SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models

Mingozzi, M; Belfiore, F; Cresci, G; Bundy, K; Bershady, M; Bizyaev, D; Blanc, G; Boquien, M; Drory, N; Fu, H; Maiolino, R; Riffel, R; Schaefer, A; Storchi-Bergmann, T; Telles, E; Tremonti, C; Zakamska, N; Zhang, K

SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models

Published version

Peer-reviewed

Repository URI

https://www.repository.cam.ac.uk/handle/1810/303995

Repository DOI

https://doi.org/10.17863/CAM.51076

Files

Published version (3.94 MB)

Accepted version (4.06 MB)

Type

Article

Authors

Mingozzi, M

Belfiore, F

Cresci, G

Bundy, K

Bershady, M

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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 $9069,9532 n e b u l a r l i n e s, w h i c h h a v e l o n g b e e n p r e d i c t e d t o b e i d e a l t r a c e r s o f t h e i o n i s a t i o n p a r a m e t e r . U n f o r t u n a t e l y, w e f i n d t h a t c u r r e n t p h o t o i o n i s a t i o n m o d e l s s u b s t a n t i a l l y o v e r − p r e d i c t [S I I I] l i n e s i n t e n s i t y, w h i l e b r o a d l y r e p r o d u c i n g o t h e r o b s e r v e d o p t i c a l l i n e r a t i o s . W e d i s c u s s h o w t o n o n e t h e l e s s m a k e u s e o f t h e i n f o r m a t i o n p r o v i d e d b y [S I I I] l i n e s b y s e t t i n g a p r i o r o n t h e i o n i s a t i o n p a r a m e t e r . F o l l o w i n g t h i s a p p r o a c h, w e d e r i v e s p a t i a l l y − r e s o l v e d m a p s a n d r a d i a l p r o f i l e s o f m e t a l l i c i t y a n d i o n i s a t i o n p a r a m e t e r . T h e m e t a l l i c i t y r a d i a l p r o f i l e s a r e c o m p a r a b l e w i t h p r e v i o u s w o r k s, w i t h m e t a l l i c i t y d e c l i n i n g t o w a r d t h e o u t e r p a r t s a n d a f l a t t e n i n g i n t h e c e n t r a l r e g i o n s, i n a g r e e m e n t w i t h i n f a l l m o d e l s o f g a l a x y f o r m a t i o n, t h a t p r e d i c t t h a t s p i r a l d i s c s b u i l d u p t h r o u g h a c c r e t i o n o f m a t e r i a l, w h i c h l e a d s t o a n i n s i d e − o u t g r o w t h . O n t h e o t h e r h a n d, i o n i s a t i o n p a r a m e t e r r a d i a l p r o f i l e s a r e f l a t f o r l o w − m a s s g a l a x i e s, w h i l e t h e i r s l o p e b e c o m e s p o s i t i v e a s g a l a x y m a s s i n c r e a s e s . H o w e v e r, t h e i o n i s a t i o n p a r a m e t e r m a p s w e o b t a i n a r e c l u m p y, e s p e c i a l l y f o r l o w − m a s s g a l a x i e s . I o n i s a t i o n p a r a m e t e r i s t i g h t l y c o r r e l a t e d w i t h t h e H$ \alpha$ equivalent width [EW(H $α$ )], 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 $α$ ), in disagreement with previous theoretical works expecting an anti-correlation.

Keywords

galaxies: ISM, galaxies: abundances, galaxies: evolution

Journal Title

Astronomy and Astrophysics

Journal ISSN

0004-6361
1432-0746

Volume Title

636

Publisher

EDP Sciences

Publisher DOI

https://doi.org/10.1051/0004-6361/201937203

Rights

Sponsorship

European Research Council (695671)
Science and Technology Facilities Council (ST/M001172/1)

STFC and ERC

Collections

Cambridge University Research Outputs