2001A&A...365...37M


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.20CEST04:13:48

2001A&A...365...37M - Astronomy and Astrophysics, volume 365, 37-48 (2001/1-2)

Dust in active nuclei. II. Powder or gravel?

MAIOLINO R., MARCONI A. and OLIVA E.

Abstract (from CDS):

In a companion paper, Maiolino et al. (2001A&A...365...28M) presented various observational evidences for ``anomalous'' dust properties in the circumnuclear region of AGNs and, in particular, the reduced EB–V/NH and AV/NH ratios, the absence of the silicate absorption feature in mid-IR spectra of Sy2s and the absence of the carbon dip in UV spectra of reddened Sy1s. In this paper we discuss various explanations for these facts. The observational constraints favor a scenario where coagulation, catalyzed by the high densities in the circumnuclear region, yields to the formation of large grains. The resulting extinction curve is featureless, flatter than Galactic and the EB–V/NH and AV/NH ratios are significantly reduced. These results should warn about an inappropriate use of the standard Galactic extinction curve and AV/NH ratio when dealing with the extreme gas conditions typical of the circumnuclear clouds of AGNs. We also investigated alternative scenarios for the observed anomalous properties of dust in AGNs. Some of these scenarios might explain some of the observed properties for a few objects, but they generally fail to account for all of the observational constraints obtained for the large sample of AGNs studied in these works.

Abstract Copyright:

Journal keyword(s): galaxies: Seyfert - galaxies: nuclei - galaxies: ISM - dust, extinction

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 NGC 1365 Sy1 03 33 36.458 -36 08 26.37 10.48 10.08 9.63 8.79 9.7 ~ 1473 2
2 IC 450 Sy1 06 52 12.32333 +74 25 37.2376   15.16 14.19     ~ 489 1
3 NGC 2992 Sy2 09 45 42.045 -14 19 34.90 13.54 13.14 12.18 12.6 12.2 ~ 764 3
4 ESO 434-40 Sy2 09 47 40.1345889569 -30 56 55.959492708   14.10 13.69 12.44   ~ 475 0
5 M 81 Sy2 09 55 33.17306143 +69 03 55.0609270   7.89 6.94     ~ 3888 5
6 NGC 4151 Sy1 12 10 32.5771747733 +39 24 21.057727323   12.18 11.48     ~ 3306 2
7 MCG-03-34-064 Sy2 13 22 24.485 -16 43 42.09   14   13.16   ~ 254 2
8 NGC 5506 AGN 14 13 14.901 -03 12 27.22   15.25 14.38     ~ 971 0
9 LEDA 68751 Sy1 22 23 49.7 -02 06 13   16.93 15.77 16.02   ~ 425 2
10 4C 11.72 BLL 22 54 10.4213843099 +11 36 38.745749268   16.02 15.82     ~ 318 1

    Equat.    Gal    SGal    Ecl

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2019.10.20-04:13:48

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