CMB-HD: An Ultra-Deep, High-Resolution Millimeter-Wave Survey Over Half the Sky

Abstract

A millimeter-wave survey over half the sky, that spans frequencies in the range of 30 to 350 GHz, and that is both an order of magnitude deeper and of higher-resolution than currently funded surveys would yield an enormous gain in understanding of both fundamental physics and astrophysics. By providing such a deep, high-resolution millimeter-wave survey (about 0.5 µKarcmin noise and 15 arcsecond resolution at 150 GHz), CMB-HD will enable major advances. It will allow 1.) the use of gravitational lensing of the primordial microwave background to map the distribution of matter on small scales (k ∼ 10 hMpc −1 ), which probes dark matter particle properties. It will also allow 2.) measurements of the thermal and kinetic Sunyaev-Zel'dovich effects on small scales to map the gas density and gas pressure profiles of halos over a wide field, which probes galaxy evolution and cluster astrophysics. In addition, CMB-HD would allow us to cross critical thresholds in fundamental physics: 3.) ruling out or detecting any new, light (< 0.1 eV), thermal particles, which could potentially be the dark matter, and 4.) testing a wide class of multi-field models that could explain an epoch of inflation in the early Universe. Such a survey would also 5.) monitor the transient sky by mapping the full observing region every few days, which opens a new window on gamma-ray bursts, novae, fast radio bursts, and variable active galactic nuclei. Moreover, CMB-HD would 6.) provide a census of planets, dwarf planets, and asteroids in the outer Solar System, and 7.) enable the detection of exo-Oort clouds around other solar systems, shedding light on planet formation. The combination of CMB-HD with contemporary ground and space-based experiments will also provide powerful synergies. CMB-HD will deliver this survey in 5 years of observing 20,000 square degrees, using two new 30-meter-class off-axis cross-Dragone telescopes to be located at Cerro Toco in the Atacama Desert. The telescopes will field about 2.4 million detectors (600,000 pixels) in total. The CMB-HD survey will be made publicly available, with usability and accessibility a priority.

Emulating Sunyaev-Zeldovich Images of Galaxy Clusters using Auto-Encoders

“…The upcoming CMB-S4 (Abazajian et al 2016), Simons Observatory (Ade et al 2019), and CMB-HD (Sehgal et al 2019) surveys will provide us with a wealth of new, high-resolution SZ maps of hundreds of thousands of clusters (Raghunathan et al 2021). In order to maximize the scientific return of these observations, we need to simulate a similar number of clusters to achieve the required statistics while controlling the systematic uncertainties of baryonic physics and mass accretion history.…”

Polarization of the Cosmic Infrared Background Fluctuations

“…Future high sensitivity and high resolution (HSHR) CMB experiments (Abazajian et al 2019;Sehgal et al 2019;Galitzki et al 2018;Benson et al 2014) will enter a new era when the CMB will be measured at very small and even nonlinear scales with unprecedented precision, and the secondary CMB changf@illinois.edu fluctuations -radio galaxies, the thermal/kinetic Sunyaev-Zel'dovich (tSZ/kSZ) effects and the cosmic infrared background (CIB) -will be precisely measured. As one of the precursors to the HSHR experiments, the SPT collaboration analyzed 2500 deg 2 data taken at 90, 150 and 220 GHz and found that the CIB emission due to the dusty star-forming galaxies is much stronger than the tSZ and kSZ at scales smaller than 4 (George et al 2015).…”

Voyage through the Hidden Physics of the Cosmic Web

“…In the coming two decades, projects such as CMB-S4 (Abazajian et al, 2019), the Simons Observatory (The Simons Observatory Collaboration et al, 2019), andLiteBIRD (Hazumi et al, 2019) will build up our knowledge of massive halos from the SZ effect and push the investigation of the millimetre CMB sky a step further. Beyond the 2030s, a high resolution, high sensitivity large millimetre telescope such as the AtLAST (Klaassen et al, 2019) and CMB-HD (Sehgal et al, 2019) concepts would bring opportunities that complement spectroscopic X-ray measurements. These features, generalised to a survey over a large area of the sky, would lead to a wealth of constraints on the thermodynamical properties (via the thermal and relativistic SZ effects), the peculiar motions (via the kinetic SZ effect) or the mass (via CMB lensing) of large scale structures.…”