The Cosmic Evolution Survey (COSMOS) is an astronomical survey designed to probe the formation and evolution of galaxies as a function of both cosmic time (redshift) and the local galaxy environment. The survey covers a 2 square degree equatorial field with spectroscopy and X-ray to radio imaging by most of the major space-based telescopes and a number of large ground based telescopes. Over 2 million galaxies are detected, spanning 75% of the age of the Universe. COSMOS is led by Caitlin Casey, Jeyhan Kartaltepe, and Vernesa Smolcic and involves more than 200 scientists in a dozen countries. More information on the COSMOS team members can be found here.
RGB image of the combined NIRCam mosaics from the first epoch of COSMOS-Web imaging.
The first images from the largest program in the James Webb Space Telescope’s first year show many types of galaxies, including dazzling examples of spiral galaxies, gravitational lensing, and evidence of galaxy mergers. Scientists from the COSMOS-Web program released mosaic images taken in early January by JWST’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI).
COSMOS-Web aims to map the earliest structures of the universe and will create a wide and deep survey of up to 1 million galaxies. Over the course of 255 hours of observing time, COSMOS-Web will map 0.6 square degrees of the sky with NIRCam, roughly the size of three full moons, and 0.2 square degrees with MIRI.
The first epoch of COSMOS-Web NIRCam observations obtained on Jan. 5-6, 2023, including the F115W, F150W, F277W, and F444W filters as a color composite. These data cover six visits or pointings out of a total of 152 visits. The total area covered by NIRCam here is ∼77arcmin^2. The relative position of this mosaic in the survey is shown at upper left. At lower left are several zoomed-in 10′′ × 10′′ cutouts and one 16′′ × 16′′ cutout showing specific galaxies selected from these first data. Image credit: COSMOS-Web/Kartaltepe, Casey, Franco, Larson, et al./RIT/UT Austin/CANDIDE
- discover and characterize thousands of galaxies in the Epoch of Reionization (6 < z < 11)
- identify and study hundreds of rare quiescent galaxies at z > 4 and
- directly measure the evolution of the stellar mass to halo mass relation out to z ~ 2.5.
Nick Scoville, the Francis L. Moseley Professor of Astronomy at Caltech (Emeritus), was recently elected to the National Academy of Sciences in recognition of his distinguished and continuing achievements in original research! Nick is the PI of the original COSMOS HST/ACS observations. Congratulations!
The new COSMOS catalog is out and its accompanying paper is accepted!
The catalog contains 1 million sources measured in more than 30 photometric bands from the UV to the infrared. For the extraction of the photometry, our international team applied a new prior-based method to go even deeper and to obtain more robust measurements for blended sources. The catalog also contains photometric redshifts and other physical properties of the galaxies measured from their photometry using spectral energy distribition (SED) fitting codes like LePhare and Eazy.
This catalog is a major milestone for COSMOS, combining its multi-wavelength data consistently, and opening up new avenues to explore galaxy evolution.
You can download the catalog at https://cosmos2020.calet.org to use it for your own science!
For the extraction of the photometry of the galaxies, a new prior-based method is used to go even deeper and to obtain more robust measurements for blended sources. Credit: J. Weaver et al. (2021).
A team of COSMOS researchers studied jets escaping active galactic nuclei (AGN) to investigate what causes their bending. For this, they used radio data from the VLA and X-ray observations from Chandra/XMM-Newton to measure the "bent angle", i.e., the angle the jets form to each other in a two-sided source. The angle is related to the environment in which the AGN hosts reside and compared to magnetohydrodynamic simulations. It is found that the evolution of the environment surrounding the sources affects their radio structures and allows for more space for jet interactions.
When the James Webb Space Telescope (JWST)—the long-awaited successor to the Hubble Space Telescope—becomes operational in 2022, one of its first orders of business will be mapping the earliest structures of the universe. A team of nearly 50 researchers led by scientists at Rochester Institute of Technology and University of Texas at Austin will attempt to do so through the COSMOS-Webb program, the largest General Observer program selected for JWST’s first year.
Over the course of 208.6 observing hours, the COSMOS-Webb program will conduct an ambitious survey of half a million galaxies with multi-band, high-resolution near infrared imaging and an unprecedented 32,000 galaxies in mid infrared. The scientists involved said that because COSMOS-Webb is a treasury program, they will rapidly release data to the public so it can lead to countless other studies by other researchers.
The COSMOS-Webb survey will map 0.6 square degrees of the sky—about the area of three full moons—using JWST’s Near Infrared Camera (NIRCam) instrument while simultaneously mapping a smaller 0.2 square degrees with the Mid Infrared Instrument (MIRI). Credit: J. Kartaltepe/RIT; C. Casey/UT Austin; A. Koekemoer/STScI