1. The star formation history of the local universe A/Prof. Andrew Hopkins (AAO) Prof. Joss Bland-Hawthorn (USyd.) & the GAMA Collaboration Madusha L.P. Gunawardhana Durham University DEX X workshop - Durham - 09/01/2014

2. Evolution of star formation UV [OII] Hα/Hβ sub-mm, radio, FIR & others Hopkins A.M., 2004, ApJ, 615, 209 Hopkins A. M. & Beacom J., 2006, ApJ, 651, 142 ★ There are various probes of star formation - Nebula emission lines: [OII], [OIII], Hα, Hβ - Photometric measures: UV, mid-IR, far-IR, radio ★ Each indicator has its advantages and drawbacks UV is a direct tracer of young (>5M ʘ ) stars but dust obscured systems are missed in UV samples, making FIR, a tracer of dusty systems, a valuable complementary to UV. ★ There are also survey selection and calibration biases - narrowband vs broadband surveys - flux/magnitude limits - surveys area (cosmic variance) - dust/AGN corrections

3. Galaxy And Mass Assembly (GAMA) ★ Multi-wavelength campaign in collaboration with ASKAP DINGO, HERSCHEL ATLAS, VISTA VIKING, VST KIDS, GALEX and the Durham ICC ★ ~300,000 redshifts over 290 square degrees (5 fields), each reaching a depth of r < 19.8 mag ★ 5 Å resolution spectra with 3700- 8800 Å coverage from AAT using 2dF fibre feed and AAOmega multi- object spectograph

4. ★ FUV, NUV, ugriz, YJHK, WISE, HERSCHEL (ASKAP, GMRT) ★ Data Release I - S.P. Driver et al., 2011, MNRAS, 413, 971 ★ Spectroscopic analysis - A.M. Hopkins et al., 2013, MNRAS, 430, 2047 - M.L.P. Gunawardhana et al., 2011, MNRAS, 415, 1647 ★ Stellar masses - E.N. Taylor et al., 2011, MNRAS, 418, 1587 Galaxy And Mass Assembly (GAMA) GAMA Data Release II is OUT! See the GAMA website: http://www.gama-survey.orghttp://www.gama-survey.org/

5. ★ Covers a wide range in SFR (0.001<SFR(M ʘ yr -1 )<100) AND in stellar mass (10 7 <M/M ʘ <10 12 ) AND extends up to z ≈ 0.35 ★ The properties of lowest SFR galaxies are investigated in Brough et al. (2011) Evolution of star formation in Hα ★ Balmer decrement is used to estimate obscuration corrections SFR vs redshift Luminosity-dependent obscuration ★ Aperture corrections are based on fibre and Petrosian r-band magnitudes

6. Hα Luminosity Functions Gunawardhana et al., 2013, MNRAS, 433, 2764

7. Schechter vs Saunders functional fits ★ Saunders et al. (1990) function is better suited at fitting the bright-end of the Hα LF ★ Salim & Lee (2012) also find that the underlying SFR distribution is better described by a Saunders function than a Schechter function. Gunawardhana et al., 2013, MNRAS, 433, 2764

8. Cosmic star formation history UV [OII] Hα/Hβ sub-mm, radio, FIR & others Hopkins A.M., 2004, ApJ, 615, 209 Hopkins A. M. & Beacom J., 2006, ApJ, 651, 142 ★ Jurek et al., ( 2013, MNRAS ) find that the bright end of the WiggleZ survey UV LF is not well described by a Schechter function due to an excess of UV luminous galaxies.

9. Local Star Formation History Gunawardhana et al., 2013, MNRAS, 433, 2764

10. Bivariate Hα/M r Distribution ★ For GAMA, the r-band apparent magnitude limit combined with requirement for Hα detection leads to an incompleteness due to missing bright Hα sources with faint r- band magnitudes 100 M ʘ yr -1 10 M ʘ yr -1 1 M ʘ yr -1 ★ The lowest-z (z<0.1) sample is the most complete with SFRs reaching as low as 0.001 M ʘ yr -1

11. Bivariate L Hα /M r Luminosity functions 0.01 M ʘ /yr 0.1 M ʘ /yr 1 M ʘ /yr 100 M ʘ /yr Gunawardhana et al., (MNRAS, submitted)

12. Bivariate functional fit vs Copula approach ★ Bivariate functional fit: Ψ (2) (L Hα, M r ) = Φ Schechter (M r ) x Φ (L Hα, M r ) ★ Bivariate distribution constructed using a Gaussian Copula following the method of Takeuchi (2010, MNRAS, 406, 1830) ρ = 0.9 Gunawardhana et al., (MNRAS, submitted)

13. SFR density plot

15. Conclusions ★ Star formation in galaxies follows a Saunders (or two-power law) distribution, NOT a Schechter function. ★ GAMA and SDSS Hα luminosity functions confirms this for the first time, making Hα finally consistent with other wavelength estimators of SFR such as IR and radio. ★ Bivariate selection influence ANY star forming sample drawn from a magnitude limited survey. As a consequence the resulting SFRDs are underestimated. ★ One way to correct this is to model the bivariate distribution ★ GAMA website ( http://www.gama-survey.org / ) http://www.gama-survey.org

16. Aperture corrections ★ Aperture corrections are based on fibre and petrosian r-band magnitudes Aperture correction vs redshift