Decoupled Black Hole Accretion and Quenching: The Relationship Between
  BHAR, SFR, and Quenching in Milky Way and Andromeda-mass Progenitors Since z
  = 2.5
  We investigate the relationship between the black hole accretion rate (BHAR)
and star-formation rate (SFR) for Milky Way (MW) and Andromeda (M31)-mass
progenitors from z = 0.2 - 2.5. We source galaxies from the Ks-band selected
ZFOURGE survey, which includes multi-wavelenth data spanning 0.3 - 160um. We
use decomposition software to split the observed SEDs of our galaxies into
their active galactic nuclei (AGN) and star-forming components, which allows us
to estimate BHARs and SFRs from the infrared (IR). We perform tests to check
the robustness of these estimates, including a comparison to BHARs and SFRs
derived from X-ray stacking and far-IR analysis, respectively. We find as the
progenit- ors evolve, their relative black hole-galaxy growth (i.e. their
BHAR/SFR ratio) increases from low to high redshift. The MW-mass progenitors
exhibit a log-log slope of 0.64 +/- 0.11, while the M31-mass progenitors are
0.39 +/- 0.08. This result contrasts with previous studies that find an almost
flat slope when adopting X-ray/AGN-selected or mass-limited samples and is
likely due to their use of a broad mixture of galaxies with different
evolutionary histories. Our use of progenitor-matched samples highlights the
potential importance of carefully selecting progenitors when searching for
evolutionary relationships between BHAR/SFRs. Additionally, our finding that
BHAR/SFR ratios do not track the rate at which progenitors quench casts doubts
over the idea that the suppression of star-formation is predominantly driven by
luminous AGN feedback (i.e. high BHARs).
