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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The astronomy and astrophysics review 6 (1995), S. 225-270 
    ISSN: 1432-0754
    Keywords: Neutron stars ; Gamma-ray bursts ; Pulsars ; Nucleosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The number of Galactic neutron stars is significant, N ∼ 108–9, but radiation from their surfaces is hard to detect. The nearest isolated neutron stars could be as close as ∼ 10 pc (the estimate sensitively depends on assumptions about initial velocities), but would probably be too old, and thus too cold, for optical detections. Thatγ-ray emission is a useful alternative window for neutron star studies was revealed through observations of pulsedγ-ray emission from the Crab and Vela pulsars (e.g. Bignami 1987). A wealth of recentγ-ray observations of neutron stars is provided by sophisticated experiments aboard the COMPTON Gamma Ray Observatory (CGRO) and several other spacecraft. We summarize the current status of the Galactic population ofγ-ray pulsars. Gamma ray bursts are also believed to be associated with neutron stars. Although data from BATSE aboard CGRO have recently challenged the standard paradigm thatγ-ray bursts (GRBs) originate on or near neutron stars in the Galactic disk, the possibility of bursts from an extended Galactic halo of high velocity neutron stars is still under consideration. Furthermore, many cosmological scenarios also invoke neutron stars as the energy source. We thus include GRBs in this review. A subset of GRBs, the soft gamma repeaters, has recently been associated with Galactic supernova remnants. Their properties and counterparts are discussed. In addition, we briefly describeγ-ray emission from slowly accreting neutron stars, and theγ-ray line afterglow resulting from production of radioactive isotopes during their birth.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-06-06
    Description: POET (Polarimeters for Energetic Transients) is a Small Explorer mission concept proposed to NASA in January 2008. The principal scientific goal of POET is to measure GRB polarization between 2 and 500 keV. The payload consists of two wide FoV instruments: a Low Energy Polarimeter (LEP) capable of polarization measurements in the energy range from 2-15 keV and a high energy polarimeter (Gamma-Ray Polarimeter Experiment - GRAPE) that will measure polarization in the 60-500 keV energy range. Spectra will be measured from 2 keV up to 1 MeV. The POET spacecraft provides a zenith-pointed platform for maximizing the exposure to deep space. Spacecraft rotation will provide a means of effectively dealing with systematics in the polarization response. POET will provide sufficient sensitivity and sky coverage to measure statistically significant polarization for up to 100 GRBs in a two-year mission. Polarization data will also be obtained for solar flares, pulsars and other sources of astronomical interest.
    Keywords: Astronomy
    Format: application/pdf
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  • 3
    Publication Date: 2018-06-12
    Description: The Energetic X-ray Imaging Survey Telescope (EXIST), under study to be the Black Hole Finder Probe in NASA's Beyond Einstein Program, would image the sky every 95 min in the energy range 10-600 keV. Although the main scientific objectives of EXIST are the systematic, all-sky survey of heavily obscured AGNs and gamma-ray bursts, there is a substantial capability of EXIST for the observation of transient and persistent hard X-ray lines from several astrophysical sources.
    Keywords: Astrophysics
    Type: New Astronomy Reviews (ISSN 1387-6473); Volume 50; 637-639
    Format: text
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  • 4
    Publication Date: 2018-06-12
    Description: We report early follow-up observations of the error box of the short burst 050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada (OSN), followed by deep VLT/FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. No evidence for a GRB afterglow was found in our Calar Alto and OSN data, no rising supernova component was detected in our FORS2 images. A potential host galaxy can be identified in our FORS2 images, even though we cannot state with certainty its association with GRB 050813. IN any case, the optical afterglow of GRB 050813 was very faint, well in agreement with what is known so far about the optical properties of afterglows of short bursts. We conclude that all optical data are not in conflict with the interpretation that GRB 050813 was a short burst.
    Keywords: Astronomy
    Format: application/pdf
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  • 5
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 7
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    Unknown
    In:  Other Sources
    Publication Date: 2011-08-24
    Description: If a gamma-ray burst (GRB) occurs in a neutral medium, ionizing radiation associated with the burst will flash-photoionize a region surrounding the source. Detection of the line emission from this ionized region can constrain the flux of ionizing radiation accompanying the GRB and the density and ionization state of the environment surrounding the burst source. If the medium is sufficiently dense then the ionized region will recombine and fade on human timescales, aiding in the detection of the burst location and further constraining the density of the medium. However, dust within the dense medium may attenuate the line flux; the burst is unlikely to melt the dust along the line-of-sight. Astronomically interesting flux limits can be established by observations with reasonable integration times on a major telescope (e.g., 3 meter or larger).
    Keywords: ASTROPHYSICS
    Type: In: Gamma-ray bursts; Proceedings of the Workshop, Univ. of Alabama, Huntsville, Oct. 16-18, 1991 (A93-40051 16-93); p. 342-346.
    Format: text
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 201 (1993), S. 347-358 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The interpretation of the observedγ-ray burstV/V max statistic in terms of spatial distributions is model-dependent. Detection ofγ-ray bursts requires the counting rate in one or more detectors to exceed a thresholdC lim determined from a time-dependent background rateB(t). The sampling depth of the burst detector is thus time-dependent, and, if burst sources are non-uniform in space, the observedV/V max distribution will be affected byB(t). We demonstrate this effect with a simple geometric distribution of standard candles and argue thatV/V max statistic without information on threshold variations is insufficient for rigorous data analysis. Peak count rates and threshold values must be given separately for all events in order to facilitate a meaningful comparison of observations with theoretical distribution models.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The traditional paradigm of a Galactic origin of gamma-ray bursts (GRBs) suffered a major reduction in popularity when BATSE revealed an isotropic but radially inhomogeneous distribution of GRBs. The lack of pronounced galactic anisotropies places severe constraints on models including significant source contributions from the usual disk, bulge, or halo components of the Milky Way. Although models can be designed to preserve the local disk origin, a perhaps more promising approach invokes a very extended Galactic halo. Populating such halos with neutron stars requires very high velocities. Injection of such neutron stars might be restricted to a phase of the early galaxy, or it may continue to the present. We discuss several observational constraints that address the question presented in the title.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2019-07-12
    Description: A new solution to the observed Galactic globular cluster metallicity distribution is proposed by considering inhomogeneous collapse of a centrally condensed proto-Galaxy. In contrast to the standard one-zone model, it is shown that, for inhomogeneous models, the metallicity distribution can be reproduced without the need to decrease the nucleosynthetic yield for metal-poor stars. Chemical evolution in free fall is calculated analytically. A hybrid hydroparticle code is developed to study the effect of supernova induced pressure.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 376; 520-530
    Format: text
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