English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We constrain gas inflow speeds in star-forming galaxies with color gradientsconsistent with inside-out disk growth. Our method combines new measurements ofdisk orientation with previously described circumgalactic absorption inbackground quasar spectra. Two quantities, a position angle and an axis ratio,describe the projected shape of each galactic disk on the sky, leaving anambiguity about which side of the minor axis is tipped toward the observer.This degeneracy regarding the 3D orientation of disks has compromised previousefforts to measure gas inflow speeds. We present HST and Keck/LGSAO imagingthat resolves the spiral structure in five galaxies at redshift $z\approx0.2$.We determine the sign of the disk inclination for four galaxies, under theassumption that spiral arms trail the rotation. We project models for bothradial infall in the disk plane and circular orbits onto each quasar sightline.We compare the resulting line-of-sight velocities to the observed velocityrange of Mg II absorption in spectra of background quasars, which intersect thedisk plane at radii between 69 and 115 kpc. For two sightlines, we constrainthe maximum radial inflow speeds as 30-40 km s$^{-1}$. We also rule out avelocity component from radial inflow in one sightline, suggesting that thestructures feeding gas to these growing disks do not have unity coveringfactor. We recommend appropriate selection criteria for building larger samplesof galaxy--quasar pairs that produce orientations sensitive to constraininginflow properties.

Resolving 3D Disk Orientation using High-Resolution Images: New Constraints on Circumgalactic Gas Inflows