GAMA-SIGMA: Exploring Galaxy Structure Through Modelling

Transcription

1 GAMA-SIGMA: Exploring Galaxy Structure Through Modelling University of St Andrews / ICRAR (UWA)

2 Science Goals Do galaxies form in two phases: bulge disk? Are ellipticals and bulges essentially the same? How is stellar mass distributed between structures? How does environment shape galaxy structure?

3 Galaxy and Mass Assembly

4 The Sérsic Profile Jose Luis Sérsic, 1963 Peng (2003)

5 The Sérsic Profile Exponential (e.g. disks) Jose Luis Sérsic, 1963 Gaussian (e.g. - stars) de Vaucouleur (e.g. ellipticals/ bulges) Peng (2003)

6 Sérsic Motivation Sérsic photometry accounts for missing light in the wings of galaxies not usually picked up by other aperture definitions.

7 Sérsic Problem How do you model these galaxies quickly and accurately?

8 GAMA-SIGMA Written in R Each galaxy: 20 sec! Magnitude Sérsic Index Half-Light Radius Position Angle Ellipticity PSF

9 SIGMA G

10 Example Profile

11 Example Profile: u K u g r i z Y J H K

12 Global Distributions ~150,000 galaxies in each band u K: Increasing n, Decreasing re SDSS ugriz UKIDSS YJHK λ/1+z

13 Volume Limited Sample Mr < < z < 0.1 nq > 2 Coverage = ugrizyjhk + NUV/FUV ~7,500 galaxies

14 Classifications Driver et al. (2011; in prep) Mr < < z < 0.1 nq > 2 Coverage = ugrizyjhk + NUV/FUV ~7,500 galaxies

15 Vol. Lim. Results Stability of elliptical shape at all λ < z < 0.1 nq > 2 Coverage = ugrizyjhk + NUV/FUV ~7,500 galaxies Size evolution of ellipticals and disks u K Stability of ellipticity for all morph. types Mr < -18

16 Halo Mass Halo Masses: Aaron Robotham Disks Spheroids

17 G G Groups/ Mergers G G G G G G G G Irregulars GAMA G G G G G G G G G Kru 40'' 40'' G Barred Spirals Edge-on Spirals Ellipticals G G Unbarred Spirals Galaxy And Mass Assembly (GAMA) Hubble Tuning-Fork

18 G G Groups/ Mergers G G G G G G G G Irregulars G GAMA G G G G G Is structural decomposition required? G Monday Leegalaxies Kelvin How do4 July you2011 morphologically classify these automatically? G G Kru 40'' 40'' G Barred Spirals Edge-on Spirals Ellipticals G G Unbarred Spirals Galaxy And Mass Assembly (GAMA) Hubble Tuning-Fork

19 All vs All

20 All vs All (Updated)

21 All vs All (Updated)

22 Automated Classification Red Blue Disks Spheroids

23 Automated Classification

24 Automated Classification

25 Automated Classification

26 Automated Classification

27 Automated Classification

28 Automated Classification

29 Automated Classification

30 Automated Classification

31 Stellar Mass Distribution 4% 56% 6% 8% 23% 4% Stellar Masses: Ned Taylor

32 Science Goals Do galaxies form in two steps: bulge disk?... Are ellipticals and bulges essentially the same? Structural decomposition required! How is stellar mass distributed between structures? ~2/3 in spheroidal dominated types How does environment shape structure? More massive clusters host earlier type galaxies

33 Summary SIGMA measurements of ~150,000 galaxy structural params Single Sérsic Recovers missing light in the wings of galaxies Multi-λ Important in probing different stellar populations Morphology Automation possible, essential for large surveys Structural Decomposition Essential next step

34 Summary SIGMA measurements of ~150,000 galaxy structural params Single Sérsic Recovers missing light in the wings of galaxies Multi-λ Important in probing different stellar populations Morphology Automation possible, essential for large surveys Structural Decomposition Essential next step Measuring the energy output of the nearby Universe with GAMA P31 Simon P. Driver and the GAMA team