A review of elliptical and disc galaxy structure, and modern scaling laws

A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

The Hα luminosity function and global star formation rate from redshifts of 1-2

We present a luminosity function for Hα emission from galaxies at redshifts between 0.7 and 1.9 based on slitless spectroscopy with the near-infrared camera and multiobject spectrometer on the Hubble Space Telescope. The luminosity function is well fit by a Schechter function over the range 6 × 10 &lt; L (Hα) &lt; 2 × 10 ergs s with L* = 7 × 10 ergs s and φ* = 1.7 × 10 Mpc for H = 50 km s Mpc and q = 0.5. We derive a volume-averaged star formation rate at z = 1.3 ± 0.5 of 0.13 M yr Mpc without correction for extinction. The star formation rate that we derive at ∼6500 Å is a factor of 3 higher than that deduced from 2800 Å continua. If this difference is caused entirely by reddening, the extinction correction at 2800 Å is quite significant. The precise magnitude of the total extinction correction at rest-frame UV wavelengths (e.g., 2800 and 1500 Å) is sensitive to the relative spatial distribution of the stars, gas, and dust, as well as to the extinction law. In the extreme case of a homogeneous foreground dust screen and a Milky Way or LMC extinction law, we derive a total extinction at 2800 Å of 2.1 mag, or a factor of 7 correction to the UV luminosity density. If we use the Calzetti reddening curve, which was derived for the model in which stars, gas, and dust are well mixed and nebular gas suffers more extinction than stars, our estimate of A is increased by more than 1 mag. 41 43 -1 42 -1 -3 -3 -1 -1 -3 0 0 ⊙ -1 280

Optical Properties of Early-Type Galaxies

We review the systematics of optical properties of elliptical and dwarf spheroidal galaxies. The scaling laws and correlations among the global properties of these systems can be used to deduce some information about their formation. Both dissipation and mergers appear to be important in the formation of elliptical galaxies. Small, but systematic differences between cluster and field ellipticals are detected, and also between normal ellipticals and brightest cluster members. The scaling laws for dwarf galaxies are very different from those of normal ellipticals, and point to a formation dominated by a single process