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Three quasars from a survey of strong 25-µm emitters

Wolstencroft, R. D. and Parker, Q. A. and Lonsdale, C. J. and Scarrott, S. M. (2000) Three quasars from a survey of strong 25-µm emitters. Monthly Notices of the Royal Astronomical Society, 311 (3). pp. 541-554. ISSN 0035-8711. doi:10.1046/j.1365-8711.2000.03049.x.

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We have carried out a spectroscopic survey of 750 sources that are strong 25-μm emitters from the IRAS Faint Source data base. Many of these sources are previously unknown active galactic nuclei including new IRAS quasars, three of which we describe here: F21382−2659, Z06367−6845 and Z05558−5008. They are all radio and X-ray quiet, and compared to the known IRAS quasars they have similar 25-μm luminosities, L(25 μm), but lower values of L(25 μm)/L(B). Their F(25 μm)/F(60 μm) IRAS colours lie in the range 0.33 to 1.08, indicating the presence of relatively warm dust, presumably in a dusty torus surrounding the central source, and with temperatures similar to those of the known IRAS quasars. The quasar with the warmest dust, F21382−2659, exhibits broad (full width at half-maximum ~4000 km s^(−1)) asymmetric Balmer lines with Hγ having an opposite asymmetry to the other broad lines; also Hβ (only) is double-peaked. Fe ii is very weak in F21382−2659 but strong in the other two quasars, and the anticorrelation between Fe ii and [O iii] holds as anticipated. Two of the quasars are unpolarized: although F21382−2659 is optically polarized (2.1 per cent at 4950 Å), we argue that this provides little insight into the orientation of its dust torus relative to the line of sight.

Item Type:Article
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Lonsdale, C. J.0000-0003-0898-406X
Additional Information:© 2000 RAS. Accepted 1999 September 1. Received 1999 September 1; in original form 1998 December 14. Article first published online: 4 Apr. 2002. We are grateful to Gavin Ramsay and Mark Cropper, to Dick Hunstead and Gordon Robertson, and to David Buckley and Patricia Whitelock, for their valuable contributions on the AAT, MOST and SAAO telescopes, respectively. We also acknowledge useful comments and suggestions by an anonymous referee that have helped to improve this paper.
Subject Keywords:fundamental parameters; quasars: emission lines; quasars: individual: Z0555825008; quasars: individual: Z0636726845; quasars: individual: F2138222659; infrared: galaxies.
Issue or Number:3
Record Number:CaltechAUTHORS:20111209-121027053
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Official Citation:Wolstencroft, R. D., Parker, Q. A., Lonsdale, C. J. and Scarrott, S. M. (2000), Three quasars from a survey of strong 25-μm emitters . Monthly Notices of the Royal Astronomical Society, 311: 541–554. doi: 10.1046/j.1365-8711.2000.03049.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28399
Deposited By: Ruth Sustaita
Deposited On:09 Dec 2011 21:24
Last Modified:09 Nov 2021 16:56

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