Open AccessAn ultrasoft X‐ray source (RX 215319−1514) and discovery of a narrow‐line Seyfert 1 galaxy
Author(s) -
Singh Kulinder Pal,
Jones Laurence R.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03136.x
Subject(s) - physics , astrophysics , rosat , galaxy , line (geometry) , astronomy , emission spectrum , spectral line , mathematics , geometry
We present results on the identification of the optical counterpart of an ultrasoft X‐ray source discovered with ROSAT . Two optical candidates – a galaxy and a star – are found within the error circle of the X‐ray source position. Optical spectroscopy of the two candidates reveals that (a) the galaxy is a narrow‐line Seyfert type 1 galaxy, and (b) the star is a late A‐type or an early F‐type. The F x F v ratio is too high for the star to be the counterpart of the X‐ray source, but consistent with that for an active galaxy. Although higher‐resolution X‐ray imaging of the region is needed to definitely settle the question of the counterpart of the X‐ray source, the narrow‐line Seyfert 1 galaxy is the best candidate. The spectral properties of the newly discovered narrow‐line Seyfert 1 galaxy are also presented, including its extreme X‐ray power‐law spectral index of Γ≥4.