Studying galaxy transformations in 3D

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

A broad consensus is emerging about the fact that galaxies transform one into the other and have their star formation suppressed (quenched) over time. This process is known to be strongly dependent on environment. Moreover it appears empirically well established that the morphological transformation and quenching are associated to the growth of the stellar bulge (e.g. Cappellari+13b). Three key elements allow one to follow galaxy transformation using integral-field spectroscopy data like MaNGA: (1) The stellar angular momentum allow one to recognize whether the galaxy underwent significant dry merging or whether its disk has survived (slow versus fast rotators e.g. Emsellem+11). We found that using the kinematic classification one gets a significantly different picture for Dressler+80 morphology-density relation (Cappellari+11b). The power of our kinematic classification will be key to trace galaxy transformations within the extensive MaNGA sample. (2) It is well established that galaxy transformations are accompanied by a global quenching, or to the fact that the luminosity-weighted stellar population appears older and more metal rich. But the spatial distribution of this age (and metallicity) variation is not so well known, especially as a function of environment and other galaxy properties. How does quenching progress within a galaxy in different environments and e.g. on the mass-size plane? (3) One of the favoured quenching mechanisms for galaxy quenching, especially at the high-mass range, is the feedback from a super-massive black hole. This fact however is empirically still quite uncertain and possibly simply wrong. We showed that using spatially resolved information on the gas emission line ratios one can recognize nuclear activity from an AGN from stellar ionization. In fact Sarzi+10 first showed that nearly all LINER-like emission, often attributed to AGNs, has nothing to do with a BH (see also Renbin+12, Singh+13, Belfiore+15). IFU data will allow us to directly link AGN activity to spatial quenching, without the "pollution" from stellar ionization. The combination of these three observables, as function of environment, will allow us to shed light on the galaxies transformation and quenching mechanism.

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N504233/1 01/10/2015 31/03/2021
1659482 Studentship ST/N504233/1 01/10/2015 31/03/2019 Mark Graham
 
Description Early Career Astronomer Travel Fund award
Amount $800 (USD)
Organisation Sloan Digital Sky Survey (SDSS-III) 
Sector Academic/University
Country United States
Start 11/2016 
End 11/2016
 
Description Pollard Fund for conference travel
Amount £675 (GBP)
Organisation University of Oxford 
Sector Academic/University
Country United Kingdom
Start 12/2017 
End 12/2017
 
Description Stargazing Live Talk at Oxford 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact I gave an outreach talk about my research in which I introduced concepts such as spectra from stars and the Doppler shift as well as the conservation os angular momentum. I presented my latest results and took questions at the end of the talk. The talk is now available online at the Podcasts directory of the Oxford university website.
Year(s) Of Engagement Activity 2018
URL https://podcasts.ox.ac.uk/im-spinning-around-watching-galaxies-rotate-or-not