This is the astro-ph blog of the Theoretical Modelling of Cosmic Structures group (TMoX) at the Max-Planck-Institute for Extraterrestrial Physics. We are an independent Max-Planck Research Group focusing on the various aspects in the formation and evolution of galaxies. Part of our focus is on the formation and evolution of early-type galaxies, super-massive black holes, the formation of the first structures in the universe and the enrichment history of the Universe. We are theoreticians using analytic modelling as well as numerical simulations in our work.

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10 September 2010

Galaxy and Mass Assembly (GAMA): Dust obscuration in galaxies and their recent star formation histories

Authors: D. B. Wijesinghe, A. M. Hopkins et al.
Link to article: arXiv:1009.0616v1

Star formation rates derived through pan-spectral analysis of a sample of ~ 30.000 galaxies drawn from the Galaxy and Mass Assembly (GAMA) survey. In order to get the SFR in different bands (by means of linear scaling factors derived from population synthesis models), dust obscuration corrections are applied to the Hα, [OII] and UV luminosities by using a range of extinction laws drawn from the literature. 
The results of this study clearly show that the fine-tuned Fischera & Dopita (2005) obscuration curve (Rv = 4.5) give the best agreement when comparing the different corrected SFR indicators. One interesting finding of the paper is that the 2200 Å feature present in the obscuration curves of the Milky way, has to be removed in order to obtain complete consistency between all SFR indicators suggesting that this feature may not be common in the average integrated attenuation of galaxy emission.
The last part of this paper attempt to give constraints on the star formation history of local Universe galaxies by comparing the corrected data with the predictions of evolutionary synthesis models. The evolutionary paths are computed by assuming an exponentially decaying SFR and give the best fit to the data by using a Baldry & Glazebrook (2003) IMF with a characteristic SFR decay of 90 Myrs, which correspond to stellar population ages of the galaxies ranging from 200 to 500 Myrs.

1 comment:

  1. I find this paper very interesting, especially for the description and comparison of the various obscuration corrections applied. The results are very well presented and show clearly that the theoretical curves of Fischera & Dopita provide the best corrections. Being not really in the field of dust attenuation, I would have like a bit more detail about that 2200 Å feature (to what mechanism is this related to exactly?) and some more explanations why it is most likely absent in the integrated attenuation over all galaxies (so, why this mechanism should be specific to the MW?).
    Apart from that I was quite disappointed about the last section of the paper about the SFH analysis. I would have like a deeper discussion, especially regarding the range of ages inferred for the stellar populations...I found them quite low for local galaxies: it would have been good to have some references on that to compare with!!! Anyway, the last paragraph about the Integrated Galaxy IMF makes very much sense and seems very promising for future studies