galaxies

First author: Matthew J. Hayes We demonstrate how the stellar and nebular conditions in star-forming galaxies modulate the emission and spectral profile of HI Lya emission line. We examine the net Lya output, kinematics, and in particular emission of blue-shifted Lya radiation, using spectroscopy from with the Cosmic Origins Spectrograph on HST, giving a sample of 87 galaxies at redshift z=0.05-0.44. We contrast the Lya spectral measurements with properties of the ionized gas (from optical spectra) and stars (from stellar modeling).

First author: Roberto Decarli Characterizing the physical conditions (density, temperature, ionization state, metallicity, etc) of the interstellar medium is critical to our understanding of the formation and evolution of galaxies. Here we present a multi-line study of the interstellar medium in the host galaxy of a quasar at z~6.4, i.e., when the universe was 840 Myr old. This galaxy is one of the most active and massive objects emerging from the dark ages, and therefore represents a benchmark for models of the early formation of massive galaxies.

First author: D. Austin We present an early analysis on the search for high redshift galaxies using the deepest public JWST imaging to date, the NGDEEP field. This data consists of 6-band NIRCam imaging on the Hubble Ultra Deep Field-Par2, covering a total area of 6.3 arcmin$^{2}$. Based on our initial reduction of the first half of this survey, we reach 5$\sigma$ depths up to mag = 29.5–29.9 between $1-5$ um.

First author: Seiji Kameno The Atacama Large Millimeter/submillimeter Array (ALMA) serendipitously detected H$2$O $J{Ka, Kc} = 10_{2,9} - 9_{3,6}$ emission at 321 GHz in NGC 1052. This is the first submillimeter maser detection in a radio galaxy and the most luminous 321-GHz H$2$O maser known to date with the isotropic luminosity of 1090 $L{\odot}$. The line profile consists of a broad velocity component with FWHM $= 208 \pm 12$ km s$^{-1}$ straddling the systemic velocity and a narrow component with FWHM $= 44 \pm 3$ km s$^{-1}$ blueshifted by 160 km s$^{-1}$.

First author: A. L. B. Ribeiro We study a sample of 936 early-type galaxies (ETGs) located in 48 low-z regular galaxy clusters with $M_{200}\geq 10^{14}~ M_\odot$ at $z< 0.1$. We examine variations in the concentration index, radius, and color gradient of ETGs as a function of their stellar mass and loci in the projected phase space (PPS) of the clusters. We aim to understand the environmental influence on the growth of ETGs according to the time since infall into their host clusters.

First author: Danila Korytov The galaxy distribution in dark matter-dominated halos is expected to approximately trace the details of the underlying dark matter substructure. In this paper we introduce halo `core-tracking’ as a way to efficiently follow the small-scale substructure in cosmological simulations and apply the technique to model the galaxy distribution in observed clusters. The method relies on explicitly tracking the set of particles identified as belonging to a halo’s central density core, once a halo has attained a certain threshold mass.

First author: Kun Xu We measure the galaxy-ellipticity (GI) correlations for the Slogan Digital Sky Survey DR12 LOWZ and CMASS samples with the shape measurements from the DESI Legacy Imaging Surveys. We model the GI correlations in an N-body simulation with our recent accurate stellar-halo mass relation from the Photometric object Around Cosmic webs (PAC) method. The large data set and our accurate modeling turns out an accurate measurement of the alignment angle between central galaxies and their host halos.

First author: Giulia Tozzi Nebular HeII$\lambda$4686\AA~line emission is useful to unveil active galactic nuclei (AGN) residing in actively star-forming (SF) galaxies, typically missed by the standard BPT classification. Here we adopt the HeII diagnostic to identify hidden AGN in the Local Universe using for the first time spatially-resolved data from the Data Release 15 of the Mapping Nearby Galaxies at APO survey (MaNGA DR15). By combining results from HeII and BPT diagnostics, we overall select 459 AGN host candidates ($\sim$10% in MaNGA DR15), out of which 27 are identified as AGN by the HeII diagram only.

First author: Fabrizio Nicastro The amount of baryons hosted in the disks of galaxies is lower than expected based on the mass of their dark-matter halos and the fraction of baryon-to-total matter in the universe, giving rise to the so called galaxy missing-baryon problem. The presence of cool circum-galactic matter gravitationally bound to its galaxy’s halo up to distances of at least ten times the size of the galaxy’s disk, mitigates the problem but is far from being sufficient for its solution.

First author: Koshy George Elliptical galaxies with blue optical colours and significant star formation are hypothesised to be major merger remnants of gas rich spiral galaxies or normal elliptical galaxies with a sudden burst of star formation. We present here a scenario where blue elliptical galaxies identified from shallow imaging surveys may fail to recover faint features indicative of a past merger activity using a nearby major merger remnant. Based on deep optical imaging data of a post merger galaxy, NGC 7252, we demonstrate that the galaxy can appear as an elliptical galaxy if observed at higher redshifts.