Other
Scientific paper
Dec 2000
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000aas...197.7409l&link_type=abstract
American Astronomical Society, 197th AAS Meeting, #74.09; Bulletin of the American Astronomical Society, Vol. 32, p.1521
Other
Scientific paper
The VLA FIRST radio survey recently discovered a new, extremely bright quasar at z = 0.192. Its magnitudes on the POSS I plates are B = 13.9 and R = 13.9, and it is of similar brightness on a UK Schmidt plate taken in 1988. Its absolute magnitude is MV = -25.9 (for H0 = 70 km s-1 Mpc-1). These properties make it the second brightest quasar known (in apparent magnitude) at z > 0.1 after 3C 273. The only other mention of this object in the literature is as PHL 1811, one of the many blue ``stars" in the Palomar-Haro-Luyten plate survey. Optically this quasar is classified as a Narrow-line Seyfert 1 galaxy (NLS1): it has narrow Hβ emission (1930 km s-1), no discernible [O 3] emission, strong optical Fe 2, and a blue optical continuum. NLS1s are known to be bright soft X-ray sources and therefore it was a complete surprise to find this object was not detected in the ROSAT All Sky Survey (RASS), with 95% confidence flux upper limit of 1.3 x 10-2 counts s-1. We observed PHL 1811 using BeppoSAX on May 16, 2000, for 38 ks. Only 65 photons were detected. The spectrum could be modelled by a power law (α = 0.5) plus Galactic absorption only, or by a power law with index fixed at α = 1.6 and intrinsic absorption best fitted as NH = 6.4 x 1022 cm-2. The observed 2--10 keV X-ray luminosity is ~ 3 x 1043 ergs s-1. The X-ray emission is very weak and the inferred α ox is 1.9--2.1, much smaller than the nominal value of 1.6 for quasars of this optical luminosity and comparable to the X-ray weakest quasars. We do not know why PHL 1811 is so weak in soft X-rays. It may be unusually intrinsically weak. Alternatively, since BALQSOs and other UV absorbed objects are known to be soft X-ray weak, PHL 1811 may turn out to be a BALQSO. Optical and BeppoSAX spectra will be presented and discussed. A preliminary FUSE spectrum will also be shown if it is observed, as planned, in the Fall of 2000.
Becker Robert H.
Halpern Jules P.
Helfand David J.
Jenkins Edward B.
Leighly Karen M.
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