Average and not so average HI discs

Average and not so average HI discs in the nearby
Universe USM virtual colloquium January 2021 KATHARINA LUTZ WITH MANY AWESOME COLLABORATORS

13/01/2021 K. Lutz - All the HI discs - USM
Outline of the talk I. Introduction: the star formation gas cycle and ISM properties of nearby galaxies II. xGASS/ xCOLDGASS: Gas-phase metallicities and gas content III. HIX: The most HI rich galaxies in the Southern Hemisphere, so far IV.SHREG: All the HI discs V. Conclusion and Outlook

The star formation – gas cycle Stars Old stars: Stellar winds Supernovae Accretion Condensation Star formation Cooling

Scaling relations - available gas regulates star formation - Catinella et al. (2018), Saintonge, …, KL, et al. (2017)

Accretion and gas content Barrera-Ballesteros et al. (2018), Bothwell et al. (2013)

How does accretion work Sancisi et al. (2008), Oosterloo et al. (2007), Fraternali et al. (2002)

Scaling relations - spin regulates HI content - Maddox et al. 2016, Obreschkow, …, KL, et al. 2016

Outline of the talk I. Introduction: the star formation gas cycle and ISM properties of nearby galaxies II. xGASS/ xCOLDGASS: Gas-phase metallicities and gas content III. HIX: The most HI rich galaxies in the Southern Hemisphere, so far IV.SHREG: All the HI discs V. Conclusion and Outlook I. Introduction: the star formation gas cycle and ISM properties of nearby galaxies II. xGASS/ xCOLDGASS: Gas-phase metallicities and gas content III. HIX: The most HI rich galaxies in the Southern Hemisphere, so far IV.SHREG: All the HI discs V. Conclusion and Outlook

Gas-phase metallicity in xGASS / xCOLDGASS galaxies • obtained longslit spectra for ~100 star forming galaxies with HI and CO observations form xGASS and xCOLDGASS

Metallicity gradients and stellar mass surface density Correlation between morphology and metallicity gradient

local metallicity and global gas content Local metallicity knows about global HI content → gas regulator model

Initial idea: Investigate HI rich galaxies Are HI-rich galaxies less efficient at forming stars or more efficient at accreting gas

HIX galaxy sample Sample selection based on this relation

HIX galaxy sample

Star formation in HIX galaxies Lutz et al. (2017) Average star formers

HIX disc on the HI mass-size relation Lutz et al. (2018) On the HI mass- size relation

Intermediate result: • HIX galaxies do not use the excess HI to form more stars • The HI discs by themselves of HIX galaxies are not special

Stabilising large HI discs Lutz et al. (2018) Analytic models: large but stable against inflow and star formation

Whence the large angular momentum? Lutz et al. (2018) Semi-analytic models: high halo spin

Metallicity in HIX galaxies Lutz et al. (2020) Not so many metals

More in progress Not so much dust Just the right amount of molecular gas

Results for HIX galaxies • Stabilise larger HI discs against more vigorous star formation and inflow due to elevated angular momentum • Likely reside in high spin haloes • No evidence for accretion There are more than 12 galaxies out there, what can we learn about them?

Stability governs many HI discs

Stability governs many HI discs Galaxies on the edge of Virgo Isolated W H ISP galaxies HI-poor field galaxies TH IN GS & Little TH IN GS galaxies Li et al. (2020), Murugeshan, …, KL et al. (2019), Murugeshan et al. (2020), Butler et al. (2017), Obreschkow et al (2016)

Next questions • In dense environments this relation doesn’t hold, when else is it breaking? • Similarly to the Fall-relation, what can the HI sAM- mass relation tell us about galaxy evolution? • How are we going to analyse these data, especially once we get all the data from Apertiv, Wallaby and the MeerKAT surveys?

The SHREG survey • Archival survey • raw data from ATCA archive • Science ready data from published surveys • Almost 500 data cubes

Kinematic modelling HI column density profiles HI rotation curves

HI mass size relation Recovering the HI mass-size relation

HI sAM -mass relation Lutz et al. (in prep) Scatter in HI angular momentum – mass relation driven by HI “morphology”

Results for SHREG galaxies • It is possible to get 3D tilted ring models for almost 200 diverse galaxies • We recover the HI mass-size relation • HI sAM-mass relation has scatter due to pressure support vs. rotation support • Next up: stellar sAM, star formation, rotation curves from machine learning, …

Overall conclusions • Angular momentum determines characteristics of HI discs • HI and ISM enrichment are tightly linked • Very HI-massive galaxies tend to reside in high spin halos, which seems to slow down evolution

Outlook • thanks to MeerKAT the future is bright: – homogenous observations of 1000s of well resolved HI discs – wide range of HI masses, environments – auxiliary data there and upcoming

What we will be able to do • measure HI, stellar and baryonic (specific) angular momentum in all these galaxies • investigate the local gas-star formation cycle and the local relation between neutral gas and metallicity/ dust • trace these through time and across different environments

Merci & Danke schön! Get in touch: Online: www.katha-lutz.de Email: [email protected] GitHub: @kathl Twitter: @astro_katharina

Average and not so average HI discs

Average and not so average HI discs

More Decks by Katharina

Featured

Transcript