SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models
Authors
Mingozzi, M
Belfiore, F
Cresci, G
Bundy, K
Bershady, M
Bizyaev, D
Blanc, G
Boquien, M
Drory, N
Fu, H
Riffel, R
Schaefer, A
Storchi-Bergmann, T
Telles, E
Tremonti, C
Zakamska, N
Zhang, K
Publication Date
2020-04-13Journal Title
Astronomy and Astrophysics
ISSN
0004-6361
Publisher
EDP Sciences
Volume
636
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Mingozzi, M., Belfiore, F., Cresci, G., Bundy, K., Bershady, M., Bizyaev, D., Blanc, G., et al. (2020). SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models. Astronomy and Astrophysics, 636 https://doi.org/10.1051/0004-6361/201937203
Abstract
We measured gas-phase metallicity, ionisation parameter and dust extinction
for 1795 representative local star-forming galaxies using integral field
spectroscopy from the SDSS-IV MaNGA survey. We self-consistently derive these
quantities by comparing observed line fluxes with photoionisation models using
a Bayesian framework. We also present the first comprehensive study of the
[SIII]$\lambda\lambda$9069,9532 nebular lines, which have long been predicted
to be ideal tracers of the ionisation parameter. Unfortunately, we find that
current photoionisation models substantially over-predict [SIII] lines
intensity, while broadly reproducing other observed optical line ratios. We
discuss how to nonetheless make use of the information provided by [SIII] lines
by setting a prior on the ionisation parameter. Following this approach, we
derive spatially-resolved maps and radial profiles of metallicity and
ionisation parameter. The metallicity radial profiles are comparable with
previous works, with metallicity declining toward the outer parts and a
flattening in the central regions, in agreement with infall models of galaxy
formation, that predict that spiral discs build up through accretion of
material, which leads to an inside-out growth. On the other hand, ionisation
parameter radial profiles are flat for low-mass galaxies, while their slope
becomes positive as galaxy mass increases. However, the ionisation parameter
maps we obtain are clumpy, especially for low-mass galaxies. Ionisation
parameter is tightly correlated with the H$\alpha$ equivalent width
[EW(H$\alpha$)], following a nearly universal relation, which we attribute to
the change of the spectral shape of ionising sources due to ageing of HII
regions. We derive a positive correlation between ionisation parameter and
metallicity at fixed EW(H$\alpha$), in disagreement with previous theoretical
works expecting an anti-correlation.
Sponsorship
STFC and ERC
Funder references
European Research Council (695671)
Science and Technology Facilities Council (ST/M001172/1)
Embargo Lift Date
2100-01-01
Identifiers
External DOI: https://doi.org/10.1051/0004-6361/201937203
This record's URL: https://www.repository.cam.ac.uk/handle/1810/303995
Rights
All rights reserved
Licence:
http://www.rioxx.net/licenses/all-rights-reserved
Statistics
Total file downloads (since January 2020). For more information on metrics see the
IRUS guide.