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Register a new userPhotometric scaling relations of lenticular and spiral galaxies
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Photometric scaling relations are studied for S0 galaxies and compared with those for spirals. New 2D K_s-band multi-component decompositions are presented for 122 early-type disk galaxies. Combining with our previous decompositions, the final sample consists of 175 galaxies. As a comparison sample we use the Ohio State University Bright Spiral Galaxy Survey (OSUBSGS), for which similar decompositions have previously been made by us. Our main results are: (1) Important scaling relations are present, indicating that the formative processes of bulges and disks in S0s are coupled like has been previously found for spirals. (2) We obtain median r_{eff}/h_r = 0.20, 0.15 and 0.10 for S0, S0/a-Sa and Sab-Sc galaxies: these are smaller than predicted by simulation models in which bulges are formed by galaxy mergers. (3) The properties of bulges of S0s are different from the elliptical galaxies, which is manifested in the M_K(bulge) vs r_{eff} relation, in the photometric plane, and to some extent also in the Kormendy relation. The bulges of S0s are similar to bulges of spirals with M_K(bulge) < -20 mag. Some S0s have small bulges, but their properties are not compatible with the idea that they could evolve to dwarfs by galaxy harassment. (4) The relative bulge flux B/T for S0s covers the full range found in the Hubble sequence. (5) The values and relations of the parameters of the disks of the S0 galaxies in NIRS0S are similar to those obtained for spirals in the OSUBSGS. Overall, our results support the view that spiral galaxies with bulges brighter than -20 mag in the K-band can evolve directly into S0s, due to stripping of gas followed by truncated star formation.
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We construct a large data set of global structural parameters for 1300 field and cluster spiral galaxies and explore the joint distribution of luminosity L, optical rotation velocity V, and disk size R at I- and 2MASS K-bands. The I- and K-band velocity-luminosity (VL) relations have log-slopes of 0.29 and 0.27, respectively with sigma_ln(VL)~0.13, and show a small dependence on color and morphological type in the sense that redder, early-type disk galaxies rotate faster than bluer, later-type disk galaxies for most luminosities. The VL relation at I- and K-bands is independent of surface brightness, size and light concentration. The log-slope of the I- and K-band RL relations is a strong function of morphology and varies from 0.25 to 0.5. The average dispersion sigma_ln(RL) decreases from 0.33 at I-band to 0.29 at K, likely due to the 2MASS selection bias against lower surface brightness galaxies. Measurement uncertainties are sigma_ln(V)~0.09, sigma_ln(L)~0.14 and somewhat larger and harder to estimate for ln(R). The color dependence of the VL relation is consistent with expectations from stellar population synthesis models. The VL and RL residuals are largely uncorrelated with each other; the RV-RL residuals show only a weak positive correlation. These correlations suggest that scatter in luminosity is not a significant source of the scatter in the VL and RL relations. The observed scaling relations can be understood in the context of a model of disk galaxies embedded in dark matter halos that invokes low mean spin parameters and dark halo expansion, as we describe in our companion paper (Dutton et al. 2007). We discuss in two appendices various pitfalls of standard analytical derivations of galaxy scaling relations, including the Tully-Fisher relation with different slopes. (Abridged).
[Abridged] We present ground-based MDM V-band and Spitzer/IRAC 3.6um-band photometric observations of the 72 representative galaxies of the SAURON Survey. In combination with the SAURON stellar velocity dispersion measured within an effective radius (se), this allows us to explore the location of our galaxies in the main scaling relations. We investigate the dependence of these relations on our recent kinematical classification of early-type galaxies (i.e. Slow/Fast Rotators) and the stellar populations. Slow Rotator and Fast Rotator E/S0 galaxies do not populate distinct locations in the scaling relations, although Slow Rotators display a smaller intrinsic scatter. Surprisingly, extremely young objects do not display the bluest (V-[3.6]) colours in our sample, as is usually the case in optical colours. This can be understood in the context of the large contribution of TP-AGB stars to the infrared, even for young populations, resulting in a very tight (V-[3.6]) - se relation that in turn allows us to define a strong correlation between metallicity and velocity dispersion. Many Sa galaxies appear to follow the Fundamental Plane defined by E/S0 galaxies. Galaxies that appear offset from the relations correspond mostly to objects with extremely young populations, with signs of on-going, extended star formation. We correct for this effect in the Fundamental Plane, by replacing luminosity with stellar mass using an estimate of the stellar mass-to-light ratio, so that all galaxies are part of a tight, single relation. The new estimated coefficients are consistent in both photometric bands and suggest that differences in stellar populations account for about half of the observed tilt with respect to the virial prediction. After these corrections, the Slow Rotator family shows almost no intrinsic scatter around the best-fit Fundamental Plane.
We study the kinematics and scaling relations of a sample of 43 giant spiral galaxies that have stellar masses exceeding $10^{11}$ $M_odot$ and optical discs up to 80 kpc in radius. We use a hybrid 3D-1D approach to fit 3D kinematic models to long-slit observations of the H$alpha$-[NII] emission lines and we obtain robust rotation curves of these massive systems. We find that all galaxies in our sample seem to reach a flat part of the rotation curve within the outermost optical radius. We use the derived kinematics to study the high-mass end of the two most important scaling relations for spiral galaxies: the stellar/baryonic mass Tully-Fisher relation and the Fall (mass-angular momentum) relation. All galaxies in our sample, with the possible exception of the two fastest rotators, lie comfortably on both these scaling relations determined at lower masses, without any evident break or bend at the high-mass regime. When we combine our high-mass sample with lower-mass data from the Spitzer Photometry & Accurate Rotation Curves catalog, we find a slope of $alpha=4.25pm0.19$ for the stellar Tully-Fisher relation and a slope of $gamma=0.64pm0.11$ for the Fall relation. Our results indicate that most, if not all, of these rare, giant spiral galaxies are scaled
It has been recently found that the characteristic photometric parameters of antitruncated discs in S0 galaxies follow tight scaling relations. We investigate if similar scaling relations are satisfied by galaxies of other morphological types. We have analysed the trends in several photometric planes relating the characteristic surface brightness and scalelengths of the breaks and the inner and outer discs of local antitruncated S0-Scd galaxies, using published data and fits performed to the surface brightness profiles of two samples of Type-III galaxies in the R and Spitzer 3.6 microns bands. We have performed linear fits to the correlations followed by different galaxy types in each plane, as well as several statistical tests to determine their significance. We have found that: 1) the antitruncated discs of all galaxy types from Sa to Scd obey tight scaling relations both in R and 3.6 microns, as observed in S0s; 2) the majority of these correlations are significant accounting for the numbers of the available data samples; 3) the trends are clearly linear when the characteristic scalelengths are plotted on a logarithmic scale; and 4) the correlations relating the characteristic surface brightnesses of the inner and outer discs and the breaks with the various characteristic scalelengths significantly improve when the latter are normalized to the optical radius of the galaxy. The results suggest that the scaling relations of Type-III discs are independent of the morphological type and the presence (or absence) of bars within the observational uncertainties of the available datasets, although larger and deeper samples are required to confirm this. The tight structural coupling implied by these scaling relations impose strong constraints on the mechanisms proposed for explaining the formation of antitruncated stellar discs in the galaxies across the whole Hubble Sequence (Abridged).
A bulge-disk decomposition is made for 737 spiral and lenticular galaxies drawn from a SDSS galaxy sample for which morphological types are estimated. We carry out the bulge-disk decomposition using the growth curve fitting method. It is found that bulge properties, effective radius, effective surface brightness, and also absolute magnitude, change systematically with the morphological sequence; from early to late types, the size becomes somewhat larger, and surface brightness and luminosity fainter. In contrast disks are nearly universal, their properties remaining similar among disk galaxies irrespective of detailed morphologies from S0 to Sc. While these tendencies were often discussed in previous studies, the present study confirms them based on a large homogeneous magnitude-limited field galaxy sample with morphological types estimated. The systematic change of bulge-to-total luminosity ratio, $B/T$, along the morphological sequence is therefore not caused by disks but mostly by bulges. It is also shown that elliptical galaxies and bulges of spiral galaxies are unlikely to be in a single sequence. We infer the stellar mass density (in units of the critical mass density) to be $Omega=$0.0021 for spheroids, i.e., elliptical galaxies plus bulges of spiral galaxies, and $Omega=$0.00081 for disks.
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