Title

A Spitzer-IRS Spectroscopic atlas of early-type galaxies in the Revised Shapley-Ames Catalog

Author

OLGA MERCEDES VEGA CASANOVA

Access level

Open Access

Summary or description

We produce an atlas of homogeneously reduced and calibrated low resolution IRS spectra of the nuclear regions of nearby early-type galaxies (i.e. Es and S0s, ETGs), in order to build a reference sample in the mid-infrared window. From the Spitzer Heritage Archive we extract ETGs in the Revised Shapley-Ames Catalog of Bright Galaxies having an IRS SL and/or LL spectrum. We recover 91 spectra out of 363 galaxies classified as ETGs in the catalog: 56 E (E0-E6), 8 mixed E/S0+S0/E, 27 S0 (both normal and barred - SB0) plus mixed types SB0/Sa+SB0/SBa. For each galaxy, we provide the fully reduced and calibrated spectrum, the intensity of nebular and molecular emission lines as well as of the Polycyclic Aromatic Hydrocarbons (PAHs) after a template spectrum of a passively evolving ETG has been subtracted. Spectra are classified into five mid-infrared classes, ranging from AGN (class-4) and star forming nuclei (class-3), transition class-2 (with PAHs) and class-1 (no-PAHs) to passively evolving nuclei (class-0). A demographic study of mid-infrared spectra shows that Es are significantly more passive than S0s:46⁺¹¹₋₁₀% of Es and 20⁺¹¹₋₇ % of S0s have a spectrum of class-0. Emission lines are revealed in 64⁺¹²₋₆ % of ETGs. The H₂S(1) line is found with similar rate in Es (34⁺¹⁰₋₈ %) and in S0s (51⁺¹⁵₋₁₂%). PAHs are detected in 47⁺⁸₋₇% of ETGs, but only 9⁺⁴₋₃% have PAHs ratios typical of star forming galaxies. Several indicators, such as peculiar morphologies and kinematics, dust–lane irregular shape, radio and X-ray properties, suggest that mid-infrared spectral classes are connected to phases of accretion/feedback phenomena occurring in the nuclei of ETGs.

Publisher

Monthly Notices of the Royal Astronomical Society

Publish date

March 19, 2013

Publication type

Article

Publication version

Accepted Version

Format

application/pdf

Language

English

Audience

Students

Researchers

General public

Citation suggestion

Rampazzo, R., et al., (2013), A Spitzer-IRS Spectroscopic atlas of early-type galaxies in the Revised Shapley-Ames Catalog, Monthly Notices of the Royal Astronomical Society, Vol. 432(1):374-403

Source repository

Repositorio Institucional del INAOE

Downloads

19

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