Current spotlights

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 24, 2017 • Current spotlights

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 • Current spotlights

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.

January 26, 2017 • Current spotlights

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: