What's the relation between the mass of galaxies and their rate for star formation? The new paper by Sarah Leslie and collaborators measures this relation for 200,000 galaxies in the COSMOS field.
This relation between rate of star formation (SFR) and mass is called the main-sequence. It is observed across a large amount of cosmic time (redshifts). The paper by Leslie et al. provides a coherent measurement of this main-sequence up to redshift of 5 (about 13 billion years in the past). To do this, they use mean stacks of 3 GHz radio-continuum images to derive average SFRs for ∼ 200,000 mass-selected galaxies.
Check out her YouTube video explaining her paper: https://www.youtube.com/watch?v=tMNp4qXp0FM
Galaxy groups and clusters are important systems for cosmology and galaxy evolution. The COSMOS survey has offered a unique data set to study the evolution of galaxy groups and clusters as well as their constituent galaxies.
In the latest contribution to this project, Dr. Gozaliasl and his collaborators provide a catalog of X-ray selected groups and clusters based on XMM and deep Chandra observations which offer an unprecedented spatial resolution in X-ray.
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).
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!
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.
Galaxies in the early Universe (< 2 billion years after the Big Bang or <10% of the current age of the Universe) experience a rapid growth in stellar mass. This goes along with a rapid evolution of their inter-stellar medium properties and physical structure. The mechanisms and physics that lead to this short early growth phase are mostly unknown. We got 70h on the Atacama Large (Sub-) Millimeter Array (ALMA) to study the gas and dust properties of young galaxies during the early growth phase to address these questions.
Greetings from Manchester! Several COSMOS team members are here at the UK ARC node ALMA regional centre this week attending the 'Measuring Star Formation in the Radio, Millimetre and Submillimetre' workshop. We're asking questions like: What is the best way to measure star formation in galaxies? What are the biases involved in our measurements and how can we overcome them? What kind of observations and telescopes do we need in the future to achieve this? We're already well on the way with amazing telescopes like ALMA, JVLA and Herschel and we look forward to the future with JWST, SKA and beyond!
The dust properties of infant galaxies
This new study uses the Hubble Space Telescope (HST) to characterize the dust properties of 10 galaxies living 12 billion years in the past. The new HST imaging data together with existing optical and ALMA (far-infrared) observations on COSMOS allowed the authors to measure the ultra-violet properties of these galaxies more accurately than ever. It turns out that these young galaxies have similar dust properties as the Small Magellanic Cloud, which is a metal-poor dwarf galaxy orbiting around our Milky Way.
Interested? - Read the whole paper: http://adsabs.harvard.edu/abs/2017arXiv170702980B
The annual COSMOS team meeting is over for another year! This was the 14th meeting and was held on the 4-7th July at the University of Kyoto in Japan. More than 70 team members from all over Europe, North America and Asia attended the meeting. We heard the latest updates on new data and data products available and new surveys underway, planned exciting future endeavours, and discussed our work on a wide range of science topics including galaxy evolution, the high redshift Universe, large scale structure, active galactic nuclei and the interplay between infrared and radio light. The local organisers did a fantastic job preparing for the week and the meeting was a great success enjoyed by all. We thank them again for all their efforts. We are already looking forward to next year's meeting in Copenhagen! Click below to read more.
COSMOS founder Nick Scoville has been awarded the 2017 Catherine Wolfe Bruce Gold Medal — an honor bestowed by the Astronomical Society of the Pacific (ASP) since 1898 for "a lifetime of outstanding research in astronomy." The COSMOS team would like to congratulate Nick on this well deserved award.
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!
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.
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.
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: https://cosmos.phys.sci.ehime-u.ac.jp/meeting2017/
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.
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.
Local density field, cosmic web environment, and galaxy type measurements for COSMOS galaxies are now available for download.
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: http://adsabs.harvard.edu/abs/2017A%26A...597A...4S
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.
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.
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.
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.
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.
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.
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).
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: http://stacks.iop.org/0004-637X/821/122
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: http://arxiv.org/abs/1604.02350 The catalog can be downloaded via anonymous FTP.
The VIMOS Ultra Deep Survey (VUDS) is a deep spectroscopic survey targeting 10,000 galaxies in the redshift range 2
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.
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.
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.
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.
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.
The official SPLASH webpage is online! Check it out: http://splash.caltech.edu
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.
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.
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.
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.
A full list of narrow, intermediate and broad-band filters used by COSMOS is now available
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.
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.
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.
We revealed the detailed shape and evolutionary behavior of the X-ray luminosity function of active galactic nuclei between 1