SIMBAD references

2014MNRAS.437.3072K - Mon. Not. R. Astron. Soc., 437, 3072-3086 (2014/February-1)

A portrait of Malin 2: a case study of a giant low surface brightness galaxy.


Abstract (from CDS):

The low surface brightness (LSB) disc galaxy Malin 2 challenges the standard theory of galaxy evolution because of its enormous total mass ∼ 2x1012 M, which must have been formed without recent major merger events. The aim of our work is to create a coherent picture of this exotic object by using new optical multicolour photometric and spectroscopic observations at the Apache Point Observatory as well as archival data sets from Gemini and wide-field surveys. We have performed Malin 2 mass modelling, we have estimated the contribution of the host dark halo and we have found that it acquired its low central density ρ0 ≃ 0.003 M/pc3 and huge isothermal sphere core radius rc = 27.3 kpc before the disc subsystem was formed. Our spectroscopic data analysis reveals complex kinematics of stars and gas in the very inner region (r = 5-7 kpc). We have measured the oxygen abundance in several clumps and we have concluded that the gas metallicity decreases from the solar value in the centre to a half of that at 20-30 kpc. We have found a small satellite projected on to the galaxy disc at 14 kpc from the centre and we have measured its mass (1/500 of the host galaxy) and gas metallicity (similar to that of the Malin 2 disc at the same distance). One of the unique properties of Malin 2 turned out to be the apparent imbalance of the interstellar media: the molecular gas is in excess with respect to the atomic gas for given values of the gas equilibrium turbulent pressure. We explain this imbalance by the presence of a significant portion of the dark gas not observable in CO and the Hi 21-cm lines. We also show that the depletion time of the observed molecular gas traced by CO is nearly the same as in normal galaxies. Our modelling of the ultraviolet-to-optical spectral energy distribution favours the exponentially declined star formation history over a single-burst scenario. We argue that the massive and rarefied dark halo which formed before the disc component describes all the observed properties of Malin 2 well and we find that there is no need to assume additional catastrophic scenarios (such as major merging) proposed previously in order to explain the origin of giant LSB galaxies.

Abstract Copyright: © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2013)

Journal keyword(s): galaxies: haloes - galaxies: individual: Malin 2 - galaxies: ISM

Simbad objects: 11

goto Full paper

goto View the reference in ADS

To bookmark this query, right click on this link: simbad:2014MNRAS.437.3072K and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact