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AGB populations in post-starburst galaxies
In a previous paper we compared the SEDs of a sample of 808 K+A galaxies from
the FUV to the MIR to the predictions of the spectrum synthesis models
explicitly using AGB components. Here we use the new AGB-light models from C.
Maraston (including less fuel for the later stages of stellar evolution and
improved calibrations) to address the discrepancies between our observations
and the AGB-heavy models used in our previous paper, which over-predict the
infrared fluxes of post-starburst galaxies by an order of magnitude. The new
models yield a much better fit to the data, especially in the near-IR, compared
to previous realizations where AGB stars caused a large excess in the H and K
bands. We { also compare the predictions of the M2013 models to those with BC03
and find that both reproduce the observations equally well. } We still find a
significant discrepancy with { both sets of models} in the Y and J bands, which
however is probably due to the spectral features of AGB stars. We also find
that { both the M2013 and the BC03 models} still over-predict the observed
fluxes in the UV bands, even invoking extinction laws that are stronger in
these bands. While there may be some simple explanations for this discrepancy,
we find that further progress requires new observations and better modelling.
Excess mid-infrared emission longward of 5m is well modelled by a
Black-Body, which may arise from dust emission from the
circumstellar envelopes of Oxygen rich M stars (expected for a metal-rich
population of AGB stars).Comment: A&A accepte
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