NH and Mg Index Trends in Elliptical Galaxies

Details NH and Mg Index Trends in Elliptical Galaxies NH and Mg Index Trends in Elliptical Galaxies

2010-09-10

arxiv.org/abs/1009.2057v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

19 pages, 6 figures, 6 tables

Scientific paper

We examine the spectrum in the vicinity of the NH3360 index of Davidge & Clark (1994), which was defined to measure the NH absorption around 3360 \AA and which shows almost no trend with velocity dispersion (Toloba et al. 2009), unlike other N- sensitive indices, which show a strong trend (Graves et al. 2007). Computing the effect of individual elements on the integrated spectrum with synthetic stellar population integrated spectra, we find that, while being well correlated with nitrogen abundance, NH3360 is almost equally well anti-correlated with Mg abundance. This prompts the definition of two new indices, Mg3334, which is mostly sensitive to magnesium, and NH3375, which is mostly sensitive to nitrogen. Rather surprisingly, we find that the new NH3375 index shows a trend versus optical absorption feature indices that is as shallow as the NH3360 index. We hypothesize that the lack of a strong index trend in these near-UV indices is due to the presence of an old metal-poor component of the galactic population. Comparison of observed index trends and those predicted by models shows that a modest fraction of an old, metal-poor stellar population could easily account for the observed flat trend in these near-UV indices, while still allowing substantial N abundance increase in the larger galaxies.

Affiliated with

Also associated with

No associations

Rating

NH and Mg Index Trends in Elliptical Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with NH and Mg Index Trends in Elliptical Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and NH and Mg Index Trends in Elliptical Galaxies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-672728