ANOMALOUSLY STEEP REDDENING LAW IN QUASARS: AN EXCEPTIONAL EXAMPLE OBSERVED IN IRAS 14026+4341

Journal Article · Sat Jun 15 04:00:00 EDT 2013 · Astronomical Journal (New York, N.Y. Online)

DOI:https://doi.org/10.1088/0004-6256/145/6/157· OSTI ID:22130637

Peng, Jiang; Hongyan, Zhou; Tuo, Ji; Xinwen, Shu; Wenjuan, Liu; Xiaobo, Dong; Huiyuan, Wang; Tinggui, Wang ^[1]; Jianguo, Wang ^[2]

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1. Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui, 230026 (China)
2. National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011 (China)

A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS 14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000 A. It has a steep rise at wavelengths shorter than 3000 A, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the H{alpha}/H{beta} ratio) in IRAS 14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/da{proportional_to}a {sup -1.4}, truncated at a maximum size of a{sub max} = 70 nm. The unusual size distribution may be caused by the destruction of large 'stardust' grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS 14026+4341 is a weak emission-line quasar (i.e., PHL 1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.

• OSTI ID: 22130637
• Journal Information: Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 6 Vol. 145; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ASTROPHYSICS
DISTRIBUTION
DUSTS
EMISSION
MAGELLANIC CLOUDS
QUASARS
SPECTRA
WAVELENGTHS