Attached are some estimates of the Star Formation Histories of the
galaxies you posted, with various options of bin numbers. I've gone
from 7 to 24 bins with each spectrum, but to be honest without knowing
the noise (and more specifically the noise as a fn of wavelength) it is
hard to really assess whether the output is reliable or not. The fits
all look good by eye - it's the fine differences that accurate spectral
noise shapes would give that could really pin down both the SFH and the
suitability of a given parametrisation.
The method I used to determine the SFH is BC03 rebinned to 10AA,
assuming noise proportional to flux. Otherwise the same approach as is
described in Panter 2006. My gut feeling is that the results in the
8/10/11 bin range are pretty good, but I emphasise that I would
normally not draw conclusions from the averaged results of a hundred
spectra, let alone one. Based on that I suggest in a hand waving manner
the 'suspicions' below. I confess that I'm a bit worried about giving
the wrong impression with these outputs, but I think that it would
still be interesting to compare the results with other analysis codes.
~10 Gyr old population with roughly solar metallicity. Possibly a small
1 Gyr pop, again solarish metallicity
Old component(s?), subsolar metallicity. Could be
log(Z/Z_\odot)=[-0.5,-1.3] for two older populations, ~11 and 4 Gyr,
older population dominant.
I think this has two components, one centred at ~10Gyr, the other at
1Gyr. Slightly higher than solar metallicity for older population,
quite a lot higher for the younger one.
Longer period of early SF - hard to say anything much about the
metallicity other than I suspect it could be two similarly aged
populations with different metallicities of a similar age, which MOPED
will fit (badly) by adjacent age bins with different metallicities.
I'm suspicious of the two younger populations - one just less than a
Gyr and one at about 0.06. I don't really trust this, but is does seem
to be consistent through the different choices of bins.
Again, two populations - possibly both a bit broad. Older seems to be
7-10 Gyr old, with a spec of something younger at ~1Gyr (as ever...).
Old component is sub solar metallicity, younger is I suspect, solar.
Old, solar metallicity component ~ 10 Gyr. Something there at 1-2 Gyr
perhaps? Hard to say. log(Z/Z_\odot) ~ -0.5
Mainly about 10 Gyr, perhaps slightly above solar metallicity, second,
younger population at about 1-Gyr. Sub solar metallicity.
7 age bins
8 age bins
10 age bins
12 age bins
24 age bins