AGN with strong forbidden high-ionisation lines selected from the Sloan Digital Sky Survey

Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

31 pages, 19 figures. Includes 12 pages (5 figures, 7 tables) of online-only material. To appear in MNRAS. Also available from

Scientific paper

We have defined a sample of 63 AGN with strong forbidden high-ionisation line (FHIL) emission. These lines, with ionisation potentials >~ 100eV, respond to a portion of the spectrum that is often difficult to observe directly, thereby providing constraints on the EUV-soft X-ray continuum. The sources are selected from the Sloan Digital Sky Survey (SDSS) on the basis of their [Fe X]6374A emission, yielding one of the largest and the most homogeneous sample of FHIL-emitting galaxies. We fit a sequence of models to both FHILs ([Fe XI], [Fe X] and [Fe VII]) and lower-ionisation emission lines ([O III], [O I], H-alpha, [N II], [S II]) in the SDSS spectra. These data are combined with X-ray measurements from Rosat, which are available for half of the sample. The correlations between these parameters are discussed for both the overall sample and subsets defined by spectroscopic classifications. The primary results are evidence that: (1) the [Fe X] and [Fe XI] lines are photoionised and their strength is proportional to the continuum flux around 250 eV; (2) the FHIL-emitting clouds form a stratified outflow in which the [Fe X] and [Fe XI] source regions extend sufficiently close to the BLR that they are partially obscured in Seyfert 2s whereas the [Fe VII] source region is more extended and is unaffected by obscuration; (3) narrow-lined Seyfert 1s (NLS1s) tend to have the strongest [Fe X] flux (relative to lower-ionisation lines); and (4) the most extreme [Fe X] ratios (such as [Fe X]/[O III] or [Fe X]/[Fe VII]) are found in the NLS1s with the narrowest broad lines and appear to be an optical-band indication of objects with strong X-ray soft excesses.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

AGN with strong forbidden high-ionisation lines selected from the Sloan Digital Sky Survey does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with AGN with strong forbidden high-ionisation lines selected from the Sloan Digital Sky Survey, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and AGN with strong forbidden high-ionisation lines selected from the Sloan Digital Sky Survey will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-370793

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.