An Investigation of Sloan Digital Sky Survey Imaging Data and Multi-Band Scaling Relations of Spiral Galaxies (with Dynamical Information)

TL;DR

This study analyzes multi-band imaging and rotational velocities of over 3000 spiral galaxies from SDSS to refine galaxy scaling relations, achieving tighter correlations and exploring baryonic mass effects.

Contribution

It introduces improved photometric parameters and scaling relations using SDSS data, with a focus on baryonic mass and dynamical information for spiral galaxies.

Findings

Refined galaxy size and luminosity measurements reduce scatter in scaling relations.

Tighter VRL relations are achieved with isophotal radii at 23.5 mag/arcsec^-2.

Baryonic mass-based relations show comparable or tighter correlations than stellar or luminosity-based ones.

Abstract

We have compiled a sample of 3041 spiral galaxies with multi-band gri imaging from the Sloan Digital Sky Survey (SDSS) Data Release 7 and available galaxy rotational velocities derived from HI line widths. We compare the data products provided through the SDSS imaging pipeline with our own photometry of the SDSS images, and use the velocities (V) as an independent metric to determine ideal galaxy sizes (R) and luminosities (L). Our radial and luminosity parameters improve upon the SDSS DR7 Petrosian radii and luminosities through the use of isophotal fits to the galaxy images. This improvement is gauged via VL and RV relations whose respective scatters are reduced by ~8% and ~30% compared to similar relations built with SDSS parameters. The tightest VRL relations are obtained with the i-band radius, R235i, measured at 23.5 mag/arcsec^-2, and the luminosity L235i, measured within R235i. Our VRL scaling relations compare well, both in scatter and slope, with similar studies (such comparisons however depend sensitively on the nature and size of the compared samples). The typical slopes, b, and observed scatters, sigma, of the i-band VL, RL and RV relations are bVL=0.27+/-0.01, bRL=0.41+/-0.01, bRV=1.52+/-0.07, and sigmaVL=0.074, sigmaRL=0.071, sigmaRV=0.154 dex. Similar results for the SDSS g and r bands are also provided. Smaller scatters may be achieved for more pruned samples. We also compute scaling relations in terms of the baryonic mass (stars + gas), Mbar, ranging from 10^8.7 Msol to 10^11.6 Msol. Our baryonic velocity-mass (VM) relation has slope 0.29+/-0.01 and a measured scatter sigma_meas = 0.076 dex. While the observed VL and VM relations have comparable scatter, the stellar and baryonic VM relations may be intrinsically tighter, and thus potentially more fundamental, than other VL relations of spiral galaxies.