ASCA Observation of the Lyman-Limit Quasar PKS 2145+067 | Zendy

Noriko Y. Yamasaki | Zendy; Teru Ishikawa | Zendy; Takaya Ohashi | Zendy

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ASCA Observation of the Lyman-Limit Quasar PKS 2145+067

Author(s) -

Noriko Y. Yamasaki,

Teru Ishikawa,

Takaya Ohashi

Publication year - 2000

Publication title -

publications of the astronomical society of japan

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.99

H-Index - 110

eISSN - 2053-051X

pISSN - 0004-6264

DOI - 10.1093/pasj/52.5.763

Subject(s) - physics , astrophysics , rosat , quasar , flux (metallurgy) , luminosity , absorption (acoustics) , photon , astronomy , galaxy , optics , materials science , metallurgy

X-ray observation of a famous Lyman-limit quasar PKS2145+067at z_em= 0.990 was carried with ASCA. The source showed a 2-10 keV flux of 1.3 E-11 erg cm^-2 sec^-1 (L_X = 2.5 E46 erg sec^-1 for H_0=50 km s^-1 Mpc^-1) described by a power-law spectrum with a photon index Gamma=1.63 +/- 0.04 . In the ASCA energy band, no excess absorption was detected implying the absorption column density at z_ ab=0.791 was less than 1.6 E21 cm^-2 if absorbing medium had a metal abundance of 0.5 solar. Comparison with previous Einstein and ROSAT observations shows that PKS2145+067 has increased its luminosity by a factor of 2--3 between 1991 and 1998

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