Galaxy formation and evolution

Abstract:

Abstract We extract with ppxf and analyse the high-order stellar kinematic moments h3 (related to skewness) and h4 (related to kurtosis) in a complete subsample of 2230 galaxies with well-sampled line-of-sight velocity distributions (σe ≳ 140 km/s) from the final data release of 10010 unique galaxies of the MaNGA survey. To reduce template mismatch, we created a stellar library based on MaStar. We used proxies for the specific angular momentum parameter ($\lambda _{R_\mathrm{e}}$) and ellipticity (ϵ) to distinguish between fast and slow rotators. Using the Pearson correlation coefficient between spatially resolved h3 and V/σ within the isophotes of 2.5 half-light radii (Re), we classified 1,599 fast rotators into: (i) 1,073 galaxies showing a strong h3 versus V/σ anti-correlation, indicative of normal rotating stellar disks as observed in earlier studies. (ii) 526 galaxies exhibiting weak or no correlation between h3 and V/σ. These galaxies are likely disturbed, showing signs of bars or merging. Further inspection revealed that 85 galaxies from the latter group contain an anti-correlated inner disk, with half of these inner disks composed of younger stellar populations, indicative of recent gas accretion and nuclear star formation. This catalogue presents measurements of high-order stellar kinematic moments, providing a basis for exploring their potential links with the kinematic structures of galaxies. We have made the newly extracted high-order kinematics publicly available for further studies on stellar dynamics and galaxy formation.

Abstract:

We present the survey design and initial results from the Parallel Ionizing Emissivity (PIE) survey. PIE is a large Hubble Space Telescope survey designed to detect Lyman continuum (LyC) emitting galaxies at 3.1 < z < 3.5 and stack their images in order to measure average LyC escape fractions as a function of galaxy properties. PIE has imaged 37 independent fields in three filters (F336W, F625W, and F814W), of which 18 are observed with a fourth band (F475W) from the accompanying PIE+ program. We use photometric colors to select candidate Lyman break galaxies (LBGs) at 3.1 < z < 3.5, which can be followed up using ground-based spectrographs to confirm their redshifts. Unlike previous surveys, we use many independent fields to remove biases caused by correlated absorption in the intergalactic medium (IGM). In this paper, we describe the survey design, photometric measurements, and the use of mock galaxy samples to optimize our color selection. With three filters, we can select a galaxy sample of which ≈90% are LBGs and over 30% lie in the 3.1 < z < 3.5 range for which we can detect uncontaminated LyC emission in F336W. We also use mock IGM sight lines to measure the expected transmission of the IGM, which will allow us to determine escape fractions from our stacked galaxies. We color-select ≈1400 galaxies, and predict that this includes ≈80 LyC-emitting galaxies and ≈500 that we can use in stacking. Finally, we present the Keck/LRIS spectrum of a galaxy at z ≈ 2.99, demonstrating that we can confirm the redshifts of z ∼ 3 galaxies from the ground.