2024/08/09 by Ivana Damjanov, Damjanov, Ivana, Margaret J. Geller +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2408.05263
openalex publication_date 2024/08/09 · openalex created_date 2024/09/10 · openalex updated_date 2026/07/28
The HectoMAP spectroscopic survey provides a unique mass-limited sample of more than 35,000 quiescent galaxies (Dn4000>1.5) covering the redshift range 0.21010 M_\odot) quiescent population at intermediate redshift. These high-quality summed spectra enable full spectrum fitting and the related extraction of the average stellar population age and metallicity. The average galaxy age increases with the central Dn4000 as expected. The correlation is essentially invariant with stellar mass; thus Dn4000 is a robust proxy for quiescent galaxy stellar population age. HectoMAP provides the first quiescent sample at intermediate redshift comparable with z∼0 mass-complete datasets. Scaling relations derived from the HectoMAP summed spectra connect stellar age and metallicity with quiescent galaxy stellar mass up to z∼0.5. Anti-correlation between the equivalent width of the [O II] emission line and stellar age, together with the mild increase in stellar age with stellar mass, supports a broad range of timescales for the mass assembly of intermediate-redshift quiescent systems. On average, the most massive galaxies (M_∗>1011 M_\odot) assemble the bulk of their stars at earlier epochs. A strong increase in the average stellar metallicity with stellar mass, along with the correlation between the [O II] equivalent width and metallicity at 0.2