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Register a new userPhysical Properties of Sub-galactic Clumps at 0.5 $leq z leq$ 1.5 in the UVUDF
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We present an investigation of clumpy galaxies in the Hubble Ultra Deep Field at 0.5 $leq z leq$ 1.5 in the rest-frame far-ultraviolet (FUV) using HST WFC3 broadband imaging in F225W, F275W, and F336W. An analysis of 1,404 galaxies yields 209 galaxies that host 403 kpc-scale clumps. These host galaxies appear to be typical star-forming galaxies, with an average of 2 clumps per galaxy and reaching a maximum of 8 clumps. We measure the photometry of the clumps, and determine the mass, age, and star formation rates (SFR) utilizing the SED-fitting code FAST. We find that clumps make an average contribution of 19% to the total rest-frame FUV flux of their host galaxy. Individually, clumps contribute a median of 5% to the host galaxy SFR and an average of $sim$4% to the host galaxy mass, with total clump contributions to the host galaxy stellar mass ranging widely from less than 1% up to 93%. Clumps in the outskirts of galaxies are typically younger, with higher star formation rates, than clumps in the inner regions. The results are consistent with clump migration theories in which clumps form through violent gravitational instabilities in gas-rich turbulent disks, eventually migrate toward the center of the galaxies, and coalesce into the bulge.
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We use combined South Pole Telescope (SPT)+Planck temperature maps to analyze the circumgalactic medium (CGM) encompassing 138,235 massive, quiescent 0.5 $leq$ z $leq$ 1.5 galaxies selected from data from the Dark Energy Survey (DES) and Wide-Field Infrared Survey Explorer (WISE). Images centered on these galaxies were cut from the 1.85 arcmin resolution maps with frequency bands at 95, 150, and 220 GHz. The images were stacked, filtered, and fit with a gray-body dust model to isolate the thermal Sunyaev-Zeldovich (tSZ) signal, which is proportional to the total energy contained in the CGM of the galaxies. We separate these $M_{star} = 10^{10.9} M_odot$ - $10^{12} M_odot$ galaxies into 0.1 dex stellar mass bins, detecting tSZ per bin up to $5.6sigma$ and a total signal-to-noise ratio of $10.1sigma$. We also detect dust with an overall signal-to-noise ratio of $9.8sigma$, which overwhelms the tSZ at 150GHz more than in other lower-redshift studies. We correct for the $0.16$ dex uncertainty in the stellar mass measurements by parameter fitting for an unconvolved power-law energy-mass relation, $E_{rm therm} = E_{rm therm,peak} left(M_star/M_{star,{rm peak}} right)^alpha$, with the peak stellar mass distribution of our selected galaxies defined as $M_{star,{rm peak}}= 2.3 times 10^{11} M_odot$. This yields an $E_{rm therm,peak}= 5.98_{-1.00}^{+1.02} times 10^{60}$ erg and $alpha=3.77_{-0.74}^{+0.60}$. These are consistent with $z approx 0$ observations and within the limits of moderate models of active galactic nuclei (AGN) feedback. We also compute the radial profile of our full sample, which is similar to that recently measured at lower-redshift by Schaan et al. (2021).
Using the CANDELS photometric catalogs for the HST/ACS and WFC3, we identified massive evolved galaxies at $3 < z < 4.5$, employing three different selection methods. We find the comoving number density of these objects to be $sim 2 times 10^{-5}$ and $8 times 10^{-6}Mpc^{-3}$ after correction for completeness for two redshift bins centered at $z=3.4, 4.7$. We quantify a measure of how much confidence we should have for each candidate galaxy from different selections and what are the conservative error estimates propagated into our selection. Then we compare the evolution of the corresponding number densities and their stellar mass density with numerical simulations, semi-analytical models, and previous observational estimates, which shows slight tension at higher redshifts as the models tend to underestimate the number and mass densities. By estimating the average halo masses of the candidates ($M_h approx 4.2, 1.9, 1.3 times 10^{12} M_odot$ for redshift bins centered at $z=3.4, 4.1, 4.7$), we find them to be consistent with halos that were efficient in turning baryons to stars and were relatively immune to the feedback effects and on the verge of transition into hot-mode accretion. This can suggest the relative cosmological starvation of the cold gas followed by an overconsumption phase in which the galaxy consumes the available cold gas rapidly as one of the possible drivers for the quenching of the massive evolved population at high redshift.
Determining the spatial distribution and intrinsic physical properties of neutral hydrogen on cosmological scales is one of the key goals of next-generation radio surveys. We use the EAGLE galaxy formation simulations to assess the properties of damped Lyman-alpha absorbers (DLAs) that are associated with galaxies and their underlying dark matter haloes between 0 $leq$ z $leq$ 2. We find that the covering fraction of DLAs increases at higher redshift; a significant fraction of neutral atomic hydrogen (HI) resides in the outskirts of galaxies with stellar mass greater than or equal to 10$^{10}$ M$_odot$; and the covering fraction of DLAs in the circumgalactic medium (CGM) is enhanced relative to that of the interstellar medium (ISM) with increasing halo mass. Moreover, we find that the mean density of the HI in galaxies increases with increasing stellar mass, while the DLAs in high- and low-halo-mass systems have higher column densities than those in galaxies with intermediate halo masses (~ 10$^{12}$ M$_odot$ at z = 0). These high-impact CGM DLAs in high-stellar-mass systems tend to be metal-poor, likely tracing smooth accretion. Overall, our results point to the CGM playing an important role in DLA studies at high redshift (z $geq$ 1). However, their properties are impacted both by numerical resolution and the detailed feedback prescriptions employed in cosmological simulations, particularly that of AGN.
We systematically determine ground-state and saddle-point shapes and masses for 1305 heavy and superheavy nuclei with $Z=98-126$ and $N=134-192$, including odd-$A$ and odd-odd systems. From these, we derive static fission barrier heights, one- and two-nucleon separation energies, and $Q_alpha$ values for g.s. to g.s transitions. Our study is performed within the microscopic-macroscopic method with the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy taken as the smooth part. We use parameters of the model that were fitted previously to masses of even-even heavy nuclei. For systems with odd numbers of protons, neutrons, or both, we use a standard BCS method with blocking. Ground-state shapes and energies are found by the minimization over seven axially-symmetric deformations. A search for saddle-points was performed by using the imaginary water flow method in three consecutive stages, using five- (for nonaxial shapes) and seven-dimensional (for reflection-asymmetric shapes) deformation spaces. The results are collected in two main tables. Calculated ground-state mass excess, nucleon separation- and $Q_alpha$ energies, total, macroscopic(normalized to the macroscopic energy at the spherical shape) and shell corrections energies, and deformations are given for each nucleus in mbox{Table 1}. mbox{Table 2} contains calculated properties of the saddle-point configurations and the fission barrier heights. In mbox{Tables 3-7}, are given calculated ground-state, inner and outer saddle-point and superdeformed secondary minima characteristics for 75 actinide nuclei, from Ac to Cf, for which experimental estimates of fission barrier heights are known. These results are an additional test of our model.
Using the near-IR spectroscopy of the MOSFIRE Deep Evolution Field (MOSDEF) survey, we investigate the role of local environment in the gas-phase metallicity of galaxies. The local environment measurements are derived from accurate and uniformly calculated photometric redshifts with well-calibrated probability distributions. Based on rest-frame optical emission lines, [NII]$lambda6584$ and H$alpha$, we measure gas-phase oxygen abundance of 167 galaxies at $1.37leq zleq1.7$ and 303 galaxies at $2.09leq zleq2.61$, located in diverse environments. We find that at $zsim1.5$, the average metallicity of galaxies in overdensities with $M_*sim10^{9.8}M_odot, 10^{10.2}M_odot$ and $10^{10.8}M_odot$ is higher relative to their field counterparts by $0.094pm0.051$, $0.068pm0.028$ and $0.052pm0.043$ dex, respectively. However, this metallicity enhancement does not exist at higher redshift, $zsim2.3$, where, compared to the field galaxies, we find $0.056pm0.043$, $0.056pm0.028$ and $0.096pm 0.034$ dex lower metallicity for galaxies in overdense environments with $M_*sim10^{9.8}M_odot, 10^{10.2}M_odot$ and $10^{10.7}M_odot$, respectively. Our results suggest that, at $1.37leq zleq2.61$, the variation of mass-metallicity relation with local environment is small ($<0.1$dex), and reverses at $zsim2$. Our results support the hypothesis that, at the early stages of cluster formation, owing to efficient gas cooling, galaxies residing in overdensities host a higher fraction of pristine gas with prominent primordial gas accretion, which lowers their gas-phase metallicity compared to their coeval field galaxies. However, as the Universe evolves to lower redshifts ($zlesssim2$), shock-heated gas in overdensities cannot cool down efficiently, and galaxies become metal-rich rapidly due to the suppression of pristine gas inflow and re-accretion of metal-enriched outflows in overdensities.
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