoni, P. [APC, Lab Astroparticule and Cosmol, UMR 7164, F-75231 Paris 05, (France); Goldoni, P. [CEA Saclay, DSM, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, (France)] (and others)

    2007-07-01

    Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor {gamma}{sub 0}. We aim to provide a direct measure of {gamma}{sub 0}. Methods. The early-time afterglow light curve carries information about {gamma}{sub 0}, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB060418 and GRB060607A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of {gamma}{sub 0} similar to 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R-dec approximate to 10{sup 17} cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB. (authors)

  18. Characterization of the flowing afterglows of an N{sub 2}-O{sub 2} reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NO{sub {beta}} UV intensity variation with the N and O atom densities

    Energy Technology Data Exchange (ETDEWEB)

    Boudam, M K [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Saoudi, B [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Moisan, M [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Ricard, A [Centre de Physique Atomique de Toulouse (CPAT), 118, route de Narbonne, Universite Paul Sabatier, 31062-Toulouse (France)

    2007-03-21

    The flowing afterglow of an N{sub 2}-O{sub 2} discharge in the 0.6-10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the N{sub 2}{sup +} 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v' = 11 ro-vibrational level of the N{sub 2}(B) state, indicating a reduced contribution from the early afterglow N{sub 2} metastable species. We have studied the influence of operating conditions (pressure, O{sub 2} content in the N{sub 2}-O{sub 2} mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3-0.5% O{sub 2} and then decreases, while the O atom density increases regularly with the O{sub 2} percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2-5 Torr range, this density is quite uniform everywhere in the chamber. The (relative

  19. Preparation and properties of long afterglow in alkaline earth silicate phosphors co-doped by Eu2O3 and Dy2O3

    International Nuclear Information System (INIS)

    Sr2MgSi2O7 host doped with Eu, Dy ions with high brightness and long afterglow was prepared by sintering at high temperature under weak reductive atmosphere. The luminescent properties of this photoluminescent pigment have been systematically studied. The analytical results indicated that the co-doped Eu and Dy ions have little influence on the structure of luminescent materials. That main emission peaks appeared at 469 nm and belonging to a broad-emission is ascribed to the 4f7→4f65d1 transition of Eu2+ in the pigment matrix. The pigment doped only with Eu ions did not have the long afterglow phenomenon. But while co-doped Dy3+ ions in the pigment matrix, the obvious long afterglow was observed, and its decay process contained fast-decay and slow-decay processes

  20. NuSTAR Observations of GRB130427A establish a single component synchrotron afterglow origin for the late optical to multi-GeV emission

    CERN Document Server

    Kouveliotou, C; Racusin, J L; Bellm, E; Vianello, G; Oates, S; Fryer, C L; Boggs, S E; Christensen, F E; Craig, W W; Dermer, C D; Gehrels, N; Hailey, C J; Harrison, F A; Melandri, A; McEnery, J E; Mundell, C G; Stern, D K; Tagliaferri, G; Zhang, W W

    2013-01-01

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (~1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/LAT > 10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.

  1. NuSTAR OBSERVATIONS OF GRB 130427A ESTABLISH A SINGLE COMPONENT SYNCHROTRON AFTERGLOW ORIGIN FOR THE LATE OPTICAL TO MULTI-GEV EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Kouveliotou, C. [Astrophysics Office/ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ra' anana 43537 (Israel); Racusin, J. L.; Gehrels, N.; McEnery, J. E.; Zhang, W. W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bellm, E.; Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Vianello, G. [W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Oates, S. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom); Fryer, C. L. [CCS-2, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, 2800 Lyngby (Denmark); Dermer, C. D. [Code 7653, National Research Laboratory, Washington, DC 20375-5352 (United States); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Melandri, A.; Tagliaferri, G. [INAF-Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy); Mundell, C. G. [Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool Science Park, Liverpool L3 5RF (United Kingdom); Stern, D. K., E-mail: chryssa.kouveliotou@nasa.gov, E-mail: granot@openu.ac.il, E-mail: judith.racusin@nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2013-12-10

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (∼1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.

  2. NuSTAR OBSERVATIONS OF GRB 130427A ESTABLISH A SINGLE COMPONENT SYNCHROTRON AFTERGLOW ORIGIN FOR THE LATE OPTICAL TO MULTI-GEV EMISSION

    International Nuclear Information System (INIS)

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (∼1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation. Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics

  3. DYNAMICS AND AFTERGLOW LIGHT CURVES OF GAMMA-RAY BURST BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    International Nuclear Information System (INIS)

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  4. DISCOVERY AND REDSHIFT OF AN OPTICAL AFTERGLOW IN 71 deg{sup 2}: iPTF13bxl AND GRB 130702A

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Leo P.; Brown, Duncan A. [LIGO Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Bradley Cenko, S.; Gehrels, Neil; McEnery, Julie [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kasliwal, Mansi M.; Mulchaey, John [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101 (United States); Perley, Daniel A.; Kulkarni, S. R.; Bellm, Eric; Barlow, Tom; Cao, Yi; Horesh, Assaf [Cahill Center for Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Ofek, Eran O.; Arcavi, Iair [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Nugent, Peter E.; Bloom, Joshua S. [Department of Astronomy, University of California Berkeley, B-20 Hearst Field Annex 3411, Berkeley, CA 94720-3411 (United States); Corsi, Alessandra [George Washington University, Corcoran Hall, Washington, DC 20052 (United States); Frail, Dale A. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Masci, Frank J., E-mail: lsinger@caltech.edu [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); and others

    2013-10-20

    We report the discovery of the optical afterglow of the γ-ray burst (GRB) 130702A, identified upon searching 71 deg{sup 2} surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory, iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the Very Large Array confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200 inch telescopes showed the afterglow to be at a redshift of z = 0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt γ-ray energy release and afterglow luminosity are intermediate between typical cosmological GRBs and nearby sub-luminous events such as GRB 980425 and GRB 060218. The bright afterglow and emerging supernova offer an opportunity for extensive panchromatic follow-up. Our discovery of iPTF13bxl demonstrates the first observational proof-of-principle for ∼10 Fermi-iPTF localizations annually. Furthermore, it represents an important step toward overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era.

  5. EVIDENCE FOR NEW RELATIONS BETWEEN GAMMA-RAY BURST PROMPT AND X-RAY AFTERGLOW EMISSION FROM 9 YEARS OF SWIFT

    International Nuclear Information System (INIS)

    When a massive star explodes as a gamma-ray burst (GRB), information about the explosion is retained in the properties of the prompt and afterglow emission. We report on new relations between the prompt and X-ray afterglow emission of Swift-detected GRBs found from Burst Alert Telescope (BAT) and X-Ray Telescope data covering 2004 December to 2013 August (754 in total). These relations suggest that the prompt and afterglow emission are closely linked. In particular, we find very strong correlations between the BAT 15-150 keV T 90 and the break times before and after the plateau phase in the 0.3-10 keV X-ray afterglow light curves. We also find a strong anticorrelation between the photon index of the GRB prompt emission and the X-ray spectral slope of the afterglow. Moreover, anticorrelations exist between the rest-frame peak energy in the prompt emission E peak, z and the X-ray afterglow decay slope during the plateau phase and the break times after the plateau phase. The rest- frame break times before and after the plateau phase are also anticorrelated with the rest-frame 15-150 keV luminosity and the isotropic energy during the prompt emission. A principal component analysis suggests that the GRB properties are primarily driven by the luminosity/energy release in the 15-150 keV band. Luminosity functions derived at different redshifts from a log N-log S analysis indicate that the density of bright bursts is significantly lower in the local universe than in the universe at z ≈ 3, where the density of bright GRBs peaks. Using cluster analysis, we find that the duration of BAT-detected short GRBs is less than 1 s. We also present a catalog of all Swift onboard-detected bursts

  6. Modeling the Multi-band Afterglow of GRB 130831A: Evidence for a Spinning-down Magnetar Dominated by Gravitational Wave Losses?

    Science.gov (United States)

    Zhang, Q.; Huang, Y. F.; Zong, H. S.

    2016-06-01

    The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ∼0.8, followed by a steep drop at around 105 s with a slope of ∼6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.

  7. Electron and ion acceleration in relativistic shocks with applications to GRB afterglows

    Science.gov (United States)

    Warren, Donald C.; Ellison, Donald C.; Bykov, Andrei M.; Lee, Shiu-Hang

    2015-09-01

    We have modelled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parametrizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow particles from particle injection at non-relativistic thermal energies to above PeV energies, including the non-linear smoothing of the shock structure due to cosmic ray (CR) backpressure. We observe the mass-to-charge (A/Z) enhancement effect believed to occur in efficient Fermi acceleration in non-relativistic shocks and we parametrize the transfer of ion energy to electrons seen in particle-in-cell (PIC) simulations. For a given set of environmental and model parameters, the Monte Carlo simulation determines the absolute normalization of the particle distributions and the resulting synchrotron, inverse Compton, and pion-decay emission in a largely self-consistent manner. The simulation is flexible and can be readily used with a wide range of parameters typical of γ-ray burst (GRB) afterglows. We describe some preliminary results for photon emission from shocks of different Lorentz factors and outline how the Monte Carlo simulation can be generalized and coupled to hydrodynamic simulations of GRB blast waves. We assume Bohm diffusion for simplicity but emphasize that the non-linear effects we describe stem mainly from an extended shock precursor where higher energy particles diffuse further upstream. Quantitative differences will occur with different diffusion models, particularly for the maximum CR energy and photon emission, but these non-linear effects should be qualitatively similar as long as the scattering mean-free path is an increasing function of momentum.

  8. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of GRB X-Ray Afterglows

    OpenAIRE

    Yu, Y. W.; Liu, X.W.; Dai, Z. G.

    2007-01-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominative in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz fa...

  9. Ultra-high Energy Neutrinos from Gamma-Ray Burst Afterglows Using the Swift-UVOT Data

    Science.gov (United States)

    Nir, Guy; Guetta, Dafne; Landsman, Hagar; Behar, Ehud

    2016-02-01

    We consider a sample of 107 gamma-ray bursts (GRBs) for which early ultra-violet emission was measured by Swift and extrapolate the photon intensity to lower energies. Protons accelerated in the GRB jet may interact with such photons to produce charged pions and subsequently ultra high energy neutrinos {\\varepsilon }ν ≥slant {10}16 eV. We use simple energy conversion efficiency arguments to predict the maximal neutrino flux expected from each GRB. We estimate the neutrino detection rate at large area radio based neutrino detectors and conclude that the early afterglow neutrino emission is too weak to be detected even by next generation neutrino observatories.

  10. Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography

    OpenAIRE

    Cegłowski, Michał; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2015-01-01

    A thin-layer chromatography-mass spectrometry (TLC-MS) setup for characterization of low molecular weight compounds separated on standard TLC plates has been constructed. This new approach successfully combines TLC separation, laser ablation, and ionization using flowing atmospheric pressure afterglow (FAPA) source. For the laser ablation, a low-priced 445-nm continuous-wave diode laser pointer, with a power of 1 W, was used. The combination of the simple, low-budget laser pointer and the FAP...

  11. An achromatic break in the afterglow of the short GRB 140903A: evidence for a narrow jet

    OpenAIRE

    Troja, E.; Sakamoto, T.; Cenko, S. B.; Lien, A.; Gehrels, N.; Castro-Tirado, A. J.; Ricci, R.; Capone, J.; Toy, V.; Kutyrev, A.; Kawai, N.; Cucchiara, A.; Fruchter, A.; Gorosabel, J.; Jeong, S.

    2016-01-01

    We report the results of our observing campaign on GRB140903A, a nearby (z=0.351) short duration (T90~0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with Chandra up to 21 days after the burst, and detected a steeper decay of the X-ray flux after approximately 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireba...

  12. The full curvature effect expected in early X-ray afterglow emission of gamma-ray bursts

    OpenAIRE

    Qin, Y. -P.

    2008-01-01

    We explore the influence of the full curvature effect on the flux of early X-ray afterglow of gamma-ray bursts (GRBs) in cases when the spectrum of the intrinsic emission is a power-law. We find that the well-known $t^{-(2+\\beta)}$ curve is present only when the intrinsic emission is extremely short or the emission arises from an exponential cooling. The time scale of this curve is independent of the Lorentz factor. The resulting light curve would contain two phases when the intrinsic emissio...

  13. Characterization of the chlorophyll thermoluminescence afterglow in dark-adapted or far-red-illuminated plant leaves

    International Nuclear Information System (INIS)

    Far red illumination of photosynthetic material induces a delayed luminescence rise, or afterglow, which has been reported in plant leaves, protoplasts or intact chloroplasts and in algal cells. but does not occur in isolated thylakoids. The rise kinetics is accelerated by increasing temperature and we show, by slowly heating a leaf sample after a far-red illumination, that the afterglow emission can be optimally resolved as a sharp thermoluminescence band. Plant material was mainly pea (Pisum sativum L., cv Kazar and Merveille de Kelvedon) and cucumber (Cucumis sativus L., cv Marketer). Comparisons were done with rape, spinach, tobacco, avocado and maize. A 0.2 degree C-1s to 0.5 degree C-1s temperature gradient, started above 0 degree C after a far red illumination, revealed a new thermoluminescence AG band, peaking between 40 degree C and 50 degree C. It exhibited the characteristic properties of the luminescence afterglow recorded at a constant temperature. The AG band was very sensitive to short incubations at both freezing and moderately warm temperatures. Increasing duration of far red illumination caused two kinetically distinct effects on the AG band and on the B band (S-2S-3 Q-B- recombination), which can be ascribed to different behaviors of proton gradients in stroma and in grana lamellae, respectively. The induction of an afterglow by far red light lasted for several minutes in the dark, at 10 degree C. Flash sequences fired in these conditions confirmed the presence of S-2 and S-3 states stable in the dark, producing luminescence by recombination with back-transferred electrons. In some plant batches, an AG band could be induced by 2 or 3 flashes in the absence of far red light, which demonstrates that a metabolic state leading to AG emission may arise spontaneously in plant leaves. The strong temperature dependence of the AG emission is discussed in terms of heat-induced conformational changes in the thylakoid membrane. We conclude that

  14. Production of highly charged heavy ions by means of a hybrid source in DC mode and in afterglow mode

    Czech Academy of Sciences Publication Activity Database

    Gammino, S.; Ciavola, G.; Torrisi, L.; Andó, L.; Celona, L.; Presti, M.; Manciagli, S.; Picciotto, A.; Mezzasalma, A. M.; Krása, Josef; Láska, Leoš; Pfeifer, Miroslav; Wolowski, J.; Woryna, E.; Parys, P.; Shirkov, G. D.; Hitz, D.

    Melville: American Institut of Physics, 2005 - (Leitner, M.), s. 15-18. (AIP Conference Proceedings. 749). ISBN 0-7354-0234-5. [ELECTRON CYCLOTRON RESONANCE ION SOURCES: 16th International Workshop on ECR Ion Sources ECRIS'04. Berkeley (US), 26.09.2004-30.09.2004] R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : ion sources * plasma heating by laser * plasma radiofrequency heating * cyclotron resonance * electric current * afterglows * tantalum * gold Subject RIV: BL - Plasma and Gas Discharge Physics

  15. The circumburst environment of a FRED GRB: study of the prompt emission and X-ray/optical afterglow of GRB 051111

    OpenAIRE

    Guidorzi, C.; Gomboc, A.; Kobayashi, S; Mundell, C. G.; Rol, E.; Bode, M.F.; Carter, D.; La Parola, V.; Melandri, A.; Monfardini, A.; Mottram, C. J.; O'Brien, P.T.; Page, K. L.; Sakamoto, T; Smith, R.J.

    2006-01-01

    We report a multi-wavelength analysis of the prompt emission and early afterglow of GRB051111 and discuss its properties in the context of current fireball models. The detection of GRB051111 by the Burst Alert Telescope on-board Swift triggered early BVRi' observations with the 2-m robotic Faulkes Telescope North in Hawaii, as well as X-ray observations with the Swift X-Ray Telescope. The prompt gamma-ray emission shows a classical FRED profile. The optical afterglow light curves are fitted w...

  16. NuSTARobservations of grb 130427a establish a single component synchrotron afterglow origin for the late optical to multi-gev emission

    OpenAIRE

    C. Kouveliotou(NASA/Marshall Space Flight Center, United States); Granot, J.; Racusin, J. L.; Bellm, E.; G. Vianello; Oates, S.; Fryer, C.L.; Boggs, S E.; Christensen, Finn Erland; Craig, W. W.; Dermer, C. D.; Gehrels, N.; Hailey, C J.; Harrison, F. A.; Melandri, A.

    2013-01-01

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (similar to 1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR obser...

  17. Effect of mixing process on the luminescent properties of SrAl_2O_4:Eu~(2+),Dy~(3+) long afterglow phosphors

    Institute of Scientific and Technical Information of China (English)

    吕霄; 孙猛; 张俊英; 王天民

    2010-01-01

    A new mixing method was developed for solid-state reaction synthesis of SrAl2O4:Eu2+,Dy3+ long afterglow phosphors.The morphology and crystal structure of the phosphors were analyzed with scanning electron microscope(SEM) and X-ray diffractometer(XRD).The excitation and emission spectra of the long afterglow phosphors were measured,and the main emission band was around 514 nm.The decay time of the product was measured and compared with the phosphors prepared using dry-mixing method and wet-mixing method.It ...

  18. Afterglow performance enhancement and mechanism studies on Y2O2S:Eu,Mg,Ti prepared via cold isostatic pressing

    International Nuclear Information System (INIS)

    Highlights: • The long-afterglow material is process-dependent. • We adopt a modified sulphide-fusion route to synthesise Y2O2S:Eu,Mg,Ti. • The afterglow results from Ti-related defects and Ti also creates harmful defects. • The Mg2+ ions effectively modulate the depth and concentration of the traps. • The codoping of Mg2+–Ti4+ ion pairs reduces the harmful defects. -- Abstract: A Y2O2S:Eu,Mg,Ti material was prepared via a modified sulphide-fusion route. Compared with the traditional solid-state reaction method, the obtained Y2O2S:Eu,Mg,Ti showed smaller, more uniform particles with higher brightness. The afterglow mechanism study indicated that the long-afterglow material is process-dependent and that its performance is determined by recipe, preparation technology and process used. The luminescence centres of Y2O2S:Ti; Y2O2S:Eu,Ti and Y2O2S:Eu,Mg,Ti are Ti4+ ions, Ti4+ + Eu3+ ions and Ti4+ + Eu3+ ions, respectively. The afterglow decay curve cannot be fitted using the exponential equation or first-, second-, third-order exponential decay multiple equations beyond 30 min. The afterglow luminescence of the materials resulted from Ti-related defects that make up two new trap levels. Ti doping created numerous harmful companying defects that decrease luminescence efficiency. Doping of Mg2+ ions facilitated the introduction of Ti4+ ions into the Y2O2S lattice to effectively modulate the depth and concentration of the trap. Doping of Mg2+–Ti4+ ion pairs reduced the number of harmful defects through the formation of a compensation-type hetero-valent substitution solid solution that greatly enhance the afterglow performance. Cold isostatic pressing promoted the entry of Ti ions into the Y2O2S crystal lattice and eliminated defects, such as preferred orientation. In addition, cold isostatic pressing reduced the E2 to 0.9 eV, which is beneficial to the long afterglow of the resulting material at room temperature

  19. Helium in natal HII regions: the origin of the X-ray absorption in gamma-ray burst afterglows

    CERN Document Server

    Watson, Darach; Andersen, Anja C; Fynbo, Johan P U; Gorosabel, Javier; Hjorth, Jens; Jakobsson, Páll; Krühler, Thomas; Laursen, Peter; Leloudas, Giorgos; Malesani, Daniele

    2012-01-01

    Soft X-ray absorption in excess of Galactic is observed in the afterglows of most gamma-ray bursts (GRBs), but the correct solution to its origin has not been arrived at after more than a decade of work, preventing its use as a powerful diagnostic tool. We resolve this long-standing problem and find that He in the GRB's host HII region is responsible for most of the absorption. We show that the X-ray absorbing column density (N_Hx) is correlated with both the neutral gas column density and with the optical afterglow extinction (Av). This correlation explains the connection between dark bursts and bursts with high N_Hx values. From these correlations we exclude an origin of the X-ray absorption which is not related to the host galaxy, i.e. the intergalactic medium or intervening absorbers are not responsible. We find that the correlation with the dust column has a strong redshift evolution, whereas the correlation with the neutral gas does not. From this we conclude that the column density of the X-ray absorpt...

  20. An achromatic break in the afterglow of the short GRB 140903A: evidence for a narrow jet

    CERN Document Server

    Troja, E; Cenko, S B; Lien, A; Gehrels, N; Castro-Tirado, A J; Ricci, R; Capone, J; Toy, V; Kutyrev, A; Kawai, N; Cucchiara, A; Fruchter, A; Gorosabel, J; Jeong, S; Levan, A; Perley, D; Sanchez-Ramirez, R; Tanvir, N; Veilleux, S

    2016-01-01

    We report the results of our observing campaign on GRB140903A, a nearby (z=0.351) short duration (T90~0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with Chandra up to 21 days after the burst, and detected a steeper decay of the X-ray flux after approximately 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle of 5 deg and a collimation-corrected total energy release of 2E50 erg. We further discuss the nature of the GRB progenitor system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star-formation rate of the host galaxy, and the lack of a bright supernova. We conclude that this event was likely originated by a compact binary merger.

  1. The Optical Afterglow and z=0.92 Early-type Host Galaxy of the Short GRB 100117A

    CERN Document Server

    Fong, Wen-fai; Chornock, Ryan; Tanvir, Nial R; Levan, Andrew J; Graham, John F; Fruchter, Andrew S; Cucchiara, Antonino; Fox, Derek B

    2010-01-01

    We present the discovery of the optical afterglow and early-type host galaxy of the short-duration GRB 100117A. The faint afterglow is detected 8.3 hr after the burst with r_AB = 25.46 +/- 0.20 mag. Follow-up optical and near-IR observations uncover a coincident compact red galaxy, identified as an early-type galaxy at a photometric redshift of z~0.6-0.9 (2-sigma) with a mass of 3x10^10 M_Sun, an age of ~1 Gyr, and a luminosity of L_B~0.5L_star. Spectroscopic observations of the host reveal a notable break corresponding to the Balmer 4000-Angstrom break at z~0.9, and stellar population spectral evolution template fits indicate z~0.915, which we adopt as the redshift of the host, with stellar population ages of ~1-3 Gyr. From a possible weak detection of [OII]-3727 emission at z=0.915 we infer an upper bound on the star formation rate of ~0.1 M_Sun per yr, leading to a specific star formation rate of 1 early-type hosts.

  2. The low-extinction afterglow in the solar-metallicity host galaxy of gamma-ray burst 110918A

    CERN Document Server

    Elliott, J; Greiner, J; Savaglio, S; E., F Olivares; Rau, A; Postigo, A de Ugarte; Sánchez-Ramírez, R; Wiersema, K; Schady, P; Kann, D A; Filgas, R; Nardini, M; Berger, E; Fox, D; Gorosabel, J; Klose, S; Levan, A; Guelbenzu, A Nicuesa; Rossi, A; Schmidl, S; Sudilovsky, V; Tanvir, N R; Thöne, C C

    2013-01-01

    Metallicity is theoretically thought to be a fundamental driver in gamma-ray burst (GRB) explosions and energetics, but is still, even after more than a decade of extensive studies, not fully understood. This is largely related to two phenomena: a dust-extinction bias, that prevented high-mass and thus likely high-metallicity GRB hosts to be detected in the first place, and a lack of efficient instrumentation, that limited spectroscopic studies including metallicity measurements to the low-redshift end of the GRB host population. The subject of this work is the very energetic GRB 110918A, for which we measure a redshift of z=0.984. GRB 110918A gave rise to a luminous afterglow with an intrinsic spectral slope of b=0.70, which probed a sight-line with little extinction (A_V=0.16 mag) typical of the established distributions of afterglow properties. Photometric and spectroscopic follow-up observations of the galaxy hosting GRB 110918A, including optical/NIR photometry with GROND and spectroscopy with VLT/X-shoo...

  3. Gamma-Ray Burst afterglows as probes of environment and blastwave physics I: absorption by host galaxy gas and dust

    CERN Document Server

    Starling, R L C; Wiersema, K; Rol, E; Curran, P A; Kouveliotou, C; Van der Horst, A J; Heemskerk, M H M

    2006-01-01

    We use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR, optical and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a MW-like extinction preferred, when testing MW, LMC and SMC extinction laws. The 2175A bump would in principle be detectable in all these afterglows, but is not present in the data. An SMC-like gas-to-dust ratio or lower value can be ruled out for 4 of the hosts analysed here (assuming SMC metallicity and extinction law) whilst the remainder of the sample have too large an error to discriminate. We provide a more accurate estimate of the line-of-sight extinction and improve upon the uncertainties for the majority of the extinction measurements made in previous studies of this sample. We discuss this method to determine extinction values in comparison with the most common...

  4. Dust Extinction in High-z Galaxies with GRB Afterglow Spectroscopy - The 2175{\\AA} Feature at z=2.45

    CERN Document Server

    Elíasdóttir, Á; Hjorth, J; Ledoux, C; Watson, D; Andersen, A C; Malesani, D; Vreeswijk, P M; Prochaska, J X; Sollerman, J; Jaunsen, A O

    2008-01-01

    We report the clear detection of the 2175A dust absorption feature in the optical afterglow spectrum of the gamma-ray burst (GRB) GRB070802 at a redshift of z=2.45. This is the highest redshift for a detected 2175A dust bump to date, and it is the first clear detection of the 2175A bump in a GRB host galaxy, while several tens of optical afterglow spectra without the bump have been recorded in the past decade. The derived extinction curve gives A_V=0.8-1.5 depending on the assumed intrinsic slope. Of the three local extinction laws, an LMC type extinction gives the best fit to the extinction curve of the host of GRB070802. Besides the 2175A bump we find that the spectrum of GRB070802 is characterized by unusually strong low-ionization metal lines and possibly a high metallicity for a GRB sightline ([Si/H]=-0.46+/-0.38, [Zn/H]=-0.50+/-0.68). In particular, the spectrum of GRB070802 is unique for a GRB spectrum in that it shows clear CI absorption features, leading us to propose a correlation between the presen...

  5. Spectral Softening in the X-Ray Afterglow of GRB 130925A as Predicted by the Dust Scattering Model

    Science.gov (United States)

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  6. A statistical study of gamma-ray burst afterglows measured by the Swift Ultra-violet Optical Telescope

    CERN Document Server

    Oates, S R; Schady, P; de Pasquale, M; Koch, T S; Breeveld, A A; Brown, P J; Chester, M M; Holland, S T; Hoversten, E A; Kuin, N P M; Marshall, F E; Roming, P W A; Still, M; Berk, D E Vanden; Zane, S; Nousek, J A

    2009-01-01

    We present the first statistical analysis of 27 UVOT optical/ultra-violet lightcurves of GRB afterglows. We have found, through analysis of the lightcurves in the observer's frame, that a significant fraction rise in the first 500s after the GRB trigger, that all lightcurves decay after 500s, typically as a power-law with a relatively narrow distribution of decay indices, and that the brightest optical afterglows tend to decay the quickest. We find that the rise could either be produced physically by the start of the forward shock, when the jet begins to plough into the external medium, or geometrically where an off-axis observer sees a rising lightcurve as an increasing amount of emission enters the observers line of sight, which occurs as the jet slows. We find that at 99.8% confidence, there is a correlation, in the observed frame, between the apparent magnitude of the lightcurves at 400s and the rate of decay after 500s. However, in the rest frame a Spearman Rank test shows only a weak correlation of low ...

  7. BRIGHT LONG AFTERGLOW PHOSPHORESCENCE GLASS MADE OF SrAl2O4: Eu2+, Dy3+ AND GLASS FRITS

    Institute of Scientific and Technical Information of China (English)

    X.Y. Zhang; Z.F. Cao; L.P. Lu; Z.H. Bai; W.Z. Wang; X.C. Wang

    2005-01-01

    Bright long afterglow phosphorescence glasses were prepared by using SrAl2O4 : Eu2+, Dy3+ phosphors and suitable glass frits together. The SrAl2O4: Eu2+,Dy3+ phosphors were initially prepared by the solid reaction method. Three kinds of glass frits were prepared to match the SrAl2O4: Eu2+,Dy3+ phosphors. Effects of the compositions of the glass frits, the ratios of the phosphors to the frits as well as the firing temperature and firing times on the properties of the samples were discussed. XRD analysis indicated the samples exhibited the typical diffraction peaks of SrAl2O4:Eu2+, Dy3+. The emission spectra of the samples showed broad bands peaking at 510nm. The excitation spectra of the samples showed broad bands ranging from 300 to 480nm. These are believed due to the 5d4f-4f transitions of Eu2+ in the SrAl2O4: Eu2+, Dy3+ phosphors. The afterglow luminescence of the samples excited by a 40W fluorescence lamp for 30min can be observed in the dark for more 10h with the naked eyes. It can find wide applications in many fields.

  8. The Statistics of the Prompt-to-Afterglow GRB Flux Ratios and the Supercritical Pile GRB Model

    CERN Document Server

    Kazanas, D; Sultana, J; Mastichiadis, A

    2015-01-01

    We present the statistics of the ratio, ${\\mathrm R}$, between the prompt and afterglow "plateau" fluxes of GRB. This we define as the ratio between the mean prompt energy flux in the {\\em Swift} BAT and the {\\em Swift} XRT, immediately following the steep transition between these two states and the beginning of the afterglow stage referred to as the "plateau". Like the distribution of other GRB observables, the histogram of ${\\mathrm R}$ is close to log-normal, with maximum at ${\\mathrm R = R}_{\\rm m} \\simeq 2,000$, FWHM of about 2 decades and with the entire distribution spanning about 6 decades in the value of ${\\mathrm R}$. We note that the peak of the distribution is close to the proton-to-electron mass ratio $({\\mathrm R}_{\\rm m} \\simeq m_p/m_e = 1836)$, as proposed by us earlier, on the basis of a specific model for the conversion of the GRB blast wave kinetic energy into radiation, before any similar analysis were made. It therefore appears that, in addition to the values of the energy of peak luminos...

  9. Evidence for an anticorrelation between the duration of the shallow decay phase of GRB X-ray afterglows and redshift

    CERN Document Server

    Stratta, G; D'Elia, V; Perri, M; Covino, S; Stella, L

    2009-01-01

    One of the most intriguing features discovered by Swift is a plateau phase in the X-ray flux decay of about 70% of the afterglows of gamma-ray bursts (GRBs). The physical origin of this feature is still being debated. We constrain the proposed interpretations, based on the intrinsic temporal properties of the plateau phase. We selected and analyzed all the Swift/XRT GRB afterglows at known redshift observed between March 2005 and June 2008 featuring a shallow decay phase in their X-ray lightcurves. For our sample of 21 GRBs we find an anticorrelation of the logarithm of the duration of the shallow phase with re dshift, with a Spearman rank-order correlation coefficient of r=-0.4 and a null hypothesis probability of 5%. When we correct the durations for cosmological dilation, the anticorrelation strenghtens, with r=-0.6 and a null hypothesis probability of 0.4%. Considering only those GRBs in our sample that have a well-measured burst peak energy (8 out of 21), we find an anticorrelation between the energy of ...

  10. A Merger Origin for Short Gamma-Ray Bursts Inferred from the Afterglow and Host Galaxy of GRB 050724

    CERN Document Server

    Berger, E; Cenko, S B; Gal-Yam, A; Soderberg, A M; Kasliwal, M; Leonard, D C; Cameron, P B; Frail, D A; Kulkarni, S R; Murphy, D C; Krzeminski, W; Piran, T; Lee, B L; Roth, K C; Moon, D S; Fox, D B; Harrison, F A; Persson, S E; Schmidt, B P; Penprase, B E; Rich, J; Peterson, B A; Cowie, L L

    2005-01-01

    Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness -- the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10^51 erg. While theoretical arguments suggest that short GRBs are produced in the merger of compact object binaries (neutron stars or black holes), the progenitors, energetics, and environments of these events remain elusive despite recent localizations. Here we report the discovery of radio, optical, and infrared afterglow emission from the short-hard GRB 050724, which unambiguously associate it with an elliptical galaxy at a redshift, z=0.257. We show that the energy release is 1-3 orders of magnitude smaller than that of long GRBs, and that the burst ejecta may be collimated in jets. More importantly, the nature of the host galaxy for...

  11. Effects of Li+ Codoping on the Optical Properties of SrAl2O4 Long Afterglow Ceramic Phosphors

    Directory of Open Access Journals (Sweden)

    Timur Sh. Atabaev

    2014-01-01

    Full Text Available Rare-earths codoped long afterglow strontium aluminate phosphors with high brightness were synthesized via a facile combustion synthesis method using urea as a fuel. The resulted phosphor particles were analyzed by using X-ray diffraction and field emission scanning electron microscope, whereas their optical properties were monitored by photoluminescence spectroscopy. The prepared SrAl2O4:Eu2+, Dy3+, Li+ samples showed a broad green-yellowish emission, peaking at 512 nm when excited by 348 nm. Compared to traditional SrAl2O4:Eu2+, Dy3+ phosphor, the initial luminescence brightness of SrAl2O4:Eu2+, Dy3+, codoped with Li+ improved from 1.89 cd/m2 to 2.71 cd/m2 and the afterglow decay time was prolonged from 103 to 121 min. The possible mechanism of SrAl2O4:Eu2+, Dy3+, Li+ phosphorescence enhancement has been discussed.

  12. Signature of a spin-up magnetar from multi-band afterglow rebrightening of GRB 100814A

    CERN Document Server

    Yu, Y B; Wu, X F; Xu, M; Geng, J J

    2015-01-01

    In recent years, more and more gamma-ray bursts with late rebrightenings in multi-band afterglows unveil the late-time activities of the central engines. GRB 100814A is a special one among the well-sampled events, with complex temporal and spectral evolution. The single power-law shallow decay index of the optical light curve observed by GROND between 640 s and 10 ks is $\\alpha_{\\rm opt} = 0.57 \\pm 0.02$, which apparently conflicts with the simple external shock model expectation. Especially, there is a remarkable rebrightening in the optical to near infrared bands at late time, challenging the external shock model with synchrotron emission coming from the interaction of the blast wave with the surrounding interstellar medium. In this paper, we invoke a magnetar with spin evolution to explain the complex multi-band afterglow emission of GRB 100814A. The initial shallow decay phase in optical bands and the plateau in X-ray can be explained as due to energy injection from a spin-down magnetar. At late time, wit...

  13. Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

    International Nuclear Information System (INIS)

    We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.

  14. The radio afterglow of Swift J1644+57 reveals a powerful jet with fast core and slow sheath

    CERN Document Server

    Mimica, P; Metzger, B D; Aloy, M A

    2015-01-01

    We model the non-thermal transient Swift J1644+57 as resulting from a relativistic jet powered by the accretion of a tidally-disrupted star onto a super-massive black hole. Accompanying synchrotron radio emission is produced by the shock interaction between the jet and the dense circumnuclear medium, similar to a gamma-ray burst afterglow. An open mystery, however, is the origin of the late-time radio rebrightening, which occurred well after the peak of the jetted X-ray emission. Here, we systematically explore several proposed explanations for this behavior by means of multi-dimensional hydrodynamic simulations coupled to a self-consistent radiative transfer calculation of the synchrotron emission. Our main conclusion is that the radio afterglow of Swift J1644+57 is not naturally explained by a jet with a one-dimensional top-hat angular structure. However, a more complex angular structure comprised of an ultra-relativistic core (Lorentz factor $\\Gamma \\sim 10$) surrounded by a slower ($\\Gamma \\sim $ 2) sheat...

  15. Probing the Nature of High-z Short GRB 090426 with Its Early Optical and X-ray Afterglows

    CERN Document Server

    Xin, Liping; Wei, Jianyan; Zhang, Bing; Lv, Houjun; Zheng, Weikang; Urata, Yuji; Im, Myungshin; Wang, Jing; Qiu, Yulei; Deng, Jinsong; Huang, Kuiyun; Hu, Jingyao; Jeon, Yiseul; Li, Huali; Han, Xuhui

    2010-01-01

    Swift GRB 090426 is a short duration burst T_{90}~0.33 seconds in the burst frame at z=2.609) with analogous properties on its host galaxy and spectrum-energy correlation to typical long duration GRBs from collapses of massive stars (Type II GRBs). We present its early optical observations with 0.8-m TNT telescope at Xinglong observatory and 1-m telescope at Mt. Lemmon Optical Astronomy Observatory LOAO in Arizona. Our well-sampled optical afterglow lightcurve covered from ~90 seconds to ~10^4 seconds post the GRB trigger shows two energy injection phases ended at ~230 seconds and ~7100 seconds, respectively. The decay slopes post the injection phases are consistent with each other (\\alpha ~1.22). The X-ray afterglow lightcurve seems to trace the optical one, although the second energy injection phase was missed due to the orbit constrain of Swift satellite. The spectral index of the X-rays is ~1.0 without temporal evolution. The X-ray emission is consistent with the forward shock models. Both the X-ray and o...

  16. Rapid formation of red long afterglow phosphor Sr3Al2O6:Eu2+, Dy3+ by microwave irradiation

    International Nuclear Information System (INIS)

    A new red long afterglow phosphor Sr3Al2O6:Eu2+, Dy3+ nanocrystalline particles were prepared using a microwave oven operated at a frequency of 2.45 GHz and a power of 680 W in a weak reductive atmosphere. The phosphor nanocrystalline particles were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results reveal that the samples are composed of single Sr3Al2O6 phase. The obtained nanocrystalline particles show small size (80-100 nm) and spherical shape. The excitation and emission spectra indicate that excitation broadband chiefly lies in visible range and the nanocrystalline particles emit strong light at 612 nm under around 473 nm excitation. The effect of Eu2+ doping concentrations of the samples on the emission intensity is studied systematically. Furthermore, comparing with conventional heating method, the microwave method has the advantages such as short heating time and low energy consumption. However, the decay speed of the afterglow for Sr3Al2O6:Eu2+, Dy3+ nanocrystalline particles is faster than that obtained by the conventional heating method

  17. Spectroscopy, thermoluminescence and afterglow studies of CaLa{sub 4}(SiO{sub 4}){sub 3}O:Ln (Ln=Ce, Nd, Eu, Tb, Dy)

    Energy Technology Data Exchange (ETDEWEB)

    Dobrowolska, Anna, E-mail: a.p.dobrowolska@tudelft.nl; Karsu, Eren Cihan; Bos, Adrie J.J.; Dorenbos, Pieter

    2015-04-15

    The spectroscopic characterization down to 10 K was performed for undoped and Ln doped CaLa{sub 4}(SiO{sub 4}){sub 3}O (Ln=Eu{sup 3+}, Eu{sup 2+}, Ce{sup 3+}, Dy{sup 3+}, Tb{sup 3+}). Based on the experimental and literature data the scheme was constructed showing the vacuum referred binding energy (VRBE) of electrons in lanthanide states and band states in CaLa{sub 4}(SiO{sub 4}){sub 3}O. This scheme predicts that co-doping with Eu{sup 2+} and Ln{sup 3+} (Ln=Dy, Nd) will induce afterglow. Thermoluminescence and afterglow were indeed measured and compared with a commercial SrAl{sub 2}O{sub 4}:Eu, Dy afterglow phosphor. - Highlights: • Luminescence spectroscopy of CaLa{sub 4}(SiO{sub 4}){sub 3}O:Ln where (Ln=Eu{sup 3+}, Eu{sup 2+}, Ce{sup 3+}, Dy{sup 3+}, Tb{sup 3+}) is presented. • The vacuum referred binding energy (VRBE) scheme is constructed. • Afterglow of CaLa{sub 4}(SiO{sub 4}){sub 3}O:Eu, Dy is measured and compared with a standard SrAl{sub 2}O{sub 4}:Eu, Dy.

  18. NuSTARobservations of grb 130427a establish a single component synchrotron afterglow origin for the late optical to multi-gev emission

    DEFF Research Database (Denmark)

    Kouveliotou, C.; Granot, J.; Racusin, J. L.;

    2013-01-01

    GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (simil...

  19. Modeling the Multi-Band Afterglow of GRB 130831A: Evidence for a Spinning-Down Magnetar Dominated by Gravitational Wave Losses?

    CERN Document Server

    Zhang, Q; Zong, H S

    2016-01-01

    The X-ray afterglow of GRB 130831A shows an "internal plateau" with a decay slope of $\\sim$ 0.8, followed by a steep drop at around $10^5$ s with a slope of $\\sim$ 6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with a...

  20. Luminescent properties of blue green Sr3Al2O5Cl2:Pr3+ and orange red Sr3Al2O5Cl2:Eu2+, Pr3+ afterglow phosphors

    International Nuclear Information System (INIS)

    The Sr3Al2O5Cl2:Eu2+, Pr3+ phosphor has been synthesized via high temperature solid state reaction. The X-ray powder diffraction confirms that the obtained samples are pure orthorhombic Sr3Al2O5Cl2 phases, with a space group of D24-P212121. Blue green emission is observed when the sample is doped with Pr3+ ions and an orange red emission with Eu2+ ions doping. Both of the samples show obvious afterglow emission. The intensity and lifetime of such afterglow can be substantially enhanced in the case of Pr3+-Eu2+ co-doped, whose afterglow can last for approximately 300 min in the dark and the intensity is five times higher than the sample single doped with Eu2+. According to the thermoluminescence glow curves, the trap depth of these double-doped samples is about 0.95 eV, which is suitable for the generation of afterglow luminescence. And Pr3+ ions help to enhance the traps concentrations and modify the trap depth, which contributes to prolong the afterglow duration and increase the afterglow intensity of the phosphors. Finally, a feasible explanation of this afterglow generation is also discussed in this work. - Highlights: • The phosphors were synthesized via the solid state reaction at 800 °C. • Sr3Al2O5Cl2:Pr3+ phosphor gives a blue green afterglow luminescence. • Sr3Al2O5Cl2:Eu2+, Pr3+ phosphor present an orange red afterglow luminescence, lasting for 300 min

  1. Photometry and spectroscopy of GRB 060526: a detailed study of the afterglow and host galaxy of a z = 3.2 gamma-ray burst

    Science.gov (United States)

    Thöne, C. C.; Kann, D. A.; Jóhannesson, G.; Selj, J. H.; Jaunsen, A. O.; Fynbo, J. P. U.; Akerlof, C. W.; Baliyan, K. S.; Bartolini, C.; Bikmaev, I. F.; Bloom, J. S.; Burenin, R. A.; Cobb, B. E.; Covino, S.; Curran, P. A.; Dahle, H.; Ferrero, A.; Foley, S.; French, J.; Fruchter, A. S.; Ganesh, S.; Graham, J. F.; Greco, G.; Guarnieri, A.; Hanlon, L.; Hjorth, J.; Ibrahimov, M.; Israel, G. L.; Jakobsson, P.; Jelínek, M.; Jensen, B. L.; Jørgensen, U. G.; Khamitov, I. M.; Koch, T. S.; Levan, A. J.; Malesani, D.; Masetti, N.; Meehan, S.; Melady, G.; Nanni, D.; Näränen, J.; Pakstiene, E.; Pavlinsky, M. N.; Perley, D. A.; Piccioni, A.; Pizzichini, G.; Pozanenko, A.; Roming, P. W. A.; Rujopakarn, W.; Rumyantsev, V.; Rykoff, E. S.; Sharapov, D.; Starr, D.; Sunyaev, R. A.; Swan, H.; Tanvir, N. R.; Terra, F.; de Ugarte Postigo, A.; Vreeswijk, P. M.; Wilson, A. C.; Yost, S. A.; Yuan, F.

    2010-11-01

    Aims: With this paper we want to investigate the highly variable afterglow light curve and environment of gamma-ray burst (GRB) 060526 at z = 3.221. Methods: We present one of the largest photometric datasets ever obtained for a GRB afterglow, consisting of multi-color photometric data from the ultraviolet to the near infrared. The data set contains 412 data points in total to which we add additional data from the literature. Furthermore, we present low-resolution high signal-to-noise spectra of the afterglow. The afterglow light curve is modeled with both an analytical model using broken power law fits and with a broad-band numerical model which includes energy injections. The absorption lines detected in the spectra are used to derive column densities using a multi-ion single-component curve-of-growth analysis from which we derive the metallicity of the host of GRB 060526. Results: The temporal behaviour of the afterglow follows a double broken power law with breaks at t = 0.090 ± 0.005 and t = 2.401 ± 0.061 days. It shows deviations from the smooth set of power laws that can be modeled by additional energy injections from the central engine, although some significant microvariability remains. The broadband spectral-energy distribution of the afterglow shows no significant extinction along the line of sight. The metallicity derived from S ii and Fe ii of [S/H] = -0.57 ± 0.25 and [Fe/H] = -1.09 ± 0.24 is relatively high for a galaxy at that redshift but comparable to the metallicity of other GRB hosts at similar redshifts. At the position of the afterglow, no host is detected to F775W(AB) = 28.5 mag with the HST, implying an absolute magnitude of the host M(1500 Å) > -18.3 mag which is fainter than most long-duration hosts, although the GRB may be associated with a faint galaxy at a distance of 11 kpc. Based in part on observations obtained with the European Southern Observatory's Very Large Telescope under proposals 077.D-0661 (PI: Vreeswijk) and 177.A-0591

  2. The extinction curves of star-forming regions from z = 0.1 to 6.7 using GRB afterglow spectroscopy

    Science.gov (United States)

    Zafar, T.; Watson, D.; Fynbo, J. P. U.; Malesani, D.; Jakobsson, P.; de Ugarte Postigo, A.

    2011-08-01

    Studies of extinction curves provide insights into the properties of interstellar dust. Until recently, however, very few extinction curves existed outside the local group. GRB afterglows are well suited to extinction studies due to their brightness, simple power-law spectra and their occurrence in distant star forming galaxies. In this paper we present results from the SED analysis of a sample of 41 GRB afterglows, from X-ray to NIR wavelengths. The sample is based on spectra from VLT-FORS, with additional data primarily from Swift. This is the largest sample of extinction curves outside the Local Group and, to date, the only extragalactic sample of absolute extinction curves based on spectroscopy. Estimates of the distribution of restframe visual extinctions, the extinction curves, and the intrinsic spectral shapes of GRB afterglows are obtained. Their correlation with H i column density as well as total and gas-phase metal column density are examined. The line-of-sight gas-to-dust and metals-to-dust ratios are determined and examined as a function of total column density, ISM metallicity and redshift. The intrinsic SEDs of the afterglows show that approximately half the sample require a cooling break between the optical and X-ray ranges. The broken power-law SEDs show an average change in the spectral index of Δβ = 0.51 with a very small standard deviation of 0.02 (excluding the outlier GRB 080210). This is consistent with the expectations from a simple synchrotron model. Such a close convergence of values suggests that the X-ray afterglows of GRBs may be used with considerably more confidence to set the absolute flux level and intrinsic spectral indices in the optical and UV. Of the sample, 63% are well described by a featureless (SMC-type) extinction curve. Almost a quarter of our sample is consistent with no significant extinction (typically AV ≲ 0.1). The 2175 Å extinction bump is detected unequivocally in 7% of our sample (3 GRBs), which all have AV

  3. On the afterglow and host galaxy of GRB 021004: A comprehensivestudy with the Hubble Space Telescope1

    Energy Technology Data Exchange (ETDEWEB)

    Fynbo, J.P.U.; Gorosabel, J.; Smette, A.; Fruchter, A.; Hjorth,J.; Pedersen, K.; Levan, A.; Burud, I.; Sahu, K.; Vreeswijk, P.M.; Bergeron, E.; Kouveliotou1, C.; Tanvir, N.; Thorsett11, S.E.; Wijers,R.A.M.J.; Castro Ceron, J.M.; Castro-Tirado, A.; Garnavich, P.; Holland,S.T.; Jakobsson, P.; Moller, P.; Nugent, P.; Pian, E.; Rhoads, J.; Thomsen, B.; Watson, D.; Woosley, S.

    2004-12-01

    We report on Hubble Space Telescope (HST) observations of the late-time afterglow and host galaxy of GRB 021004 (z = 2.33).Although this gamma-ray burst (GRB) is one of the best observed so far in terms of sampling in the time domain, multi-wavelength coverage and polarimetric observations, there is large disagreement between different measurements and interpretations of this burst in the literature. We have observed the field of GRB 021004 with the HST at multiple epochs from 3 days until almost 10 months after the burst. With STI S prism and G430L spectroscopy we cover the spectral region from about 2000 Angstrom to 5700 Angstrom corresponding to 600 1700 Angstrom in the rest frame. From the limit on the flux recovery bluewards of the Lyman-limit we constrain the H I column density to be above 1 x 1018 cm-2 (5 sigma). Based on ACS and N ICMOS imaging we find that the afterglow evolved a chromatically within the errors (any variation must be less then 5 percent) during the period of HST observations. The color changes observed by other authors during the first four days must be related to a 'noisy' phenomenon superimposed on an afterglow component with a constant spectral shape. This also means that the cooling break has remained on the blue side of the optical part of the spectrum for at least two weeks after the explosion. The optical to X-ray slope OX is consistent with being the same at 1.4 and 52.4 days after the burst. This indicates that the cooling frequency is constant and hence, according to fireball models, that the circumburst medium has a constant density profile. The late-time slope of the light curve (alpha 2, F nu proportional to t-alpha2) is in the range 2 = 1.8-1.9, although inconsistent with a single power-law. This could be due to a late-time flattening caused by the transition to non-relativistic expansion or due to excess emission (a 'bump' in the light curve) about 7 days afterburst. The host galaxy is like most

  4. Fast Radio Bursts and Their Gamma-Ray or Radio Afterglows as Kerr–Newman Black Hole Binaries

    Science.gov (United States)

    Liu, Tong; Romero, Gustavo E.; Liu, Mo-Lin; Li, Ang

    2016-07-01

    Fast radio bursts (FRBs) are radio transients lasting only about a few milliseconds. They seem to occur at cosmological distances. We propose that these events can originate in the collapse of the magnetospheres of Kerr–Newman black holes (KNBHs). We show that the closed orbits of charged particles in the magnetospheres of these objects are unstable. After examining the dependencies on the specific charge of the particle and the spin and charge of the KNBH, we conclude that the resulting timescale and radiation mechanism fit well with extant observations of FRBs. Furthermore, we argue that the merger of a KNBH binary is a plausible central engine for the potential gamma-ray or radio afterglow following certain FRBs and can also account for gravitational wave (GW) events like GW 150914. Our model leads to predictions that can be tested by combined multi-wavelength electromagnetic and GW observations.

  5. Wide field X-ray telescopes: Detecting X-ray transients/afterglows related to gamma ray bursts

    International Nuclear Information System (INIS)

    The recent discovery of X-ray afterglows of GRBs opens the possibility of analyses of GRBs by their X-ray detections. However, imaging X-ray telescopes in current use mostly have limited field of view. Alternative X-ray optics geometries achieving very large fields of view have been theoretically suggested in the 70ies but not constructed and used so far. We review the geometries and basic properties of the wide-field X-ray optical systems based on one- and two-dimensional lobster-eye geometry and suggest technologies for their development and construction. First results of the development of double replicated X-ray reflecting flats for use in one-dimensional X-ray optics of lobster eye type are presented and discussed. Optimum strategy for locating GRBs upon their X-ray counterparts is also presented and discussed

  6. Two types of softening detected in x-ray afterglows of Swift bursts: internal and external shock origins?

    International Nuclear Information System (INIS)

    The softening process observed in the steep decay phase of early x-ray afterglows of Swift bursts has remained a puzzle since its discovery. The softening process can also be observed in the later phase of the bursts and its cause has also been unknown. Recently, it was suggested that, influenced by the curvature effect, emission from high latitudes would shift the Band function spectrum from a higher energy band to a lower band, and this would give rise to the observed softening process accompanied by a steep decay of the flux density. The curvature effect scenario predicts that the terminating time of the softening process would be correlated with the duration of the process. In this paper, on the basis of the data from the UNLV GRB (University of Nevada, Las Vegas, Gamma-Ray Burst) group web-site, we found an obvious correlation between the two quantities. In addition, we found that the softening process can be divided into two classes: the early type softening (ts,max≤'4000' s) and the late type softening (ts,max>'4000' s). The two types of softening show different behaviors in the duration versus terminating time plot. In the relation between the variation rates of the flux density and spectral index during the softening process, a discrepancy between the two types of softening is also observed. According to their timescales and the discrepancy between them, we propose that the two types are of different origins: the early type is of internal shock origin and the late type is of external shock origin. The early softening is related to the steep decay just following the prompt emission, whereas for the late decay one typically conceives the transition from flat decay to late afterglow decay. We suspect that there might be a great difference in Lorentz factor between the two classes, which is responsible for the observed discrepancy

  7. SrAl2O4∶Eu2+, Nd3+ and Dy3+ Long Afterglow Phosphor

    Institute of Scientific and Technical Information of China (English)

    何大伟; 吕菁华; 崔兴龙

    2003-01-01

    The SrAl2O4∶Eu2+, Nd3+ and SrAl2O4∶Eu2+, Dy3+ long afterglow phosphor were synthesized. Their excitation and emission spectra at different excitation and afterglow characteristics were analyzed after the excitation power was taken off. The effects of Eu2+, Dy3+, Nd3+ mole concentrations on phosphorescence characteristics were also discussed. It is crucial to have trapping levels located at a suitable depth related to the thermal release rate at room temperature. The incorporation of Nd3+ ions as an auxiliary activator into the SrAl2O4∶Eu2+ system causes very intense and long phosphorescence. The response time of SrAl2O4∶Eu2+, Dy3+ phosphors is quicker than that of SrAl2O4∶Eu2+, Nd3+. Phosphorescence characteristics of SrAl2O4∶Eu2+, Nd3+ is much better than those of SrAl2O4∶Eu2+, Dy3+. The integrate area of the excitation spectrum of SrAl2O4∶Eu2+, Nd3+ phosphor is larger than that of SrAl2O4∶Eu2+, Dy3+ phosphor within the range of 250~360 nm. For phosphorescence characteristics to the system of SrAl2O4∶Eu2+, Nd3+ phosphor, the optimum concentration of Nd3+ trivalent rare earth ions is 0.05 mol.

  8. Optical diagnostics and mass spectrometry on the afterglow of an atmospheric pressure Ar/O$_2$ radiofrequency plasma used for polymer surface treatment

    CERN Document Server

    Duluard, Corinne Y; Hubert, Julie; Reniers, François

    2016-01-01

    In the context of polymer surface treatment, the afterglow of an atmospheric pressure Ar/O$_2$ radiofrequency plasma is characterized by optical emission spectroscopy, laser induced fluorescence and mass spectrometry. The influence of the O$_2$ gas flow rate and the source power on the plasma properties (gas temperature, Ar excitation temperature, relative concentrations of O atoms and OH radicals) are evaluated. We show that for plasma torch-to-substrate distances lower than 6 mm, the afterglow creates a protective atmosphere, thus the plasma gas composition interacting with the substrate is well controlled. For higher distances, the influence of ambient air can no longer be neglected and gradients in Ar, O$_2$ and N$_2$ concentrations are measured as a function of axial and vertical position.

  9. Evidence for Circumburst Extinction of Gamma-Ray Bursts with Dark Optical Afterglows and Evidence for a Molecular Cloud Origin of Gamma-Ray Bursts

    CERN Document Server

    Reichart, D E; Reichart, Daniel E.; Price, Paul A.

    2003-01-01

    First, we show that the gamma-ray bursts with dark optical afterglows (DOAs) cannot be explained by a failure to image deeply enough quickly enough, and argue that circumburst extinction is the most likely solution. If so, many DOAs will be ``revived'' with rapid follow up and NIR searches in the HETE-2 and Swift eras. Next, we consider the effects of dust sublimation and fragmentation, and show that DOAs occur in clouds of size R > 10L_{49}^{1/2} pc and mass M > 3x10^5L_{49} M_{sun}, where L is the luminosity of the optical flash. Stability considerations show that such clouds cannot be diffuse, but must be molecular. Consequently, we compute the expected column density distribution of bursts that occur in Galactic-like molecular clouds, and show that the column density measurements from X-ray spectra of afterglows, DOAs and otherwise, satisfy this expectation in the source frame.

  10. On-line Determination of the Deuterium Abundance in Breath Water Vapour by Flowing Afterglow Mass Spectrometry with Applications to Measurements of Total Body Water

    Czech Academy of Sciences Publication Activity Database

    Španěl, Patrik; Smith, D.

    2001-01-01

    Roč. 15, č. 1 (2001), s. 25-32. ISSN 0951-4198 R&D Projects: GA ČR GA203/00/0632 Grant ostatní: Royal Society(GB) Joint project Institutional research plan: CEZ:AV0Z4040901 Keywords : flowing afterglow * mass spectrometry * stable isotopes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.478, year: 2001

  11. Sterilization/disinfection using reduced-pressure plasmas: some differences between direct exposure of bacterial spores to a discharge and their exposure to a flowing afterglow

    International Nuclear Information System (INIS)

    The use of plasma for sterilization or disinfection offers a promising alternative to conventional steam or chemical approaches. Plasma can operate at temperatures less damaging to some heat-sensitive medical devices and, in contrast to chemicals, can be non-toxic and non-polluting for the operator and the environment, respectively. Direct exposure to the gaseous discharge (comprising an electric field and ions/electrons) or exposure to its afterglow (no E-field) can both be envisaged a priori, since these two methods can achieve sterility. However, important issues must be considered besides the sterility goal. Direct exposure to the discharge, although yielding a faster inactivation of microorganisms, is shown to be potentially more aggressive to materials and sometimes subjected to the shadowing effect that precludes the sterilization of complex-form items. These two drawbacks can be successfully minimized with an adequate flowing-afterglow exposure. Most importantly, the current paper shows that direct exposure to the discharge can lead to the dislodgment and release of viable microorganisms from their substratum. Such a phenomenon could be responsible for the recontamination of sterilized devices as well as possible contamination of the ambient surroundings, additionally yielding an erroneous over-appreciation of the inactivation efficiency. The operation of the N2–O2 flowing afterglow system being developed in our group is such that there are no ions and electrons left in the process chamber (late-afterglow regime) in full contrast with their presence in the discharge. The dislodgment and release of spores could be attributed, based on the literature, to their electrostatic charging by electrons, leading to an (outward) electrostatic stress that exceeds the adhesion of the spores on their substrate. (paper)

  12. Long-lived plasma and fast quenching of N2(C3Π u ) by electrons in the afterglow of a nanosecond capillary discharge in nitrogen

    Science.gov (United States)

    Lepikhin, N. D.; Klochko, A. V.; Popov, N. A.; Starikovskaia, S. M.

    2016-08-01

    Quenching of electronically excited nitrogen state, {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u},{{v}\\prime}=0\\right) , in the afterglow of nanosecond capillary discharge in pure nitrogen is studied. It is found experimentally that an additional collisional mechanism appears and dominates at high specific deposited energies leading to the anomalously fast quenching of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) in the afterglow. On the basis of obtained experimental data and of the analysis of possible quenching agents, it is concluded that the anomalously fast deactivation of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) can be explained by quenching by electrons. Long-lived plasma at time scale of hundreds nanoseconds after the end of the pulse is observed. High electron densities, about 1014 cm‑3 at 27 mbar, are sustained by reactions of associative ionization. Kinetic 1D numerical modeling and comparison of calculated results with experimentally measured electric fields in the second high-voltage pulse 250 ns after the initial pulse, and electron density measurements in the afterglow confirm the validity of the suggested mechanism.

  13. Influence of La3+ and Dy3+ on the properties of the long afterglow phosphor CaAl2O4:Eu2+,Nd3+

    Institute of Scientific and Technical Information of China (English)

    TENG Xiaoming; ZHUANG Weidong; HE Huaqiang

    2008-01-01

    The long afterglow phosphor CaAl2O4:Eu2+,Nd3+ was prepared by the high temperature solid-state reaction method,and the influence of La3+ and Dy3+ on the properties of the long afterglow phosphor was studied by X-ray diffraction (XRD),photoluminescence (PL),and thermoluminescence (TL),The XRD pattern shows the host phase of CaAl2O4 is produced and no impurity phase appears.The peak wavelength of the phosphor does not vary with La3+ and Dy3+ doping.It implies that the crystal field,which affects the 5d electron states of Eu2+ is not changed dramatically after doping of La3+ and Dy3+.The TL spectra indicate that the phosphor doped with La3+ or Dy3+ produces different depths of trap energy level.In the mechanism of long afterglow luminescence,it is considered that La3+ or Dy3+ works as trap energy level.The decay time lies on the number of electrons in the trap energy level and the rate of the electrons returning to the excitation level.

  14. iPTF14yb: The First GRB Discovered Outside the Gamma-Ray Bandpass and the Rate of Orphan Afterglows

    Science.gov (United States)

    Cenko, Stephen

    2015-04-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, the first unambiguous detection of an afterglow-like transient identified outside the γ-ray bandpass. Subsequent to our discovery announcement, the ``parent'' γ-ray burst GRB 140226A was identified by the InterPlanetary Network of high-energy detectors. We demonstrate an association between iPTF14yb and GRB 140226A based both on probabilistic arguments and by comparing iPTF14yb with the known population of long GRB afterglows and host galaxies. We furthermore estimate the rate of iPTF14yb-like transients based on iPTF observations, and demonstrate it is consistent with the rate of on-axis long GRBs. Finally, we briefly discuss the implications of the non-detection to date of bona fide ``orphan'' afterglows (i.e., those lacking entirely in high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  15. A Decade of Short-duration Gamma-ray Burst Broad-band Afterglows: Energetics, Circumburst Densities, and Jet Opening Angles

    CERN Document Server

    Fong, Wen-fai; Margutti, Raffaella; Zauderer, B Ashley

    2015-01-01

    We present a comprehensive catalog and analysis of broad-band afterglow observations for 103 short-duration gamma-ray bursts (GRBs), comprised of all short GRBs from November 2004 to March 2015 with prompt follow-up observations in the X-ray, optical, near-infrared and/or radio bands. These afterglow observations have uncovered 71 X-ray detections, 30 optical/NIR detections, and 4 radio detections. Employing the standard afterglow synchrotron model, we perform joint probability analyses for a subset of 38 short GRBs with well-sampled light curves to infer the burst isotropic-equivalent energies and circumburst densities. For this subset, we find median isotropic-equivalent gamma-ray and kinetic energies of E_gamma,iso~2x10^51 erg, and E_K,iso~(1-3)x10^51 erg, respectively, depending on the values of the model input parameters. We further find that short GRBs occur in low-density environments, with a median density of n~(3-15)x10^-3 cm^-3, and that ~80-95% of bursts have densities of less than 1 cm^-3. We inve...

  16. Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph and FORS2 spectroscopy of the GRB 081008 afterglow

    Science.gov (United States)

    D'Elia, V.; Campana, S.; Covino, S.; D'Avanzo, P.; Piranomonte, S.; Tagliaferri, G.

    2011-11-01

    We aim at studying the gamma-ray burst (GRB), GRB 081008, environment by analysing the spectra of its optical afterglow. Ultraviolet and Visual Echelle Spectrograph/Very Large Telescope (UVES/VLT) high-resolution spectroscopy of GRB 081008 was secured ˜5 h after the Swift-BAT trigger. Our data set also comprises three VLT/FORS2 nearly simultaneous spectra of the same source. The availability of nearly simultaneous high- and low-resolution spectra for a GRB afterglow is an extremely rare event. The GRB-damped Lyman α system at z= 1.9683 shows that the interstellar medium (ISM) of the host galaxy is constituted by at least three components which contribute to the line profiles. Component I is the redmost one, and is 20 and 78 km s-1 redward components II and III, respectively. We detect several ground state and excited absorption features in components I and II. These features have been used to compute the distances between the GRB and the absorbers. Component I is found to be 52 ± 6 pc away from the GRB, while component II presents few excited transitions and its distance is 200+60- 80 pc. Component III only features a few, low-ionization and saturated lines suggesting that it is even farther from the GRB. Component I represents the closest absorber ever detected near a GRB. This (relatively) low distance can possibly be a consequence of a dense GRB environment, which prevents the GRB prompt/afterglow emission to strongly affect the ISM up to higher distances. The hydrogen column density associated with GRB 081008 is log NH/cm-2= 21.11 ± 0.10, and the metallicity of the host galaxy is in the range of [X/H] =-1.29 to -0.52. In particular, we found [Fe/H] =-1.19 ± 0.11 and [Zn/H] =-0.52 ± 0.11 with respect to solar values. This discrepancy can be explained by the presence of dust in the GRB ISM, given the opposite refractory properties of iron and zinc. By deriving the depletion pattern for GRB 081008, we find the optical extinction in the visual band to be AV

  17. Sterilization/disinfection of medical devices using plasma: the flowing afterglow of the reduced-pressure N2-O2 discharge as the inactivating medium

    Science.gov (United States)

    Moisan, Michel; Boudam, Karim; Carignan, Denis; Kéroack, Danielle; Levif, Pierre; Barbeau, Jean; Séguin, Jacynthe; Kutasi, Kinga; Elmoualij, Benaïssa; Thellin, Olivier; Zorzi, Willy

    2013-07-01

    Potential sterilization/disinfection of medical devices (MDs) is investigated using a specific plasma process developed at the Université de Montréal over the last decade. The inactivating medium of the microorganisms is the flowing afterglow of a reduced-pressure N2-O2 discharge, which provides, as the main biocidal agent, photons over a broad ultraviolet (UV) wavelength range. The flowing afterglow is considered less damaging to MDs than the discharge itself. Working at gas pressures in the 400—700 Pa range (a few torr) ensures, through species diffusion, the uniform filling of large volume chambers with the species outflowing from the discharge, possibly allowing batch processing within them. As a rule, bacterial endospores are used as bio-indicators (BI) to validate sterilization processes. Under the present operating conditions, Bacillus atrophaeus is found to be the most resistant one and is therefore utilized as BI. The current paper reviews the main experimental results concerning the operation and characterization of this sterilizer/disinfector, updating and completing some of our previously published papers. It uses modeling results as guidelines, which are particularly useful when the corresponding experimental data are not (yet) available, hopefully leading to more insight into this plasma afterglow system. The species flowing out of the N2-O2 discharge can be divided into two groups, depending on the time elapsed after they left the discharge zone as they move toward the chamber, namely the early afterglow and the late afterglow. The early flowing afterglow from a pure N2 discharge (also called pink afterglow) is known to be comprised of N2+ and N4+ ions. In the present N2-O2 mixture discharge, NO+ ions are additionally generated, with a lifetime that extends over a longer period than that of the nitrogen molecular ions. We shall suppose that the disappearance of the NO+ ions marks the end of the early afterglow regime, thereby stressing our intent

  18. Hubble Space Telescope observations of the afterglow, supernova and host galaxy associated with the extremely bright GRB 130427A

    CERN Document Server

    Levan, A J; Fruchter, A S; Hjorth, J; Pian, E; Mazzali, P; Perley, D A; Cano, Z; Graham, J; Hounsell, R A; Cenko, S B; Fynbo, J P U; Kouveliotou, C; Pe'er, A; Misra, K; Wiersema, K

    2013-01-01

    We present Hubble Space Telescope observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova associated with an intrinsically extremely luminous burst (E_iso >10^54 erg), much more luminous than almost all previous GRBs with spectroscopically associated supernovae. We use the combination of the image quality and UV capability of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light ~17 rest-frame days after the burst. We find that the burst originated ~4 kpc from the nucleus of a moderately star forming (1 Msol/yr), possibly interacting disc galaxy. ACS grism observations show that the associated supernova, SN 2013cq, is well fit in the red by an SN 1998bw-like supernovae of similar luminosity and velocity (v~15,000 km/s). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v~30,000 km/s), but this SN fai...

  19. A flowing atmospheric pressure afterglow as an ion source coupled to a differential mobility analyzer for volatile organic compound detection.

    Science.gov (United States)

    Bouza, Marcos; Orejas, Jaime; López-Vidal, Silvia; Pisonero, Jorge; Bordel, Nerea; Pereiro, Rosario; Sanz-Medel, Alfredo

    2016-05-23

    Atmospheric pressure glow discharges have been widely used in the last decade as ion sources in ambient mass spectrometry analyses. Here, an in-house flowing atmospheric pressure afterglow (FAPA) has been developed as an alternative ion source for differential mobility analysis (DMA). The discharge source parameters (inter-electrode distance, current and helium flow rate) determining the atmospheric plasma characteristics have been optimized in terms of DMA spectral simplicity with the highest achievable sensitivity while keeping an adequate plasma stability and so the FAPA working conditions finally selected were: 35 mA, 1 L min(-1) of He and an inter-electrode distance of 8 mm. Room temperature in the DMA proved to be adequate for the coupling and chemical analysis with the FAPA source. Positive and negative ions for different volatile organic compounds were tested and analysed by FAPA-DMA using a Faraday cup as a detector and proper operation in both modes was possible (without changes in FAPA operational parameters). The FAPA ionization source showed simpler ion mobility spectra with narrower peaks and a better, or similar, sensitivity than conventional UV-photoionization for DMA analysis in positive mode. Particularly, the negative mode proved to be a promising field of further research for the FAPA ion source coupled to ion mobility, clearly competitive with other more conventional plasmas such as corona discharge. PMID:27141552

  20. MAGNETICALLY DRIVEN WINDS FROM DIFFERENTIALLY ROTATING NEUTRON STARS AND X-RAY AFTERGLOWS OF SHORT GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows, lasting 10-104 s. These features are generally taken as evidence of a long-lived central engine powered by the magnetic spin-down of a uniformly rotating, magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field, which is built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic, and ideal magnetohydrodynamic simulations, showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a simple scaling relation

  1. Influence of gas and treatment time on the surface modification of EPDM rubber treated at afterglow microwave plasmas

    International Nuclear Information System (INIS)

    The ethylene propylene diene monomer (EPDM) rubber possesses excellent physical/chemical bulk properties, is cost-effective, and has been used in the mechanical and aerospace industry. However, it has an inert surface and needs a surface treatment in order to improve its adhesion properties. Plasma modification is the most accepted technique for surface modification of polymers without affecting the properties of the bulk. In this study, an afterglow microwave plasma reactor was used to generate the plasma species responsible for the EPDM surface modification. The plasma modified surfaces were analyzed by means of contact angle measurement, adhesion tests, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Two experimental variables were analyzed: type of the plasma gases and exposure time were considered. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed and the best conditions tested there was an increase of the rupture strength of about 27%, that can be associated mainly with the creation of oxygen containing functional groups on the rubber surface (C-O, C-O-C and C=O) identified by spectroscopic methods. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed. In various conditions tested the contact angles easily decreased more than 500%. What can be concluded that high wettability is a necessary condition to obtain good adhesion, but this is not a sufficient condition.

  2. Spectral Softening in X-ray Afterglow of GRB 130925A as Predicted by Dust Scattering Model

    CERN Document Server

    Zhao, Yi-Nan

    2014-01-01

    Gamma-ray bursts (GRBs) usually occurs in a dense star-forming region with massive circum-burst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences, and sometimes can dominate the X-ray afterglow. In most of the previous studies, only Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius $a\\leq 0.1\\,{\\rm \\mu m}$) in the diffuse interstellar medium. When the size of the grains may significantly increase as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculat...

  3. Two types of softening detected in X-ray afterglows of Swift bursts: internal and external shock origins?

    CERN Document Server

    Qin, Y -P; Fan, J H; Lu, R -J

    2008-01-01

    The softening process observed in the steep decay phase of early X-ray afterglows of Swift bursts has remained a puzzle since its discovery. The softening process can also be observed in the later phase of the bursts and its cause has also been unknown. Recently, it was suggested that, influenced by the curvature effect, emission from high latitudes would shift the Band function spectrum from higher energy band to lower band, and this would give rise to the observed softening process accompanied by a steep decay of the flux density. The curvature effect scenario predicts that the terminating time of the softening process would be correlated with the duration of the process. In this paper, based on the data from the UNLV GRB group web-site, we found an obvious correlation between the two quantities. In addition, we found that the softening process can be divided into two classes: the early type softening ($t_{s,max}\\leq "4000"s$) and the late type softening ($t_{s,max} > "4000"s$). The two types of softening s...

  4. Flowing atmospheric pressure afterglow combined with laser ablation for direct analysis of compounds separated by thin-layer chromatography.

    Science.gov (United States)

    Cegłowski, Michał; Smoluch, Marek; Reszke, Edward; Silberring, Jerzy; Schroeder, Grzegorz

    2016-01-01

    A thin-layer chromatography-mass spectrometry (TLC-MS) setup for characterization of low molecular weight compounds separated on standard TLC plates has been constructed. This new approach successfully combines TLC separation, laser ablation, and ionization using flowing atmospheric pressure afterglow (FAPA) source. For the laser ablation, a low-priced 445-nm continuous-wave diode laser pointer, with a power of 1 W, was used. The combination of the simple, low-budget laser pointer and the FAPA ion source has made this experimental arrangement broadly available, also for small laboratories. The approach was successfully applied for the characterization of low molecular weight compounds separated on TLC plates, such as a mixture of pyrazole derivatives, alkaloids (nicotine and sparteine), and an extract from a drug tablet consisting of paracetamol, propyphenazone, and caffeine. The laser pointer used was capable of ablating organic compounds without the need of application of any additional substances (matrices, staining, etc.) on the TLC spots. The detection limit of the proposed method was estimated to be 35 ng/cm(2) of a pyrazole derivative. PMID:26563110

  5. Coasting external shock in wind medium: an origin for the X-ray plateau decay component in Swift GRB afterglows

    CERN Document Server

    Shen, Rongfeng

    2011-01-01

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a \\rho ~ r^{-2}, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blastwave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, \\Gamma_0 \\leq 46 (\\epsilon_e/0.1)^{-0.24} (\\epsilon_B/0.01)^{0.17}; the isotropic equivalent total ejecta energy is E_{iso} ~ 10^{53} (\\epsilon_e/0.1)^{-1.3} (\\epsilon_B/0.01)^{-0.09} (t_b/10^4 s) erg, where \\epsilon_e and \\epsilon_B are the fractions of the total energy at the shock downstream that are carried by electrons and the m...

  6. Influence of gas and treatment time on the surface modification of EPDM rubber treated at afterglow microwave plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maia, J.V. da, E-mail: jaisondamaia@hotmail.com [Plasmas and Processes Laboratory, Department of Physics, Technological Institute of Aeronautics, 12228-900 S. J. dos Campos, SP (Brazil); Department of Physics, Federal Institute of Santa Catarina, 89251-000 Jaraguá do Sul, SC (Brazil); Pereira, F.P. [Plasmas and Processes Laboratory, Department of Physics, Technological Institute of Aeronautics, 12228-900 S. J. dos Campos, SP (Brazil); Dutra, J.C.N.; Mello, S.A.C. [EBO, Chemistry Division, IAE, CTA, 12228-900 S. J. dos Campos, SP (Brazil); Becerra, E.A.O. [Department of Physics, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, RJ (Brazil); Massi, M.; Sobrinho, A.S. da Silva [Plasmas and Processes Laboratory, Department of Physics, Technological Institute of Aeronautics, 12228-900 S. J. dos Campos, SP (Brazil)

    2013-11-15

    The ethylene propylene diene monomer (EPDM) rubber possesses excellent physical/chemical bulk properties, is cost-effective, and has been used in the mechanical and aerospace industry. However, it has an inert surface and needs a surface treatment in order to improve its adhesion properties. Plasma modification is the most accepted technique for surface modification of polymers without affecting the properties of the bulk. In this study, an afterglow microwave plasma reactor was used to generate the plasma species responsible for the EPDM surface modification. The plasma modified surfaces were analyzed by means of contact angle measurement, adhesion tests, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Two experimental variables were analyzed: type of the plasma gases and exposure time were considered. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed and the best conditions tested there was an increase of the rupture strength of about 27%, that can be associated mainly with the creation of oxygen containing functional groups on the rubber surface (C-O, C-O-C and C=O) identified by spectroscopic methods. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed. In various conditions tested the contact angles easily decreased more than 500%. What can be concluded that high wettability is a necessary condition to obtain good adhesion, but this is not a sufficient condition.

  7. Influence of gas and treatment time on the surface modification of EPDM rubber treated at afterglow microwave plasmas

    Science.gov (United States)

    da Maia, J. V.; Pereira, F. P.; Dutra, J. C. N.; Mello, S. A. C.; Becerra, E. A. O.; Massi, M.; Sobrinho, A. S. da Silva

    2013-11-01

    The ethylene propylene diene monomer (EPDM) rubber possesses excellent physical/chemical bulk properties, is cost-effective, and has been used in the mechanical and aerospace industry. However, it has an inert surface and needs a surface treatment in order to improve its adhesion properties. Plasma modification is the most accepted technique for surface modification of polymers without affecting the properties of the bulk. In this study, an afterglow microwave plasma reactor was used to generate the plasma species responsible for the EPDM surface modification. The plasma modified surfaces were analyzed by means of contact angle measurement, adhesion tests, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Two experimental variables were analyzed: type of the plasma gases and exposure time were considered. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed and the best conditions tested there was an increase of the rupture strength of about 27%, that can be associated mainly with the creation of oxygen containing functional groups on the rubber surface (CO, COC and CO) identified by spectroscopic methods. The predominant failure mode was adhesive, for long treatment times a mixture of adhesive and cohesive failure can be observed. In various conditions tested the contact angles easily decreased more than 500%. What can be concluded that high wettability is a necessary condition to obtain good adhesion, but this is not a sufficient condition.

  8. Kinetics of excited states and radicals in a nanosecond pulse discharge and afterglow in nitrogen and air

    Science.gov (United States)

    Shkurenkov, Ivan; Burnette, David; Lempert, Walter R.; Adamovich, Igor V.

    2014-12-01

    The present kinetic modelling calculation results provide key new insights into the kinetics of vibrational excitation of nitrogen and plasma chemical reactions in nanosecond pulse, ‘diffuse filament’ discharges in nitrogen and dry air at a moderate energy loading per molecule, ˜0.1 eV per molecule. It is shown that it is very important to take into account Coulomb collisions between electrons because they change the electron energy distribution function and, as a result, strongly affect populations of excited states and radical concentrations in the discharge. The results demonstrate that the apparent transient rise of N2 ‘first level’ vibrational temperature after the discharge pulse, as detected in the experiments, is due to the net downward V-V energy transfer in N2-N2 collisions, which increases the N2(X 1Σ, v = 1) population. Finally, a comparison of the model's predictions with the experimental data shows that NO formation in the afterglow occurs via reactive quenching of multiple excited electronic levels of nitrogen molecule, N2\\ast , by O atoms. ) published in this volume, which focuses on the kinetic modelling of the experiments. This paper presents the results of the experiments.

  9. Vibrational and rotational CARS measurements of nitrogen in afterglow of streamer discharge in atmospheric pressure fuel/air mixtures

    International Nuclear Information System (INIS)

    The use of nonequilibrium plasma generated by nanosecond discharges to ignite fuel/air mixtures, known as transient plasma ignition (TPI), has been shown to effectively reduce ignition delay and improve engine performance relative to spark ignition for combustion engines. While this method is potentially useful for many engine applications, at present the underlying physics are poorly understood. This work uses coherent anti-Stokes Raman spectroscopy (CARS) to measure the rotational and vibrational excitation of nitrogen molecules in the discharge afterglow in a variety of fuel/air mixtures outside the limits of combustion in order to elucidate the thermal behaviour of TPI. The time evolution of relative populations of vibrationally excited states of nitrogen in the electronic ground state are reported for each gas mixture; it is shown that generation of these vibrationally excited states is inefficient during the discharge in air but that generation occurs at a high rate roughly 5 µs following the discharge; with the addition of fuels vibrationally excited states are observed during the discharge but an increase in population is still seen at 5 µs. Possible mechanisms for this behaviour are discussed. In addition, rotational temperature increases of at least 500 K are reported for all gas mixtures. The effect of this temperature increase on ignition, reaction rates, and thermal energy pathways are discussed.

  10. Influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma

    CERN Document Server

    Duluard, C Y; Hubert, J; Reniers, F

    2016-01-01

    The influence of ambient air on the flowing afterglow of an atmospheric pressure Ar/O2 radiofrequency plasma has been investigated experimentally. Spatially resolved mass spectrometry and laser induced fluorescence on OH radicals were used to estimate the intrusion of air in between the plasma torch and the substrate as a function of the torch-to-substrate separation distance. No air is detected, within the limits of measurement uncertainties, for separation distances smaller than 5 mm. For larger distances, the effect of ambient air can no longer be neglected, and radial gradients in the concentrations of species appear. The Ar 4p population, determined through absolute optical emission spectroscopy, is seen to decrease with separation distance, whereas a rise in emission from the N2(C--B) system is measured. The observed decay in Ar 4p and N2(C) populations for separation distances greater than 9mm is partly assigned to the increasing collisional quenching rate by N2 and O2 molecules from the entrained air....

  11. The Afterglow and Early-Type Host Galaxy of the Short GRB 150101B at z=0.1343

    CERN Document Server

    Fong, Wen-fai; Chornock, Ryan; Berger, Edo; Shappee, Benjamin J; Levan, Andrew J; Tanvir, Nial R; Smith, Nathan; Milne, Peter A; Laskar, Tanmoy; Fox, Derek B; Lunnan, Ragnhild; Blanchard, Peter K; Hjorth, Jens; Wiersema, Klaas; van der Horst, Alexander J; Zaritsky, Dennis

    2016-01-01

    We present the discovery of the X-ray and optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z=0.1343 +/- 0.0030. This makes GRB 150101B the most nearby short GRB with an early-type host galaxy discovered to date. Fitting the spectral energy distribution of the host galaxy results in an inferred stellar mass of ~7x10^10 M_sol, stellar population age of ~2-2.5 Gyr, and star formation rate of 9 deg. Using observations extending to ~30 days, we place upper limits of <(2-4)x10^41 erg s^-1 on associated kilonova emission. We compare searches following previous short GRBs to existing kilonova models, and demonstrate the difficulty of performing effective kilonova searches from cosmological short GRBs using current ground-based facilities. We show that at the Advanced LIGO/VIRGO horizon distance of 200 Mpc, searches reaching depths of ~23-24 AB mag are necessary to probe a meaningful range of kilonova models.

  12. Preparation and properties of long afterglow in alkaline earth silicate phosphors co-doped by Eu{sub 2}O{sub 3} and Dy{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sabbagh Alvani, A.A. [Department of Polymer Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of)]. E-mail: sabbagh_alvani@aut.ac.ir; Moztarzadeh, F. [Faculty of Biomedical Engineering, Amirkabir University of Technology, 424, Hafez Avenue, Tehran (Iran, Islamic Republic of); Sarabi, A.A. [Department of Polymer Engineering, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2005-11-15

    Sr{sub 2}MgSi{sub 2}O{sub 7} host doped with Eu, Dy ions with high brightness and long afterglow was prepared by sintering at high temperature under weak reductive atmosphere. The luminescent properties of this photoluminescent pigment have been systematically studied. The analytical results indicated that the co-doped Eu and Dy ions have little influence on the structure of luminescent materials. That main emission peaks appeared at 469 nm and belonging to a broad-emission is ascribed to the 4f{sup 7}{yields}4f{sup 6}5d{sup 1} transition of Eu{sup 2+} in the pigment matrix. The pigment doped only with Eu ions did not have the long afterglow phenomenon. But while co-doped Dy{sup 3+} ions in the pigment matrix, the obvious long afterglow was observed, and its decay process contained fast-decay and slow-decay processes.

  13. Short GRB 130603B: Discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess

    Energy Technology Data Exchange (ETDEWEB)

    Fong, W.; Berger, E.; Margutti, R.; Chornock, R.; Migliori, G.; Zauderer, B. A.; Lunnan, R.; Laskar, T. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Metzger, B. D. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Desch, S. J. [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1404 (United States); Meech, K. J.; Sonnett, S. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Dickey, C.; Hedlund, A. [Pomona College, 610 N. College Ave., Claremont, CA 91711 (United States); Harding, P. [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215 (United States)

    2014-01-10

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ≈(0.6-1.7) × 10{sup 51} erg and a circumburst density of ≈5 × 10{sup –3}-30 cm{sup –3}. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E {sub γ} ≈ (0.5-2) × 10{sup 49} erg and E {sub K} ≈ (0.1-1.6) × 10{sup 49} erg. Along with previous measurements and lower limits we find a median opening angle of ≈10°. Using the all-sky observed rate of 10 Gpc{sup –3} yr{sup –1}, this implies a true short GRB rate of ≈20 yr{sup –1} within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at ≳ 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  14. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    Energy Technology Data Exchange (ETDEWEB)

    Levan, A. J. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Tanvir, N. R.; Wiersema, K. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom); Fruchter, A. S.; Hounsell, R. A.; Graham, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Hjorth, J.; Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Pian, E. [INAF, Trieste Astronomical Observatory, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2 Liverpool Science Park 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. A. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Cano, Z. [Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavik (Iceland); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Kouveliotou, C. [Science and Technology Office, ZP12, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Pe' er, A. [Department of Physics, University College Cork, Cork (Ireland); Misra, K., E-mail: a.j.levan@warwick.ac.uk [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital-263 002 (India)

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  15. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    International Nuclear Information System (INIS)

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E iso > 1054 erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v ph ∼ 15, 000 km s–1). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v ph ∼ 30, 000 km s–1), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M ☉ yr–1), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  16. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    Science.gov (United States)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; Cenko, S. B.; Fynbo, J. P. U.; Kouveliotou, C.; Pe'er, A.; Misra, K.; Wiersema, K.

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  17. Coasting External Shock in Wind Medium: An Origin for the X-ray Plateau Decay Component in Swift GRB Afterglows

    Science.gov (United States)

    Shen, Rongfeng; Matzner, C. D.

    2012-01-01

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a ρ r-2, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blastwave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, Γ0 ≤ 46 (ɛe/0.1)-0.24 (ɛB/0.01)0.17 the isotropic equivalent total ejecta energy is Eiso 1053 (ɛe/0.1)-1.3 (ɛB/0.01)-0.09 (tb/104 s) erg, where ɛe and ɛB are the fractions of the total energy at the shock downstream that are carried by electrons and the magnetic field, respectively, and tb is the end of the plateau. Our finding supports Wolf-Rayet stars as the progenitor stars of some GRBs. It raises intriguing questions about the origin of an intermediate-Γ0 ejecta, which we speculate is connected to the GRB jet emergence from its host star. For the remaining 45% of the sample, the post-plateau decline is too rapid to be explained in the coasting-in-wind model, and energy injection appears to be required.

  18. Memory effects in the afterglow: open questions on long-lived species and the role of surface processes

    International Nuclear Information System (INIS)

    The memory effect, the phenomenon that some active species survive very long afterglow periods and affect subsequent breakdown, was observed more than 40 years ago. The effects have been observed even over periods of several hours. Attempts to explain the memory effect in nitrogen were mostly based on hypothetical metastables and on the A3Σ state. However, such explanations had to neglect some quenching processes which are known to be very effective under the conditions of the experiments. The explanation based on atoms remaining from the previous discharge and recombining on the cathode to produce initial electrons was shown to be fully consistent with all the experimental data for nitrogen including a wide range of pressures and the addition of oxygen impurities. The memory effect was also shown to be sensitive to the work function of the cathode material. Thus, an attempt was made to use the memory effect as a diagnostic tool to establish the data on the dominant loss of nitrogen atoms from the discharge which is recombination on the walls of the tube. However, a possible role of higher vibrational levels has not been fully addressed, mainly due to the shortage of data. On the other hand, the memory effect which was observed for rare gases cannot be explained on the basis of the standard data unless the presence of molecular impurities is invoked. Another open issue would be the role of charges accumulated on the glass surfaces and whether those may be released to the gas phase. The aim of this paper is to summarize the achievements of the model based on atom recombination and to point out how the breakdown model associated with the memory effect may be completed and how it may be applied in practical discharges. (author)

  19. Measurement of vibrationally excited O{sub 2}(v = 6) in the afterglow of pulsed positive corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Ryo [Department of Advanced Energy, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 227-8568 (Japan); Oda, Tetsuji [Department of Electrical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 (Japan)], E-mail: ryo-ono@k.u-tokyo.ac.jp

    2009-08-01

    The density of vibrationally excited O{sub 2}(v = 6) in the afterglow of a pulsed positive corona discharge is measured using time-resolved laser-induced predissociation fluorescence. Discharge occurs in a 13 mm point-to-plane gap in humid air under atmospheric pressure. When the discharge voltage is 32 kV, the O{sub 2}(v = 6) density at a distance of 2.5 mm from the anode tip is 4 x 10{sup 14} cm{sup -3} at t = 2 {mu}s, where t is the postdischarge time, then decreases to 3 x 10{sup 13} cm{sup -3} by t = 15 {mu}s. The corresponding vibrational temperatures of O{sub 2}, T{sub v}, are 1400 K at t = 2 {mu}s and 1100 K at t = 15 {mu}s, which are calculated by assuming the vibrational equilibrium of O{sub 2}. It is shown that the T{sub v} of O{sub 2} in the secondary streamer channel is much higher than that in the primary streamer channel. Since the cross section of dissociative attachment (e + O{sub 2} {yields} O + O{sup -}) for a low electron energy (<5 eV) increases markedly with the T{sub v} of O{sub 2}, the high T{sub v} in the secondary streamer may lead to a marked increase in O atom production in the secondary streamer in spite of its low mean electron energy (1-2 eV)

  20. EFFECT OF ALKALINE IONS ON THE PHASE EVOLUTION, PHOTOLUMINESCENCE, AND AFTERGLOW PROPERTIES OF SrAl2O4: Eu2+, Dy3+ PHOSPHOR

    OpenAIRE

    HYUNHO SHIN; SHAFQAT ULLAH; KWANGHYUN CHUNG

    2012-01-01

    A series of SrAl2O4: Eu2+, Dy3+ long-afterglow (LAG) phosphors with varying concentration of Li+, Na+ and K+, has been synthesized. The increased concentration of the three types of alkaline ions does not decrease the quantity of the total luminescent phases (SrAl2O4 plus Sr4Al14O25), but a different set of secondary phases has been evoluted for the K+-added series due to the failure of the incorporation of relatively large K+ (1.38 Å) to the Sr2+ (1.18 Å) site in the hosts, unlike the cases ...

  1. Development of time-of-flight neutron detector with fast-decay and low-afterglow scintillator for fast ignition experiment

    Directory of Open Access Journals (Sweden)

    Nagai T.

    2013-11-01

    Full Text Available A fast-decay and low-afterglow liquid scintillator was developed for the fast ignition experiment at the Institute of Laser Engineering (ILE. The liquid scintillator was coupled to a gated photomultiplier (PMT, and the gating performance under high-intensity γ-rays was experimentally checked. In 2010, a detector with a high detection efficiency of 10−4 was developed and installed in this experiment. The neutron yield in the fast heating experiment was successfully measured using this detector.

  2. Evidence for Circumburst Extinction of Gamma-Ray Bursts with Dark Optical Afterglows and Evidence for a Molecular Cloud Origin of Gamma-Ray Bursts

    OpenAIRE

    Reichart, Daniel E.; Price, Paul A.

    2002-01-01

    First, we show that the gamma-ray bursts with dark optical afterglows (DOAs) cannot be explained by a failure to image deeply enough quickly enough, and argue that circumburst extinction is the most likely solution. If so, many DOAs will be ``revived'' with rapid follow up and NIR searches in the HETE-2 and Swift eras. Next, we consider the effects of dust sublimation and fragmentation, and show that DOAs occur in clouds of size R > 10L_{49}^{1/2} pc and mass M > 3x10^5L_{49} M_{sun}, where L...

  3. Note: Light output enhanced fast response and low afterglow 6Li glass scintillator as potential down-scattered neutron diagnostics for inertial confinement fusion

    International Nuclear Information System (INIS)

    The characteristics of an APLF80+3Ce scintillator are presented. Its sufficiently fast decay profile, low afterglow, and an improved light output compared to the recently developed APLF80+3Pr, were experimentally demonstrated. This scintillator material holds promise for applications in neutron imaging diagnostics at the energy regions of 0.27 MeV of DD fusion down-scattered neutron peak at the world's largest inertial confinement fusion facilities such as the National Ignition Facility and the Laser Megajoule.

  4. The extinction curves of star-forming regions from z=0.1 to 6.7 using GRB afterglow spectroscopy

    CERN Document Server

    Zafar, Tayyaba; Fynbo, Johan P U; Malesani, Daniele; Jakobsson, Pall; Postigo, Antonio de Ugarte

    2011-01-01

    GRB afterglows are well suited to extinction studies due to their brightness, simple power-law spectra and the occurrence of GRBs in distant star forming galaxies. In this paper we present results from the SED analysis of a sample of 41 GRB afterglows, from X-ray to NIR wavelengths. This is the largest sample of extinction curves outside the Local Group and, to date, the only extragalactic sample of absolute extinction curves based on spectroscopy. Visual extinction correlation with HI column density as well as total and gas-phase metal column density are examined. Approximately half the sample require a cooling break between the optical and X-ray regimes. The broken power-law SEDs show an average change in the spectral index of delta_beta=0.51 with a standard deviation of 0.02. This is consistent with the expectation from a simple synchrotron model. Of the sample, 63% are well described by the SMC-type extinction curve and have moderate or low extinction, with AV1.0. We find an anti-correlation between gas-t...

  5. VLT/X-shooter spectroscopy of the afterglow of GRB 130606A: Chemical abundances and reionisation at $z\\sim6$

    CERN Document Server

    Hartoog, O E; Fynbo, J P U; Goto, T; Krühler, T; Vreeswijk, P M; De Cia, A; Xu, D; Møller, P; Covino, S; D'Elia, V; Flores, H; Goldoni, P; Hjorth, J; Jakobsson, P; Krogager, J -K; Kaper, L; Ledoux, C; Levan, A J; Milvang-Jensen, B; Sollerman, J; Sparre, M; Tagliaferri, G; Tanvir, N R; Postigo, A de Ugarte; Vergani, S D; Wiersema, K; Datson, J; Salinas, R; Mikkelsen, K; Aghanim, N

    2014-01-01

    The reionisation of the universe is thought to have ended around z~6, as inferred from spectroscopy of distant bright background sources such as quasars (QSO) and gamma-ray burst (GRB) afterglows. Furthermore, spectroscopy of a GRB afterglow provides insight in its host galaxy, which is often too dim and distant to study otherwise. We present the high S/N VLT/X-shooter spectrum of GRB130606A at z=5.913. We aim to measure the degree of ionisation of the IGM between 5.025.6. GRBs are useful probes of the IGM ionisation state of the early Universe, but because of internal scatter we need a larger statistical sample to draw robust conclusions. The high [Si/Fe] in the host can be due to dust depletion, alpha-element enhancement or a combination. The very high value of [Al/Fe]=2.40+/-0.78 might be connected to the stellar population history. We estimate the host metallicity to be -1.5<[M/H]<-1.2 (3%-6% of solar). [truncated

  6. The shallow-decay phase in both optical and x-ray afterglows of Swift GRB 090529A: Energy injection into a wind-type medium?

    CERN Document Server

    Xin, L P; Kann, D A; Xu, D; Gorosabel, J; Leloudas, G; Wei, J Y; Andreev, M; Qin, S F; Ibrahimov, M; Han, X H; Postigo, A de Ugarte; Qiu, Y L; Deng, J S; Volnova, A; Jakobsson, P; Castro-Tirado, A J; Aceituno, F; Fynbo, J P U; Wang, J; Sanchez-Ramirez, R; Kouprianov, V; Zheng, W K; Tello, J C; Wu, C

    2012-01-01

    The energy injection model is usually proposed to interpret the shallow-decay phase in Swift GRB X-ray afterglows. However, very few GRBs have simultaneous signatures of energy injection in their optical and X-ray afterglows. Here, we report optical observations of GRB 090529A from 2000 sec to $\\sim10^6$ sec after the burst, in which an achromatic decay is seen at both wavelengths. The optical light curve shows a decay from 0.37 to 0.99 with a break at $\\sim10^5$ sec. In the same time interval, the decay indices of the X-ray light curve changed from 0.04 to 1.2. Comparing these values with the closure relations, the segment after 3$\\times10^{4}$ sec is consistent with the prediction of the forward shock in an ISM medium without any energy injection. The shallow-decay phase between 2000 to 3$\\times10^{4}$ sec could be due to the external shock in a wind-type-like medium with an energy injection under the condition of $\

  7. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. I. Absorption by Host-Galaxy Gas and Dust

    Science.gov (United States)

    Starling, R. L. C.; Wijers, R. A. M. J.; Wiersema, K.; Rol, E.; Curran, P. A.; Kouveliotou, C.; van der Horst, A. J.; Heemskerk, M. H. M.

    2007-06-01

    We use a new approach to obtain limits on the absorbing columns toward an initial sample of 10 long gamma-ray bursts observed with BeppoSAX and selected on the basis of their good optical and near-infrared (NIR) coverage, from simultaneous fits to NIR, optical, and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a Milky Way-like (MW) extinction preferred when testing MW, LMC, and SMC extinction laws. The 2175 Å bump would in principle be detectable in all these afterglows, but is not present in the data. An SMC-like gas-to-dust ratio or lower value can be ruled out for four of the hosts analyzed here (assuming SMC metallicity and extinction law), while the remainder of the sample have too large an error to discriminate. We provide a more accurate estimate of the line-of-sight extinction and improve on the uncertainties for the majority of the extinction measurements made in previous studies of this sample. We discuss this method for determining extinction values in comparison with the most commonly employed existing methods.

  8. GRB 130925A: an ultra-long Gamma Ray Burst with a dust-echo afterglow, and implications for the origin of the ultra-long GRBs

    CERN Document Server

    Evans, P A; Osborne, J P; O'Brien, P T; Tanvir, N R; Frederiks, D D; Pal'shin, V D; Svinkin, D S; Lien, A; Cummings, J; Xiong, S; Zhang, B -B; Götz, D; Savchenko, V; Negoro, Hitoshi; Nakahira, Satoshi; Suzuki, Kazuhiko; Wiersema, K; Starling, R L C; Castro-Tirado, A J; Beardmore, A P; Sánchez-Ramírez, R; Gorosabel, J; Jeong, S; Kennea, J A; Burrows, D N; Gehrels, N

    2014-01-01

    GRB~130925A was an unusual GRB, consisting of 3 distinct episodes of high-energy emission spanning $\\sim$20 ks, making it a member of the proposed category of `ultra-long' bursts. It was also unusual in that its late-time X-ray emission observed by \\swift\\ was very soft, and showed a strong hard-to-soft spectral evolution with time. This evolution, rarely seen in GRB afterglows, can be well modelled as the dust-scattered echo of the prompt emission, with stringent limits on the contribution from the normal afterglow (i.e. external shock) emission. We consider and reject the possibility that GRB~130925A was some form of tidal disruption event, and instead show that if the circumburst density around GRB~130925A is low, the long duration of the burst and faint external shock emission are naturally explained. Indeed, we suggest that the ultra-long GRBs as a class can be explained as those with low circumburst densities, such that the deceleration time (at which point the material ejected from the nascent black ho...

  9. Strategies for Prompt Searches for GRB Afterglows: The Discovery of GRB 001011 Optical/Near-Infrared Counterpart Using Colour-Colour Selection

    Science.gov (United States)

    Gorosabel, J.; Fynbo, J. U.; Hjorth, J.; Wolf, C.; Andersen, M. I.; Pedersen, H.; Christensen, L.; Jensen, B. L.; Moller, P.; Afonso, J.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We report the discovery of the optical and near-infrared counterpart to GRB 001011. The GRB 001011 error box determined by Beppo-SAX was simultaneously imaged in the near-infrared by the 3.58-m. New Technology Telescope and in the optical by the 1.54-m Danish Telescope - 8 hr after the gamma-ray event. We implement the colour-colour discrimination technique proposed by Rhoads (2001) and extend it using near-IR data as well. We present the results provided by an automatic colour-colour discrimination pipe-line developed to discern the different populations of objects present in the GRB 001011 error box. Our software revealed three candidates based on single-epoch images. Second-epoch observations carried out approx. 3.2 days after the burst revealed that the most likely candidate had faded thus identifying it with the counterpart to the GRB. In deep R-band images obtained 7 months after the burst a faint (R=25.38 plus or minus 0.25) elongated object, presumably the host galaxy of GRB 001011, was detected at the position of the afterglow. The GRB 001011 afterglow is the first discovered with the assistance of colour-colour diagram techniques. We discuss the advantages of using this method and its application to boxes determined by future missions.

  10. Soft X-ray Transmission Spectroscopy of Warm/Hot Intergalactic Medium: Mock Observation of Gamma-Ray Burst X-ray Afterglow

    CERN Document Server

    Kawahara, H; Sasaki, S; Suto, Y; Kawai, N; Mitsuda, K; Ohashi, T; Yamasaki, N; Kawahara, Hajime; Yoshikawa, Kohji; Sasaki, Shin; Suto, Yasushi; Kawai, Nobuyuki; Mitsuda, Kazuhisa; Ohashi, Takaya; Yamasaki, Noriko

    2005-01-01

    We discuss the detectability of Warm/Hot Intergalactic medium (WHIM) via the absorption lines toward bright gamma-ray burst (GRB) afterglows with future X-ray satellite missions like XEUS. We create mock absorption spectra for bright GRB afterglows ($\\sim 40$ per year over the entire sky) using a light-cone output of a cosmological hydrodynamic simulation. We assume that WHIM is under collisional and photo-ionization equilibrium. If we adopt the constant metallicity of $Z=0.1Z_\\odot$, approximately one O{\\sc vii} absorption line system with $>3\\sigma$ will be detected on average along a random line-of-sight up to $z=0.3$ if XEUS starts observing within a couple of hours after the GRB alert. However the above number is very sensitive to the adopted, and currently unknown, metallicity of the WHIM. We also discuss a feasibility of a follow-up observation for the emission line counterpart with a small dedicated X-ray mission like DIOS (Diffuse Intergalactic Oxygen Surveyor) and reliability of the estimate of the ...

  11. Synthesis of Long Afterglow Phosphor CaAl2Si2O8:Eu2+, Dy3+ via Sol-Gel Technique and Its Optical Properties

    Institute of Scientific and Technical Information of China (English)

    Wang Yinhai; Wang Zhiyu; Zhang Pengyue; Zhang Fuan; Fan Xianping; Qian Guodong

    2005-01-01

    The long afterglow phosphor CaAl2Si2O8:Eu2+, Dy3+ was prepared by a sol-gel method. The sol-gel process and the structure of the phosphor were investigated by means of X-ray diffraction analysis (XRD). It is found that the single anorthite phase formed at about 1000 ℃, which is 300 ℃ lower than that required for the conventional solid state reaction. The obtained phosphor powders are easier to grind than those of solid state method and the partical size of phosphor has a relative narrow distribution of 200 to 500 nm. The photoluminescence and afterglow properties of the phosphor were also characterized. An obvious blue shift occurs in the excitation and emission spectra of phosphors obtained by sol-gel and solid state reaction methods. The change of the fluorescence spectra can be attributed to the sharp decrease of the crystalline grain size of the phosphor resulted from the sol-gel technique.

  12. A Correlation Between the Intrinsic Brightness and Average Decay Rate of Gamma-ray Burst X-ray Afterglow Light Curves

    CERN Document Server

    Racusin, J L; de Pasquale, M; Kocevski, D

    2016-01-01

    We present a correlation between the average temporal decay ({\\alpha}X,avg,>200s) and early-time luminosity (LX,200s) of X-ray afterglows of gamma-ray bursts as observed by Swift-XRT. Both quantities are measured relative to a rest frame time of 200 s after the {\\gamma}-ray trigger. The luminosity average decay correlation does not depend on specific temporal behavior and contains one scale independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. (2012) in the optical light curves observed by Swift-UVOT. The correlation indicates that on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light curve morphologies and observational selection effects, and how either geometrical effe...

  13. The density profiles of N2(A3Σu+) and N2(a′Σu-) in the Pink Afterglow of the DC nitrogen flowing discharge

    International Nuclear Information System (INIS)

    Highlights: • The N2 flowing post-discharge is studied by optical emission spectroscopy. • The N2(C) and N2+(B) relative densities were measured along the post-discharge. • A kinetic numerical model fits the N2(C) and N2+(B) densities in the afterglow. • The model calculates a coefficient used to obtain the N2(A) and N2(a′) densities. • Coefficient and the measured N2(C) density provide the N2(A) and N2(a′) densities. - Abstract: We have studied by optical emission spectroscopy (OES) the afterglow of a nitrogen DC flowing discharge in such experimental conditions that the Pink Afterglow (PA) was present in the post-discharge. The spectra were recorded in the range of 360–435 nm. The emissions of the second positive system of the nitrogen molecules concerning the transitions N2(C3Πu, v) → N2(B3Πg, v′) with Δv = −2 and the emissions of the first negative system concerning the transitions N2+(B2Σu+,v)→N2+(X2Σg+,v′) with Δv = −1 were utilized to furnish the relative density of the N2(C3Πu, 0 ⩽ v ⩽ 4) and the N2+(B2Σu+,0⩽v⩽6) populations from that we have estimated the total density of the N2(C3Πu) and N2+(B2Σu+) electronic states. A kinetic numerical model was constructed for modeling the nitrogen post-discharge. The density profiles of the electronic states N2(C3Πu) and N2+(B2Σu+) obtained experimentally were fitted by the calculated density profiles furnished by the model. In this sense, we have calibrated the numerical model that will be employed in the calculation of the coefficients applied in the estimation of the N2(A3Σu+) and N2(a′Σu-) density profiles. We have developed a method of combined application of the OES and numerical modeling which permits the estimation of the N2(A3Σu+) and N2(a′Σu-) density profiles from the measured density of the N2(C3Πu) state corrected by the calculated coefficients. The estimated density profiles are compared to the calculated ones generated by the kinetic model. The N2

  14. Roles of doping ions in afterglow properties of blue CaAl2O4:Eu2+,Nd3+ phosphors

    International Nuclear Information System (INIS)

    Eu2+ doped and Nd3+ co-doped calcium aluminate (CaAl2O4:Eu2+,Nd3+) phosphor was prepared by a urea-nitrate solution combustion method at furnace temperatures as low as 500 °C. The produced CaAl2O4:Eu2+,Nd3+ powder was investigated in terms of phase composition, morphology and luminescence by X-Ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infra Red spectroscopy (FTIR) and Photoluminescence (PL) techniques respectively. XRD analysis depicts a dominant monoclinic phase that indicates no change in the crystalline structure of the phosphor with varying concentration of Eu2+ and Nd3+. SEM results show agglomerates with non-uniform shapes and sizes with a number of irregular network structures having lots of voids and pores. The Energy Dispersive X-ray Spectroscopy (EDS) and (FTIR) spectra confirm the expected chemical components of the phosphor. PL measurements indicated one broadband excitation spectra from 200 to 300 nm centered around 240 nm corresponding to the crystal field splitting of the Eu2+ d-orbital and an emission spectrum in the blue region with a maximum on 440 nm. This is a strong indication that there was dominantly one luminescence center, Eu2+ which represents emission from transitions between the 4f7 ground state and the 4f6–5d1 excited state configuration. High concentrations of Eu2+ and Nd3+ generally reduce both intensity and lifetime of the phosphor powders. The optimized content of Eu2+ is 1 mol% and for Nd3+ is 1 mol% for the obtained phosphors with excellent optical properties. The phosphor also emits visible light at around 587 and 616 nm. Such emissions can be ascribed to the 5D0–7F1 and 5D0–7F2 intrinsic transition of Eu3+ respectively. The decay characteristics exhibit a significant rise in initial intensity with increasing Eu2+ doping concentration while the decay time increased with Nd3+ co-doping. The observed afterglow can be ascribed to the generation of suitable traps due to the presence of the Nd

  15. UVES/VLT high resolution spectroscopy of GRB 050730 afterglow: probing the features of the GRB environment

    Energy Technology Data Exchange (ETDEWEB)

    D' Elia, V.; Fiore, F.; Piranomonte, S.; Sbordone, L.; Stella, L.; Antonelli, L.A.; Fontana, A.; Giannini, T.; Guetta, D.; Israel, G.; Testa, V. [INAF, Osservatorio Astron Roma, I-00044 Frascati, (Italy); Meurs, E.J.A.; Vergani, S.D.; Ward, P. [Dunsink Observ, Dublin 15, (Ireland); Chincarini, G.; Tagliaferri, G.; Campana, S.; Fugazza, D.; Molinari, E.; Moretti, A. [INAF, Osservatorio Astron Brera, I-23807 Merate, LC, (Italy); Chincarini, G. [Univ Milano Bicocca, I-20126 Milan, (Italy); Melandri, A. [Liverpool John Moores Univ, Astron Res Inst, Birkenhead, Merseyside, (United Kingdom); Norci, L.; Vergani, S.D. [Dublin City Univ, Sch Phys Sci, Dublin 9, (Ireland); Pellizza, L.; Filliatre, P. [Dublin City Univ, NCPST, Dublin 9, (Ireland); Perna, R.; Lazzati, D. [CEA Saclay, DSM, DAPNIA, Serv Astrophys, F-91191 Gif Sur Yvette, (France)] (and others)

    2007-07-01

    Aims. The aim of this paper is to study the Gamma Ray Burst (GRB) environment through the analysis of the optical absorption features due to the gas surrounding the GRB. Methods. To this purpose we analyze high resolution spectroscopic observations (R = 20000-45000, corresponding to 14 kms{sup -1} at 4200 Angstroms and 6.6 kms{sup -1} at 9000 Angstroms of the optical afterglow of GRB050730, obtained with UVES-VLT {approx} 4 h after the GRB trigger. Results. The spectrum shows that the ISM of the GRB host galaxy at z = 3.967 is complex, with at least five components contributing to the main absorption system. We detect strong CII*, SiII*, OI* and FeII* fine structure absorption lines associated to the second and third component. Conclusions. For the first three components we derive information on the relative distance from the site of the GRB explosion. Component 1, which has the longest wavelength, highest positive velocity shift, does not present any fine structure nor low ionization lines; it only shows very high ionization features, such as C IV and O VI, suggesting that this component is very close to the GRB site. From the analysis of low and high ionization lines and fine structure lines, we find evidences that the distance of component 2 from the site of the GRB explosion is 10-100 times smaller than that of component 3. We evaluated the mean metallicity of the z = 3.967 system obtaining values approximate to 10{sup -2} of the solar metallicity or less. However, this should not be taken as representative of the circum-burst medium, since the main contribution to the hydrogen column density comes from the outer regions of the galaxy while that of the other elements presumably comes from the ISM closer to the GRB site. Furthermore, difficulties in evaluating dust depletion correction can modify significantly these values. The mean [C/Fe] ratio agrees well with that expected by single star-formation event models. Interestingly the [C/Fe] of component 2 is

  16. Ionized helium afterglow study

    International Nuclear Information System (INIS)

    In order to take into account the characteristics of ionized helium, under relaxation conditions, in the determination of the unknown coefficients of the reaction rates and more particularly those of the recombination of H2+ ions, a method has been developed which consists in recovering, using a system of differential equations with coupled partial derivatives, the set of all the physical quantities which can at the moment be measured as a function of time in a helium after-discharge. The energy balance of the maxwellian electrons and the speed distribution function of the electrons were studied in details and calculated as a function of time and location in space. The non-maxwellian electrons were included in the calculations. Measurements were made over a large range of experimental conditions using 5 different diagnoses: UHF interferometry in the X band, UHF radiometry in the X band, mass spectrometry, optical absorption spectrometry and optical emission spectrometry. All experimental data, obtained at 293 deg K and at seven different pressures ranging from 5 to 100 Torr were perfectly reproduced by the proposed system of differential equations, with the same reaction rate coefficients and the same constants. The method developed here gives a complete solution for the helium after-discharge at room temperature over a wide range of experimental conditions. It underlines the important reactions within the ionized gas, gives the absolute value and the dependences of the electron-He2+ ion recombination coefficient and allows the determination of the elementary mechanisms causing these dependences. It also gives the coefficients and the reaction rates of all the other elementary mechanisms which, besides recombination, determine the relaxation of ionized helium

  17. On the difficulty of N({sup 4}S) atom recombination to explain the appearance of the pink afterglow in a N{sub 2} flowing discharge

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Sa, P A [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Departamento de Fisica, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto (Portugal); Guerra, V [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal)

    2006-01-07

    The possibility that the pink afterglow (PA) of a flowing nitrogen discharge occurs as a result of recombination of N({sup 4}S) atoms is evaluated and discussed, based on a detailed kinetic model for a microwave discharge and post-discharge. The present simulation shows that the N{sub 2}{sup +}(B{sup 2}{sigma}{sub u}{sup +},v) states responsible for the emission of the PA cannot be created via an indirect mechanism initiated with atomic recombination. Alternatively, it is indicated that the PA may have its origin in non-resonant vibration-vibration energy-exchange processes between N{sub 2}(X{sup 1}{sigma}{sub g}{sup +},v) molecules, which lead to an overpopulation of high levels of the vibrational manifold.

  18. 环境友好水性蓄能型发光涂料的制备%Preparation of Long Afterglow Energy Storage Waterborne Luminescent Paint

    Institute of Scientific and Technical Information of China (English)

    马洪霞; 葛纪龙

    2014-01-01

    With styrene-acrylic emulsion as film-forming substances, alkaline earth silicate luminescent powder as the main pigment, water as solvent and some other additives, a long afterglow energy storage waterborne luminescent paint was prepared. The influence of the amount of styrene-acrylic emulsion, the particle size and amount of luminescent powder and other additives on the performance of the luminous paint was discussed.%以苯丙乳液为主要成膜物,碱土硅酸盐发光粉为主要颜料,水为溶剂,加入其它助剂,制成一种环境友好型水性长余辉蓄能型发光涂料,讨论了乳液的选择、发光粉的粒径和加入量以及助剂对涂料性能的影响。

  19. Improvement of water resistance of long afterglow SrAl2O4: Dy, Eu phosphor by coating with SiO2 film

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The long afterglow SrAl2O4:Dy,Eu phosphor is liable to hydrolyze in water with deterioration of the luminescent property. SrAl2O4:Dy,Eu phosphors were therefore heated at 60-90℃ in TEOS sol to form a surface gel and then heat-treated at 400℃ to obtain SiO2 coated phosphors. Observation by Transmission Electron Microscope (TEM) and X-ray photoelectron spectroscopy (XPS) shows that a thin silica film forms on the surface of the phosphors. The coating procedure can be illustrated by a four-step process and the transparent silica film can suppress the hydrolysis process, so that the luminescent properties of the phosphors are unimpaired or even better.

  20. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    Science.gov (United States)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  1. Absorptions in the afterglows of high-frequency rare-gas discharges and their interpretation in terms of paired-electron gas plasma

    International Nuclear Information System (INIS)

    A study of absorptions in the afterglows of four rare gases following long-pulse high-frequency electrodeless discharge energization is reported in the pressure range 0.05 to 1.5 Torr. It is found that the phenomena can be interpreted using the revised model for the pair gas previously applied to magnetized plasmas. The absorptions occur when the measuring cavity resonant frequency is the same as the oscillatory frequency of a population of aggregated pairs. Excited states are formed as a result of the absorptions. Electron densities calculated on this premise are found to be close in magnitude to mean densities derived from the cavity method. The pair aggregation numbers, n', vary from 1 to 5 at low power to from 2 to 7 at high power. The method of energization of the pulsed discharges is changed into a low-current arc discharge and found to produce a free-electron gas in the afterglow which does not exhibit absorptions. The same result is obtained in xenon gas by increasing the power input into the electrodeless discharge to maximum values (∼ 2kW peak). The resultant increase in electron density in xenon causes the destruction of the paired gas which is replaced by a free-electron gas. The absorptions disappear, showing that they are caused by the paired gas. The destruction of the pair gas in xenon by increase of electron density enables a trial to be made of a possible binding mechanism for the pairs, the spin magnetic potential, VS. A simple calculation for VS is made and from this the maximum pair gas density, nM, in each of the four rare gases is calculated. This leads to a determination for the radius of the xenon atom from results at two pressures as 2.9 and 3.0 x 10-10 m

  2. Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid micro-volume samples

    Science.gov (United States)

    Schaper, J. Niklas; Pfeuffer, Kevin P.; Shelley, Jacob T.; Bings, Nicolas H.

    2012-01-01

    One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed “drop-on-demand” (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (~17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 µg/mL, without sample pretreatment, were obtained. PMID:23025277

  3. Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

    Science.gov (United States)

    Schaper, J Niklas; Pfeuffer, Kevin P; Shelley, Jacob T; Bings, Nicolas H; Hieftje, Gary M

    2012-11-01

    One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 μg/mL, without sample pretreatment, were obtained. PMID:23025277

  4. Determination of state-to-state electron-impact rate coefficients between Ar excited states: a review of combined diagnostic experiments in afterglow plasmas

    Science.gov (United States)

    Zhu, Xi-Ming; Cheng, Zhi-Wen; Carbone, Emile; Pu, Yi-Kang; Czarnetzki, Uwe

    2016-08-01

    Electron-impact excitation processes play an important role in low-temperature plasma physics. Cross section and rate coefficient data for electron-impact processes from the ground state to excited states or between two excited states are required for both diagnostics and modeling works. However, the collisional processes between excited states are much less investigated than the ones involving the ground state due to various experimental challenges. Recently, a method for determining electron excitation rate coefficients between Ar excited states in afterglow plasmas was successfully implemented and further developed to obtain large sets of collisional data. This method combines diagnostics for electron temperature, electron density, and excited species densities and kinetic modeling of excited species, from which the electron excitation rate coefficients from one of the 1s states to the other 1s states or to one of 2p or 3p states are determined (states are in Paschen’s notation). This paper reviews the above method—namely the combined diagnostics and modeling in afterglow plasmas. The results from other important approaches, including electron-beam measurement of cross sections, laser pump-probe technique for measuring rate coefficients, and theoretical calculations by R-matrix and distorted-wave models are also discussed. From a comparative study of these results, a fitted mathematical expression of excitation rate coefficients is obtained for the electron temperature range of 1–5 eV, which can be used for the collisional-radiative modeling of low-temperature Ar plasmas. At last, we report the limitations in the present dataset and give some suggestions for future work in this area.

  5. Preparation of long afterglow luminescence ceramic glaze brick with recycling waste glass and its properties%废玻璃再生利用制备长余辉蓄光釉面砖及其性能的研究

    Institute of Scientific and Technical Information of China (English)

    吕霄; 林元华; 张中太; 唐子龙; 温长英

    2001-01-01

    SrAl2O4 :Eu, Dy long afterglow luminescence powders were synthesized by the traditional ceramicpreparing method. The main emission peak lies in a 520 nm wavelength, and the afterglow time was longerthan 20 h. The long afterglow luminescence glaze was obtained by calcining the mixture of low melt point B -Si glass and SrAl2O4: Eu, Dy luminescence materials. Waste glass, small amount of additives and clay wereused as the main raw materials of ceramic brick, and the low melting point luminescent glaze was coated onthe ceramic brick. Finally, the long afterglow ceramic glaze brick can be fabricated under suitable synthesisconditions.%利用传统陶瓷制备方法合成了SrAl2O4:Eu,Dy长余辉发光粉体,该磷光体主发射波长位于520nm,余辉时间长达20h以上.将该发光粉掺人适量的低熔点玻璃料,经780℃烧成30 min合成了性能较好的低温发光釉料.以废玻璃、粘土为主要原料添加其它少量助剂,经过成型、预烧,将低温发光釉料涂覆在其上,在一定温度下烧成,制得长余辉蓄光釉面砖.

  6. Real-time analysis of ambient organic aerosols using aerosol flowing atmospheric-pressure afterglow mass spectrometry (AeroFAPA-MS)

    Science.gov (United States)

    Brüggemann, Martin; Karu, Einar; Stelzer, Torsten; Hoffmann, Thorsten

    2015-04-01

    Organic aerosol accounts for a major fraction of atmospheric aerosols and has implications on the earth's climate and human health. However, due to the chemical complexity its measurement remains a major challenge for analytical instrumentation.1 Here, we present the development, characterization and application of a new soft ionization technique that allows mass spectrometric real-time detection of organic compounds in ambient aerosols. The aerosol flowing atmospheric-pressure afterglow (AeroFAPA) ion source utilizes a helium glow discharge plasma to produce excited helium species and primary reagent ions. Ionization of the analytes occurs in the afterglow region after thermal desorption and results mainly in intact molecular ions, facilitating the interpretation of the acquired mass spectra. In the past, similar approaches were used to detect pesticides, explosives or illicit drugs on a variety of surfaces.2,3 In contrast, the AeroFAPA source operates 'online' and allows the detection of organic compounds in aerosols without a prior precipitation or sampling step. To our knowledge, this is the first application of an atmospheric-pressure glow discharge ionization technique to ambient aerosol samples. We illustrate that changes in aerosol composition and concentration are detected on the time scale of seconds and in the ng-m-3 range. Additionally, the successful application of AeroFAPA-MS during a field study in a mixed forest region in Central Europe is presented. Several oxidation products of monoterpenes were clearly identified using the possibility to perform tandem MS experiments. The acquired data are in agreement with previous studies and demonstrate that AeroFAPA-MS is a suitable tool for organic aerosol analysis. Furthermore, these results reveal the potential of this technique to enable new insights into aerosol formation, growth and transformation in the atmosphere. References: 1) IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The

  7. 彩色稀土铝酸锶夜光涤纶纤维的余辉和热释光特性%The Afterglow and Thermoluminescence Characteristics of Rare-earth Aluminate Strontium Luminous PET Fiber with Different Color

    Institute of Scientific and Technical Information of China (English)

    郭雪峰; 葛明桥

    2012-01-01

    以成纤聚合物PET为纤维基材,添加SrAl2O4:Eu2+,Dy3+发光材料制备了5种具有不同色相的稀土铝酸锶夜光涤纶纤维样品,采用X射线衍射仪、荧光光谱仪、长余辉测试仪、微机热释光剂量仪表征了纤维的晶相结构、激发发射光谱、余辉衰减规律和热释光性能,着重阐述了纤维余辉衰减规律和陷阱分布情况.结果表明,无机透明色料对纤维的余辉衰减规律影响不大,但样品的余辉初始亮度不同,呈现白色纤维>绿色纤维>黄色纤维>蓝色纤维>红色纤维,添加色料的色相与色光越接近,余辉亮度越高.另外,无机透明色料对热释峰发光强度产生一定的影响,白色、黄色和绿色夜光纤维的E值相对较小,而蓝色和红色夜光纤维的E值相对较大,与纤维余辉曲线结果基本吻合.%Rare-earth aluminate strontium luminous PET fiber samples with five kinds of different hues were prepared by adding the fiber-forming polymers PET chips as base materials and SrAl2O4 :Eu2+ ,Dy3+ luminescent materials. The phase composition, fluorescence spectrum, afterglow decay laws and thermoluminescent characteristics of the fiber were measured by XRD, fluorescence spectrum tester, afterglow tester and TL dosimeter. The afterglow decay laws and trap distribution were mainly elaborated. The results indicated that inorganic transparent pigments have little impact on the afterglow decay laws, but the afterglow initial brightness of samples were different, which presented the rules of white fiber>green fiber>yellow fiber>blue fiber>red fiber. The closer the hues of pigments are, the higher the afterglow brightness of samples are. In addition, the inorganic transparent pigments affected the luminescent intensity of thermoluminescent peak to some extent. The E values of white, yellow and green luminescent fiber was lower than that of blue and red luminescent fiber relatively, which coincided with the results of the afterglow curves

  8. The 80 Ms follow-up of the X-ray afterglow of GRB 130427A challenges the standard forward shock model

    CERN Document Server

    De Pasquale, M; Kann, D A; Oates, S R; Schulze, S; Zhang, B; Cano, Z; Gendre, B; Malesani, D; Rossi, A; Troja, E; Piro, L; Boër, M; Stratta, G; Gehrels, N

    2016-01-01

    GRB 130427A was the brightest gamma-ray burst detected in the last 30 years. With an equivalent isotropic energy output of $8.5\\times10^{53}$ erg and redshift $z=0.34$, it uniquely combined very high energetics with a relative proximity to Earth. As a consequence, its X-ray afterglow has been detected by sensitive X-ray observatories such as XMM-Newton and Chandra for a record-breaking baseline longer than 80 million seconds. We present the X-ray light-curve of this event over such an interval. The light-curve shows a simple power-law decay with a slope $\\alpha = 1.309 \\pm 0.007$ over more than three decades in time (47 ks - 83 Ms). We discuss the consequences of this result for a few models proposed so far to interpret GRB 130427A, and more in general the significance of this outcome in the context of the standard forward shock model. We find that this model has difficulty in explaining our data, in both cases of constant density and stellar-wind circumburst media, and requires far-fetched values for the phy...

  9. Low-Resolution Spectroscopy of Gamma-ray Burst Optical Afterglows: Biases in the Swift Sample and Characterization of the Absorbers

    CERN Document Server

    Fynbo, J P U; Prochaska, J X; Malesani, D; Ledoux, C; Postigo, A de Ugarte; Nardini, M; Vreeswijk, P M; Hjorth, J; Sollerman, J; Chen, H -W; Thoene, C C; Bjoernsson, G; Bloom, J S; Castro-Tirado, A J; Christensen, L; De Cia, A; Gorosabel, J U; Jaunsen, A; Jensen, B L; Levan, A; Maund, J; Masetti, N; Milvang-Jensen, B; Palazzi, E; Perley, D A; Pian, E; Rol, E; Schady, P; Starling, R; Tanvir, N; Watson, D J; Wiersema, K; Xu, D; Augusteijn, T; Grundahl, F; Telting, J; Quirion, P -O

    2009-01-01

    (Abridged). We present a sample of 77 optical afterglows (OAs) of Swift detected GRBs for which spectroscopic follow-up observations have been secured. We provide linelists and equivalent widths for all detected lines redward of Ly-alpha. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray selected sample of Swift bursts with optimal conditions for ground-based follow up from the period March 2005 to September 2008; 146 bursts fulfill our sample criteria. We derive the redshift distribution for this sample and conclude that less than 19% of Swift bursts are at z>7. We compare the high energy properties for three sub-samples of bursts in the sample: i) bursts with redshifts measured from OA spectroscopy, ii) bursts with detected OA, but no OA-based redshift, and iii) bursts with no detection of the OA. The bursts in group i) have significantly less excess X-ray absorption than bursts in the other...

  10. Prompt, early, and afterglow optical observations of five gamma-ray bursts (GRBs 100901A, 100902A, 100905A, 100906A, and 101020A)

    CERN Document Server

    Gorbovskoy, E S; Lipunov, V M; Kornilov, V G; Belinski, A A; Shatskiy, N I; Tyurina, N V; Kuvshinov, D A; Balanutsa, P V; Chazov, V V; Kuznetsov, A; Zimnukhov, D S; Kornilov, M V; Sankovich, A V; Krylov, A; Ivanov, K I; Chvalaev, O; Poleschuk, V A; Konstantinov, E N; Gress, O A; Yazev, S A; Budnev, N M; Krushinski, V V; Zalozhnich, I S; Popov, A A; Tlatov, A G; Parhomenko, A V; Dormidontov, D V; Sennik, V; Yurkov, V V; Sergienko, Yu P; Varda, D; Kudelina, I P; Castro-Tirado, A J; Gorosabel, J; Sánchez--Ramírez, R; Jelinek, M; Tello, J C

    2011-01-01

    We present results of the prompt, early, and afterglow optical observations of five gamma-ray bursts, GRBs 100901A, 100902A, 100905A, 100906A, and 101020A, made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II net), the 1.5-m telescope of Sierra-Nevada Observatory, and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before cessation of gamma-ray emission, at 113 s and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted with two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. More detailed analysis of GRB 100901A and GRB 100906A supplemented by Swift data provides the following results and indicates different origins of the prompt optical radiation in the two bursts. The light curves patterns and spectral distributions suggest a common production site of the pr...

  11. Measurement of charge-transfer rate coefficients of He2+ with selected atomic and molecular species in high-pressure afterglows

    International Nuclear Information System (INIS)

    High-pressure, volume-dominated glow discharges for use as laser media have gained interest in the past decade as a result of the development of a variety of external ionization and discharge-stabilization techniques. In such systems, charge-transfer processes occur by way of bimolecular and termolecular reaction channels at atmospheric pressure, with the latter gaining in relative importance due to its dependence on gas pressure. Therefore, it is essential to characterize these termolecular reaction rates and recognize the fact that these reactions must be included among all other processes considering in modeling the high-pressure lasers and discharge media. This dissertation reports the measurements of bimolecular and termolecular charge-transfer reactions of He2+ into nonassociative produce channels. In this study, the population of He2+ was monitored as a function of time by detection of the N2+ (B → X) transition at 391.4 nm in high-pressure afterglows of mixed gases excited by a fast electrical-discharge system capable of operation up to 6 atm. From these data, pressure dependent rate coefficients have been extracted and subsequently resolved into contributions from bimolecular and termolecular components for reactions of He2+ with N2, O2, CO2, Ar, and Xe

  12. Low-resolution Spectroscopy of Gamma-ray Burst Optical Afterglows: Biases in the Swift Sample and Characterization of the Absorbers

    Science.gov (United States)

    Fynbo, J. P. U.; Jakobsson, P.; Prochaska, J. X.; Malesani, D.; Ledoux, C.; de Ugarte Postigo, A.; Nardini, M.; Vreeswijk, P. M.; Wiersema, K.; Hjorth, J.; Sollerman, J.; Chen, H.-W.; Thöne, C. C.; Björnsson, G.; Bloom, J. S.; Castro-Tirado, A. J.; Christensen, L.; De Cia, A.; Fruchter, A. S.; Gorosabel, J.; Graham, J. F.; Jaunsen, A. O.; Jensen, B. L.; Kann, D. A.; Kouveliotou, C.; Levan, A. J.; Maund, J.; Masetti, N.; Milvang-Jensen, B.; Palazzi, E.; Perley, D. A.; Pian, E.; Rol, E.; Schady, P.; Starling, R. L. C.; Tanvir, N. R.; Watson, D. J.; Xu, D.; Augusteijn, T.; Grundahl, F.; Telting, J.; Quirion, P.-O.

    2009-12-01

    We present a sample of 77 optical afterglows (OAs) of Swift detected gamma-ray bursts (GRBs) for which spectroscopic follow-up observations have been secured. Our first objective is to measure the redshifts of the bursts. For the majority (90%) of the afterglows, the redshifts have been determined from the spectra. We provide line lists and equivalent widths (EWs) for all detected lines redward of Lyα covered by the spectra. In addition to the GRB absorption systems, these lists include line strengths for a total of 33 intervening absorption systems. We discuss to what extent the current sample of Swift bursts with OA spectroscopy is a biased subsample of all Swift detected GRBs. For that purpose we define an X-ray-selected statistical sample of Swift bursts with optimal conditions for ground-based follow-up from the period 2005 March to 2008 September; 146 bursts fulfill our sample criteria. We derive the redshift distribution for the statistical (X-ray selected) sample and conclude that less than 18% of Swift bursts can be at z > 7. We compare the high-energy properties (e.g., γ-ray (15-350 keV) fluence and duration, X-ray flux, and excess absorption) for three subsamples of bursts in the statistical sample: (1) bursts with redshifts measured from OA spectroscopy; (2) bursts with detected optical and/or near-IR afterglow, but no afterglow-based redshift; and (3) bursts with no detection of the OA. The bursts in group (1) have slightly higher γ-ray fluences and higher X-ray fluxes and significantly less excess X-ray absorption than bursts in the other two groups. In addition, the fractions of dark bursts, defined as bursts with an optical to X-ray slope βOX 39% in group (3). For the full sample, the dark burst fraction is constrained to be in the range 25%-42%. From this we conclude that the sample of GRBs with OA spectroscopy is not representative for all Swift bursts, most likely due to a bias against the most dusty sight lines. This should be taken into

  13. EFFECT OF ALKALINE IONS ON THE PHASE EVOLUTION, PHOTOLUMINESCENCE, AND AFTERGLOW PROPERTIES OF SrAl2O4: Eu2+, Dy3+ PHOSPHOR

    Directory of Open Access Journals (Sweden)

    HYUNHO SHIN

    2012-12-01

    Full Text Available A series of SrAl2O4: Eu2+, Dy3+ long-afterglow (LAG phosphors with varying concentration of Li+, Na+ and K+, has been synthesized. The increased concentration of the three types of alkaline ions does not decrease the quantity of the total luminescent phases (SrAl2O4 plus Sr4Al14O25, but a different set of secondary phases has been evoluted for the K+-added series due to the failure of the incorporation of relatively large K+ (1.38 Å to the Sr2+ (1.18 Å site in the hosts, unlike the cases of smaller Li+ (0.76 Å and Na+ (1.02 Å ions. PL excitation, PL emission, and LAG luminescence, are decreased by all investigated alkaline ions, which would be due to the diminished incorporation of Eu2+ and Dy3+ activators into the luminescent hosts by the alkaline ions. For the cases of the Li+ and Na+-added series, the incorporated Li+ or Na+ to the luminescent hosts would also limit the activation of Eu2+ and charge trapping/detrapping of Dy3+ to yield the diminished PL properties and LAG luminescence. The type of defect complex formed by the addition of Li+ and Na+ ions has been deduced and compared with that formed when no alkaline ion is added.

  14. Co-Precipitation Synthesis and Spectral Characteristics of Long Afterglow Phosphor Y2O2S:Sm3+, Mg2+, Ti4+

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Y2O2S:Sm3+, Mg2+, Ti4+ phosphor was synthesized by co-precipitation method. The crystalline structure of all synthesized phosphors was investigated by XRD. The result showed that all synthesized phosphors had a hexagonal crystal structure, which was the same as Y2O2S. The emission spectrum and excitation spectrum were measured, and the effect of Sm3+ molar ratio on the spectra was discussed. The emission spectra of the phosphors showed three emission peaks due to typical transitions of Sm3+(4G5/2→6HJ, J=5/2, 7/2, 9/2), and the emission peaks at 606 nm was stronger than others. With the increase of Sm3+ molar ratio, the emission intensity was strengthened. The excitation peaks were ascribed to the representative energy transition 4f→4f of Sm3+ ions. The results indicated that the Y2O2S:Sm3+,Mg2+, Ti4+ phosphor prepared by co-precipitation method was an efficient long afterglow phosphor.

  15. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of rho and Structure of the Circumburst Medium

    Science.gov (United States)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.

    2008-01-01

    We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 medium.

  16. Gamma-Ray Burst Afterglows as Probes of Environment and Blastwave Physics II: The Distribution of p and Structure of the Circumburst Medium

    Science.gov (United States)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltevrede, P.

    2007-01-01

    We constrain blastwave parameters and the circumburst media of a subsample of BeppoSAX Gamma-Ray Bursts. For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical and nIR afterglow data. The spectral fits have been done in count space and include the effects of metallicity, and are compared with the previously reported optical and X-ray temporal behaviour. Assuming the fireball model, we can find a mean value of p for the sample as a whole of 2.035. A statistical analysis Of the distribution demonstrates that the p values in this sample are inconsistent with a single universal value for p at the 3sigma level or greater. This approach provides us with a measured distribution of circumburst density structures rather than considering only the cases of k = 0 (homogeneous) and k = 2 (wind-like). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly wind-like. The fifth source has a value of 0 less than or equal to k less than or equal to 1, consistent with a homogeneous circumburst medium.

  17. Optical light curve of GRB 121011A: a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium

    CERN Document Server

    Xin, Li-Ping; Qiu, Yu-Lei; Deng, Jin-Song; Wang, Jing; Han, Xu-Hui

    2016-01-01

    We reported the optical observations of GRB 121011A by 0.8-m TNT telescope at Xinglong observatory, China. The light curve of optical afterglow shows a smooth and featureless bump during the epoch of $\\sim$130 sec and $\\sim$5000 sec with a rising index of $1.57\\pm0.28$ before the break time of $539\\pm44$ sec, and a decaying index of about $1.29\\pm0.07$ up to the end of our observations. Meanwhile, the X-ray light curve decays in a single power-law with a slop of about $1.51\\pm0.03$ observed by $XRT$ onboard ${\\rm} Swift$ from 100 sec to about 10000 sec after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysi...

  18. Gamma-Ray Burst Afterglows as Probes of Environment and Blast Wave Physics. II. The Distribution of rho and Structure of the Circumburst Medium

    Science.gov (United States)

    Starling, R. L. C.; vanderHorst, A. J.; Rol, E.; Wijers, R. A. M. J.; Kouveliotou, C.; Wiersema, K.; Curran, P. A.; Weltervrede, P.

    2008-01-01

    We constrain blast wave parameters and the circumburst media ofa subsample of 10 BeppoSAX gamma-ray bursts (GRBs). For this sample we derive the values of the injected electron energy distribution index, p, and the density structure index of the circumburst medium, k, from simultaneous spectral fits to their X-ray, optical, and NIR afterglow data. The spectral fits have been done in count space and include the effects ofmetallicity, and are compared with the previously reported optical and X-ray temporal behavior. Using the blast wave model and some assumptions which include on-axis viewing and standard jet structure, constant blast wave energy, and no evolution of the microphysical parameters, we find a mean value ofp for the sample as a whole of 9.... oa -0.003.0" 2 a_ statistical analysis of the distribution demonstrates that the p-values in this sample are inconsistent with a single universal value forp at the 3 _ level or greater, which has significant implications for particle acceleration models. This approach provides us with a measured distribution ofcircumburst density structures rather than considering only the cases of k ----0 (homogeneous) and k - 2 (windlike). We find five GRBs for which k can be well constrained, and in four of these cases the circumburst medium is clearly windlike. The fifth source has a value of 0 < k < 1, consistent with a homogeneous circumburst medium.

  19. Coasting External Shock in Wind Medium: An Origin for the X-Ray Plateau Decay Component in Swift Gamma-Ray Burst Afterglows

    Science.gov (United States)

    Shen, Rongfeng; Matzner, Christopher D.

    2012-01-01

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a ρvpropr -2, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blast wave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, Γ0 <= 46(epsilon e /0.1)-0.24(epsilon B /0.01)0.17; the isotropic equivalent total ejecta energy is E iso ~ 1053(epsilon e /0.1)-1.3(epsilon B /0.01)-0.09(tb /104 s) erg, where epsilon e and epsilon B are the fractions of the total energy at the shock downstream that are carried by electrons and the magnetic field, respectively, and tb is the end of the plateau. Our finding supports Wolf-Rayet stars as the progenitor stars of some GRBs. It raises intriguing questions about the origin of an intermediate-Γ0 ejecta, which we speculate is connected to the GRB jet emergence from its host star. For the remaining 45% of the sample, the post-plateau decline is too rapid to be explained in the coasting-in-wind model, and energy injection appears to be required.

  20. COASTING EXTERNAL SHOCK IN WIND MEDIUM: AN ORIGIN FOR THE X-RAY PLATEAU DECAY COMPONENT IN SWIFT GAMMA-RAY BURST AFTERGLOWS

    International Nuclear Information System (INIS)

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a ρ∝r–2, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blast wave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, Γ0 ≤ 46(εe/0.1)–0.24(εB/0.01)0.17; the isotropic equivalent total ejecta energy is Eiso ∼ 1053(εe/0.1)–1.3(εB/0.01)–0.09(tb /104 s) erg, where εe and εB are the fractions of the total energy at the shock downstream that are carried by electrons and the magnetic field, respectively, and tb is the end of the plateau. Our finding supports Wolf-Rayet stars as the progenitor stars of some GRBs. It raises intriguing questions about the origin of an intermediate-Γ0 ejecta, which we speculate is connected to the GRB jet emergence from its host star. For the remaining 45% of the sample, the post-plateau decline is too rapid to be explained in the coasting-in-wind model, and energy injection appears to be required.

  1. COASTING EXTERNAL SHOCK IN WIND MEDIUM: AN ORIGIN FOR THE X-RAY PLATEAU DECAY COMPONENT IN SWIFT GAMMA-RAY BURST AFTERGLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Shen Rongfeng; Matzner, Christopher D., E-mail: rfshen@astro.utoronto.ca, E-mail: matzner@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Ontario M5S 3H4 (Canada)

    2012-01-01

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a {rho}{proportional_to}r{sup -2}, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blast wave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, {Gamma}{sub 0} {<=} 46({epsilon}{sub e}/0.1){sup -0.24}({epsilon}{sub B}/0.01){sup 0.17}; the isotropic equivalent total ejecta energy is E{sub iso} {approx} 10{sup 53}({epsilon}{sub e}/0.1){sup -1.3}({epsilon}{sub B}/0.01){sup -0.09}(t{sub b} /10{sup 4} s) erg, where {epsilon}{sub e} and {epsilon}{sub B} are the fractions of the total energy at the shock downstream that are carried by electrons and the magnetic field, respectively, and t{sub b} is the end of the plateau. Our finding supports Wolf-Rayet stars as the progenitor stars of some GRBs. It raises intriguing questions about the origin of an intermediate-{Gamma}{sub 0} ejecta, which we speculate is connected to the GRB jet emergence from its host star. For the remaining 45% of the sample, the post-plateau decline is too rapid to be explained in the coasting-in-wind model, and energy injection appears to be required.

  2. Synergy effect of heat and UV photons on bacterial-spore inactivation in an N{sub 2}-O{sub 2} plasma-afterglow sterilizer

    Energy Technology Data Exchange (ETDEWEB)

    Boudam, M K; Moisan, M, E-mail: michel.moisan@umontreal.c [Groupe de Physique des Plasmas, Universite de Montreal, C.P. 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada)

    2010-07-28

    As a rule, medical devices (MDs) made entirely from metals and ceramics can withstand, for sterilization purposes, elevated temperatures such as those encountered in autoclaves (moist heat {>=}120 {sup 0}C) or Poupinel (Pasteur) ovens (dry heat {>=}160 {sup 0}C). This not the case with MDs containing polymers: 70 {sup 0}C seems to be a limit beyond which their structural and functional integrity will be compromised. Nonetheless, all the so-called low-temperature sterilization techniques, relying essentially on some biocidal chemistry (e.g. ethylene oxide, H{sub 2}O{sub 2}, O{sub 3}), are operated at temperatures close to 65 {sup 0}C, essentially to enhance the chemical reactivity of the biocidal agent. Based on this fact, we have examined the influence of increasing the temperature of the polystyrene Petri dish containing B. atrophaeus bacterial spores when exposing them to UV radiation coming from an N{sub 2}-O{sub 2} flowing plasma afterglow. We have observed that, for a given UV radiation intensity, the inactivation rate increases with the temperature of the Petri dish, provided heat and UV photons are applied simultaneously, a clear case of synergistic effect. More specifically, it means that (i) simply heating the spores at temperatures below 65 {sup 0}C without irradiating them with UV photons does not induce mortality; (ii) there is no additional increase in the inactivation rate when the Petri has been pre-heated and then brought back to ambient temperature before the spores are UV irradiated; (iii) no additional inactivation results from post-heating spores previously inactivated with UV radiation. Undoubtedly, the synergistic effect shows up only when the physico-chemical agents (UV photons and temperature) are simultaneously in action.

  3. Synergy effect of heat and UV photons on bacterial-spore inactivation in an N2-O2 plasma-afterglow sterilizer

    Science.gov (United States)

    Boudam, M. K.; Moisan, M.

    2010-07-01

    As a rule, medical devices (MDs) made entirely from metals and ceramics can withstand, for sterilization purposes, elevated temperatures such as those encountered in autoclaves (moist heat >=120 °C) or Poupinel (Pasteur) ovens (dry heat >=160 °C). This not the case with MDs containing polymers: 70 °C seems to be a limit beyond which their structural and functional integrity will be compromised. Nonetheless, all the so-called low-temperature sterilization techniques, relying essentially on some biocidal chemistry (e.g. ethylene oxide, H2O2, O3), are operated at temperatures close to 65 °C, essentially to enhance the chemical reactivity of the biocidal agent. Based on this fact, we have examined the influence of increasing the temperature of the polystyrene Petri dish containing B. atrophaeus bacterial spores when exposing them to UV radiation coming from an N2-O2 flowing plasma afterglow. We have observed that, for a given UV radiation intensity, the inactivation rate increases with the temperature of the Petri dish, provided heat and UV photons are applied simultaneously, a clear case of synergistic effect. More specifically, it means that (i) simply heating the spores at temperatures below 65 °C without irradiating them with UV photons does not induce mortality; (ii) there is no additional increase in the inactivation rate when the Petri has been pre-heated and then brought back to ambient temperature before the spores are UV irradiated; (iii) no additional inactivation results from post-heating spores previously inactivated with UV radiation. Undoubtedly, the synergistic effect shows up only when the physico-chemical agents (UV photons and temperature) are simultaneously in action.

  4. Synergy effect of heat and UV photons on bacterial-spore inactivation in an N2-O2 plasma-afterglow sterilizer

    International Nuclear Information System (INIS)

    As a rule, medical devices (MDs) made entirely from metals and ceramics can withstand, for sterilization purposes, elevated temperatures such as those encountered in autoclaves (moist heat ≥120 0C) or Poupinel (Pasteur) ovens (dry heat ≥160 0C). This not the case with MDs containing polymers: 70 0C seems to be a limit beyond which their structural and functional integrity will be compromised. Nonetheless, all the so-called low-temperature sterilization techniques, relying essentially on some biocidal chemistry (e.g. ethylene oxide, H2O2, O3), are operated at temperatures close to 65 0C, essentially to enhance the chemical reactivity of the biocidal agent. Based on this fact, we have examined the influence of increasing the temperature of the polystyrene Petri dish containing B. atrophaeus bacterial spores when exposing them to UV radiation coming from an N2-O2 flowing plasma afterglow. We have observed that, for a given UV radiation intensity, the inactivation rate increases with the temperature of the Petri dish, provided heat and UV photons are applied simultaneously, a clear case of synergistic effect. More specifically, it means that (i) simply heating the spores at temperatures below 65 0C without irradiating them with UV photons does not induce mortality; (ii) there is no additional increase in the inactivation rate when the Petri has been pre-heated and then brought back to ambient temperature before the spores are UV irradiated; (iii) no additional inactivation results from post-heating spores previously inactivated with UV radiation. Undoubtedly, the synergistic effect shows up only when the physico-chemical agents (UV photons and temperature) are simultaneously in action.

  5. Effect of Dust Extinction on the Gamma-ray Burst Afterglows%尘埃消光对伽玛射线暴余辉的影响

    Institute of Scientific and Technical Information of China (English)

    吕谷靖; 邵琅; 金志平; 韦大明

    2011-01-01

    In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on rigorous Mie theory and latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters.Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity, however, the shape of the extinction curve is mainly determined by the size distribution of the dust grains.If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity; on the contrary,if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger extinction quantity.These results might provide an important insight into understanding the origin of the optically dark GRBs.%为了研究尘埃消光对伽玛射线暴余辉的影响,基于严格的Mie理论和最新的星际尘埃光学性质,进行了高精度的数值计算,并分析具有不同物理参数的尘埃所产生的消光曲线.结果表明,介质密度和金属丰度是决定消光总量的主要物理参数,而尘埃颗粒大小的分布则是产生不同消光曲线轮廓的重要物理参数.如果尘埃颗粒相互聚集形成导致尺度增大,将产生较平或者较灰的消光曲线,同时绝对总量将减少;相反,如果尘埃颗粒由于某种原因发生离解导致尺度变小,将产生较陡的消光曲线,同时消光总量将增加.这些结果将对理解光学暗暴的形成机制提供重要的启示.

  6. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Science.gov (United States)

    Murase, Kohta; Kashiyama, Kazumi; Mészáros, Peter

    2016-06-01

    Tenuous wind bubbles, which are formed by the spin-down activity of central compact remnants, are relevant in some models of fast radio bursts (FRBs) and super-luminous supernovae. We study their high-energy signatures, focusing on the role of pair-enriched bubbles produced by young magnetars, rapidly-rotating neutron stars, and magnetized white dwarfs. (i) First, we study the nebular properties and the conditions allowing for escape of high-energy gamma-rays and radio waves, showing that their escape is possible for nebulae with ages of ≳ 10 - 100 yr. In the rapidly-rotating neutron star scenario, we find that radio emission from the quasi-steady nebula itself may be bright enough to be detected especially at sub-mm frequencies, which is relevant as a possible counterpart of pulsar-driven SNe and FRBs. (ii) Second, we consider the fate of bursting emission in the nebulae. We suggest that an impulsive burst may lead to a highly relativistic flow, which would interact with the nebula. If the shocked nebula is still relativistic, pre-existing non-thermal particles in the nebula can be significantly boosted by the forward shock, leading to short-duration (maybe millisecond or longer) high-energy gamma-ray flashes. Possible dissipation at the reverse shock may also lead to gamma-ray emission. (iii) After such flares, interactions with the baryonic ejecta may lead to afterglow emission with a duration of days to weeks. In the magnetar scenario, this burst-in-bubble model leads to the expectation that nearby (˜10 - 100 Mpc) high-energy gamma-ray flashes may be detected by the High-Altitude Water Cherenkov Observatory and the Cherenkov Telescope Array, and the subsequent afterglow emission may be seen by radio telescopes such as the Very Large Array. (iv) Finally, we discuss several implications specific to FRBs, including constraints on the emission regions and limits on soft gamma-ray counterparts.

  7. Study on Heat Treatment of Nanocrystalline Yttrium Oxide Sulfide Red Long Afterglow Phosphor%红色长余辉发光材料纳米硫氧化钇的热处理研究

    Institute of Scientific and Technical Information of China (English)

    刘晓霞; 李向果; 彭桂花; 梁振华

    2012-01-01

    对燃烧法合成的红色长余辉发光材料纳米Y2 O2S:Eu3+,Mg2+,Ti4+进行了热处理,采用X-射线粉末衍射仪(XRD)、扫描电镜(SEM)、荧光光谱仪(PL)、亮度计等对发光材料进行了表征.结果表明,最佳热处理温度为800℃;热处理后的发光材料的主要物相仍为Y2O2S、粒径略有增大、宽带吸收峰略有红移、发射峰位置不变、初始亮度提高、衰减变慢.%Heat treatment of nanocrystalline Y2O2S:Eu3+ ,Mg2+ ,Ti4+ red long afterglow phosphor synthe-sized by combustion method was carried out in the article. The phosphor was characterized by XRD,SEM,PL and luminance meter. The results showed that the optimum heat treatment temperature was 800℃. After heat treatment,the main phase of phosphor was Y2O2S,the particle size increased slightly,the broadband absorption peak had a slight red-shift,the emission peak didn't change in position,the initial brightness increased and declined slowly.

  8. Polarization Evolution of the GRB 020405 Afterglow

    OpenAIRE

    S. Covino(INAF - Oss. Astronomico di Brera); Malesani, D.; Ghisellini, G.; Lazzati, D.; Alighieri, S. di Serego; Stefanon, M.; Cimatti, A.; Della Valle, M.; Fiore, F.; Goldoni, P.; Kawai, N.; Israel, G. L.; Floc'h, E. Le; Mirabel, I. F.; Ricker, G.

    2002-01-01

    Polarization measurements for the optical counterpart to GRB 020405 are presented and discussed. Our observations were performed with the VLT-UT3 (Melipal) during the second and third night after the gamma-ray burst discovery. The polarization degree (and the position angle) appears to be constant between our two observations at a level around (1.5 - 2)%. The polarization can be intrinsic but it is not possible to unambiguously exclude that a substantial fraction of it is induced by dust in t...

  9. On Beaming Effects in Afterglow Light Curves

    OpenAIRE

    Moderski, R.; Sikora, M.; Bulik, T.

    1999-01-01

    The most luminous GRBs can be explained in terms of models involving stellar mass central engines only if the ejecta are beamed. As was pointed out by Rhoads, the dynamics of the blast wave, formed by the beamed ejecta sweeping the external gas, can be significantly modified by the sideways expansion. This is because in this case the surface of the blast wave increases faster than just due to the radial divergence and so the blast wave deceleration rate increases faster. According to analytic...

  10. MAGIC low energy observation of GRB090102 afterglow

    CERN Document Server

    Carosi, A; de Almeida, U Barres; Bastieri, D; González, J Becerra; Colombo, E; Garczarczyk, M; Covino, S; La Barbera, A; Spiro, S; Domínguez, A; Gaug, M; Longo, F; Scapin, V

    2011-01-01

    Hints for a GeV component in the emission from GRBs are known since the EGRET observations during the '90s and they have been recently confirmed by the data of the Fermi satellite. These results have, however, shown that a fully satisfactory interpretative framework of the GRB phenomena is still lacking. The MAGIC telescope opens the possibility to extend the measurement of GRBs in the several tens up to hundreds of GeV energy range. From the theoretical point of view, both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy photons (E>30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB090102 (z=1.547) field from 03:14:52 UT to 06:54:01 UT are analyzed to derive upper limits to the GeV/TeV emission. We compare these results to the expec...

  11. Reactions between NO/+/ and metal atoms using magnetically confined afterglows

    Science.gov (United States)

    Lo, H. H.; Clendenning, L. M.; Fite, W. L.

    1977-01-01

    A new method of studying thermal energy ion-neutral collision processes involving nongaseous neutral atoms is described. A long magnetic field produced by a solenoid in a vacuum chamber confines a thermal-energy plasma generated by photoionization of gas at very low pressure. As the plasma moves toward the end of the field, it is crossed by a metal atom beam. Ionic products of ion-atom reactions are trapped by the field and both the reactant and product ions move to the end of the magnetic field where they are detected by a quadrupole mass filter. The cross sections for charge transfer between NO(+) and Na, Mg, Ca, and Sr and that for rearrangement between NO(+) and Ca have been obtained. The charge-transfer reaction is found strongly dominant over the rearrangement reaction that forms metallic oxide ions.

  12. A gravitational wave afterglow in binary neutron star mergers

    CERN Document Server

    Doneva, Daniela D; Pnigouras, Pantelis

    2015-01-01

    We study in detail the f-mode secular instability for rapidly rotating neutron stars, putting emphasis on supermassive models which do not have a stable nonrotating counterpart. Such neutron stars are thought to be the generic outcome of the merger of two standard mass neutron stars. In addition we take into account the effects of strong magnetic field and r-mode instability, that can drain a substantial amount of angular momentum. We find that the gravitational wave signal emitted by supramassive neutron stars can reach above the Advance LIGO sensitivity at distance of about 20Mpc and the detectability is substantially enhanced for the Einstein Telescope. The event rate will be of the same order as the merging rates, while the analysis of the signal will carry information for the equation of state of the post-merging neutron stars and the strength of the magnetic fields.

  13. Complicated variations in the early optical afterglow of GRB 090726

    Czech Academy of Sciences Publication Activity Database

    Šimon, Vojtěch; Polášek, Cyril; Jelínek, M.; Hudec, René; Štrobl, Jan

    2010-01-01

    Roč. 510, February (2010), A49/1-A49/5. ISSN 0004-6361 R&D Projects: GA ČR GA205/08/1207 Grant ostatní: GA ČR(CZ) GA102/09/0997; ESA(XE) ESA-PECS project No. 98058 Institutional research plan: CEZ:AV0Z10030501 Keywords : gamma-ray burst * radiation mechanisms * plasmas Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.410, year: 2010

  14. The Gamma-ray Afterglows of Tidal Disruption Events

    CERN Document Server

    Chen, Xian; Guillochon, James

    2015-01-01

    A star wandering too close to a supermassive black hole (SMBH) will be tidally disrupted. Previous studies of such "tidal disruption event" (TDE) mostly focus on the stellar debris that are bound to the system, because they give rise to luminous flares. On the other hand, half of the stellar debris in principle are unbound and can steam to a great distance, but so far there is no clear evidence that this "unbound debris steam" (UDS) exists. Motivated by the fact that the circum-nuclear region around SMBHs is usually filled with dense molecular clouds (MCs), here we investigate the observational signatures resulting from the collision between an UDS and a MC, which is likely to happen hundreds of years after a TDE. We focus on $\\gamma$-ray emission ($0.1-10^5$ GeV), which comes from the encounter of shock-accelerated cosmic rays with background protons and, more importantly, is not subject to extinction. We show that because of the high proton density inside the MC, the peak $\\gamma$-ray luminosity is at least...

  15. Magnetar giant flares and afterglows as relativistic magnetized explosions

    CERN Document Server

    Lyutikov, M

    2006-01-01

    (Abridged) We propose that giant flares on Soft Gamma-Ray Repeaters produce relativistic, strongly magnetized, weakly baryon loaded magnetic clouds, somewhat analogous to solar coronal mass ejection (CME) events. Flares are driven by unwinding of internal non-potential magnetic fields which leads to slow build-up of magnetic energy outside of the neutron star. For large magnetospheric currents, corresponding to a large twist of external magnetic field, magnetosphere becomes dynamically unstable on \\Alfven crossing times scale of inner magnetosphere, $t_A \\sim R_{NS}/c \\sim 30 \\mu$sec. Released magnetic energy results in formation of a strongly magnetized, pair-loaded, quasi-spherically expanding flux rope, topologically connected by magnetic field to the neutron star during the prompt flare emission. Magnetic stresses of the tied flux rope lead to late collimation of the expansion, on time scales longer than giant flare duration. Relativistic bulk motion of the expanding magnetic cloud, directed at an angle $...

  16. NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion

    Science.gov (United States)

    2005-10-01

    Intricate wisps of glowing gas float amid a myriad of stars in this image created by combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory. The gas is a supernova remnant, cataloged as N132D, ejected from the explosion of a massive star that occurred some 3,000 years ago. This titanic explosion took place in the Large Magellanic Cloud, a nearby neighbor galaxy of our own Milky Way. The complex structure of N132D is due to the expanding supersonic shock wave from the explosion impacting the interstellar gas of the LMC. Deep within the remnant, the Hubble visible light image reveals a crescent-shaped cloud of pink emission from hydrogen gas, and soft purple wisps that correspond to regions of glowing oxygen emission. A dense background of colorful stars in the LMC is also shown in the Hubble image. The large horseshoe-shaped gas cloud on the left-hand side of the remnant is glowing in X-rays, as imaged by Chandra. In order to emit X-rays, the gas must have been heated to a temperature of about 18 million degrees Fahrenheit (10 million degrees Celsius). A supernova-generated shock wave traveling at a velocity of more than four million miles per hour (2,000 kilometers per second) is continuing to propagate through the low-density medium today. The shock front where the material from the supernova collides with ambient interstellar material in the LMC is responsible for these high temperatures. Chandra image of N132D Chandra image of N132D, 2002 It is estimated that the star that exploded as a supernova to produce the N132D remnant was 10 to 15 times more massive than our own Sun. As fast-moving ejecta from the explosion slam into the cool, dense interstellar clouds in the LMC, complex shock fronts are created. A supernova remnant like N132D provides a rare opportunity for direct observation of stellar material, because it is made of gas that was recently hidden deep inside a star. Thus it provides information on stellar evolution and the creation of chemical elements such as oxygen through nuclear reactions in their cores. Such observations also help reveal how the interstellar medium (the gas that occupies the vast spaces between the stars) is enriched with chemical elements because of supernova explosions. Later on, these elements are incorporated into new generations of stars and their accompanying planets. Visible only from Earth's southern hemisphere, the LMC is an irregular galaxy lying about 160,000 light-years from the Milky Way. The supernova remnant appears to be about 3,000 years old, but since its light took 160,000 years to reach us, the explosion actually occurred some 163,000 years ago. This composite image of N132D was created by the Hubble Heritage team from visible-light data taken in January 2004 with Hubble's Advanced Camera for Surveys, and X-ray images obtained in July 2000 by Chandra's Advanced CCD Imaging Spectrometer. This marks the first Hubble Heritage image that combines pictures taken by two separate space observatories. The Hubble data include color filters that sample starlight in the blue, green, and red portions of the spectrum, as well as the pink emission from glowing hydrogen gas. The Chandra data are assigned blue in the color composite, in accordance with the much higher energy of the X-rays, emitted from extremely hot gas. This gas does not emit a significant amount of optical light, and was only detected by Chandra. Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) Acknowledgment: J.C. Green (Univ. of Colorado) and the Cosmic Origins Spectrograph (COS) GTO team; NASA/CXO/SAO Electronic image files, video, illustrations and additional information are available at: http://hubblesite.org/news/2005/30 http://heritage.stsci.edu/2005/30 The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Ag

  17. GRBs in optical: optical afterglows and optical transients

    Czech Academy of Sciences Publication Activity Database

    Hudec, René

    Arcetri : IAA, 1999. s. 26. [Workshop on astrophysics of relativistic sources. 02.06.1999-05.06.1999, Marciana Marina] R&D Projects: GA ČR GA205/99/0145 Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  18. MAGIC upper limits on the GRB 090102 afterglow

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Carmona, E; Carosi, A; Fidalgo, D Carreto; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Caneva, G; De Lotto, B; Mendez, C Delgado; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Eisenacher, D; Elsaesser, D; Farina, E; Ferenc, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giavitto, G; Godinović, N; Muñoz, A González; Gozzini, S R; Hadasch, D; Hayashida, M; Herrero, A; Hildebrand, D; Hose, J; Hrupec, D; Idec, W; Kadenius, V; Kellermann, H; Knoetig, M L; Kodani, K; Konno, Y; Krause, J; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lewandowska, N; Lindfors, E; Lombardi, S; López, M; López-Coto, R; López-Oramas, A; Lorenz, E; Lozano, I; Makariev, M; Mallot, K; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Meucci, M; Miranda, J M; Mirzoyan, R; Moralejo, A; Munar-Adrover, P; Nakajima, D; Niedzwiecki, A; Nilsson, K; Nishijima, K; Nowak, N; Orito, R; Overkemping, A; Paiano, S; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Partini, S; Persic, M; Prada, F; Moroni, P G Prada; Prandini, E; Preziuso, S; Puljak, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Rügamer, S; Saggion, A; Saito, T; Saito, K; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Stamatescu, V; Stamerra, A; Steinbring, T; Storz, J; Sun, S; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Tibolla, O; Torres, D F; Toyama, T; Treves, A; Vogler, P; Wagner, R M; Zandanel, F; Zanin, R; Bouvier, A; Tajima, H; Longo, F

    2013-01-01

    Indications of a GeV component in the emission from GRBs are known since the EGRET observations during the 1990's and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy photons (E>30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z=1.547) field and Fermi Large Area Telescope (LAT) data in the same time interval are analysed to derive upper limits of the ...

  19. External Shocks, UHECRs, and the Early Afterglow of GRBs

    OpenAIRE

    Dermer, Charles D.

    2006-01-01

    Highly variable gamma-ray pulses and X-ray flares in GRB light curves can result from external shocks rather than central engine activity under the assumption that the GRB blast-wave shell does not spread. Acceleration of cosmic rays to 10^{20} eV energies can take place in the external shocks of GRBs. Escape of hadronic energy in the form of UHECRs leads to a rapidly decelerating GRB blast wave, which may account for the rapid X-ray declines observed in Swift GRBs.

  20. Probing the environment of gravitational wave transient sources with TeV afterglow emission

    CERN Document Server

    Zhu, Qin-Yu

    2016-01-01

    Recently, Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) detected gravitational wave (GW) transients from mergers of binary black holes (BHs). The system may also produce a wide-angle, relativistic outflow if the claimed short GRB detected by GBM is in real association with GW 150914. It was suggested that mergers of double neutron stars (or neutron star-black hole binaries), another promising source of GW transients, also produce fast, wide-angle outflows. In this paper, we calculate the high-energy gamma-ray emission arising from the blast waves driven by these wide-angle outflows. We find that TeV emission arising from the inverse-Compton process in the relativistic outflow resulted from mergers of binary BHs similar to those in GW 150914 could be detectable by ground-based IACT telescopes such as Cherenkov Telescope Array (CTA) if the sources occur in { a dense medium with density $n > 0.3 cm^{-3}$}. For neutron star-neutron star (NS-NS) and NS-BH mergers, TeV emission from the wide-...