Paper detail

Local galaxies with compact cores as the possible descendants of massive compact quiescent galaxies at high redshift

In order to test a possible evolutionary scenario of high-$z$ compact quiescent galaxies (cQGs) that they can survive as local compact cores embedded in local massive galaxies with different morphology classes, we explore the star formation histories of local compact cores according to their spectral analysis. We build a sample of 182 massive galaxies with compact cores (${M}_{*,{\rm core}} > 10^{10.6} {\rm M}_\odot$) at $0.02 \leq z \leq 0.06$ from SDSS DR7 spectroscopic catalogue. STARLIGHT package is used to analyze the median stacked spectra and derive the stellar ages and metallicities. Our main results show that local compact cores have the average age of about $12.1\pm0.6$ Gyr, indicating their early formation at $z > 3$, which is consistent with the formation redshifts of cQGs at $1<z<3$. Together with previous studies, our result that local compact cores have similar formation redshifts as those of high-$z$ cQGs, supports that local massive galaxies with compact cores are possible descendants of cQGs. Morphological study of local galaxies with compact cores suggests that there would be multiple possible evolutionary paths for high-$z$ cQGs: most of them ($> 80\%$) will evolve into local massive ETGs according to dry minor merger, while some of them ($\sim 15\%$) will build a substantial stellar/gas discs according to the late-time gas accretion and sustaining star formation, and finally grow up to spiral galaxies.