Conveners
The Nature of Galactic Halos: Block 1
- Francesco De Paolis
- Asghar Qadir (None)
Description
By the rotation curves of spiral galaxies, the X-ray emission of ellipticals and the dynamics of the galaxy clusters, we know that there is much more matter in the outer reaches of these systems than is accounted for by visible matter, including gas and dust. Even this is confirmed by the primordial nucleosynthesis and CMB observations, we also know that there is much more baryonic matter than that accounted for in the above forms. This is the so-called "missing baryon problem". It is important, then, to accurately determine the content and nature of the galactic halos and try to "see" the halos by alternate means. That will be the purpose of this session.
A complete census of baryons in the late universe is a long-standing challenge due to the intermediate temperate and rarefied character of the majority of cosmic gas. To gain insight into this problem, we extract measurements of the kinematic Sunyaev-Zel'dovich (kSZ) effect from the cross-correlation of angular redshift fluctuations, a novel probe that contains precise information about the...
Recently, a diffuse emission of 1-100 GeV gamma-rays has been detected from the direction of M31, extending up to ~ 200 kpc from its center.
The interpretation of the extended gamma-ray emission by the escape of cosmic rays produced in the galactic disk or in the galactic center is problematic.
Here we argue that a cosmic ray origin (either leptonic or hadronic) of the gamma-ray emission...
There has recently been interest in Primordial Black Holes (PBHs) as a dark matter (DM) candidate. Constraints on the PBH abundance is obtained through lensing, accretion, dynamical effects and also the analysis of the gravitational wave (GW) events. PBHs may exist and populate today the galactic halos with a wide mass range, from about 10-14MSun up to thousands, or more, of solar masses....
Intermediate Mass Black Holes (IMBHs) are a class of black holes with masses in the range 10^2-10^5 solar masses, which can not directly derive from stellar evolution. Looking for these objects and estimating their abundance is important for understanding the nature and distribution of the Dark Matter in the galactic halo. Since February 2018 to January 2020 the LMC and SMC have been...
The detailed analysis of Planck CMB data has shown the presence of temperature asymmetries towards the halos of several spiral galaxies. This is probably due to the rotation of cold clouds (which we called" virial clouds ") present in the halos, that rotate about the rotational axis of the galaxies. It had been proposed that these are pure hydrogen clouds that should be in equilibrium with...
Instead of appealing to dark matter to explain the flat rotation curves of galaxies, it had been proposed that the law of gravitation should be modified. However, the idea had been to modify Newton's law. Harko et al. (Phys. Rev. D 84 (2011) 024020) suggested that modified gravity be used. Qadir, Lee and Kim (Int. J. Mod. Phys. D 26 (2017) 1741001) had proposed a modification of the...
