The time profiles of many gamma-ray bursts observed by BATSE consist of distinct pulses, which of... more The time profiles of many gamma-ray bursts observed by BATSE consist of distinct pulses, which offers the possibility of characterizing the temporal structure of these bursts using a relatively small set of pulse shape parameters. This pulse analysis has previously been performed ...
ABSTRACT This presentation summarizes the linear diffusion model applied to the evolution of the ... more ABSTRACT This presentation summarizes the linear diffusion model applied to the evolution of the double-peaked outburst in the transient source XTE J1118+480. The model treats the two outbursts as episodic mass deposition at the outer radius of the disk followed by evolution of disk structure according to a diffusion process. Light curves with fast-rise, exponential decay profile are a general consequence of the diffusion process. Deconvolution of the light curve proves to be feasible and gives an input function specifying mass deposition at the outer disk edge as well as the total mass of the disk, both as functions of time. The derived evolution of total disk mass can be correlated with the observed evolution of the 0.1 Hz QPO as observed by USA and RXTE. We discuss how the model applies to other transients and other X-ray outbursts. Basic research in X-ray astronomy at the Naval Research Laboratory is supported by ONR/NRL. Work at SLAC was supported by Department of Energy contract DE-AC 03-76-SFO0515.
Journal of Cosmology and Astroparticle Physics, 2008
We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) for indirectly... more We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) for indirectly detecting weakly interacting massive particles (WIMPs) through the γ-ray signal that their pair annihilation produces. WIMPs are among the favorite candidates for explaining the compelling evidence that about 80% of the mass in the Universe is non-baryonic dark matter (DM). They are serendipitously motivated by various extensions of the standard model of particle physics such as supersymmetry and universal extra dimensions (UED). With its unprecedented sensitivity and its very large energy range (20 MeV to more than 300 GeV) the main instrument on board the GLAST satellite, the Large Area Telescope (LAT), will open a new window of discovery. As our estimates show, the LAT will be able to detect an indirect DM signature for a large class of WIMP models given a cuspy profile for the DM distribution. Using the current state of the art Monte Carlo and event reconstruction software developed within the LAT collaboration, we present preliminary sensitivity studies for several possible sources inside and outside the Galaxy. We also discuss the potential of the LAT to detect UED via the electron/positron channel. Diffuse background modeling and other background issues that will be important in setting limits or seeing a signal are presented.
The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented.... more The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (> | | b 10), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.
Installation of the PEP-II electron and positron Injection beamlines in the SLAC linac housing is... more Installation of the PEP-II electron and positron Injection beamlines in the SLAC linac housing is now underway. Utilization of the existing high power, low emittance beams available at SLAC required that a great portion of the systems for pulsed extraction and transport of 9.0 GeV electrons and 3.1 GeV positrons for injection into the PEP-II rings will reside in the existing linac housing. Approximately 4.7 kilometers of these beamlines will be completed during the summer of 1995. All components, including orbit correctors and diagnostic instruments, required for extraction and transport of the electron beam will be in place and ready for commissioning as soon as this fall. The positron transport line in the housing will also be complete except for the pulsed extraction system. These systems are described, along with the status of the construction and installation of the important subsystems such as magnets and power supplies, vacuum systems, instrumentation and controls. The plan f...
EGRET, aboard NASA's CGRO satellite, has made important contributions to establishing limits on W... more EGRET, aboard NASA's CGRO satellite, has made important contributions to establishing limits on WIMP dark matter in the galaxy. This paper will review these EGRET results. Based on past limits and theoretical estimates, future potential dark matter results from GLAST are projected.
... The B Factory will consist of two rings of equal size, a 9 GeV electron ring sod a 3. I GeV p... more ... The B Factory will consist of two rings of equal size, a 9 GeV electron ring sod a 3. I GeV positron riog, each with 1658 bunches with total circulating curreots of 1.5 aod 2.1 amperes respectively. ... Linac q&ion mtc [pps] Linr cumnt 1 lOl()$ per puke]** Invariant lina~ anittance Im-nd] ...
The Gamma-ray Large Area Space Telescope (GLAST) is a proposed next-generation high-energy gamma-... more The Gamma-ray Large Area Space Telescope (GLAST) is a proposed next-generation high-energy gamma-ray telescope for studying astrophysical sources in the 10 MeV to 300 GeV energy range. One of the principal goals of the mission will be an all-sky survey with deep exposure. We present the projected sensitivity limits and source localization regions for the survey based on detailed Monte Carlo simulations of the interactions of gamma rays in GLAST, a realistic orbital observation mode, and various celestial gamma-ray backgrounds. We also estimate the size and reliability of the resulting source catalog.
The time profiles of many gamma-ray bursts observed by BATSE consist of distinct pulses, which of... more The time profiles of many gamma-ray bursts observed by BATSE consist of distinct pulses, which offers the possibility of characterizing the temporal structure of these bursts using a relatively small set of pulse shape parameters. This pulse analysis has previously been performed ...
ABSTRACT This presentation summarizes the linear diffusion model applied to the evolution of the ... more ABSTRACT This presentation summarizes the linear diffusion model applied to the evolution of the double-peaked outburst in the transient source XTE J1118+480. The model treats the two outbursts as episodic mass deposition at the outer radius of the disk followed by evolution of disk structure according to a diffusion process. Light curves with fast-rise, exponential decay profile are a general consequence of the diffusion process. Deconvolution of the light curve proves to be feasible and gives an input function specifying mass deposition at the outer disk edge as well as the total mass of the disk, both as functions of time. The derived evolution of total disk mass can be correlated with the observed evolution of the 0.1 Hz QPO as observed by USA and RXTE. We discuss how the model applies to other transients and other X-ray outbursts. Basic research in X-ray astronomy at the Naval Research Laboratory is supported by ONR/NRL. Work at SLAC was supported by Department of Energy contract DE-AC 03-76-SFO0515.
Journal of Cosmology and Astroparticle Physics, 2008
We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) for indirectly... more We investigate the sensitivity of the Gamma-ray Large Area Space Telescope (GLAST) for indirectly detecting weakly interacting massive particles (WIMPs) through the γ-ray signal that their pair annihilation produces. WIMPs are among the favorite candidates for explaining the compelling evidence that about 80% of the mass in the Universe is non-baryonic dark matter (DM). They are serendipitously motivated by various extensions of the standard model of particle physics such as supersymmetry and universal extra dimensions (UED). With its unprecedented sensitivity and its very large energy range (20 MeV to more than 300 GeV) the main instrument on board the GLAST satellite, the Large Area Telescope (LAT), will open a new window of discovery. As our estimates show, the LAT will be able to detect an indirect DM signature for a large class of WIMP models given a cuspy profile for the DM distribution. Using the current state of the art Monte Carlo and event reconstruction software developed within the LAT collaboration, we present preliminary sensitivity studies for several possible sources inside and outside the Galaxy. We also discuss the potential of the LAT to detect UED via the electron/positron channel. Diffuse background modeling and other background issues that will be important in setting limits or seeing a signal are presented.
The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented.... more The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (> | | b 10), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.
Installation of the PEP-II electron and positron Injection beamlines in the SLAC linac housing is... more Installation of the PEP-II electron and positron Injection beamlines in the SLAC linac housing is now underway. Utilization of the existing high power, low emittance beams available at SLAC required that a great portion of the systems for pulsed extraction and transport of 9.0 GeV electrons and 3.1 GeV positrons for injection into the PEP-II rings will reside in the existing linac housing. Approximately 4.7 kilometers of these beamlines will be completed during the summer of 1995. All components, including orbit correctors and diagnostic instruments, required for extraction and transport of the electron beam will be in place and ready for commissioning as soon as this fall. The positron transport line in the housing will also be complete except for the pulsed extraction system. These systems are described, along with the status of the construction and installation of the important subsystems such as magnets and power supplies, vacuum systems, instrumentation and controls. The plan f...
EGRET, aboard NASA's CGRO satellite, has made important contributions to establishing limits on W... more EGRET, aboard NASA's CGRO satellite, has made important contributions to establishing limits on WIMP dark matter in the galaxy. This paper will review these EGRET results. Based on past limits and theoretical estimates, future potential dark matter results from GLAST are projected.
... The B Factory will consist of two rings of equal size, a 9 GeV electron ring sod a 3. I GeV p... more ... The B Factory will consist of two rings of equal size, a 9 GeV electron ring sod a 3. I GeV positron riog, each with 1658 bunches with total circulating curreots of 1.5 aod 2.1 amperes respectively. ... Linac q&ion mtc [pps] Linr cumnt 1 lOl()$ per puke]** Invariant lina~ anittance Im-nd] ...
The Gamma-ray Large Area Space Telescope (GLAST) is a proposed next-generation high-energy gamma-... more The Gamma-ray Large Area Space Telescope (GLAST) is a proposed next-generation high-energy gamma-ray telescope for studying astrophysical sources in the 10 MeV to 300 GeV energy range. One of the principal goals of the mission will be an all-sky survey with deep exposure. We present the projected sensitivity limits and source localization regions for the survey based on detailed Monte Carlo simulations of the interactions of gamma rays in GLAST, a realistic orbital observation mode, and various celestial gamma-ray backgrounds. We also estimate the size and reliability of the resulting source catalog.
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Papers by E. Bloom