Projects and Collaborations
The interest and work of our group divides into two broad science areas: the evolution of galaxies, and the observation of galaxy clusters through the Sunyaev-Zel'dovich (SZ) effect. Furthermore, we support the ALMA operations and its users through our ALMA Regional Center (ARC) node at Bonn/Cologne, we operate (with partners) the NANTEN2 submillimeter telescope in Chile, and we participate in the construction of the CCAT-prime submillimeter telescope.
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COSMOS
The galaxy evolution group at AIfA holds an active collaboration with the Cosmic Evolution Survey (COSMOS), is a member of the VLA COSMOS European core team and has international, non-COSMOS related collaborations which are described below. Synergies with other wavelengths include the 2 millimetre observations of the COSMOS field with the GISMO survey (B. Magnelli, et al.). With the the 'A3COSMOS' project, we harvest the ALMA archive to create a spotty, deep survey of the COSMOS field.
At X-rays, we investigate the effects of large-scale environment on radio AGN using the X-ray groups in COSMOS and search for radio/X-ray coincidence of non-thermal radio emission from AGN, which can be used for predictions of upcoming X-ray surveys (E. Vardoulaki, in collaboration with Finoguenov, Gozaliasl, Delvecchio et al.). In the far-IR we mined the ALMA archive to study sub-mm sources in COSMOS, amongst others (A^3-COSMOS; Liu, Magnelli, Schinnerer, Bertoldi, Lang, Leslie, Jimenez Andrade, Vardoulaki et al.). Finally in the infrared we investigate the well known relation between infrared and radio emission in galaxies using COSMOS sources (Molnar, Leslie, Vardoulaki, Sargent, Schinnerer, Smolcic, Magnelli, Bertoldi, et al.).
Besides the COSMOS collaboration, researchers from the galaxy evolution group at AIfA are leading and are active members of several international projects. These include statistical studies of local galaxies regarding the linearity of IR/radio relation in the local universe (Molnar, Leslie, Vardoulaki, Sargent, Schinnerer, Smolčić, Magnelli, Bertoldi, et al.), and high-redshift studies of sub-mm galaxies using gravitational lensed sources (K. Harrington, PhD project), as well as the Mustang 3mm survey towards GOOD-N field with GBT (B. Magnelli et al.). Finally, researchers in AIfA are actively involved in the international collaboration of the Evolutionary Map of the Universe (EMU) survey (E. Vardoulaki: development, classification and radio galaxy zoo).
High Redshift Quasars
We study the condition and impact of star-formation in galaxies at the cosmic epoch when galaxies assembled and most stars in the universe formed. Through observations of prominent molecular and atomic spectral lines, we unveil the detailed structures, dynamics and conditions of the interstellar medium of distant and super-average star-forming galaxies.
We also measure the star formation activity, gas content and distribution in representative samples of star-forming galaxies, using deep continuum interferometric observations. Looking ahead, we hope to use our novel sub-mm telescope CCAT-prime, exploiting its unique capability to study the impact of environment on the star-forming activity of high-redshift galaxies.
Millimeter Galaxy Surveys
We lead and assist new millimeter wavelength blank field surveys to explore the formation history and properties of the highest redshift star-forming galaxies. Surveys at longer wavelength are known to find SMG at higher mean redshift than the shorter wavelength sub-mm surveys. We led an ambitious 2mm survey covering a significant fraction of the COSMOS field using GISMO at the IRAM-30m. We discovered 12 sources that suggest a 2 mm selection function with a median redshift of z ∼ 4 (Magnelli et al., in prep.), while prior SMG samples have median z ∼ 2.3. We discovered 12 sources that suggests a 2 mm selection function with a median redshift of z∼4, while prior SMG samples have median z ∼ 2.3.
We also led a 3 mm survey towards the entire GOODS-N field using 25 hours of MUSTANG-2 at the GBT, for which observations are completed and the data reduction is ongoing. We have also been involved in a deep 1.1 mm survey of the GOODS-S field using ALMA. This survey is the deepest over such large area made to date by ALMA. It contains massive galaxies (M∗ > 1011M⊙) with a median redshift of ∼2.9, yet their star formation rates are lower than those of classic SMGs, probing for the first time at mm wavelengths the bulk of the z ∼ 3 SFG population.
We have also been participating in large NOEMA and ALMA deep spectroscopic surveys lead by Fabian Walter and our former CRC student Manuel Aravena.
We plan to continue this efforts by “creating” surveys from the ALMA archive and preparing observations with CCAT-prime.
ALMA Archive Mining (A3COSMOS)
A3COSMOS is a joint project between our research group and that led by E. Schinnerer at the Max-Planck-Institut für Astronomie (MPIA). Its goal is the full exploration of the ALMA observations toward millions of galaxies in the COSMOS two square degree field. ALMA is the most powerful and sensitive (sub-)millimeter interferometer array, but its small field of view (~30") makes dedicated large-area surveys very expensive, in fact too expensive for the large samples of galaxies needed to properly understand galaxy evolution throughout cosmic history. Fortunately, through many individual Principal Investigators (PI) observations, ALMA has by now deeply mapped a significant area of some popular extra-galactic survey fields, such as the COSMOS field.
The goal of our A3COSMOS project has been to exploit the ALMA science archive to assemble albeit spotty, but deep (sub)millimeter survey of the COSMOS field. Our carefully and uniformly reduced database is provided to the COSMOS collaboration and the larger astronomy community. It can be used to study the formation of galaxies by measuring their star formation and interstellar medium properties, or performing 'blind' CO and [CII] line searches.
To assemble this database, we developed an automatic tool to query, retrieve and image the ALMA archive. The MPIA group developed a pipeline to perform the source extraction within these images and cross-match those with the wealth of panchromatic observations available in the COSMOS field. Our database, which we update annually, currently covers an area of about 520 square arcmin including 2500 galaxies detected with ALMA. This unique sample allows us to pursue a number of exciting studies.
Recently, we extended A3COSMOS to include ALMA observations from the GOODS-South field, which is another extra-galactic survey field with plenty of panchromatic data. GOODS-South spans 10 by 16 arcmin, and along the multitude of individual ALMA pointings, it includes several ALMA blind surveys, adding up to about 150 square arcmin of area including 800 galaxies.
ALMA Regional Centre
As a novel, high-tech observatory, ALMA challenges users with a high level of complexity in planning and data analysis. Therefore, it was decided early-on in the project that ALMA should provide high-level user support and deliver science-ready data product, allowing astronomers from various backgrounds to benefit from its exquisite capabilities. These services are now provided by the ALMA Regional Centers (ARC) of each of the three partners (ESO, NRAO, NAOJ).
The European ARC, coordinated by ESO, consists of ARC nodes located across Europe. The German ARC node is hosted by our group together with the group of Prof. Peter Schilke at the University of Cologne. We assist users in the preparation of their proposals, we ensure that the observed data meet the scientific goals, and we provide help with the calibration of their data. We are also dedicated to training and teaching radioastronomy and interferometry basics and higher level ALMA techniques.
Naturally, our group benefits from the local expertise in our research activities. In particular, we developed an automatic tool to exploit the capabilities of the ALMA Archive in for extragalactic deep field surveys.
Please visit our German ARC node page.
LEGO ALMA
A description of the working principles of our LEGO model of the ALMA Radiointerferometre can be found here. It has been used in the past at a variety of public events, such as with school children or on invitation at ministry open days.