T. L. Cline

University of California, San Diego, San Diego, CA, United States

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Publications (274)596.59 Total impact

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    ABSTRACT: GRB 110918A is the brightest long GRB detected by Konus-WIND during its 19 years of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final IPN localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderare $E_{peak}$ of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z=0.984, a huge isotropic-equivalent energy release $E_{iso}=(2.1\pm0.1)\times10^{54}$ erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity $L_{iso}=(4.7\pm0.2)\times10^{54}$erg s$^{-1}$. A tail of the soft gamma-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. Swift/XRT and Swift/UVOT observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and ISM-like circumburst environment implied. We conclude that, among multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.7-3.4 deg results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of $z\sim7.5$ for Konus-WIND, and $z\sim12$ for Swift/BAT, which stresses the importance of GRBs as probes of the early Universe.
    The Astrophysical Journal 12/2013; 779(2):151. · 6.73 Impact Factor
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    ABSTRACT: Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0–5408, gave a burst with an estimated isotropic energy >1044 erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 × 1044 d 2 1 erg and 1.4 × 1047 d 2 1 erg, respectively, where and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.
    The Astrophysical Journal Letters 05/2011; 734(2):L35. · 6.35 Impact Factor
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    ABSTRACT: Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >10^{44} erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between November 2006 and June 2009, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0x10^{44} d_1^2 erg and 1.4x10^{47} d_1^2 erg respectively, where d_1 = d_{0501} / 1 kpc and d_{0501} is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.
    11/2010;
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    ABSTRACT: In 2008 August, the new soft gamma-ray repeater SGR 0501+4516 was discovered by Swift. The source was soon confirmed by several groups in space- and ground-based multi-wavelength observations. In this letter we report the analysis of five short bursts from the recently discovered SGR, detected with Konus-Wind gamma-ray burst spectrometer. Properties of the time histories of the observed events, as well as results of multi-channel spectral analysis, both in the 20--300 keV energy range, show, that the source exhibits itself as a typical SGR. The bursts durations are <0.75 s and their spectra above 20 keV can be fitted by optically-thin thermal bremsstrahlung (OTTB) model with kT of 20--40 keV. The spectral evolution is observed, which resembles the SGR 1627-41 bursts, where a strong hardness-intensity correlation was noticed in the earlier Konus-Wind observations. The peak energy fluxes of all five events are comparable to highest those for known SGRs, so a less distant source is implied, consistent with the determined Galactic anti-center direction. Supposing the young supernova remnant HB9 (at the distance of 1.5 kpc) as a natal environment of the source, the peak luminosities of the bursts are estimated to be (2--5)x10^{40} erg s-1. The values of the total energy release, given the same assumptions, amount to (0.6--6)x10^{39} erg. These estimations of both parameters are typical for short SGR bursts.
    The Astrophysical Journal 02/2009; 698. · 6.73 Impact Factor
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    ABSTRACT: The Transient Gamma-Ray Spectrometer (TGRS) experiment is a high-resolution germanium detector launched on the WIND satellite on 1994 November 1. Although primarily intended to study gamma-ray bursts and solar flares, TGRS also has the capability of studying slower transients (e.g., X-ray novae) and certain steady sources. We present here results on the narrow 511 keV annihilation line from the general direction of the Galactic center accumulated over the period 1995 January through 1995 October. These results were obtained from the TGRS occultation mode, in which a lead absorber occults the Galactic center region for of each spacecraft rotation, thus chopping the 511 keV signal. The occulted region is a band in the sky of width 16° that passes through the Galactic center. We detect the narrow annihilation line from the Galactic center with flux = (1.64 ± 0.09) × 10-3 photons cm-2 s-1. The data are consistent with a single point source at the Galactic center, but a distributed source of extent up to ~30° cannot be ruled out. No evidence for temporal variability on timescales longer than 1 month was found.
    The Astrophysical Journal 01/2009; 463(2):L75. · 6.73 Impact Factor
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    ABSTRACT: The Gamma-Ray Optical Counterpart Search Experiment (GROCSE) has searched for contemporaneous optical counterparts to gamma-ray bursts (GRBs) using an automated rapidly slewing wide field of view optical telescope at Lawrence Livermore National Laboratory. The telescope was triggered in real time by the Burst and Transient Source Experiment (BATSE) data telemetry stream as processed and distributed by the BATSE COordinates DIstribution NEtwork (BACODINE). GROCSE recorded sky images for 28 GRB triggers between 1994 January and 1996 June. The analysis of the 12 best events is presented here, half of which were recorded during detectable gamma-ray emission. No optical counterparts have been detected to limiting magnitudes mV ≤ 8.5 despite nearly complete coverage of burst error boxes.
    The Astrophysical Journal 01/2009; 482(2):L125. · 6.73 Impact Factor
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    ABSTRACT: The Transient Gamma-Ray Spectrometer (TGRS) on the Wind satellite is designed to perform spectroscopy of bright gamma-ray bursts in the ~20-8000 keV energy range, having a resolution 5-30 times better than that of earlier generation detectors. GRB 950822 was the brightest burst observed by TGRS in its first year of operation, with a peak flux (1024 ms) of ~78.3 photons cm-2 s-1 and a fluence (50-300 keV) of ~1.4 × 10-4 ergs cm-2; therefore, the GRB data in this paper represent the first high-resolution spectroscopy ever performed on a burst of this brightness. The continuum spectrum of GRB 950822 has the classical gamma-ray burst shape and exhibits typical evolution from hard to soft over the course of the burst. We found no evidence of line features or any other spectral fine structure with significance greater than 3.5 σ in our data.
    The Astrophysical Journal 01/2009; 491(2):697. · 6.73 Impact Factor
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    ABSTRACT: We have obtained spectra of the Galactic center at energies of 400-600 keV from high-resolution data acquired by the Transient Gamma-Ray Spectrometer Ge detector on board the WIND mission during 1995-1997. The data were obtained using an on-board occulter and are relatively free from systematics and backgrounds. Analysis of the spectra reveals a well-resolved electron-positron annihilation line at 511 keV and the associated continuum due to annihilation via positronium formation. Measurements of the line width and the continuum-to-line ratio allow some constraints to be placed on the interstellar sites where annihilation occurs.
    The Astrophysical Journal 01/2009; 501(1):L55. · 6.73 Impact Factor
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    ABSTRACT: We report on the very early time search for an optical afterglow from GRB 971227 with the Livermore Optical Transient Imaging System (LOTIS). LOTIS began imaging the "original" BATSE error box of GRB 971227 ~14 s after the onset of gamma-ray emission. Continuous monitoring of the position throughout the evening yielded a total of 499 images (10 s integration). Analysis of these images revealed no steady optical afterglow brighter than R = 12.3 ± 0.2 in any single image. Co-addition of the LOTIS images also failed to uncover transient optical emission. In particular, assuming a constant early-time flux, no optical afterglow brighter than R = 14.2 ± 0.2 was present within the first 1200 s, and no optical afterglow brighter than R = 15.0 ± 0.2 was present in the first 6.0 hr. Follow-up observations by other groups revealed a likely X-ray afterglow and a possible optical afterglow. Although subsequent deeper observations could not confirm a fading source, we show that these transients are not inconsistent with our present knowledge of the characteristics of gamma-ray burst afterglows. We also demonstrate that with the upgraded thermoelectrically cooled CCDs, LOTIS is capable of either detecting very early time optical afterglow or placing stringent constraints on the relationship between the gamma-ray emission and the longer wavelength afterglow in relativistic blast-wave models.
    The Astrophysical Journal 12/2008; 519(1):L25. · 6.73 Impact Factor
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    ABSTRACT: A search for spectral lines in gamma-ray bursts detected with the Transient Gamma-Ray Spectrometer has been unable to confirm their existence. The spectrometer, aboard the Wind spacecraft, has detected gamma-ray bursts and other transients since 1995. We have performed a systematic search for narrow spectral lines in gamma-ray bursts detected with this instrument that augments and extends the results of a similar search of bursts detected with BATSE. This search procedure tests for statistically significant lines at all possible times and durations during a burst using the method of maximum likelihood and C-statistic. Simulations demonstrated the effectiveness of this procedure, particularly on Poisson distributed data, for distinguishing real features from statistical fluctuations. The most promising line candidates were consistent with chance fluctuations, given the large number of spectra searched.
    The Astrophysical Journal 12/2008; 543(1):77. · 6.73 Impact Factor
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    ABSTRACT: We present a possible Cepheid-like luminosity estimator for the long gamma-ray bursts based on the variability of their light curves. To construct the luminosity estimator, we use CGRO/BATSE data for 13 bursts, Wind/Konus data for five bursts, Ulysses/GRB data for one burst, and NEAR/XGRS data for one burst. Spectroscopic redshifts, peak fluxes, and high-resolution light curves are available for 11 of these bursts; partial information is available for the remaining nine bursts. We find that the isotropic equivalent peak luminosities L of these bursts positively correlate with a rigorously constructed measure V of the variability of their light curves. We fit to these data a model that accommodates both intrinsic scatter (statistical variance) and extrinsic scatter (sample variance). We find that L ~ V. If one excludes GRB 980425 from the fit, on the grounds that its association with SN 1998bw at a redshift of z = 0.0085 is not secure, the luminosity estimator spans ≈2.5 orders of magnitude in L, and the slope of the correlation between L and V is positive with a probability of 1 - (1.4 × 10-4) (3.8 σ). Although GRB 980425 is excluded from this fit, its L and V values are consistent with the fitted model, which suggests that GRB 980425 may well be associated with SN 1998bw and that GRB 980425 and the cosmological bursts may share a common physical origin. If one includes GRB 980425 in the fit, the luminosity estimator spans ≈6.3 orders of magnitude in L, and the slope of the correlation is positive with a probability of 1 - (9.3 × 10-7) (4.9 σ). In either case, the luminosity estimator yields best-estimate luminosities that are accurate to a factor of ≈4, or best-estimate luminosity distances that are accurate to a factor of ≈2. Regardless of whether GRB 980425 should be included in the fit, its light curve is unique in that it is much less variable than the other ≈17 light curves of bursts in our sample for which the signal-to-noise ratio is reasonably good.
    The Astrophysical Journal 12/2008; 552(1):57. · 6.73 Impact Factor
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    ABSTRACT: In 1998 June-July, the Konus-Wind burst spectrometer observed a series of bursts from the new soft gamma repeater SGR 1627-41. Time histories and energy spectra of the bursts have been studied, revealing fluences and peak fluxes in the ranges 3 × 10-7 to 7.5 × 10-6 ergs cm-2 and 10-5 to 10-4 ergs cm-2 s-1, respectively. One event, 18 June 6153.5 s UT, stands out dramatically from this series. Its fluence is ~7 × 10-4 ergs cm-2, and its peak flux is ~2 × 10-2 ergs cm-2 s-1. These values from a source at a distance of 5.8 kpc yield an energy output of ~3 × 1042 ergs and a maximum luminosity of ~8 × 1043 ergs s-1 for isotropic emission, similar to the values for the famous 1979 March 5 and 1998 August 27 events. In terms of energy, this event is another giant outburst seen in a third soft gamma repeater! However, this very energetic burst differs significantly from the other giant outbursts. It exhibits no separate initial pulse with a fast rise time, no extended tail, and no pulsations. It is rather similar to ordinary repeated bursts, but is a few hundred times stronger in intensity. According to the magnetar model by Thompson & Duncan, such a burst may be initiated by a strong starquake when a crust fracture propagates over the whole surface of a neutron star.
    The Astrophysical Journal 12/2008; 519(2):L151. · 6.73 Impact Factor
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    ABSTRACT: The light curve, energy spectra, energetics, and IPN localization of an exceedingly intense short duration hard spectrum burst, GRB 070201, obtained from Konus-Wind, INTEGRAL (SPI-ACS), and MESSENGER data are presented. The total fluence of the burst and the peak flux are $S = 2.00_{-0.26}^{+0.10} \times 10^{-5}$ erg cm$^{-2}$ and $F_{max} = 1.61_{-0.50}^{+0.29} \times 10^{-3}$ erg cm$^{-2}$ s$^{-1}$. The IPN error box has an area of 446 square arcminutes and covers the peripheral part of the M31 galaxy. Assuming that the source of the burst is indeed in M31 at a distance of 0.78 Mpc, the measured values of the fluence $S$ and maximum flux $F_{max}$ correspond to a total energy of $Q = 1.5 \times 10^{45}$ erg, and a maximum luminosity $L = 1.2 \times 10^{47}$ erg s$^{-1}$. These data are in good agreement with the corresponding characteristics of the previously observed giant flares from other soft gamma repeaters. The evidence for the identification of this event as a giant flare from a soft gamma repeater in the M31 galaxy is presented.
    The Astrophysical Journal 12/2007; 680(1). · 6.73 Impact Factor
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    ABSTRACT: The light curve, energy characteristics, and localization of the short hard burst GRB 051103 are considered. Evidence for identifying this event with a giant flare from a soft gamma repeater in the nearby M81 group of interacting galaxies is discussed.
    Astronomy Letters 12/2006; 33(1):19-24. · 0.93 Impact Factor
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    ABSTRACT: We analyze the data obtained when the Konus-Wind gamma-ray spectrometer detected a giant flare in SGR 1806-20 on December 27, 2004. The flare is similar in appearance to the two known flares in SGR 0526-66 and SGR 1900+14 while exceeding them significantly in intensity. The enormous X-ray and gamma-ray flux in the narrow initial pulse of the flare leads to almost instantaneous deep saturation of the gamma-ray detectors, ruling out the possibility of directly measuring the intensity, time profile, and energy spectrum of the initial pulse. In this situation, the detection of an attenuated signal of Compton back-scattering of the initial pulse emission by the Moon with the Helicon gamma-ray spectrometer onboard the Coronas-F satellite was an extremely favorable circumstance. Analysis of this signal has yielded the most reliable temporal, energy, and spectral characteristics of the pulse. The temporal and spectral characteristics of the pulsating flare tail have been determined from Konus-Wind data. Its soft spectra have been found to contain also a hard power-law component extending to 10 MeV. A weak afterglow of SGR 1806-20 decaying over several hours is traceable up to 1 MeV. We also consider the overall picture of activity of SGR 1806-20 in the emission of recurrent bursts before and after the giant flare. Comment: 29 pages including 18 figures; to appear in Astronomy Letters, 2007, 33, p 1-18
    Astronomy Letters 12/2006; · 0.93 Impact Factor
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    ABSTRACT: Interplanetary spacecraft have been used with orbiting satellites for over 25 years to precisely localize gamma ray transients by the measurement of their timedelay geometry. The first interplanetary network (IPN) made both discoveries and controversies, and the latest is making possible a significant number of GRB counterpart observations. The IPN technique was pursued with dedicated payloads, with piggy-back experiments, and by the creative modifications of other experiments. The achievement of the NEAR in-flight software revision added a distant vertex to the array of Ulysses and the near-Earth group of GGS-Wind Konus, Beppo-Sax and Rossi-XTE. This 3-way long-baseline network culminated IPN history by, in the year 2000 alone, enabling over one-third of the afterglow searches and 5 redshift measurements. Future IPN possibilities are also outlined.
    02/2006: pages 375-377;
  • Thomas Cline, Neil Gehrels, Jay Norris
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    ABSTRACT: Swift is a next-generation, multi-wavelength observatory for transient gamma-ray astromomy. A NASA mission with an international collaboration, Swift is in development for launch in 2004. It is designed to make breakthroughs in determining the origin of gamma-ray bursts (GRBs) and in using GRBs to probe the early Universe. This mission features a wide-field, 15-150 keV, gamma ray imager that will detect over 100 GRBs per year of all durations and spectral types, including X-ray rich, and localize them with better than 4 arc-minute accuracy. Autonomous, on-board source localization will enable rapid reorientation of two narrow-field optical/UV and X-ray telescopes to determine arc-second source localizations and to perform optical, UV, and x-ray spectrophotometry. A strong outreach program and the afterglow campaigns should make possible great advances in the understanding of the early Universe.
    02/2006;
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    ABSTRACT: The giant outburst from SGR 1806-20 was observed on 2004 December 27 by many spacecraft. This extremely rare event exhibits a striking similarity to the two giant outbursts thus far observed, on 1979 March 5 from SGR 0526-66 and 1998 August 27 from SGR 1900+14. All the three outbursts start with a short giant radiation pulse followed by a weaker tail. The tail pulsates with the period of neutron star rotation of $\sim$5--8 s, to decay finally in a few minutes. The enormous intensity of the initial pulse proved to be far above the saturation level of the gamma-ray detectors, with the result that the most valuable data on the time structure and energy spectrum of the pulse is lost. At the time of the December 27 outburst, a Russian spacecraft Coronas-F with a $\gamma$-ray spectrometer aboard was occulted by the Earth and could not see the outburst. It succeeded, however, in observing a weak reflected signal due to the $\gamma$-rays Compton scattered by the Moon. This has been the first observation of a cosmic gamma-ray flare reflected from a celestial body. Here we report, that the detection of a weakened back-scattered initial pulse combined with direct observations by the Konus $\gamma$-ray spectrometer on the Wind spacecraft permitted us to reliably reconstruct the intensity, time history, and energy spectra of the outburst.
    03/2005;
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    ABSTRACT: Two authors, P. T. Boyd and M. Still, were inadvertently left off the author list in our original paper. We apologize for the omission.
    The Astrophysical Journal 03/2005; 621(1):558. · 6.73 Impact Factor
  • Astrophysical Journal. 01/2005; 621(1):558-558.

Publication Stats

2k Citations
596.59 Total Impact Points

Institutions

  • 1989–2008
    • University of California, San Diego
      • Center for Astrophysics and Space Sciences (CASS)
      San Diego, CA, United States
  • 2006
    • NASA
      Washington, West Virginia, United States
  • 1995–2005
    • Ioffe Physical Technical Institute
      • Laboratory of Experimental Astrophysics
      Sankt-Peterburg, St.-Petersburg, Russia
  • 2004
    • Pennsylvania State University
      • Department of Astronomy and Astrophysics
      University Park, Maryland, United States
  • 2001
    • Universities Space Research Association
      Houston, Texas, United States
  • 1997
    • Clemson University
      • Department of Physics and Astronomy
      Anderson, IN, United States