Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

The Stellar to Baryonic MassFunction of Galaxies: from SDSS

to GAMA with ASKAP

Ivan Baldry (Liverpool JMU)

SDSS: Sloan Digital Sky SurveyGAMA: Galaxy And Mass Assembly surveyASKAP: Australian Square Kilometer Array Pathfinder

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Credits

• BGD08 paper (IB, K. Glazebrook, S. Driver)• GAMA team (SD, IB, S. Bamford, A.

Hopkins, J. Liske, J. Loveday, P. Norberg, J.Peacock … )– see http://www.eso.org/~jliske/gama/ for full

team list• ASKAP-DINGO project (M. Meyer, L.

Staveley-Smith [UWA] … )

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

The stellar mass density• Assuming Ωb=0.045, H0=70, then Ωs/Ωb =

– 3.5% (Li & White 2009) (Chabrier IMF, SDSSdata)

– 8.3% (Driver et al. 2007) (diet Salpeter IMF,Millennium Galaxy Catalog data)

– 4 to 8% (BGD08), 3 to 7% (Gallazzi et al. 2007)• Uncertainties/considerations:

– IMF, priors, SP model, dust treatment– definition (remaining versus formed stellar mass)– corrections to galaxy total magnitudes– volume corrections, cosmic variance

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

A solution for the sub-structure problem?

Benson, Frenk, Lacey, Baugh & Cole 2002

“Photo-ionization suppresses the formation of smallgalaxies, so that surviving satellites are preferentially thosethat formed before the universe re-ionized [at z~6-10].”

… applies tofield galaxiesas well.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Sloan Digital Sky SurveyNYU-VAGC sample

• 49968 galaxies 0.0033<z<0.05 (Blantonet al. 2005)

• Photometry checked• Flow corrections for z<0.02

– e.g. impact discussed by Masters et al. 04• Stellar masses (Kauffmann et al. ’03;

Gallazzi et al. ’05; KG; Panter et al. ’07)• Visibility volumes for each galaxy

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Surface brightness (SB) limit

BGD08

Low completeness (>23), as determined byBlanton et al. 2005

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Field galaxy stellar MF

BGD08

lowerlimits

Excess of faintgalaxies abovesingle Schechter fitseen in CfA2 andLCRS; Huchra 1999

At faint end, slopes of linesare -1.6 (dashed), -1.8(dotted), -2.0, (for alpha2).Dashed line is a doubleSchechter function fit toM>108 Msolar data.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Distribution ofstellar mass

Fits only areshown. The double-Sch. function is avery good fit to theBGD08 data.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Estimating (cold) gas masses

BGD08

cf. Kannappan(2004), Zhanget al. (2009)

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Baryonic Mass Functions

Bell et al.this paper

BGD08

2003

scaled by Ωb/Ωm

solid line: using simple starsto stars+gas conversion(function of stellar mass)

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Galaxy And Mass Assembly(GAMA)

[spectroscopy using AAOmega, the 2dFupgrade on the Anglo-Australian Telescope;

with to come: VISTA (IR), VST (optical),Herschel (far-IR), GALEX (UV), ASKAP

(21cm+) … ]

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

GAMA primary science goals

• Group halo mass function• Galaxy stellar (baryonic) mass function• Merger rates• Selection (~1000 / deg2)

– r<19.4, 19.8 (SDSS)– K<15.7 (17.5AB) (UK IR Telescope) & r<20.5

• Area: 140 (250 planned) square degrees

Ivan Baldry, Liverpool JMU; Unveiling the Mass FunctionIB et al in prep.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Halo mass function:using group finder,velocity dispersions,mock catalogues.

Figure by P. Norberg

PREDICTED

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Preliminary GSMF

Figure by S. Driver

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Results from 88839redshifts - projectedto complete 120K

n(z) for GAMA survey: next two slides focus on z<0.03 shownby red box.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Low-mass galaxies from mag-limited z surveys

SDSS r<17.8

GAMA r<19.8

centi-L* galaxies

milli-L* galaxies

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Cyan oval shows objects consistent with being high-SB end of the low-L galaxy distribution.Yellow oval shows objects that are possibly star clusters or nucleated cores of galaxies.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Blind neutral Hydrogen surveys

• HI Parkes All-Sky Survey (HIPASS) finished– ~10000 sources; 15’ res.

• Arecibo Legacy Fast ALFA (ALFALFA) survey inprogress– ~25000 sources; 7000 sq. deg; 3.5’ res.

• Australian SKA Pathfinder (ASKAP) from 201?– Widefield ASKAP L-band Legacy All-sky Blind surveY

(WALLABY); > 500000 sources expected.– Deep Investigation of Neutral Gas Origins (DINGO)

(GAMA regions); 10 arcsec res.

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Australian SKA Pathfinder

10’’ resolutionpossible

M. Meyer et al. DINGO survey(and WALLABY survey)

PREDICTED

Measure baryonic MF down to~107.5 Msolar at z<0.03

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Conclusions/Summary• Careful analysis of GSMF shows an upturn

with slope -1.6 (or steeper)– projected >0.1 galaxy Mpc-3 dex-1 (at ~ 107 Msolar)

• Implied galaxy baryonic MF has upturn withslope about -1.9 (possibly)

• Upturn is consistent with CDM and photo-ionization suppression model (?)

• New survey GAMA (r<19.4, 19.8): 140+ deg2

– http://www.eso.org/~jliske/gama/– http://www.physics.uwa.edu.au/~mmeyer/dingo/– Deep g-to-K imaging to come … from end of this year?

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Extra Slides

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

M-L ratio limit in r<17.8 sample

BGD08

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Mr > -13.5 galaxies in GAMA

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Deep optical-IR imaging is stillneeded!

• SB limit implies missing galaxies andincorrect photometry

• Targeting everything fainter than 19.5 isvery inefficient for z<0.05 dwarfs (and itis hard to get spectra)

• Optimised filters for 4000-A break,emission lines (+ J-K for stellar bump)

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

GAMA regions

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Ivan Baldry, Liverpool JMU; Unveiling the Mass Function

Galaxy Evolution versus Environment and Mass(with GAMA - over last 5 Gyr)

Hopkins & Beacom 2006

GAMA