Consistent dynamical and stellar masses with potential light IMF in massive quiescent galaxies at $3 < z < 4$ using velocity dispersions measurements with MOSFIRE

Understand

We present the velocity dispersion measurements of four massive $\sim10^{11}M_\odot$ quiescent galaxies at $3.2 < z < 3.7$ based on deep H and K$-$band spectra using the Keck/MOSFIRE near-infrared spectrograph.

• We find high velocity dispersions of order $\sigma_e\sim250$ km/s based on strong Balmer absorption lines and combine these with size measurements based on HST/WFC3 F160W imaging to infer dynamical masses.
• The velocity dispersion are broadly consistent with the high stellar masses and small sizes.
• Together with evidence for quiescent stellar populations, the spectra confirm the existence of a population of massive galaxies that formed rapidly and quenched in the early universe $z>4$.