Confirming the Quiescent Galaxy Population out to $z=3$: A Stacking
  Analysis of Mid-, Far-Infrared and Radio Data
  We present stringent constraints on the average mid-, far-infrared and radio
emissions of $\sim$14200 quiescent galaxies (QGs), identified out to $z=3$ in
the COSMOS field via their rest-frame NUV$-$r and r$-$J colors, and with
stellar masses $M_{\star}=10^{9.8-12.2} \,M_{\odot} $. Stacking in deep Spitzer
(MIPS $24\,\mu$m), Herschel (PACS and SPIRE), and VLA (1.4 GHz) maps reveals
extremely low dust-obscured star formation rates for QGs (SFR
$<0.1-3\,M_{\odot}$yr$^{-1}$ at $z \leqslant 2$ and $<6-18\,M_{\odot}$yr$^{-1}$
at $z > 2$), consistent with the low unobscured SFRs
($<0.01-1.2\,M_{\odot}$yr$^{-1}$) inferred from modeling their
ultraviolet-to-near-infrared photometry. The average SFRs of QGs are
$>10\times$ below those of star-forming galaxies (SFGs) within the $M_{\star}$-
and $z$-ranges considered. The stacked 1.4 GHz signals (S/N $> 5$) are, if
attributed solely to star formation, in excess of the total (obscured plus
unobscured) SFR limits, suggestive of a widespread presence of low-luminosity
active galactic nuclei (AGN) among QGs. Our results reaffirm the existence of a
significant population QGs out to $z = 3$, thus corroborating the need for
powerful quenching mechanism(s) to terminate star formation in galaxies at
earlier epochs.
