HST/WFC3 Near-Infrared spectroscopy of quenched galaxies at z~1.5 from the WISP Survey: Stellar population properties

We combine Hubble Space Telescope (HST) G102 & G141 NIR grism spectroscopy with HST/WFC3-UVIS, HST/WFC3-IR and Spitzer/IRAC[3.6\mu m] photometry to assemble a sample of massive (log(M_star/M_sun) ~ 11) and quenched galaxies at z~1.5. Our sample of 41 galaxies is the largest with G102+G141 NIR spectroscopy for quenched sources at these redshifts. In contrast to the local Universe, z~1.5 quenched galaxies in the high-mass range have a wide range of stellar population properties. We find their SEDs are well fitted with exponentially decreasing SFHs, and short star-formation time-scales (\tau 2 and the z~1.5 RS. According to their estimated ages, the time required for quenched galaxies OFF the RS to join their counterparts ON the z~1.5 RS is of the order of ~1Gyr.