Kavli Affiliate: Roberto Maiolino
| Summary:
We present the UV-to-NIR size evolution of a sample of 161 quiescent galaxies (QGs) with $M_*>10^10M_odot$ over $0.5<z<5$. With deep multi-band NIRCam images in GOODS-South from JADES, we measure the effective radii ($R_e$) of the galaxies at rest-frame 0.3, 0.5 and 1$μm$. On average, QGs are 45% (15%) more compact at rest-frame 1$μm$ than they are at 0.3$μm$ (0.5$μm$). Regardless of wavelengths, the $R_e$ of QGs strongly evolves with redshift, and this evolution depends on stellar mass. For lower-mass QGs with $M_*=10^10-10^10.6M_odot$, the evolution follows $R_esim(1+z)^-1.1$, whereas it becomes steeper, following $R_esim(1+z)^-1.7$, for higher-mass QGs with $M_*>10^10.6M_odot$. To constrain the physical mechanisms driving the apparent size evolution, we study the relationship between $R_e$ and the formation redshift ($z_form$) of QGs. For lower-mass QGs, this relationship is broadly consistent with $R_esim(1+z_form)^-1$, in line with the expectation of the progenitor effect. For higher-mass QGs, the relationship between $R_e$ and $z_form$ depends on stellar age. Older QGs have a steeper relationship between $R_e$ and $z_form$ than that expected from the progenitor effect alone, suggesting that mergers and/or post-quenching continuous gas accretion drive additional size growth in very massive systems. We find that the $z>3$ QGs in our sample are very compact, with mass surface densities $Σ_egtrsim10^10 M_odot/rmkpc^2$, and their $R_e$ are possibly even smaller than anticipated from the size evolution measured for lower-redshift QGs. Finally, we take a close look at the structure of GS-9209, one of the earliest confirmed massive QGs at $z_specsim4.7$. From UV to NIR, GS-9209 becomes increasingly compact, and its light profile becomes more spheroidal, showing that the color gradient is already present in this earliest massive QG.
| Search Query: arXiv Query: search_query=au:”Maiolino Roberto”&id_list=&start=0&max_results=10
Read More