Evaporation of Primordial Black Holes in the Early Universe: Mass and Spin Distributions

Andrew Cheek Many cosmological phenomena lead to the production of primordial black holes in the early Universe. These phenomena often create a population of black holes with extended mass and spin distributions. As these black holes evaporate via Hawking radiation, they can modify various cosmological observables, lead to the production of dark matter, modify the number of effective relativistic degrees of freedom, $N_{\rm eff}$, source a stochastic gravitational wave background and alter the dynamics of baryogenesis.

Evidence for AGN-Regulated Cooling in Clusters at $z \sim 1.4$: A Multi-Wavelength View of SPT-CL J0607-4448

First author: Megan Masterson We present a multi-wavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607), which is one of the most distant clusters discovered by the South Pole Telescope (SPT) at $z=1.4010\pm0.0028$. The high-redshift cluster shows clear signs of being relaxed with well-regulated feedback from the active galactic nucleus (AGN) in the brightest cluster galaxy (BCG). Using Chandra X-ray data, we construct thermodynamic profiles and determine the properties of the intracluster medium.

f(T) cosmology against the cosmographic method: A new study using mock and observational data

First author: M. Sabiee In this paper, we study the power-law $f(T)$ model using Hubble diagrams of type Ia supernovae (SNIa), quasars (QSOs), Gamma Ray Bursts (GRBs) and the measurements from baryonic acoustic oscillations (BAO) in the framework of the cosmographic method. Using mock data for SNIa, QSOs and GRBs generated based on the power-law $f(T)$ model, we show whether different cosmographic methods are suitable to reconstruct the distance modulus or not.

From dark matter halos to pre-stellar cores: High resolution follow-up of cosmological Lyman-Werner simulations

First author: Lewis R. Prole Molecular hydrogen allows cooling in primordial gas, facilitating its collapse into Population III stars within primordial halos. Lyman-Werner (LW) radiation from these stars can escape the halo and delay further star formation by destroying H$2$ in other halos. As cosmological simulations show that increasing the background LW field strength increases the average halo mass required for star formation, we perform follow-up simulations of selected halos to investigate the knock-on effects this has on the Population III IMF.

Fundamentals of Stellar Parameters Estimation through CMD of Star Clusters: Open (NGC2360) and Globular (NGC 5272)

Kanwar Preet Kaur The fundamentals of estimating essential stellar parameters of an open cluster-NGC 2360 and globular clusters-NGC 5272 are presented extensively in this work. Here, the evaluation of stellar parameters, by manually fitting the appropriate isochrones on the color magnitude diagrams (CMDs), of the selected star clusters is discussed comprehensively. Aperture photometry and PSF fitting photometry are conducted on g, r, and i standard band filter images of Sloan Digital Sky Survey (SDSS) using the aperture photometry tool (APT) to obtain the respective CMDs.

Gas dynamical friction as a binary formation mechanism in AGN discs

First author: Stanislav DeLaurentiis In this paper, we study how gaseous dynamical friction (DF) affects the motion of fly-by stellar-mass black holes (sBHs) embedded in active galactic nucleus (AGN) discs. We perform 3-body integrations of the interaction of two co-planar sBHs in nearby, initially circular orbits around the supermassive black hole (SMBH). We find that DF can facilitate the formation of gravitationally bound near-Keplerian binaries in AGN discs, and we delineate the discrete ranges of impact parameters and AGN disc parameters for which such captures occur.

Gas-phase metallicity break radii of star-forming galaxies in IllustrisTNG

First author: Alex M. Garcia We present radial gas-phase metallicity profiles, gradients, and break radii at redshift $z = 0 - 3$ from the TNG50-1 star-forming galaxy population. These metallicity profiles are characterized by an emphasis on identifying the steep inner gradient and flat outer gradient. From this, the break radius, $r_{\rm Break}$, is defined as the region where the transition occurs. We observe the break radius having a positive trend with mass that weakens with redshift.

Gas-rich, field ultra-diffuse galaxies host few globular clusters

S. Jang Hubble Space Telescope (HST) photometry is providing an extensive analysis of globular clusters (GCs). In particular, the pseudo two-colour diagram dubbed 'chromosome map (ChM)' allowed to detect and characterize their multiple populations with unprecedented detail. The main limitation of these studies is the small field of view of HST, which makes it challenging to investigate some important aspects of the multiple populations, such as their spatial distributions and the internal kinematics in the outermost cluster regions.

Gas-rich, field ultra-diffuse galaxies host few globular clusters

Michael G. Jones We present Hubble Space Telescope imaging of 14 gas-rich, low surface brightness and ultra-diffuse galaxies (UDGs) in the field at distances of 25-36 Mpc. An inspection of point-like sources brighter than the turnover magnitude of the globular cluster luminosity function and within twice the half-light radii of each galaxy reveals that, unlike those in denser environments, gas-rich, field UDGs host very few old globular clusters (GCs). Most of the targets (nine) have zero candidate GCs, with the remainder having one or two candidates each.

Globular cluster formation with multiple stellar populations: A single-binary composite scenario

Kenji Bekki We discuss a GC formation scenario in which the first generation (1G) of single asymptotic giant branch (AGB) stars and intermediate-mass close binaries (IMCBs) eject gas, from which the second generation (2G) of stars can be formed. The two key parameters in the scenario are the fractions of binary stars (f_b) and the slopes (alpha) of the stellar initial mass functions (IMFs) for 1G stars. Principle results derived by analytic and one-zone models of GC formation are as follows.