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NASA NTRS2017

Photospheric Emission in the Joint GBM and Konus Prompt Spectra of GRB 120323A

GRB 120323A is a very intense short gamma-ray burst (GRB) detected simultaneously during its prompt gamma-ray emission phase with the Gamma-Ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Space Telescope and the Konus experiment on board the Wind satellite. GBM and Konus operate in the kiloelectronvolt - megaelectronvolt regime; however, the GBM range is broader toward both the low and the high parts of the gamma-ray spectrum. Analyses of such bright events provide a unique opportunity to check the consistency of the data analysis as well as cross-calibrate the two instruments. We performed time-integrated and coarse time-resolved spectral analysis of GRB 120323A prompt emission. We conclude that the analyses of GBM and Konus data are only consistent when using a double-hump spectral shape for both data sets; in contrast, the single hump of the empirical Band function, traditionally used to fit GRB prompt emission spectra, leads to significant discrepancies between GBM and Konus analysis results. Our two-hump model is a combination of a thermal-like and a non-thermal component. We interpret the first component as a natural manifestation of the jet photospheric emission.

Guiriec, S.↗
NASA NTRS2000

Modelling Hard Gamma-Ray Emission from Supernova Remnants

The observation by the CANGAROO experiment of TeV emission from SN 1006, in conjunction with several instances of non-thermal X-ray emission from supernova remnants, has led to inferences of super-TeV electrons in these extended sources. While this is sufficient to propel the theoretical community in their modelling of particle acceleration and associated radiation, the anticipated emergence in the next decade of a number of new experiments probing the TeV and sub-TeV bands provides further substantial motivation for modellers. In particular, the quest for obtaining unambiguous gamma-ray signatures of cosmic ray ion acceleration defines a "Holy Grail" for observers and theorists alike. This review summarizes theoretical developments in the prediction of MeV-TeV gamma-rays from supernova remnants over the last five years, focusing on how global properties of models can impact, and be impacted by, hard gamma-ray observational programs, thereby probing the supernova remnant environment. Properties of central consideration include the maximum energy of accelerated particles, the density of the unshocked interstellar medium, the ambient magnetic field, and the relativistic electron-to-proton ratio. Criteria for determining good candidate remnants for observability in the TeV band are identified.

Baring, Matthew↗
NASA NTRS1974

Apollo scientific experiments data handbook

A brief description of each of the Apollo scientific experiments was described, together with its operational history, the data content and formats, and the availability of the data. The lunar surface experiments described are the passive seismic, active seismic, lunar surface magnetometer, solar wind spectrometer, suprathermal ion detector, heat flow, charged particle, cold cathode gage, lunar geology, laser ranging retroreflector, cosmic ray detector, lunar portable magnetometer, traverse gravimeter, soil mechanics, far UV camera (lunar surface), lunar ejecta and meteorites, surface electrical properties, lunar atmospheric composition, lunar surface gravimeter, lunar seismic profiling, neutron flux, and dust detector. The orbital experiments described are the gamma-ray spectrometer, X-ray fluorescence, alpha-particle spectrometer, S-band transponder, mass spectrometer, far UV spectrometer, bistatic radar, IR scanning radiometer, particle shadows, magnetometer, lunar sounder, and laser altimeter. A brief listing of the mapping products available and information on the sample program were also included.

Eichelman, W. F.↗
NASA NTRS1996

The Response of the BATSE LADs to Radiation From the Crab Nebula and Plans for Radioactivity Studies on Space Station

The Burst And Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO) was designed to measure X-rays and gamma rays with energies from about 50 keV to above 2 MeV. As with many scientific investigations, the success of the original experiment lead to additional areas of research interest. In the case of BATSE the ability to observe the radiation from sources down to about 20 keV became readily apparent. This lead to a continuing program of measuring the spectrum of radiation from stellar objects at these lower energies. One of these, the Crab Nebula, has a very steady radiation flux and, thus, has become a "standard candle" for such measurements. The Large Area Detectors (LADS) on BATSE contain a 1.27-cm thick, 25.4-cm radius NaI(Tl) detector behind a 6.35-mm thick polystyrene Charged Particle Detector (CPD) used to "veto" charged particles signals. The detectors have been calibrated with a series of gamma and X-ray sources and the results carefully simulated with a Monte Carlo code. In the calibration process the computer simulation accounts for scattering from material in the counting room as well as the BATSE structure. For an orbiting detector, scattering from the entire spacecraft must be modeled as well as for all covering material over the detectors. Five years after CGRO was launched on April 5, 1991, a large body of observational data has been taken of the Crab Nebula. The technique used for these observations, and for many other X-ray sources, is Earth occultation. From the perspective of the spacecraft, the Earth occults most stellar objects once in orbit, i.e., the signal is lost as the source sets and is regained as the source rises. A careful analysis of the continuing signals from all sources measured allows for an accurate measurement of the spectrum of a given source. An analysis of this data from the Crab has indicated that the LADs are very responsive at energies as low as 20 keV-at energies below the range of calibration. While the model accounts for many of the interactions of the photons with the detectors, the observation of nonstatistical deviations at low energy and at small angles has suggested a need to recalibrate at energies where the attenuation effects are increasing exponentially.

Laird, C. E.↗
NASA NTRS1999

"X-Ray Transients in Star-Forming Regions" and "Hard X-Ray Emission from X-Ray Bursters"

This grant funded work on the analysis of data obtained with the Burst and Transient Experiment (BATSE) on the Compton Gamma-Ray Observatory. The goal of the work was to search for hard x-ray transients in star forming regions using the all-sky hard x-ray monitoring capability of BATSE. Our initial work lead to the discovery of a hard x-ray transient, GRO J1849-03. Follow-up observations of this source made with the Wide Field Camera on BeppoSAX showed that the source should be identified with the previously known x-ray pulsar GS 1843-02 which itself is identified with the x-ray source X1845-024 originally discovered with the SAS-3 satellite. Our identification of the source and measurement of the outburst recurrence time, lead to the identification of the source as a Be/X-ray binary with a spin period of 94.8 s and an orbital period of 241 days. The funding was used primarily for partial salary and travel support for John Tomsick, then a graduate student at Columbia University. John Tomsick, now Dr. Tomsick, received his Ph.D. from Columbia University in July 1999, based partially on results obtained under this investigation. He is now a postdoctoral research scientist at the University of California, San Diego.

Halpern, Jules P.↗
NASA NTRS2002

Understanding the Long-Term Spectral Variability of Cygnus X-1 with Burst and Transient Source Experiment and All-Sky Monitor Observations

We present a comprehensive analysis of all observations of Cyg X-1 by the Compton Gamma Ray Observatory Burst and Transient Source Experiment (BATSE; 20-300 keV) and by the Rossi X-Ray Timing Explorer all-sky monitor (ASM; 1.5-12 keV) until 2002 June, including approximately 1200 days of simultaneous data. We find a number of correlations between fluxes and hardnesses in different energy bands. In the hard (low) spectral state, there is a negative correlation between the ASM 1.5-12 keV flux and the hardness at any energy. In the soft (high) spectral state, the ASM flux is positively correlated with the ASM hardness but uncorrelated with the BATSE hardness. In both spectral states, the BATSE hardness correlates with the flux above 100 keV, while it shows no correlation with the 20-100 keV flux. At the same time, there is clear correlation between the BATSE fluxes below and above 100 keV. In the hard state, most of the variability can be explained by softening the overall spectrum with a pivot at approximately 50 keV. There is also another, independent variability pattern of lower amplitude where the spectral shape does not change when the luminosity changes. In the soft state, the variability is mostly caused by a variable hard (Comptonized) spectral component of a constant shape superposed on a constant soft blackbody component. These variability patterns are in agreement with the dependencies of the rms variability on the photon energy in the two states. We also study in detail recent soft states from late 2000 until 2002. The last of them has lasted thus far for more than 200 days. Their spectra are generally harder in the 1.5-5 keV band and similar or softer in the 3-12 keV band than the spectra of the 1996 soft state, whereas the rms variability is stronger in all the ASM bands. On the other hand, the 1994 soft state transition observed by BATSE appears very similar to the 1996 one. We interpret the variability patterns in terms of theoretical Comptonization models. In the hard state, the variability appears to be driven mostly by changing flux in seed photons Comptonized in a hot thermal plasma cloud with an approximately constant power supply. In the soft state, the variability is consistent with flares of hybrid, thermal/nonthermal, plasma with variable power above a stable cold disk. The spectral and timing differences between the 1996 and 2000-2002 soft states are explained by a decrease of the color disk temperature. Also, on the basis of broadband pointed observations simultaneous with those of the ASM and BATSE, we find the intrinsic bolometric luminosity increases by a factor of approximately 3-4 from the hard state to the soft one, which supports models of the state transition based on a change of the accretion rate.

Zdziarski, Andrzej A.↗
NASA NTRS1995

Gamma Ray Astronomy; E2 Symposium of COSPAR Scientific Commission E, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

This issue on gamma ray astronomy presents many results from observations made with the Compton Gamma Ray Observatory (CGRO) and other spaceborne experiments and includes studies of Seyfert galaxies, X-ray binaries, neutron stars, diffuse cosmic background radiation, pulsars, blazars, gamma ray bursts, the galactic center, and the distribution of Aluminum-26 in the galaxy. The issue begins with a survey of Compton Telescope (COMPTEL) results and concludes with future prospects for the field.

Gehrels, N.↗
NASA NTRS2012

The History and Legacy of BATSE

The BATSE experiment on the Compton Gamma-ray Observatory was the first large detector system specifically designed for the study of gamma-ray bursts. The eight large-area detectors allowed full-sky coverage and were optimized to operate in the energy region of the peak emission of most GRBs. BATSE provided detailed observations of the temporal and spectral characteristics of large samples of GRBs, and it was the first experiment to provide rapid notifications of the coarse location of many them. It also provided strong evidence for the cosmological distances to GRBs through the observation of the sky distribution and intensity distribution of numerous GRBs. The large number of GRBs observed with the high- sensitivity BATSE detectors continues to provide a database of GRB spectral and temporal properties in the primary energy range of GRB emission that will likely not be exceeded for at least another decade. The origin and development of the BATSE experiment, some highlights from the mission and its continuing legacy are described in this paper.

Fishman, Gerald J.↗
NASA NTRS1998

Recent Outbursts from the Transient X-Ray Pulsar Cep X-4 (GS 2138+56)

We report on X-ray observations of the 66 s period transient X-ray pulsar Cep X-4 (GS 2138+56) with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO) and with the Rossi X-ray Timing Explorer (RXTE). Two outbursts from Cep X-4 were observed with BATSE in 1993 June-July and 1997 July. Spin periods of P(sub spin) = 66.2510 +/- 0.0009 s on 1993 June 25 (MJD 49,163) and P(sub spin) = 66.27 68 +/- 0.0007 s on 1997- July 12 (MJD 50,641) were each measured from 2 day spans of BATSE data near each outburst's peak. Cep X-4 showed an average spin down rate of P/P = (8.7 +/- 0.2) x 10(exp -5)/ yr between the 1993 and 1997 outbursts. After BATSE could no longer detect Cep X-4, public observations were performed on 1997 July 18 & 25 with the Proportional Counter Array (PCA) on RXTE. A spin period Of P(sub spin) = 66.28 +/- 0.02 s was measured from observations on 1997 July 18 (MJD 50,647). Significant aperiodic noise, with an rms variance of approx. 18% in the frequency range 0.01 - 1.0 Hz was observed on both days. Energy and intensity dependent pulse shape variations were also seen in these data. Recently published optical observations associate Cep X-4 with a Be companion star.

Wilson, Colleen A.↗
NASA NTRS1999

Gamma-Ray Burst Subclasses: Separating Instrumental Biases from Potential Source Populations

Instrumental effects mar gamma-ray burst observations. These effects can alter whether or not bursts trigger, as well as changing measured burst properties. The Burst And Transient Source Experiment (BATSE) on NASA's Compton Gamma-Ray Observatory (CGRO) has provided the largest database of gamma-ray bursts observed to date. It also provides an excellent laboratory for studying instrumental biases. We examine trigger biases and burst property biases as they pertain to previously identified gamma-ray burst classes. We also study some burst class properties in the new age of burst afterglow studies.

Hakkila, Jon↗
NASA NTRS2012

FERMI Observations of Gamma -Ray Emission From the Moon

We report on the detection of high-energy γ -ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmicray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3 GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(greater than100 MeV) = (1.04 plus or minus 0.01 [statistical error] plus or minus 0.1 [systematic error]) × 10(sup −6) cm(sup −2) s(sup −1). This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(greater than100 MeV)≈5×10(sup −7) cm(sup −2) s(sup −1), when solar activity was relatively high. The higher gamma -ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of gamma-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy gamma-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

fermi↗
NASA NTRS1992

Low-mass X-ray binaries and gamma-ray bursts

More than twenty years after their discovery, the nature of gamma-ray burst sources (GRBs) remains mysterious. The results from BATSE experiment aboard the Compton Observatory show however that most of the sources of gamma-ray bursts cannot be distributed in the galactic disc. The possibility that a small fraction of sites of gamma-ray bursts is of galactic disc origin cannot however be excluded. We point out that large numbers of neutron-star binaries with orbital periods of 10 hr and M dwarf companions of mass 0.2-0.3 solar mass are a natural result of the evolution of low-mass X-ray binaries (LMXBs). The numbers and physical properties of these systems suggest that some gamma-ray burst sources may be identified with this endpoint of LMXB evolution. We suggest an observational test of this hypothesis.

Lasota, J. P.↗
NASA NTRS1994

The rarity of soft gamma-ray repeaters deduced from reactivation of SGR1806-20

Only two different types of gamma-ray transient sources are presently known: over one thousand Gamma-Ray Bursters (GRBs) and only three Soft Gamma-Ray repeaters (SGRs). The latter are distinguished by their propensity for recurrent burst behaviour, in contrast to the nonrepeating GRB sources. Recurrent emission from one of the repeaters, SGR1900 + 14, has been detected earlier by the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory. Here we report renewed burst activity from SGR1806 - 20, the most prolific of the three known SGRs. This detection of reactivation of this source has been rapidly followed by identification of an X-ray counterpart, which also coincides with a compact radio source now identified as a plerionic (pulsar-powered) supernova remnant. In combination, these results are leading to a convergence of ideas about the nature of SGRs, which can now be firmly identified as neutron stars. That BATSE has detected no new sources in its two and a half years of operation indicates that SGRs are rare in our Galaxy.

Kouveliotou, C.↗
NASA NTRS2007

Monitoring Accreting X-ray Pulsars with the GLAST Burst Monitor

Accreting pulsars are exceptionally good laboratories for probing the detailed physics of accretion onto magnetic stars. While similar accretion flows also occur in other types of astrophysical systems, e.g. magnetic CVs, only neutron stars have a small enough moment of inertia for the accretion of angular momentum to result in measurable changes in spin-frequency in a timescale of days. Long-term monitoring of accreting pulsar spin-frequencies and fluxes was demonstrated with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Here we present sample results from BATSE, discuss measurement techniques appropriate for GBM, and estimate the expected GBM sensitivity.

Wilson, Colleen A.↗
NASA NTRS1985

The Figaro experiment for the observation of time marked sources in the low energy gamma-ray range

The only two firmly identified galactic gamma-ray sources in the second COS B catalogue are the pulsars PSR 0531+21 (Crab) and PSR 0833-45 (Vela). In the region between 100 keV and 10 MeV the detailed shape of the emission is particularly important, since one expects a turn-off which is related to geometry of the source. A marginal evidence of such a turn-off just below 1 MeV has been reported for the Vela pulsar. In order to study sources with a well marked time signature in this energy band, the FIGARO - French Italian Gamma Ray Observatory was designed. The first version was launched in November 1983 from the Sao Manuel base (Brazil), and was destroyed in a free fall following a balloon burst at an altitude of 50 mbar. A brief description is given of the new improved version of the experiment, FIGARO 2, which is nearly completed and whose launch is scheduled before summer 1986.

Agnetta, G.↗
NASA NTRS1994

Gamma-ray observations of NGC 253 and M82 with OSSE

Gamma-ray observations of the nearby starburst galaxies NGC 253 and M82 over the energy range (0.05-10) MeV have been obtained with the Oriented Scintillation Spectrometer Experiment (OSSE) spectrometer on the Compton Gamma-Ray Observatory (CGRO). The priority of these galaxies as OSSE targets had been established on the grounds that the average supernova rate may be high in starbursts as indicated by infrared and radio observations, and at distances of approximately 3 Mpc a significant chance of supernova gamm-ray line detection exists. NGC 253 was detected in continuum emission up to 165 keV with a total significance of 4.4 sigma and an estimated luminosity of 3 x 10(exp 40) ergs/s. The spectrum is best fit by a power law of photon index approximately 2.5. We consider the possible contribution of different emission mechanisms, including inverse Compton scattering, bremsstrahlung, discrete sources, and Type Ia/Ib supernova continuum to the measured flux. No significant continuum flux was observed from M82. A search for the gamma-ray line from the decay of the most abundant radioactive element produced in supernovae (Ni-56 yields Co-56 yields Fe-56) yielded no significant detection: the 3 sigma upper limits to the line fluxes at 0.158, 0.812, 0.847, and 1.238 MeV for both galaxies are obtained.

Bhattacharya, D.↗
NASA NTRS1973

Continued development of the Combined Pulsed Neutron Experiment (CPNE) for lunar and planetary surfaces

Current progress is reported on the inelastic scattering, capture, and activation gamma ray portions of the Combined Pulsed Neutron Experiment (CPNE). Experiments are described which have enabled a reduction in weight of the experimental probe to 7.3 kg. Parametric studies are described which enabled the optimization of experimental parameters (e.g., gate time settings, neutron pulse rate, etc.). Estimated detection sensitivities using this light weight probe and the optimized experimental parameters are discussed.

Mandler, J. W.↗
NASA NTRS1988

Upper limits to the high-energy gamma-ray and hard X-ray flux from SN 1987A on day 55

A balloon-borne experiment was carried out on April 19, 1987 from Alice Springs, Australia to detect high-energy gamma-rays and hard X-rays from the supernova SN 1987A in the Large Magellanic Cloud. An optical spark chamber for measuring the high-energy gamma-rays and a multiwire proportional counter for measuring the hard X-rays shared a common balloon platform. No positive emission was observed by either detector. The gamma-ray upper limit obtained indicates that either the expanding supernova shell was opaque to gamma-rays at the time of the flight, or that the supernova cosmic ray luminosity was less than about 10 to the 40th erg/s. The X-ray upper limit obtained confirms the opacity of the shell to Comptonized hard X-rays.

Sood, R. K.↗