From HandWiki

ZFOURGE or the FourStar Galaxy Evolution Survey is a large and deep medium-band imaging survey which aims to establish an observational benchmark of galaxy properties at redshift z > 1. The survey is using a very efficient near-infrared FOURSTAR instrument on the Magellan Telescopes, surveying in all three HST legacy fields: COSMOS, CDFS, and UDS.[1]

Scientific aims

ZFOURGE aims to create a benchmark of properties at z > 1 by deriving 1-2% accurate redshifts of ∼60,000 galaxies at 1 < z < 3.

While majority of L∗ galaxies are too faint for spectroscopy, which resulted in inaccurate broadband photometric redshifts in the previous times. To mend that FourStar is equipped with innovative "medium-bandwidth" filters from 1 − 1.8μm, which enable redshifts to z = 3.5.

This allows ZFOURGE to observe galaxy samples from the low mass at z > 1, to measure the value of mass and environment in transformation of galaxies, measure galaxy scaling relations. It will also explore the shape of the stellar mass function to z = 3, and find luminous galaxies at z = 6-9, and identify high-redshift 1.5 < z < 2.5 (proto)clusters.[2]


The Fourstar Galaxy Evolution Survey (ZFOURGE) is conducted using the FourStar imager (Persson et al. 2013) on the 6.5m Magellan Baade telescope at Las Campanas Observatory. It is using medium-band filters in the near-IR (van Dokkum et al. 2009) which allows for samplings at wavelengths that bracket the Balmer break of galaxies leading to more well-constrained photometric redshifts at 1 < z < 4 than with broadband filters alone. This dataset provides a comprehensive sampling of the 0.3 – 8 micron spectral energy distribution of galaxies.

ZFOURGE is composed of three 11′ x 11′ pointings with coverage in the CDFS (Giacconi et al. 2002), COSMOS (Capak et al. 2007) and UDS (Lawrence et al. 2007). The 5sigma depth in a circular aperture of D=0.6" in the Ks band is 26.2-26.5 in the CDFS, COSMOS and UDS fields respectively at a typical seeing of ~0.4″. For more information regarding ZFOURGE consult Straatman et al. (2016).[3]


External links