One of the most interesting findings of recent ALMA [CII]158um galaxy surveys (e.g. ALPINE, REBELS, CRISTAL) has been the clear presence of extended [CII] line emission among massive star-forming galaxies at z=4-6, beyond the rest-frame UV and dust continuum emission and extending out to ~10-kpc. Despite being key to understanding the interplay between star formation activity and feedback processes in the circumgalactic medium (CGM), the origin of such [CII] “halos’’ remains enigmatic. We have started a comprehensive program, titled “Origin of the [CII] Halos in Distant Systems” (ORCHIDS), aiming to unravel the nature of these extended [CII] features. Leveraging the capabilities of JWST/NIRSpec and Keck/KCRM IFU observations, through our awarded JWST GO3 program (ID: 5974; PI: M. Aravena, co-PI: J. González-López), we will scrutinize a carefully selected sample of eight massive star-forming galaxies at redshifts z~5-6. Our targets have been recently confirmed to exhibit [CII] halos through high-resolution ALMA imaging from the CRISTAL survey. Our observations are designed to rigorously test the most plausible scenarios predicting the nature of [CII] halos. These observations will yield a full characterization of the baryonic cycle in these systems, yielding a unique probe of (i) the kinematics and distribution of the star formation and ionized gas, enabling us to discern outflows, multiple component systems and extended dense atomic and ionized gas in the CGM as the origin for [CII] halos (JWST/NIRSpec + Keck/KCRM); (ii) test associations with Lyman-alpha halos/blobs; (iii) the galaxies’ gas excitation and shocks (JWST/NIRSpec); and (iv) provide resolved measurements of various star-forming tracers.

The COSMOS High-z ALMA-MIRI Population Survey (CHAMPS; PI: A. Faisst, co-PI: M. Aravena et al.) is an ALMA large program in Cycle 11 that will obtain a 0.18 deg2 blank-field survey at 1.1mm in the COSMOS field, covering 3x the area of existing ALMA surveys, to push our understanding of the dusty Universe. ALMA CHAMPS complements deep, high-resolution MIRI and NIRCam observations from two JWST Cycle 1 programs with essential sub-mm observations. This will enable us to construct UV-FIR multiwavelength SEDs of ~30,000 MIRI-detected sources, including ~1200 bright, dusty sources directly detected with ALMA out to z~6, and additional ~120,000 sources with NIRCam-only detections from stacking. With this large area, we will find dusty high-z galaxies and provide limits to sub-mm properties of fainter sources via stacking. This program provides a unique opportunity to combine cutting-edge multiwavelength data to robustly measure the amount of obscured star formation across cosmic time, and the evolution of the dust and gas properties of galaxies and AGN.

At IEA- UDP, we are focused on the study of the ~100s CO line emitters expected in CHAMPS, their characterization, and measurements of the CO luminosity function and evolution of the cosmic molecular gas density.

ASPECS represents one of the first systematics efforts to conduct a 3-dimensional mapping of the best studied cosmological deep field: the Hubble Ultra Deep field (HUDF). ASPECS constitutes a molecular deep field, obtained by scanning the full ALMA bands 3 and 6 (3mm and 1mm bands, respectively) over a significant area of this field. Thereby, blind searches for molecular line (CO/CII) and dust continuum emission can be done. We performed a pilot project by imaging a 1 arcmin^2 region, resulting in 7 high impact peer-reviewed publications. We were awarded an ALMA large program (the 1st extragalactic large program) to expand our pilot project to an area 5x larger, effectively covering what has been called the "eXtremely Deep Field" (XDF). ASPECS has had a critical legacy value in view of future efforts with JWST, etc. We are working on similar efforts in other deep fields like the COLDz project M. Aravena is a co-leading the ASPECS project together with F. Walter (MPIA), C. Carilli (NRAO) and R. Decarli (INAF/Bologna). 

For more info and visuals,  go to: http://www.aspecs.info

Over the last decade, we have conducted intensive campaigns to study starbursting submillimeter galaxies (SMGs; or DSFGs) in the COSMOS field. This region of the sky has some of the deepest and most complete multi-wavelength observations allowing for precise studies of galaxy formation and evolution of this enigmatic population of galaxies, which is being revolutionized with observations from the COSMOS-Webb project. SMGs are typically discovered in large surveys of the sky, with single-dish telescope/bolometer surveys with relatively poor angular resolution. To identify their actual location and counterpart in optical/near-infrared images, we have performed higher angular observations with the Plateau de Bureau Interferometer (PdBI; now NOEMA) and ALMA at (sub)millimeter wavelengths. Their identifications enable us to study their actual properties like the star formation rates, stellar masses, sizes, etc. For a few interesting objects, we have obtained detailed follow-up observations with ALMA, VLT/MUSE, Magellan, etc, to characterize their properties further. Additionally, we have pushed for the detection of the most distant SMGs, conducting ALMA deep field observations at 2-mm wavelength, which preferentially select more distant objects, through the MORA and exMORA projects. 

Several of these galaxies are found to be clustered in small groups of SMGs, resembling the early formation of the most massive galaxies in the Universe. This project has been ongoing with close collaboration with C. Casey (U. Texas at Austin), A. Long (U. Texas A&M), V. Smolcic (Uni. Zagreb), D. Riechers (U. Cornell), L. Guaita (UNAB, Chile), D. Brisbin (ex UDP-postdoc; now ALMA JAO), O. Miettinen (U. Zagreb) and many others.

The CONCERTO (CarbON CII line in post-rEionisation and ReionisaTiOn epoch) instrument is a low-resolution spectrometer based on the lumped element kinetic inductance detectors (LEKID) technology. It has large-field-of-view and operates in the range between 130 – 310 GHz. CONCERTO’s Principal Investigator is Guilaine Lagache from the Laboratoire d’Astrophysique de Marseille (France) and the Instrument Scientist is Alessandro Monfardini from Institut Néel (France). 

We are conducting a key survey of about 1.4 sq. deg. in the COSMOS field with CONCERTO. We aim to map the 3D fluctuations of the [CII] line intensity through the cosmic reionization epoch. For this, our survey will exploit a technique known as “intensity mapping” which probes cosmic structures by measuring the aggregate line emission from all galaxies across redshift. The [CII] line is a promising choice for its brightness and its role as a tracer of star-formation activity. Our survey will give the first constraints on the power spectrum of [CII]- emitting galaxies at z ≥ 5 (see Figure 3), allowing us to measure : (i) the typical halo mass scale of star-forming galaxies, (ii) the star formation rate density, (iii) the number counts of [CII]-emitters, (iv) the average ISM conditions in high- z galaxies. Our survey also measures the CO and [CI] intensity fluctuations arising from z ≤ 2.5 galaxies, yielding (v) the spatial distribution and abundance of molecular gas at cosmic noon. Cross-correlation with multi-wavelength data (e.g. LAE, LBGs) will provide (vi) additional astrophysical information, as on early metal enrichment and global history of reionization. M. Aravena is co-PI of the CONCERTO survey in COSMOS (PI: G. Lagache), and we aim to focus in points (iv)-(vi) above. This work is done in collaboration with G. Lagache (Marseille),  A. Beelen (Marseille), C. De Breuck (ESO), E. Ibar (U. Valparaiso),  and the CONCERTO team.