1998/02/09 by J. Siebert, Siebert, J., W. Brinkmann +1
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9802101
8 pages, 4 figures, accepted for publication in A&A
arxiv created 1998/02/09 · openalex publication_date 1998/02/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present ROSAT HRI observations of six quasars with redshifts >3.4: PKS 0335-122, S4 0620+389, B1422+231, PKS 2215+02, Q 2239-386 and PC 2331+0216. We include the observation of the radio-quiet quasar BG 57 9, whose redshift has recently been revised to z = 0.965. S4 0620+389, B1422+231, PKS 2215+02 and BG 57 9 are detected in the ROSAT energy band (0.1-2.4 keV). 2 sigma upper limits are given for the remaining objects. All X-ray sources are point like to the limit of the HRI point spread function. We report marginal evidence for X-ray variability in S4 0620+389 on timescales of several hours (rest frame). No significant X-ray variability is found in the gravitationally lensed quasar B1422+231 on rest frame timescales of hours and months. We present the spectral energy distributions for six of the high redshift quasars and compare them to the mean distribution of low redshift quasars.