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.
The brightest and most massive galaxies in the universe, the Brightest Cluster Galaxies (BCGs), tell a unique story of galaxy evolution. Today, BCGs are quiescent ellipticals hosted in relaxed galaxy clusters, with pasts fraught with mergers and high star formation rates (SFRs).
In a recent publication, Cooke et al. investigate how this active past may depend on local environment by estimating star formation in BCG progenitors in the COSMOS field out to a redshift of z ~ 3 (more than 11 billion years in the past). To estimate star formation rates, they fit progenitor observations with various models from the far-ultraviolet to far-infrared wavelengths. They find that BCG progenitors gain stellar mass in three phases, with effects due to local environment manifesting at z < 1.25 (9 billion years in the past).
The image shows the stellar mass growth of of galaxies in the field (meaning isolated) in blue and dense environments (meaning in clusters) in red.
For more information, check out the full paper!
The Hyper Suprime-Cam (HSC) team made the second data release public!
The HSC on the 8-meter Subaru telescope in Hawaii also covers the COSMOS field. The increased depth in the g, r, i, z, and Y-band in DR2 is crucial for the study of the first galaxies in our universe. But it doesn't stop there - also galaxies that cease their star-formation can be studied in detail with these data.
The increase in depth is stunning - between 0.7 and 1.7 AB magnitudes with new limiting magnitudes of (depth of old observations in parenthesis) 28.4 (27.6) , 28.0 (27.0), 27.7 (26.9), 27.1 (26.4), and (26.6) 24.9 in g, r, i, z, and Y-band, respectively.
The image shows a comparison of the previous Suprime-Cam data (right) vs. HSC DR2 data(left) in I-band on a small field of COSMOS. Note the much deeper imaging of HSC DR2 (also compare the insets).
More information on the HSC data release 2: https://hsc-release.mtk.nao.ac.jp/doc/index.php/tools-2/
We are pleased to announce the details of the 2019 COSMOS Team meeting in New York City 14-17 May 2019.
Please visit the meeting website here to register:
The registration + abstract deadline is April 15. Thanks to the generous support of the Center for Computational Astrophysics at the Flatiron Institute, there will be no upfront registration cost for the meeting.
We look forward to seeing you in New York in a couple short months!
The Cosmic Evolution Survey (COSMOS) has officially changed hands this week, the second major leadership hand-off since the survey began in 2003. Caitlin Casey, Jeyhan Kartaltepe, and Vernesa Smolčić have taken over as the project's leaders as the collaboration enters its fifteenth year.
Peter Capak has led the COSMOS team for the past nine years with the help of Simon Lilly. "Since taking over leadership of COSMOS in 2010 we have replaced almost every data set we started with including major programs on Chandra, J-VLA, Keck, Spitzer, Subaru, and the VLT,” Capak shared. “In the coming years COSMOS science will likely center around observations with ALMA, J-VLA, and JWST. Casey, Kartaltepe and Smolčić are ideally placed to lead the science in these areas."
Capak is stepping aside due to his significant rolls in future space missions, including Euclid, WFIRST, and SPHEREx. Nick Scoville, the founder and first leader of COSMOS, handed over the reins to Capak in 2010.
On 24-28th March 2018 the International Astronomical Union (IAU) held its huge Communicating Astronomy with the Public (CAP2018) conference in Fukuoka, Japan. COSMOS was represented at the meeting by team member Jacinta Delhaize from the University of Zagreb, who gave a talk on the various public outreach and communications initiatives of COSMOS.
She spoke about the various successes and challenges of engaging the public in such a large multi-national, multi-wavelength astronomical consortium. This is important because we think our data and science is great and we want to share it with everyone! The main challenge is that our astronomers, therefore the members of the public who we are trying to reach, are dispersed throughout the world over many different time zones and languages.
Therefore we mainly communicate our science using online platforms. We have this website and a presence on Facebook, Twitter and You Tube. We use these platforms to share our video blogs, news, press releases and more.
Stepping away from the virtual realm, we have our wonderful Artist-in-Residence Karel Nel, who creates renowned artworks inspired by COSMOS research. We also sometimes run public Astronomy on Tap events at the pub alongside our annual team meetings.
If you have any feedback or suggestions about other initiatives or website content you'd like to see, please let us know!
Jacinta presents the COSMOS public outreach and communication initiatives at the IAU'S CAP2018 conference in Fukuoka, Japan.
The DEIMOS 10K spectroscopic catalog contains 10718 object out to z = 6 in the COSMOS field observed through multi-slit spectroscopy with the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope. The objects have been selected from a variety of input catalogs based on multi-wavelength observations in the field, and thus have a diverse selection function, which enables the study of the diversity in the galaxy population.
The distribution of redshifts and K-band magnitudes of galaxies in the DEIMOS 10K spectroscopic catalog. The colors (stacked per bin) indicate the different target samples from which the galaxies have been selected.