The 2dF Galaxy Redshift Survey: the number and luminosity density of galaxies

Abstract

A B S T R A C TWe present the bivariate brightness distribution (BBD) for the 2dF Galaxy Redshift Survey (2dFGRS) based on a preliminary subsample of 45 000 galaxies. The BBD is an extension of the galaxy luminosity function, incorporating surface brightness information. It allows the measurement of the local luminosity density, j B , and of the galaxy luminosity and surface brightness distributions, while accounting for surface brightness selection biases.The recovered 2dFGRS BBD shows a strong luminosity±surface brightness relation M B G 2X4^1 X5 0X5 m e Y providing a new constraint for galaxy formation models. In terms of the number density, we find that the peak of the galaxy population lies at M B $ 216X0 magX Within the well-defined selection limits (224 , M B , 216X0 magY 18X0 , m e , 24X5 mag arcsec 22 ) the contribution towards the luminosity density is dominated by conventional giant galaxies (i.e., 90 per cent of the luminosity density is contained within 222X5 , M , 217X5Y 18X0 , m e , 23X0X The luminosity-density peak lies away from the selection boundaries, implying that the 2dFGRS is complete in terms of sampling the local luminosity density, and that luminous low surface brightness galaxies are rare. The final value we derive for the local luminosity density, inclusive of surface brightness corrections, is j B 2X49^0X20 Â 10 8 h 100 L ( Mpc 23 X Representative Schechter function parameters are M* 219X75^0X05Y f* 2X02^0X02 Â 10 22 and a 21X09^0X03X Finally, we note that extending the conventional methodology to incorporate surface brightness selection effects has resulted in an increase in the luminosity density of ,37 per cent. Hence surface brightness selection effects would appear to explain much of the discrepancy between previous estimates of the local luminosity density. q 2001 RAS

Identifying the progenitor set of present-day early-type galaxies: a view from the standard model

“…Most importantly, the full suite of calibrated parameters that drives the model predictions reproduces a fundamental set of spectro-photometric properties of the observed galaxy population in the Universe. GALICS produces good agreement to the galaxy luminosity functions observed by the 2dF survey in the B and K bands (Cross et al 2001). The (B−V) colours of spiral galaxies closely follow the observed data of Buta et al (1994), both in terms of average values and scatter.…”

The z ≤ 0.1 surface brightness distribution

“…To account for this, all subsequent analysis of the Andreon & Cuillandre (2002) data of Andreon & Cuillandre (2002) gives a line whose slope is marginally increasing with decreasing central surface brightness (slope = 0.08). This is in marked difference to the results shown by Cross et al (2001) which shows an almost Gaussian distribution to the SBD (Fig. 1).…”

“…As the Cross et al (2001) results are both highly significant and seem in contradiction to the studies done by, e.g. and McGaugh (1996), further investigation is clearly warranted.…”

“…Unlike many previous SBD studies (bar that of Cross et al 2001), the data from Andreon & Cuillandre (2002) contains not just disk systems, but galaxies ranging from E and S0 through pure disk systems. As a result, at the bright end (e.g.…”

“…Using a subsample of galaxies taken from the 2dF Galaxy Redshift Survey, Cross et al (2001) found the local SBD to be best represented by a broadened version of Freeman's (1970) original SBD. If this is correct it would have far-reaching implications.…”