1610.05310
Star formation in intermediate redshift 0.2<z<0.7 brightest cluster galaxies
Cooke, et al
Present a multi-wavelength photometric and spectroscopic study of 42 BCGs in 2 samples of clusters of galaxies chosen for the study for gravitational lensing. The study's initial sample combines 25 BCGs from CLASH and 37 BCGs from SGAS with a a total redshift range of 0.2<z<0.7. Using archival GALEX, HST, WISE, Herschel, and VLA data, determine the BCGs' stellar mass, radio power, and SFR. The radio power is higher than expected if due to SF, consistent with the BCGs being AGN-powered radio sources. This suggests that the AGN and SF are both fueled by cold gas in the host galaxy. The sSFR is low and constant with z. The mean sSFR is 9.42e-12/yr which corresponds to a mass doubling time of 105 billion years. These findings are consistent with models for hierarchical formation of BCGs which suggest that SF is no longer a significant channel for galaxy growth for z<1. Instead, stellar growth (of order a factor of at least 2) during this period is expected to occur mainly via minor dry mergers.
1610.05313
Large molecular gals reservoirs in ancestors of Milky Way-mass galaxies 9 billion years ago
Papovich, et al
Large detections of molecular gas from CO emission in galaxies at z=1.2-1.3, selected to have the stellar mass and SFR of the progenitors of today's MW-mass galaxies, reveals large molecular gas masses, comparable to or exceeding the galaxy stellar masses, implying most of the baryons are in cold gas, not stars. The galaxies' total luminosities from SF and CO luminosities yield long gas-consumption timescales. Compared to local spiral galaxies, the SF efficiency, estimated from the ratio of total IR luminosity to CO emission, has remained nearly constant since z=1.2, despite the order of magnitude decrease in gas fraction, consistent with results for other galaxies at this epoch. Therefore the physical processes that determine the rate at which gas cools to form stars in distant galaxies appear to be similar to that in local galaxies.
1610.05508
The Euclid mission design
Racca, et al
Euclid is a space-based optical/NIR survey mission of ESA to investigate the nature of DE, DM and gravity by observing the geometry of the Universe and on the formation of structures over cosmo timescales. Euclid will use 2 probes of the signature of DM and energy; WL, which requires measurement of the shape and photometric redshifts of distant galaxies, and galaxy clustering, based on the measurement of the 3d distribution of galaxies through their spectroscopic redshifts. The mission is scheduled for launch in 2020 and is designed for 6 years of nominal survey operations. The Euclid spacecraft is composed of a service module and a payload module. The Service Module comprises all the conventional spacecraft subsystems, the instruments warm electronic units, the sun shield and the solar arrays. In particular the service module provides the extremely challenging pointing accuracy required by the scientific objectives. The Payload Module consists of a 1.2m 3-mirror Korsch type telescope and of 2 instruments, the visible imager and the NIR spectro-photometer, both covering a large common field-of-view enabling to survey more than 35% of the entire sky. All sensor data are downlinked using K-band transmission and processed by a dedicated ground segment for science data processing. The Euclid data and catalogues will be made available to the public at the ESA Science Data Centre.
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