Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 0706.3624

Absorption line-strengths of 18 late-type spiral galaxies observed with SAURON

Katia Ganda·Reynier F. Peletier·Richard M. McDermid·Jesús Falcón-Barroso·P. T. de Zeeuw·Roland Bacon·Michele Cappellari·Roger L. Davies·Eric Emsellem·Davor Krajnović·Harald Kuntschner·Marc Sarzi·Glenn van de Ven
View original source ↗Read source document ↗Export metadata ↓

Abstract

We present absorption line-strength maps for a sample of 18 Sb-Sd galaxies observed using the integral-field spectrograph SAURON. The SAURON spectral range allows the measurement of the Lick/IDS indices Hbeta, Fe5015 and Mgb, which can be used to estimate the stellar population parameters. We present here the two-dimensional line-strength maps for each galaxy. From the maps, we learn that late-type spiral galaxies tend to have high Hbeta and low Fe5015 and Mgb values, and that the Hbeta index has often a positive gradient over the field, while the metal indices peak in the central region. We investigate the relations between the central line-strength indices and their correlations with morphological type and central velocity dispersion, and compare the observed behaviour with that for ellipticals, lenticulars and early-type spirals from the SAURON survey. We find that our galaxies lie below the Mg - sigma relation determined for elliptical galaxies and that the indices show a clear trend with morphological type. From the line-strength maps we calculate age, metallicity and abundance ratio maps and discuss the results from a one-SSP approach and from a two-SSP approach. Late-type galaxies are generally younger and more metal poor than ellipticals and have abundance ratios closer to solar values. We also explore a continuous star formation scenario, and try to recover the star formation history using the evolutionary models of Bruzual & Charlot (2003), assuming constant or exponentially declining star formation rate (SFR). We find a correlation between the e-folding time-scale tau of the starburst and the central velocity dispersion: more massive galaxies tend to have shorter tau, suggesting that the star formation happened long ago and has now basically ended, while for smaller objects with larger values of tau it is still active.

Explore related subjects

astro-ph

Keep this discovery

BibTeXRIS

Katia Ganda, Reynier F. Peletier, Richard M. McDermid, Jesús Falcón-Barroso, P. T. de Zeeuw, Roland Bacon, Michele Cappellari, Roger L. Davies, Eric Emsellem, Davor Krajnović, Harald Kuntschner, Marc Sarzi, Glenn van de Ven. 2007-06-25. Absorption line-strengths of 18 late-type spiral galaxies observed with SAURON. https://doi.org/10.1111/j.1365-2966.2007.12121.x

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2016

Large Number, Dark Matter, Dark Energy, and the Superstructures in the Universe (with Extension)

Since there are dark matter particles (neutrino) with mass about 10^(-1)eV in the universe, the superstructures with a scale of 10^(19) solar mass [large number A is about 10^(19)] appeared around the era of the hydrogen recombination. The redshift z distributions of quasars support the existence of superstructures. Since there are superstructures in the universe, it is not necessary for the hypothesis of dark energy. While neutrino is related to electro-weak field, the fourth stable elementary particles (delta particle) with mass about 10^(0)eV to 10^(1)eV is related to gravitation-"strong" field, which suggests p + anti(p)--> n/anti(n) + anti(delta particle)/(delta particle) and that some new meta-stable baryons appeared near the TeV region. Therefore, a twofold standard model diagram is proposed, and related to many experiment phenomena: The new meta-stable baryons' decays produce delta particles, which are helpful to explain the Dijet asymmetry phenomena at LHC of CERN, the different results for the Fermilab's data peak, etc; However, according to the (B-L) invariance, the sterile "neutrino" from "the event excess in MiniBooNe" can not be the fourth neutrino but rather the delta particle; We think that the delta particles are related to the phenomenon about neutrinos FTL, and that anti-neutrinos are faster than neutrinos. FTL is also related to the cosmic inflation, singular point disappearance, and abnormal red shift of SN Ia. Some experiments and observations are suggested. In the Extension section, we clarify "mass tree", our finite universe, cosmic dual expansions, dual SM etc. And the LHC can look for new particles with decay products graviton/delta particle and new interaction indeed.

astro-ph↗
arXiv2016

Distribution functions for a family of axially symmetric galaxy models

We present the derivation of distribution functions for the first four members of a family of disks, previously obtained in (MNRAS, 371, 1873, 2006), which represent a family of axially symmetric galaxy models with finite radius and well behaved surface mass density. In order to do this we employ several approaches that have been developed starting from the potential-density pair and, essentially using the method introduced by Kalnajs (Ap. J., 205, 751, 1976) we obtain some distribution functions that depend on the Jacobi integral. Now, as this method demands that the mass density can be properly expressed as a function of the gravitational potential, we can do this only for the first four discs of the family. We also find another kind of distribution functions by starting with the even part of the previous distribution functions and using the maximum entropy principle in order to find the odd part and so a new distribution function, as it was pointed out by Dejonghe (Phys. Rep., 133, 217, 1986). The result is a wide variety of equilibrium states corresponding to several self-consistent finite flat galaxy models.

astro-ph↗
arXiv2016

Cosmic-Ray Nuclei, Antiprotons and Gamma-rays in the Galaxy: a New Diffusion Model

We model the transport of cosmic ray nuclei in the Galaxy by means of a new numerical code. Differently from previous numerical models we account for a generic spatial distribution of the diffusion coefficient. We found that in the case of radially uniform diffusion, the main secondary/primary ratios (B/C, N/O and sub-Fe/Fe) and the modulated antiproton spectrum match consistently the available observations. Convection and re-acceleration do not seem to be required in the energy range we consider: $1 < E < 10^3$ GeV/nucleon. We generalize these results accounting for radial dependence of the diffusion coefficient, which is assumed to trace that of the cosmic ray sources. While this does not affect the prediction of secondary/primary ratios, the simulated longitude profile of the diffuse $γ$-ray emission is significantly different from the uniform case and may agree with EGRET measurements without invoking ad hoc assumptions on the galactic gas density distribution.

astro-ph↗