What is the amount of baryonic dark matter in galaxies?

TL;DR

This paper challenges current dust models in galaxies, suggesting they underestimate baryonic dark matter by ignoring large particles and compact bodies, which could significantly alter galaxy mass estimates and dynamics.

Contribution

It highlights the importance of large dust particles and macroscopic bodies in baryonic dark matter, proposing they are more abundant than previously thought.

Findings

Dust models are incomplete and biased by assumptions.

Large particles and bodies are supported by observational evidence.

Baryonic dark matter could be an order of magnitude more abundant.

Abstract

In this paper, we re-evaluate the estimates of dust mass in galaxies and demonstrate that current dust models are incomplete and based on a priori assumptions. These models suffer from a circularity problem and account for only a small portion of dust, specifically submicron-sized grains. They overlook larger dust particles and other macroscopic bodies, despite observational evidence supporting their existence. This evidence includes the observed (sub)millimeter excess in dust emission spectra and the power-law size distribution with an index {\gamma} ~ 3.5-4.0, which has been measured for large particles and compact bodies across diverse environments. Examples of these large particles include large dust grains and meteoroids detected by satellites, near-Earth objects colliding with Earth, fragments in the Main Asteroid Belt and the Kuiper Belt, interstellar 'Oumuamua-like objects, and exoplanets. As a result, dust-type baryonic dark matter may be more abundant throughout the galaxy by one order of magnitude or even more than previously assumed, with a significant portion of its mass concentrated in large compact bodies. Additionally, black holes may contribute significantly to the total mass of baryonic dark matter. Consequently, current galaxy models do not provide reliable estimates of baryonic mass in galaxies. Clearly, a substantially larger amount of baryonic dark matter in galaxies would have major implications for theories of galaxy dynamics and evolution.