The rest-frame optical sizes of massive galaxies with suppressed star formation at $z\sim4$

Understand

We present the rest-frame optical sizes of massive quiescent galaxies (QGs) at $z\sim4$ measured at $K'$-band with the Infrared Camera and Spectrograph (IRCS) and AO188 on the Subaru telescope.

• Based on a deep multi-wavelength catalog in the Subaru XMM-Newton Deep Survey Field (SXDS), covering a wide wavelength range from the $u$-band to the IRAC $8.0\mu m$ over 0.7 deg$^2$, we evaluate photometric redshift to identify massive ($M_{\star}\sim10^{11}\ M_\odot$) galaxies with suppressed star formation.
• These galaxies show a prominent 4000$\rm \AA$ break feature at $z\sim4$, suggestive of an evolved stellar population.
• We then conduct follow-up $K'$-band imaging with adaptive optics for the five brightest galaxies ($K_{AB,total}=22.5\sim23.4$).