Simultaneous X-ray, ultraviolet, and optical observations of the BL Lacertae object PKS 2155-304

Journal Article · Thu Jun 01 00:00:00 EDT 1989 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/167532· OSTI ID:5643651

Treves, A; Morini, M; Chiappetti, L; Fabian, A; Falomo, R ^[1]; Osservatorio Astrofisico, Padua ^[2]

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1. Milano Universita (Italy)
2. Italy

A series of observations at optical, UV, and X-ray frequencies of PKS 2155-304, one of the brightest BL Lac objects is reported. Spectral fits given for various epochs show that the medium energy data are well fitted by single power laws plus absorption, with energy index between 1.5 and 2. Marginal evidence for an absorption edge at about 7 keV is found, as is evidence for some spectral depression at about 1 keV. This may be modeled with an edge at 660 + or - 26 eV with optical depth tau = 1.8 + or - 0.2. Energy distributions on several occasions are reconstructed, and the optical, UV, and X-ray intensities are found to be correlated in all cases but one. The variability amplitudes decrease and the time scales increase with decreasing frequency. These results indicate a synchrotron origin for the X-rays and distinct but connected emission regions for the X-ray, UV, and optical bands. 46 refs.

• OSTI ID: 5643651
• Journal Information: Astrophysical Journal; (USA), Vol. 341; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BL LACERTAE OBJECTS
ULTRAVIOLET SPECTRA
VISIBLE SPECTRA
X-RAY SPECTRA
COSMIC X-RAY SOURCES
ENERGY SPECTRA
ORIGIN
SATELLITES
SYNCHROTRON RADIATION
BREMSSTRAHLUNG
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
ELECTROMAGNETIC RADIATION
RADIATIONS
SPECTRA
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources