Results from Stacking Grism Spectra of Galaxies at 0.6 < z < 1.2 in the Probing Evolution And Reionization Survey (PEARS)
Abstract
We present results from median stacking of low-resolution grism spectra for ~1700 galaxies at 0.6 < z < 1.2. The data are from the Probing Evolution And Reionization Survey (PEARS) which is a 200 orbit HST ACS G800L grism survey in GOODS-N and GOODS-S. The visible and near-IR coverage of the grism, 6000A to 9500A, provides rest-frame visible wavelength coverage from ~3000A to ~6000A for the redshift range of our sample. We median stack galaxies of similar rest-frame u-r color and stellar mass by selecting them based on their location in our u-r color vs stellar mass diagram. The grism spectra are stacked in bins of 0.3 in u-r color and 0.5 dex in stellar mass over a range of 0.0 < u-r < 3.0 and 7.0 < log(M) [M_sol] < 11.5 with an average of ~30 galaxies per bin. We find that blue cloud galaxies typically show bluer continua, Balmer breaks and also show H-beta and [OIII] emission lines that are blended together due to the low-resolution of the grism. Red sequence galaxies typically show strong 4000A breaks and redder continua and, at lower significance, also the G-band and Mgb absorption features characteristic of late type stars. We also observe that green valley galaxies, which form ~6% of the total sample, typically show weaker 4000A breaks and relatively flatter continua at wavelengths redder than 4000A.
- Publication:
-
American Astronomical Society Meeting Abstracts #228
- Pub Date:
- June 2016
- Bibcode:
- 2016AAS...22811805J