Conveners
New Horizons in Cosmology with CMB Spectral Distortions: Block 1
- Jens Chluba (JBCA)
- Andrea Ravenni (Jodrell Bank Centre for Astrophysics, University of Manchester)
New Horizons in Cosmology with CMB Spectral Distortions: Block 2
- Andrea Ravenni (Jodrell Bank Centre for Astrophysics, University of Manchester)
- Jens Chluba (JBCA)
Description
The study of cosmic microwave background (CMB) has revolutionized Cosmology as a whole, granting us a fine and quantitative understanding of how our Universe works. In the upcoming years, precision spectroscopy, possible with existing technology, can give us access to a new dimension in CMB studies. Measurements of the small departures of the CMB energy spectrum from a perfect black-body — called CMB spectral distortions (SD) — will further our understanding of recombination, reionization and structure formation as well as dark matter and particle physics.
This session is meant to trace a path from the experimental prospect to new theoretical investigations that can make the most of precise SD measurements, bringing together experts in theory and observation. From the experimental point of view we aim at providing an overview of the observational projects that are currently being discussed — ranging from ground to lunar and to space ones — alongside a discussion about the challenges that will have to be faced and how to best address them. From the theoretical point of view the program will include review talks on the state-of-the art of SD science, with special attention to new directions that could provide the starting point for new studies.
Abstract not provided.
I will review the current status of primordial black holes and their relation with spectral distortions.
We propose that the free-free spectrum in the CMB frequency range provides the constraint on the dark matter halo formation in the early universe
and the density fluctuations on small scales.
When dark matter halos form, gas in the dark matter halos can be heated
and ionized depending on their virial temperature.
Although such hot ionized gas is cooled and recombined to the neutral state...
Photons propagating through the Universe acquire the effective mass that depends on the local density of free charges. This means that if a light new particle that mixes with photons (e.g. dark photon or axions) exists in Nature, photons can be resonantly converted into such particles at numerous places along a typical line of sight. In particular, this can result in specific distortions both...
Cosmic Microwave Background (CMB) is a powerful probe to the Universe which carries signatures of cosmic secrets over a vast range of redshifts. Along with spatial fluctuations, spectral distortions of CMB blackbody are also a rich source of cosmological information. In my talk, I will introduce a new kind of spectral distortion of CMB which can arise due to the conversion of CMB photons into...
CMB spectral distortions is one of the cleanest probe for electromagnetic energy injection scenarios in the pre-recombination universe. Energy injection without the addition of extra photons gives rise to CMB spectral distortion below z<2*10^6 due to inefficiency of photon non-conserving processes. During this epoch, Compton scattering is the dominant process which drives the evolution of...
The thermal Sunyaev-Zeldovich (tSZ) effect is produced by the inverse Compton scattering of cosmic microwave background (CMB) photons by hot electrons, particularly in galaxies clusters. It has been used as a powerful probe to constrain the cosmological parameters, given its particular sensitivity to sigma8 and omega_m.
We present a new all-sky tSZ map constructed from the latest Planck PR4...
We investigate the combined effect of cosmic magnetic field and a possible non-standard interaction between baryons and dark matter (DM) on the thermal Sunyaev−Zel’dovich (tSZ) effect which depends on the temperature and the ionization state of the intergalactic medium. The drag force between the baryons and DM due to the relative velocity between them, and their temperature difference results...
We propose a new method for probing inflationary models of primordial black hole (PBH) production, using only CMB physics at relatively large scales. In these scenarios, the primordial power spectrum profile for curvature perturbations is characterized by a pronounced dip, followed by a rapid growth towards small scales, leading to a peak responsible for PBH formation. We focus on scales...
The dissipation of primordial perturbation modes with wavenumbers $50\,{\rm Mpc}^{-1} < k < 10^4 \,{\rm Mpc}^{-1}$ in the early Universe cause $\mu$-type spectral distortions to the average CMB blackbody radiation. Besides, some inflation scenarios (multi-field or single-field inflation with modified initial state) predict large primordial non-Gaussianity at these scales, so that non-Gaussian...
I will discuss the science case for a sensitive spectro-polarimetric survey of the microwave sky. Such a survey would provide a tomographic and dynamic census of the three-dimensional distribution of hot gas, velocity flows, early metals, dust, and mass distribution in the entire Hubble volume. It would also exploit CMB temperature and polarisation anisotropies down to fundamental limits, and...
The cosmic microwave background (CMB) acts as a backlight to the entire observable universe, and the ideas for using its distortion signatures, imprinted upon by the intervening large-scale structure, are an endless source of astrophysical probes that are limited only by our experimental reach. I review some of the ideas collected while responding to ESA's Voyage 2050 proposal call,...
The COSmic Monopole Observer (COSMO) is an experiment to measure spectral distortions of the Cosmic Microwave Background (CMB). Deviations from a pure blackbody spectrum are expected at low level (< 1 ppm) due to several astrophysical and cosmological phenomena, and promise to provide important independent information on the early and late phases of the universe. They have never been detected...
Spectral distortions (SDs) of the cosmic microwave background (CMB) provide a powerful tool for studying particle physics. We study the distortion signals from decaying particles that convert directly into photons at different epochs during cosmic history, focusing on injection energies Einj ≲ 20 keV. We consider the effect of blackbody-induced stimulated decay, which can modify the injection...
Current measurements of the CMB anisotropies have given us unprecedented precision surrounding the standard ΛCDM model of cosmology and the parameters that make up this model. The data accrued by collaborations like Planck have even allowed us to test additional models of fundamental physics. These models have grown more recently in the context of diluting the tension between low-redshift and...
Although both early and late-time modifications of the ΛCDM model have been proposed to address the Hubble tension, compelling arguments suggest that for a solution to be successful it needs to modify the expansion history of the universe prior to recombination. This greatly increases the importance of precise CMB observations, and in this talk I will make the argument for CMB spectral...
Possible interactions of dark matter (DM) with Standard Model (SM) particles can be tested with spectral distortions of the cosmic microwave background (CMB). In particular, a non-relativistic DM particle that scatters elastically with photons, electrons or nuclei imprints a negative chemical potential μ to the CMB spectrum, as I will explain in this talk. I will show how this effect can be...
With the success of the ESA Planck mission, the concordance cosmological models is established as the reference framework. However, outstanding questions about this model are still unanswered. In particular the simplest inflationary model proposed as the origin of the initial matter perturbations is favoured by Planck measurement of the spectral index and low non-Gaussianity. Nevertheless, it...
