J/AJ/145/157 Reddening curve of IRAS 14026+4341 (Jiang+, 2013)
Anomalously steep reddening law in quasars: an exceptional example observed in
IRAS 14026+4341.
Jiang P., Zhou H., Ji T., Shu X., Liu W., Wang J., Dong X., Bai J.,
Wang H., Wang T.
<Astron. J., 145, 157 (2013)>
=2013AJ....145..157J 2013AJ....145..157J
ADC_Keywords: QSOs ; Reddening
Keywords: dust, extinction - quasars: individual: IRAS 14026+4341
Abstract:
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 IRAS14026+4341. By
comparing the observed spectrum to the quasar composite spectrum, we
derive a reddening curve in the rest-frame wavelength range of
1200-10000Å. It has a steep rise at wavelengths shorter than
3000Å, 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 Hα/Hβ ratio) in
IRAS14026+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∝a-1.4, truncated at a maximum
size of amax=70nm. 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
IRAS14026+4341 is a weak emission-line quasar (i.e., PHL1811
analogies) with heavy dust reddening and blueshifted broad absorption
lines.
Description:
IRAS 14026+4341 was detected on 1994 April 27 during the Two Micron
All Sky Survey (2MASS; Cutri et al., 2003, II/246) in the J, H, and
Ks bands. The quasar was also imaged in SDSS on 2003 March 11 in the
u, g, r, i, and z bands. We use the SDSS point-spread function
magnitudes in this paper, since the object is not resolved in the SDSS
images. Its magnitudes in the Far-UV (FUV) and Near-UV (NUV) bands
were measured by GALEX on 2004 June 5.
THe FUV spectrum, covering a wavelength range of 1570-2330Å, was
obtained with the Faint Object Spectrograph (FOS) on board the Hubble
Space Telescope (HST) by Turnshek et al. (1997ApJ...476...40T 1997ApJ...476...40T) using
the G190H grating on 1994 July 7. Hines et al. (2001ApJ...563..512H 2001ApJ...563..512H)
conducted a spectropolarimetric observation of IRAS 14026+4341 with
HST/FOS, using four positions of Waveplate B and the G270H grating, on
1995 September 11 (wavelength coverage from 2210Å to 3300Å). The
SDSS spectrum was observed on 2004 April 20, providing wavelength
coverage in the optical (λ∼3800-9200Å). We observed IRAS
14026+4341 using the Yunnan Faint Object Spectrograph and Camera
(YFOSC) mounted on the Lijiang GMG 2.4m telescope on 2011 April 15.
G14 (600mm-1) grating provides a wavelength range of 3200-7800Å
and a resolution of R∼1300. On 2012 April 16, we observed the IRAS
14026+4341 using TripleSpec on the 200inch Hale telescope (R∼3500,
λ∼10000-24000Å).
Objects:
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RA (ICRS) DE Designation(s)
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14 04 38.79 +43 27 07.4 IRAS 14026+4341 = 2MASS J14043881+4327072
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 11 88 Reddening curve for 0.1<λ<1µm
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
J/ApJS/206/4 : SED and bolometric corrections for luminous QSOs
(Krawczyk+, 2013)
J/ApJS/183/17 : The SDSS DR5/XMM-Newton quasar survey (Young+, 2009)
J/AJ/138/845 : BVRI observations of 235 bright quasars (Ojha+, 2009)
J/MNRAS/382/412 : Catalog of SDSS-DR5/2MASS spectroscopic quasars (Ofek, 2007)
J/ApJ/664/53 : UV photometry of GALEX QSO candidates (Atlee+, 2007)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 um-1 sigma [1/9.7] Inverse wavelength σ=1/λ
5- 11 F7.5 mag E [0/5.5345] Reddening value at sigma
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 28-May-2014