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Record Details

Record 50 of 55123
Cyclotron Line Measurements with INTEGRAL
Author and Affiliation:
Pottschmidt, K.(NASA Goddard Space Flight Center, Greenbelt, MD, United States)
Kreykenbohm, I.(Erlangen-Nuernberg Univ., Germany)
Caballero, I.(Institut fur Astronomie und Astrophysik, Germany)
Fritz, S.(Institut fur Astronomie und Astrophysik, Germany)
Schoenherr, G.(American Inst. of Physics, New York, NY, United States)
Kretschmar, P.(European Space Astronomy Centre, Madrid, Spain)
Wilms, J.(Erlangen-Nuernberg Univ., Germany)
McBride, V. A.(Southampton Univ., United Kingdom)
Suchy, S.(California Univ., San Diego, CA, United States)
Rothschild, R. E.(California Univ., San Diego, CA, United States)
Abstract: Due to its broadband energy coverage, INTEGRAL has made important contributions to observing and interpreting cyclotron lines, which are present in the 10-100 keV range of a sample of accreting pulsars. In these systems photons with energies fulfilling the resonance condition inelastically Compton scatter off electrons quantized in the accretion column above the neutron star's magnetic pole(s). This process gives rise to the broad, absorption-like lines or 'cyclotron resonant scattering features' (CRSF). The observed lines allow to directly measure the B-fields of these sources, resulting in values of a few times 1E12G. In this overview I will present recent highlights regarding CRSF observations as well as discuss current ideas and models for the physical conditions in the accretion column. Among the former are the stability of the spectrum of Vela X-1 during giant flares in 2003, the observation of three cyclotron lines during the 2004 outburst of V0332+53, the confirmation of the fundamental line at approximately 45 keV during a 2005 normal outburst of A0535-26, and the simultaneous detection of the two lines in the dipping source 4U 1907+09 (for which also a torque reversal was detected for the first time). Through these and other observations it has become increasingly apparent that two types of observations can potentially be used to constrain the accretion column geometry: the determination of energy ratios for multiple harmonic lines (only two sources with greater than 2 lines are known), was well as the evolution of the fundamental line centroid, which, for different sources, may or may not be correlated with flux. Furthermore, first steps have been taken away from the usual phenomenological description of the lines, towards a physical approach based on self-consistent CRSF modeling. Initial applications are presented.
Publication Date: Mar 31, 2008
Document ID:
20080030241
(Acquired Aug 05, 2008)
Subject Category: ASTROPHYSICS
Document Type: Conference Paper
Meeting Information: INTEGRAL Session of the 10th HEAD Meeting; 31 Mar. - 3 Apr. 2008; Los Angeles, CA; United States
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: CYCLOTRONS; LINE SPECTRA; RESONANCE SCATTERING; ASTRONOMICAL SPECTROSCOPY; PULSARS; DEPOSITION; CENTROIDS
Availability Source: Other Sources
Availability Notes: Abstract Only
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