A Census of Thermally-Pulsing AGB stars in the Andromeda Galaxy and a
  First Estimate of their Contribution to the Global Dust Budget
  We present a near-complete catalog of the metal-rich population of
Thermally-Pulsing Asymptotic Giant Branch stars in the northwest quadrant of
M31. This metal-rich sample complements the equally complete metal-poor
Magellanic Cloud AGB catalogs produced by the SAGE program. Our catalog
includes HST wide-band photometry from the Panchromatic Hubble Andromeda
Treasury survey, HST medium-band photometry used to chemically classify a
subset of the sample, and Spitzer mid- and far-IR photometry that we have used
to isolate dust-producing AGB stars. We have detected 346,623 AGB stars; these
include 4,802 AGB candidates producing considerable dust, and 1,356 AGB
candidates that lie within clusters with measured ages, and in some cases
metallicities. Using the Spitzer data and chemical classifications made with
the medium-band data, we have identified both carbon- and oxygen-rich AGB
candidates producing significant dust. We have applied color--mass-loss
relations based on dusty AGB stars from the LMC to estimate the dust injection
by AGB stars in the PHAT footprint. Applying our color relations to a subset of
the chemically-classified stars producing the bulk of the dust, we find that
~97.8% of the dust is oxygen-rich. Using several scenarios for the dust
lifetime, we have estimated the contribution of AGB stars to the global dust
budget of M31 to be 0.9-35.5%, which is in line with previous estimates in the
Magellanic Clouds. Follow-up observations of the M31 AGB candidates with the
JWST will allow us to further constrain stellar and chemical evolutionary
models, and the feedback and dust production of metal-rich evolved stars.
