Early evolution of galaxies and of large-scale structure from CMB experiments

Next generation CMB experiments with arcmin resolution will, for free, lay the foundations for a real breakthrough on the study of the early evolution of galaxies and galaxy clusters, thanks to the detection of large samples of strongly gravitationally lensed galaxies and of proto-clusters of dusty galaxies up to high redshifts. This has an enormous legacy value. High resolution follow-up of strongly lensed galaxies will allow the direct investigation of their structure and kinematics up to z~6, providing direct information on physical processes driving their evolution. Follow-up of proto-clusters will allow an observational validation of the formation history of the most massive dark matter halos up to z~4, well beyond the redshift range accessible via X-ray or SZ measurements. These experiments will also allow a giant leap forward in the determination of polarization properties of extragalactic sources, and will provide a complete census of cold dust available for star formation in the local universe.Comment: Science white paper submitted to the Astro2020 US Decadal Surve

Radio sources in next-generation CMB surveys

CMB surveys provide, for free, blindly selected samples of extragalactic radio sources at much higher frequencies than traditional radio surveys. Next-generation, ground-based CMB experiments with arcmin resolution at mm wavelengths will provide samples of thousands radio sources allowing the investigation of the evolutionary properties of blazar populations, the study of the earliest and latest stages of radio activity, the discovery of rare phenomena and of new transient sources and events. Space-borne experiments will extend to sub-mm wavelengths the determinations of the SEDs of many hundreds of blazars, in temperature and in polarization, allowing us to investigate the flow and the structure of relativistic jets close to their base, and the electron acceleration mechanisms. A real breakthrough will be achieved in the caracterization of the polarization properties. The first direct counts in polarization will be obtained, enabling a solid assessment of the extra-galactic source contamination of CMB maps and allowing us to understand structure and intensity of magnetic fields, particle densities and structures of emitting regions close to the base of the jet.Comment: Science white paper submitted to the Astro2020 US Decadal Surve

Extragalactic astrophysics with next-generation CMB experiments

Planck, SPT, and ACT surveys have clearly demonstrated that Cosmic Microwave Background (CMB) experiments, while optimized for cosmological measurements, have made important contributions to the field of extragalactic astrophysics in the last decade. Future CMB experiments have the potential to make even greater contributions. One example is the detection of high-z galaxies with extreme gravitational amplifications. The combination of flux boosting and of stretching of the images has allowed the investigation of the structure of galaxies at z ≃ 3 with the astounding spatial resolution of about 60 pc. Another example is the detection of proto-clusters of dusty galaxies at high z when they may not yet possess the hot intergalactic medium allowing their detection in X-rays or via the Sunyaev-Zeldovich effect. Next generation CMB experiments, like PICO, CORE, CMB-Bharat from space and Simons Observatory and CMB-S4 from the ground, will discover several thousands of strongly lensed galaxies out to z ~ 6 or more and of galaxy proto-clusters caught in the phase when their member galaxies where forming the bulk of their stars. They will also detect tens of thousands of local dusty galaxies and thousands of radio sources at least up to z ≃ 5. Moreover they will measure the polarized emission of thousands of radio sources and of dusty galaxies at mm/sub-mm wavelengths

Early evolution of galaxies and of large-scale structure from CMB experiments

Next generation CMB experiments with arcmin resolution will, for free, lay the foundations for a real breakthrough on the study of the early evolution of galaxies and galaxy clusters, thanks to the detection of large samples of strongly gravitationally lensed galaxies and of proto-clusters of dusty galaxies up to high redshifts. This has an enormous legacy value. High resolution follow-up of strongly lensed galaxies will allow the direct investigation of their structure and kinematics up to z~6, providing direct information on physical processes driving their evolution. Follow-up of proto-clusters will allow an observational validation of the formation history of the most massive dark matter halos up to z~4, well beyond the redshift range accessible via X-ray or SZ measurements. These experiments will also allow a giant leap forward in the determination of polarization properties of extragalactic sources, and will provide a complete census of cold dust available for star formation in the local universe

Radio sources in next-generation CMB surveys

CMB surveys provide, for free, blindly selected samples of extragalactic radio sources at much higher frequencies than traditional radio surveys. Next-generation, ground-based CMB experiments with arcmin resolution at mm wavelengths will provide samples of thousands radio sources allowing the investigation of the evolutionary properties of blazar populations, the study of the earliest and latest stages of radio activity, the discovery of rare phenomena and of new transient sources and events. Space-borne experiments will extend to sub-mm wavelengths the determinations of the SEDs of many hundreds of blazars, in temperature and in polarization, allowing us to investigate the flow and the structure of relativistic jets close to their base, and the electron acceleration mechanisms. A real breakthrough will be achieved in the caracterization of the polarization properties. The first direct counts in polarization will be obtained, enabling a solid assessment of the extra-galactic source contamination of CMB maps and allowing us to understand structure and intensity of magnetic fields, particle densities and structures of emitting regions close to the base of the jet

Modelling high-resolution ALMA observations of strongly lensed dusty star-forming galaxies detected by Herschel

We present modelling of ∼0.1 arcsec resolution Atacama Large Millimetre/submillimetre Array imaging of seven strong gravitationally lensed galaxies detected by the Herschel Space Observatory. Four of these systems are galaxy–galaxy strong lenses, with the remaining three being group-scale lenses. Through careful modelling of visibilities, we infer the mass profiles of the lensing galaxies and by determining the magnification factors, we investigate the intrinsic properties and morphologies of the lensed submillimetre sources. We find that these submillimetre sources all have ratios of star formation rate to dust mass that are consistent with, or in excess of, the mean ratio for high-redshift submillimetre galaxies and low redshift ultra-luminous infrared galaxies. Reconstructions of the background sources reveal that the majority of our sample display disturbed morphologies. The majority of our lens models have mass density slopes close to isothermal, but some systems show significant differences