Observational manifestations of "cosmological dinosaurs'' at redshifts $z\sim20$

TL;DR

This paper investigates the observational signatures of massive primordial black holes, termed 'cosmological dinosaurs', at high redshift, focusing on their 21 cm line absorption features and implications for early universe studies.

Contribution

It introduces a model predicting specific 21 cm absorption signatures around primordial black holes at redshift ~20, linking spectral features to black hole mass and discussing detection methods.

Findings

Deep 21 cm absorption shells depend on black hole mass.

Spectral signatures are spherical and centered around black holes.

Detection strategies for 'cosmological dinosaurs' are proposed.

Abstract

We consider a primordial black hole of very high mass, $10^9-10^{10}M_\odot$, surrounded by dark matter and barionic halo at redshifts $z\sim20$ without any local sources of energy release. Such heavy and concentrated objects in the early universe were previously called ``cosmological dinosaurs''. Spectral distribution and spatial variation of the brightness in the 21 cm line of atomic hydrogen are calculated with the theory of radiation transfer. It is shown that a narrow and deep absorption arises in the form of the spherical shell around the primordial black hole at the certain radius. The parameters of this shell depend almost exclusively on the mass of the black hole. The hardware and methodological aspects of the search for such objects are discussed.