ﻻ يوجد ملخص باللغة العربية
(Abridged) We present a non-parametric cell-based method of selecting highly pure and largely complete samples of spiral galaxies using photometric and structural parameters as provided by standard photometric pipelines and simple shape fitting algorithms, demonstrably superior to commonly used proxies. Furthermore, we find structural parameters derived using passbands longwards of the $g$ band and linked to older stellar populations, especially the stellar mass surface density $mu_*$ and the $r$ band effective radius $r_e$, to perform at least equally well as parameters more traditionally linked to the identification of spirals by means of their young stellar populations. In particular the distinct bimodality in the parameter $mu_*$, consistent with expectations of different evolutionary paths for spirals and ellipticals, represents an often overlooked yet powerful parameter in differentiating between spiral and non-spiral/elliptical galaxies. We investigate the intrinsic specific star-formation rate - stellar mass relation ($psi_* - M_*$) for a morphologically defined volume limited sample of local universe spiral galaxies, defined using the cell-based method with an appropriate parameter combination. The relation is found to be well described by $psi_* propto M_*^{-0.5}$ over the range of $10^{9.5} M_{odot} le M_* le 10^{11} M_{odot}$ with a mean interquartile range of $0.4,$dex. This is somewhat steeper than previous determinations based on colour-selected samples of star-forming galaxies, primarily due to the inclusion in the sample of red quiescent disks.
We contend that a single power law halo mass distribution is appropriate for direct matching to the stellar masses of observed Local Group dwarf galaxies, allowing the determination of the slope of the stellar mass-halo mass relation for low mass gal
Abridged - We quantify the effect of the galaxy group environment (for 12.5 < log(M_group/Msun) < 14.0) on the star formation rates of the (morphologically-selected) population of disk-dominated local Universe spiral galaxies (z < 0.13) with stellar
We investigate the star formation histories (SFHs) of massive red spiral galaxies with stellar mass $M_ast>10^{10.5}M_odot$, and make comparisons with blue spirals and red ellipticals of similar masses. We make use of the integral field spectroscopy
We present an analysis of the z ~ 0 morphology-environment relation for 911 bright (M_B < -19) galaxies, matching classical RC3 morphologies to the SDSS-based group catalog of Yang et al. We study how the relative fractions of spirals, lenticulars, a
We present a demographic analysis of integrated star formation and gas properties for a sample of galaxies representative of the overall population at z~0. This research was undertaken in order to characterise the nature of star formation and interst