2003A&A...398..101M


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.27CET12:06:32

2003A&A...398..101M - Astronomy and Astrophysics, volume 398, 101-106 (2003/1-4)

VLT 3-5 micron spectroscopy and imaging of NGC 1068: Does the AGN hide nuclear starburst activity?

MARCO O. and BROOKS K.J.

Abstract (from CDS):

Near-infrared 3-5 micron spectroscopic and imaging observations of NGC 1068 have been obtained with the VLT at an angular resolution of ∼0.4arcsec. The [L-M] color index has been derived as a function of distance to the central source of the AGN and found to show significant variations. In particular, there is a blue excess of 0.2mag in the vicinity of the dust/molecular torus. The 3.28µm polycyclic aromatic hydrocarbon (PAH) emission feature has been tentatively detected toward the central 70pc of the AGN, with a luminosity of 7.4x1039erg/s. PAH emission is thought to be a strong indicator of nuclear starburst activity. Using the measured PAH 3.28µm flux we estimate that the nuclear starburst activity in NGC 1068 may contribute up to 1 percent of the total infrared luminosity. Such a very small contribution is supported by the measured equivalent width of the PAH 3.28µm emission feature, 1.2nm, which is one hundred times smaller than for starburst-dominated galaxies. Absorption features at 3.4µm, corresponding to carbonaceous dust have also been clearly identified yielding an optical depth value of τ3.4=0.14. From this we derive an extinction of AV=28mag toward the central source. The temperature and mass of the hot dust present in the inner 200 parsecs of the central source are estimated from the L- and M-band photometry. For an average temperature of Tgrain∼475K, we find M_hot dust∼0.6M☉_. Barely detected and at L band only, the contribution of the kilo-parsec-scale ring of star formation is found to be negligible in the 3-5µm domain.

Abstract Copyright:

Journal keyword(s): galaxies: individual: NGC 1068 - galaxies: Seyfert - galaxies: nuclei - infrared: galaxies - galaxies: starburst

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * 9 Cet BY* 00 22 51.7883318927 -12 12 33.972374893 7.29 7.05 6.39     G2.5V 456 0
2 M 77 GiP 02 42 40.771 -00 00 47.84 9.70 9.61 8.87 10.1 9.9 ~ 4162 2
3 HD 205772 * 21 38 41.4716091129 -41 02 52.170873282   8.32 8.40     A5IV/V 17 0

    Equat.    Gal    SGal    Ecl

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2021.01.27-12:06:32

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