The Science Questions That Drive the CMB-HD Project

Science Questions that Drive CMB-HD

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What is the distribution of matter on small scales?

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What are the particle properties of dark matter?

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How did gas evolve in and around dark matter halos?

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How did galaxies form?

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Do new light particles exist that were in equilibrium with known particles in the early Universe?

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Do axion-like particles exist?

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Do primordial gravitational waves exist from an epoch of inflation?

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If inflation happened, did it arise from multiple or a single new field?

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What is the census of bodies in the outer Solar System?

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Do Oort clouds exist around other stars?

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What is the physics behind the various bright transient phenomena in the sky?

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What are the population distributions of star-forming galaxies and active galactic nuclei?

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Was the early Universe magnetized and did that provide the seeds of galactic magnetic fields?

Specific CMB-HD Science Objectives

1. Measure the small-scale matter power spectrum from weak gravitational lensing using the CMB as a backlight; with this...

2. Measure the number of light particle species that were in thermal equilibrium with the known standard-model particles at...

3. Measure the primordial non-Gaussian fluctuations in the CMB, characterized by the parameter fNL, with an uncertainty of...

4. Remove 90% of the CMB B-mode fluctuations from gravitational lensing over half the sky, leaving only 10% remaining...

5. Separately measure the density, pressure, temperature, and velocity profiles of intrahalo gas, as a function of halo mass and...

6. Probe the gas physics in and around halos out to z ∼ 2 and with masses below 1012 M⊙, by stacking low-mass and...

7. Detect dwarf-size planets in our Solar System hundreds of AU from the Sun, and Earth-sized planets thousands of...

8. Detect exo-Oort clouds around other stars, opening a new window on planetary studies. Advance the study of debris disks around large stellar populations.

9. Survey half the sky with roughly daily cadence, and make daily maps with a noise sensitivity of 1 mJy at 150 GHz...

10. Obtain a catalog of high-redshift dusty star-forming galaxies and active galactic nuclei down to a flux limit of 0.5 mJy at 150 GHz...

11. Probe the existence of primordial magnetic fields (PMFs) to find evidence for magnetogenesis in the early Universe...

12. Constrain or discover axion-like particles by observing the resonant conversion of CMB photons into axions in the magnetic...


Sehgal, N et al, CMB-HD:
Astro2020 RFI Response, Feb 2020,