galaxies

First author: Grecco A. Oyarzun We combine an unprecedented MaNGA sample of over 3,000 passive galaxies in the stellar mass range 10^{9}-10^{12} Msun with the Sloan Digital Sky Survey group catalog by Tinker to quantify how central and satellite formation, quantified by radial profiles in stellar age, $[Fe/H]$, and $[Mg/Fe]$, depends on the stellar mass of the galaxy (M*) and the mass of the host halo (Mh). After controlling for M* and Mh, the stacked spectra of centrals and satellites beyond the effective radius (r_e) show small, yet significant differences in multiple spectral features at the 1% level.

First author: Jiayi Sun We measure empirical relationships between the local star formation rate (SFR) and properties of the star-forming molecular gas on 1.5 kpc scales across 80 nearby galaxies. These relationships, commonly referred to as “star formation laws,” aim at predicting the local SFR surface density from various combinations of molecular gas surface density, galactic orbital time, molecular cloud free-fall time, and the interstellar medium dynamical equilibrium pressure. Leveraging a multiwavelength database built for the PHANGS survey, we measure these quantities consistently across all galaxies and quantify systematic uncertainties stemming from choices of SFR calibrations and the CO-to-H$_2$ conversion factors.

First author: K T Vinod We use the recently discovered simple photometric parameter Central Intensity Ratio (CIR, Aswathy & Ravikumar 2018) determined for a sample of 57 nearby (z < 0.02) Seyfert galaxies to explore the central features of galaxies and their possible connection with galaxy evolution. The sample of galaxies shows strong anti-correlation between CIR and mass of their central supermassive black holes (SMBH). The SMBH masses of ellipticals are systematically higher for a given CIR value than that for lenticulars and spirals in the sample.

First author: C. Zhou Clusters of galaxies are sensitive to the most nonlinear peaks in the cosmic density field. The weak gravitational lensing of background galaxies by clusters can allow us to infer their masses. However, galaxies associated with the local environment of the cluster can also be intrinsically aligned due to the local tidal gradient, contaminating any cosmology derived from the lensing signal. We measure this intrinsic alignment in Dark Energy Survey (DES) Year 1 redMaPPer clusters.

First author: P. Serra The MeerKAT Fornax Survey maps the distribution and kinematics of atomic neutral hydrogen gas (HI) in the nearby Fornax galaxy cluster using the MeerKAT telescope. The 12 deg^2 survey footprint covers the central region of the cluster out to ~ Rvir and stretches out to ~ 2 Rvir towards south west to include the NGC 1316 galaxy group. The HI column density sensitivity (3 sigma over 25 km/s) ranges from 5e+19/cm^2 at a resolution of ~ 10" (~ 1 kpc at the 20 Mpc distance of Fornax) down to ~ 1e+18/cm^2 at ~ 1’ (~ 6 kpc), and slightly below this level at the lowest resolution of ~ 100" (~ 10 kpc).

First author: Sharon Lapiner We utilize high-resolution cosmological simulations to reveal that high-redshift galaxies tend to undergo a robust wet compaction' event when near a golden’ stellar mass of $\sim 10^{10} M_{\odot}$. This is a gaseous shrinkage to a compact star-forming phase, a blue nugget' (BN), followed by central quenching of star formation to a compact passive stellar bulge, a red nugget’ (RN), and a buildup of an extended gaseous disc and ring.

First author: Yucheng Zhang Line-intensity mapping (LIM) is a promising technique to constrain the global distribution of galaxy properties. To combine LIM experiments probing different tracers with traditional galaxy surveys and fully exploit the scientific potential of these observations, it is necessary to have a physically motivated modeling framework. As part of developing such a framework, in this work we introduce and model the conditional galaxy property distribution (CGPD), i.

First author: Daniela Calzetti Multi-wavelength images from the Hubble Space Telescope covering the wavelength range 0.27-1.6 $\mu$m show that the central area of the nearby dwarf galaxy NGC4449 contains several tens of compact sources that are emitting in the hydrogen recombination line Pa$\beta$ (1.2818 $\mu$m) but are only marginally detected in H$\alpha$ (0.6563 $\mu$m) and undetected at wavelengths $\lambda\le$0.55 $\mu$m. An analysis of the spectral energy distributions (SEDs) of these sources indicates that they are likely relatively young star clusters heavily attenuated by dust.

First author: Clár-Bríd Tohill The morphology of a galaxy has been shown to encode the evolutionary history and correlates strongly with physical properties such as stellar mass, star formation rates and past merger events. While the majority of galaxies in the local universe can be classified on the Hubble sequence, little is known about the different types of galaxies we observe at high redshift. The irregular morphology of these galaxies makes visual classifications difficult, and with the future of astronomy consisting of many “Big Data” surveys we need an efficient, and unbiased classification system in place.

First author: Alexander Beckett We examine to what extent disk and outflow models can reproduce observations of H I gas within a few virial radii of galaxies in pairs and groups. Using highly-sensitive HST/COS and FOS spectra of the Q0107 quasar triplet covering Ly$\alpha$ for z$\lesssim$1, as well as a deep galaxy redshift survey including VIMOS, DEIMOS, GMOS and MUSE data, we test simple disk and outflow models against the H I absorption along three lines-of-sight (separated by 200-500 kpc) through nine galaxy groups in this field.