Dissecting galaxies: separating star formation, shock excitation and AGN activity in the central region of NGC 613
Abstract
The most rapidly evolving regions of galaxies often display complex optical spectra with emission lines excited by massive stars, shocks and accretion on to supermassive black holes. Standard calibrations (such as for the star formation rate) cannot be applied to such mixed spectra. In this paper, we isolate the contributions of star formation, shock excitation and active galactic nucleus (AGN) activity to the emission line luminosities of individual spatially resolved regions across the central 3 × 3 kpc^2 region of the active barred spiral galaxy NGC 613. The star formation rate and AGN luminosity calculated from the decomposed emission line maps are in close agreement with independent estimates from data at other wavelengths. The star formation component traces the B-band stellar continuum emission, and the AGN component forms an ionization cone which is aligned with the nuclear radio jet. The optical line emission associated with shock excitation is cospatial with strong H2 and [Fe II] emission and with regions of high ionized gas velocity dispersion (σ ≳ 100 km s^(−1)). The shock component also traces the outer boundary of the AGN ionization cone and may therefore be produced by outflowing material interacting with the surrounding interstellar medium. Our decomposition method makes it possible to determine the properties of star formation, shock excitation and AGN activity from optical spectra, without contamination from other ionization mechanisms.
Additional Information
© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Received: 03 October 2016. Revision Received: 20 June 2017. Accepted: 20 June 2017. Published: 27 June 2017. BG gratefully acknowledges the support of the Australian Research Council as the recipient of a Future Fellowship (FT140101202). LK and MD acknowledge the support of the Australian Research Council (ARC) through Discovery project DP130103925. Support for AMM is provided by NASA through Hubble Fellowship grant #HST-HF2-51377 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. JKB acknowledges support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020. The Australia Telescope Compact Array is part of the Australia Telescope, which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.Attached Files
Published - stx1559.pdf
Submitted - 1707-03404.pdf
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Additional details
- Eprint ID
- 81442
- Resolver ID
- CaltechAUTHORS:20170914-122830303
- FT140101202
- Australian Research Council
- DP130103925
- Australian Research Council
- HST-HF2-51377
- Space Telescope Science Institute
- NAS5-26555
- NASA
- CE110001020
- Australian Research Council
- Commonwealth Scientific and Research Organization (CSIRO)
- Associated Universities, Inc.
- Created
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2017-09-14Created from EPrint's datestamp field
- Updated
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2023-09-28Created from EPrint's last_modified field