June 7, 2017 • Current spotlights

The VLA-COSMOS 3 GHz Large Project - Deep space studies with a new radio sky survey

An international team of astronomers has conducted a powerful new survey of the sky at radio wavelengths. This has provided some of the most advanced data with which to examine the life-cycle of galaxies over the past 13 billion years of the universe’s history. This survey, and several of the key scientific findings, will be presented in an upcoming VLA-COSMOS special issue of the Astronomy & Astrophysics journal. Go to the full article for more information and to view our exciting video series!

May 26, 2017 • Current spotlights


DEVILS (the Deep Extragalactic VIsible Legacy Survey), a spectroscopic campaign aimed at bridging the near and distant Universe by undertaking the highest completeness survey, got approved and will start taking spectra right now. The survey aims for about 58k galaxies at 0.3 < z < 1.0 with r < 22 and Y < 21.2 over 6 square-degrees including COSMOS and SXDS. The spectra are taken with the AAOmega and 2dF spectrographs on the Australian Astronomical Telescope.

DEVILS will allow a detailed study of the evolution of galaxies and structure, and the dark matter baryon interface on <Mpc scales.

March 30, 2017 • Current spotlights

The fate of massive Galaxies

The dominant processes that stop the formation of stars in galaxies is currently still unknown. Similarly, we do not know what grows galaxies after they stop their star formation and therefore should not change their size and mass anymore. Likely the life of very massive galaxies is very different than that of low-mass galaxies.

This new study on COSMOS targets to answering these questions for the most massive galaxies in our Universe by using the COSMOS/UltraVISTA near-infrared data.

Interested? Find the paper here or read the full article!

March 29, 2017 • Other announcements

Registration for the COSMOS meeting 2017 is now open

The registration for the COSMOS meeting 2017 in Kyoto (Japan) is now open! Go and get yourself a talk slot now!

The meeting takes place from July 4-7, 2017. The deadline for registration is April 14. The abstract deadline is May 19.

Go to this page to register:


March 24, 2017 • Other announcements

Hello from Heidelberg!

The COSMOS-VLA European core team are meeting in Heidelberg, Germany this week for a busy-week/workshop. We are talking about our work on galaxy evolution, which we have studied using our sensitive, high-resolution radio continuum observations of the COSMOS field taken with the Karl G. Jansky Very Large Array (VLA). We are discussing how to measure the amount of star formation happening in distant galaxies, what radio wavelengths can teach us about AGN (galaxies hosting active supermassive black holes), mysterious sub-millimetre galaxies in the very distant Universe, and more! Thanks to the local organisers Philipp Lang and Eva Schinnerer for all their hard work.

March 13, 2017 • Science stories

COSMOS unravelling the cosmic web

A team of researchers, led by Behnam Darvish, have been able to examine the cosmic web in great detail thanks to the plethora of high-quality COSMOS data available. The team have used the accurate photometric redshifts available within COSMOS, out to large cosmic distances, to map the density field within COSMOS. That is, they have determined the location of clusters of galaxies, filaments of the cosmic web and "normal" density regions called "the field." The cosmic web is the large-scale, complex network of galaxies, dark matter and gas that pervades throughout the Universe. The team found that a galaxy's position within the cosmic web plays an important role in determining the evolutionary pathway taken by the galaxy. They found that the cosmic web has a different influence on the rate of star formation within central galaxies (existing inside regions of high gravitational potential) compared to satellite galaxies (existing on the outskirts of these clusters). These findings will pave the way for exciting future work with upcoming telescopes such as LSST, Euclid, and WFIRST.

March 8, 2017 • Data and observation announcements

Density field, Cosmic Web environment, and galaxy type measurements

Local density field, cosmic web environment, and galaxy type measurements for COSMOS galaxies are now available for download.

January 26, 2017 • Science stories

Do sub-millimeter galaxies (SMGs) live in over-dense regions in the early Universe?

A new study on COSMOS shows that between 35% and 60% of SMGs (i.e., highly star-forming galaxies) between z = 0 and z = 5 (1 billion years after the Big Bang) indeed reside in over-dense environments. However, the study also shows that the occurrence of SMGs occupying over-dense regions is lower at z < 3 compared to z > 3. This might indicate that highly star-forming galaxies can only be formed in high density regions at early cosmic epochs, while at later times, modest over-densities allow SMGs to form. For more information, check out their paper:

September 2, 2016 • Science stories

Record-breaking Galaxy Cluster Discovered

COSMOS data across many different wavelengths, including X-ray, infrared and radio, has been used to set the record for the most distant galaxy cluster ever discovered. We may be seeing the cluster, named CL J1001+0220, just after it's formation and while it is in the process of a big 'baby-boom' of star formation.

August 19, 2016 • Science stories

Spitzer to observe COSMOS for 1500 hours

A further 1500h of Spitzer time has been awarded to complete a survey of the COSMOS field. The program has been approved in Spitzer Cycle-13 to PI I. Labbe and COSMOS Co-I Karina Caputi. This will complete the legacy of Spitzer/IRAC over COSMOS by extending the deep coverage to cover the full 1.8 sq degree field, producing a nearly homogenous and contiguous map unparalleled in terms of area and depth. This will complement ongoing optical-to-NIR surveys and reconfirm COSMOS as a unique field for probing the bright end of the z=6-11 universe and the formation of large-scale structures.

August 10, 2016 • Science stories

ALMA to set its sights on COSMOS

Several hours of highly competitive Atacama Large Millimeter Array (ALMA) Cycle 4 time has been awarded to COSMOS astronomers to target various objects in the COSMOS field. ALMA is a revolutionary millimetre/sub-millimeter telescope and COSMOS astronomers will use it to gain a deeper understanding of how galaxies formed and evolved. They will study how the galaxy environment impacts star formation, examine the sizes and structures of enigmatic sub-millimetre galaxies, reveal the properties of galaxies in the high redshift Universe, and more. Congratulations to everyone involved! See the full article for details of the successful proposals.

July 28, 2016 • Science stories

Why do dead galaxies grow in size?

Quiescent galaxies do not form stars anymore, however, their population averaged size is increasing over time. Using stacked zCOSMOS spectra, Fagioli et al. measured their ages as a function of size and find that small galaxies are older than large ones. This indicates that the increase of the average size of quiescent galaxies with cosmic time is due to the addition of newly quenched, bigger star-forming galaxies at later times to the quiescent population. This is not true anymore for the most massive galaxies, which individually grow in size, possibly due to dry mergers.

July 12, 2016 • Other announcements

SED3FIT combines stellar, dust, and AGN emission

The code SED3FIT (Berta et al. 2013a) is now publicly available. It performs galaxy SED fitting with a combination of three components: stellar emission; dust emission from star formation; and a possible dusty torus/AGN.

July 1, 2016 • Data and observation announcements

Going deep with UltraVISTA

Our proposal "Completing the legacy of UltraVISTA" on COSMOS has been accepted. In the next 3 years, the VISTA telescope will image the COSMOS field (1.5 on 1.5 degrees) to its final depth in J, H, and Ks. It will finally reach equal depth across the whole field in these filters. In three years time, we will be able to reach 26, 25.7, and 25.3 AB magnitudes (5-sigma) in J, H, and Ks, respectively. This will double the area on COSMOS at this depth and will be an important step for better measurements and the identification of high redshift galaxies.

May 13, 2016 • Science stories

Why do galaxies stop forming stars?

This new study uses the COSMOS survey to measure the local environment (density) around galaxies at z < 3 and connects it to their star formation rates. The study suggests that the shutdown of star formation due to galaxies falling into dense environment (e.g., causing stripping and heating of gas) is dominant at z < 1. At higher redshifts, quenching of star formation is likely triggered by galaxy internal processes (feedback, etc).

April 23, 2016 • Science stories

SPLASH as precursor of JWST

A new paper by COSMOS member Andreas Faisst and team shows how to use Spitzer colors to derive emission line properties of 3 < z < 6 galaxies. Optical emission lines at z > 4 cannot be measured spectroscopically with current facilities. Since emission lines "contaminate" the Spitzer 3.6um and 4.5um channels, these can be used to estimate optical line emission without the need of spectra. The study of emission lines provides important information about galaxy formation in the early universe and also provides a sample of galaxies for future JWST follow-up. The ApJ paper is in print and can be retrieved here:

April 12, 2016 • Data and observation announcements

The COSMOS2015 catalog is now public!

The COSMOS2015 catalogue combines the >30 band photometry and SED fits (photometric redshifts, stellar masses, SFRs, etc) of half a million sources up to z=6 spread over the 2 square-degrees of COSMOS. In particular, it uses the new UltraVISTA images, as well as the Spitzer SPLASH photometry! The paper by Laigle et al. (2016) explaining the catalog can be found on the arXiv now: The catalog can be downloaded via anonymous FTP.

April 6, 2016 • Data and observation announcements

VUDS first Public Data Release paper available

The VIMOS Ultra Deep Survey (VUDS) is a deep spectroscopic survey targeting 10,000 galaxies in the redshift range 2

March 24, 2016 • Data and observation announcements

UltraVISTA DR3 imaging on COSMOS is public

UltraVISTA is an Ultra Deep, near-infrared survey with ESO's VISTA surveys telescope. Over the course of 5 years, UltraVISTA is imaging the COSMOS field in 5 bands (Y, J, H, Ks, NB118) and therefore represents a key survey on COSMOS. The 3rd data release (DR3) is now public and can be downloaded on the ESO archive web-page.

March 22, 2016 • Science stories

Feedback in action in a quasar at z=1.5

Winds and outflows of gas in quasars are thought to have a significant impact on their host galaxies. A group of researchers, led by COSMOS's Marcella Brusa, have mapped the kinematics of quasar XID5395, a merging luminous quasar at z=1.5. The team identified this curious object using extensive COSMOS multiwavength data. They then observed XID5395 with the Subaru telescope and the ESO/SINFONI spectrograph and found the quasar to be in a turbulent situation. Winds up to 1300km/s, induced by the nuclear activity, are sweeping the surrounding gas outwards. It is thought that this will halt, or 'quench', star formation in the host galaxy of the quasar. XID5395 gives us a rare opportunity to see strong feedback in action and to study how this phenomenon impacts the evolutionary pathways of galaxies. Click here to read more about this galaxy caught in its life-changing phase.

March 22, 2016 • Data and observation announcements

Final Data Release of zCOSMOS-bright Redshift Survey

zCOSMOS (PI Simon Lilly, ESO Large Programme 175.A-0839) is a large redshift survey undertaken in the COSMOS field using the VIMOS spectrograph. About 600 hours were awarded to this Large Programme, which was executed between 2005 and 2010. This new release completes the zCOSMOS-bright survey and includes 20689 wavelength calibrated 1-d spectra and associated 5×5 arcsecond image cut-outs for each target.

March 22, 2016 • Data and observation announcements

JCMT dedicates over 500 hours to deep submillimeter mapping in COSMOS

The James Clerk Maxwell Telescope, now owned and operated by the East Asian Core Observatories Association (EACOA) has recently announced its large legacy programs it will embark on between the end of 2015 to January of 2019, dedicating half of the observatory's time and resources through several collaborative large projects. Two of these projects focus on observations of the COSMOS field.

March 22, 2016 • Science stories

Rare galaxies provide clues on cluster formation

COSMOS researcher Caitlin Casey has found that the formation of the most massive structures in the Universe — clusters of galaxies — happened with a bang! This conclusion was reached after looking in detail at galaxy protoclusters - collections of galaxies in the early Universe that may eventually form a galaxy cluster.

January 15, 2016 • Other announcements

The official SPLASH webpage is online!

The official SPLASH webpage is online! Check it out:

December 3, 2015 • Data and observation announcements

14 nights at Keck to systematically measure the galaxy color-redshift relation

Members of the COSMOS team were recently awarded Keck time (10 nights through NASA and 4 nights through Caltech) to begin a program designed to systematically measure the galaxy color-redshift relation, in preparation for the upcoming dark energy missions WFIRST and Euclid.

November 25, 2015 • Other announcements

New exhibition by COSMOS Artist-in-Residence

The COSMOS Artist-in-Residence, Karel Nel, has recently exhibited his new works in London. The exhibition, named 'Observe', was partly inspired by results presented at the June 2015 COSMOS Team Meeting in Helsinki.

November 19, 2015 • Science stories

The Birth of Monsters

ESO’s VISTA survey telescope has spied a horde of previously hidden massive galaxies that existed when the Universe was in its infancy. By discovering and studying more of these galaxies than ever before, astronomers have, for the first time, found out exactly when such monster galaxies first appeared. Read the full press release here.

October 22, 2015 • Science stories

ALMA telescope unveils rapid formation of new stars in distant galaxies

Researchers have found that 'starburst' galaxies in the Universe 9 billion years ago were more efficient at forming stars than average galaxies today. 'Starburst' galaxies display unusually huge bursts of newly-formed stars and are likely caused by a collision between two large galaxies. A new study published in Astrophysical Journal letters on October 15, led by John Silverman at the Kavli Institute for the Physics and Mathematics of the Universe, has helped to understand exactly why such huge bursts of star formation occur. The researchers used the new, sensitive Atacama Large Millimeter Array (ALMA) in Chile to study carbon monoxide (CO) gas in seven starburst galaxies that existed when the Universe was only four billion years old. They found that the amount of CO gas in these galaxies is not special, but that these galaxies seem to be particularly efficient at turning their gas into stars. This study also relied on a variety of powerful telescopes available through the COSMOS survey, including the Spitzer Observatory, the Herschel Observatory and the Subaru Telescope.

August 18, 2015 • Other announcements

New resource available

A full list of narrow, intermediate and broad-band filters used by COSMOS is now available

August 18, 2015 • Other announcements

COSMOS Co-I Bahram Mobasher receives $4.5 million to encourage minorities in STEM

COSMOS Co-I Bahram Mobasher has received nearly $4.5 million from NASA to develop research, education, training and collaborative opportunities in big data and visualization at the University of California, Riverside.

July 13, 2015 • Science stories

A precocious black hole

A research team, led by ETH Zurich researcher Benny Trakhtenbrot, has discovered a gigantic black hole that is much more massive than we expect it to be.

June 25, 2015 • Science stories

Discovering a New Stage in the Galactic Lifecycle

CONFIRMED: Galaxies contained far less dust in the early stages of their evolution! Using ALMA, COSMOS team leader Peter Capak and collaborators picked up the signature of [CII] (emitted by gas) and continuum (emitted by dust) in nine 'normal' galaxies at redshift 5 to 6 - only 1 billion years after the Big Bang.

June 22, 2015 • Science stories

Detailed Shape and Evolutionary Behavior of the X-Ray Luminosity Function of Active Galactic Nuclei

We revealed the detailed shape and evolutionary behavior of the X-ray luminosity function of active galactic nuclei between 143 erg s-1. The two-break flat-top structures and overall downsizing is suggestive of a two-phase AGN evolution scenario, consisting of major merger triggerings and secular processes. Read the paper at

June 20, 2015 • Press releases

Measuring Galaxy Growth

June 15, 2015 • Press releases

Marching to the beat: Subaru’s FMOS reveals the well-orchestrated growth of massive galaxies in the early Universe

June 15, 2015 • Press releases

University of Hawaii Astronomer Helps Solve Massive Galaxy Mystery

June 14, 2015 • Press releases

Hubble Helps Solve Mystery of Ultra-Compact, Burned-Out Galaxies