Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2312.06031

The PHANGS-AstroSat Atlas of Nearby Star Forming Galaxies

Hamid Hassani·Erik Rosolowsky·Eric W. Koch·Joseph Postma·Joseph Nofech·Harrisen Corbould·David Thilker·Adam K. Leroy·Eva Schinnerer·Francesco Belfiore·Frank Bigiel·Mederic Boquien·Melanie Chevance·Daniel A. Dale·Oleg V. Egorov·Eric Emsellem·Simon C. O. Glover·Kathryn Grasha·Brent Groves·Kiana Henny·Jaeyeon Kim·Ralf S. Klessen·Kathryn Kreckel·J. M. Diederik Kruijssen·Janice C. Lee·Laura A. Lopez·Justus Neumann·Hsi-An Pan·Karin M. Sandstrom·Sumit K. Sarbadhicary·Jiayi Sun·Thomas G. Williams
View original source ↗Read source document ↗Export metadata ↓

Abstract

We present the Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-AstroSat atlas, which contains ultraviolet imaging of 31 nearby star-forming galaxies captured by the Ultraviolet Imaging Telescope (UVIT) on the AstroSat satellite. The atlas provides a homogeneous data set of far- and near-ultraviolet maps of galaxies within a distance of 22 Mpc and a median angular resolution of 1.4 arcseconds (corresponding to a physical scale between 25 and 160 pc). After subtracting a uniform ultraviolet background and accounting for Milky Way extinction, we compare our estimated flux densities to GALEX observations, finding good agreement. We find candidate extended UV disks around the galaxies NGC 6744 and IC 5332. We present the first statistical measurements of the clumping of the UV emission and compare it to the clumping of molecular gas traced with ALMA. We find that bars and spiral arms exhibit the highest degree of clumping, and the molecular gas is even more clumped than the FUV emission in galaxies. We investigate the variation of the ratio of observed FUV to H$α$ in different galactic environments and kpc-sized apertures. We report that $\sim 65$% variation of the $\log_{10}$(FUV/H$α$) can be described through a combination of dust attenuation with star formation history parameters. The PHANGS-AstroSat atlas enhances the multi-wavelength coverage of our sample, offering a detailed perspective on star formation. When integrated with PHANGS data sets from ALMA, VLT-MUSE, HST and JWST, it develops our comprehensive understanding of attenuation curves and dust attenuation in star-forming galaxies.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Hamid Hassani, Erik Rosolowsky, Eric W. Koch, Joseph Postma, Joseph Nofech, Harrisen Corbould, David Thilker, Adam K. Leroy, Eva Schinnerer, Francesco Belfiore, Frank Bigiel, Mederic Boquien, Melanie Chevance, Daniel A. Dale, Oleg V. Egorov, Eric Emsellem, Simon C. O. Glover, Kathryn Grasha, Brent Groves, Kiana Henny, Jaeyeon Kim, Ralf S. Klessen, Kathryn Kreckel, J. M. Diederik Kruijssen, Janice C. Lee, Laura A. Lopez, Justus Neumann, Hsi-An Pan, Karin M. Sandstrom, Sumit K. Sarbadhicary, Jiayi Sun, Thomas G. Williams. 2026-07-10. The PHANGS-AstroSat Atlas of Nearby Star Forming Galaxies. https://arxiv.org/abs/2312.06031

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

A Rest-frame K-band View of Bulge Growth in Massive Star-forming Galaxies at z~2

We study bulge formation in 16 massive dusty star-forming galaxies at z~2 by combining JWST MIRI F770W imaging, NIRCam imaging in eight bands, and ALMA 870 micron data. At the median redshift of z=2.18, the F770W band probes the rest-frame 2.4 micron light, close to the rest-frame K band, and traces the stellar mass distribution with much less dust attenuation than the NIRCam bands. The effective radii measured in F770W agree with those of the 870 micron dust emission, with a median ratio of 0.95, and are typically 23% smaller than those in F444W. The rest-frame K-band imaging is therefore essential to measure the true extent of the stellar mass, which is as compact as the dusty star-forming regions. In stacks of the 16 galaxies at a matched resolution, the 870 micron and F770W profiles agree closely out to 8 kpc, and a bulge plus disk decomposition of the F770W stack gives a bulge-to-total ratio of 0.50. Fitting the SEDs in radial bins with CIGALE, we find that the attenuation decreases from A_V = 3.7 mag at the center to 1.9 mag at r >~ 7 kpc, while the specific star formation rate profile is flat. In most of the galaxies, the bulge is already in place inside the dusty core. In two galaxies, by contrast, the 870 micron emission is 3 to 6 times more compact than the F770W light, which suggests that they are still in the bulge-building compaction phase. Our sample may thus catch massive galaxies in several phases of bulge formation.

astro-ph.GA↗
arXiv2026

Spatially Resolved Physical Properties of Young Star Clusters and Star-forming Clumps in the Brightest z>6 Galaxy, the Strongly Lensed Cosmic Spear at z=6.2

We present spatially resolved analysis of stellar populations in the brightest $z>6$ galaxy known to date (AB mag 23), the strongly lensed MACS0308$-$zD1 (dubbed the ``Cosmic Spear'') at $z_{\rm spec}=6.2$. New JWST NIRCam imaging and high-resolution NIRSpec IFU spectroscopy span the rest-frame ultraviolet to optical. The NIRCam imaging reveals bright star-forming clumps and a tail consisting of three distinct, extremely compact star clusters that are multiply-imaged by gravitational lensing. The star clusters have delensed effective radii of $R_{\rm{eff}} \lesssim 8$ pc, stellar masses of $M_{*} \sim 10^{6}-10^{7}\,M_{\odot}$, and high stellar mass surface densities of $Σ_{*} \gtrsim 2\times 10^{4}\,M_{\odot}~\rm{pc}^{-2}$. While their stellar populations are very young ($\sim 6-11$ Myr), their dynamical ages exceed unity, consistent with the clusters being gravitationally bound systems. Placing the star clusters in the size vs.~stellar mass density plane, we find they occupy a region similar to other high-redshift star clusters within galaxies observed recently with JWST, being significantly more massive and denser than local star clusters. Spatially resolved analysis of the brightest clump reveals a compact, intensely star-forming core. The ionizing photon production efficiency ($ξ_{\rm{ion}}$) is slightly suppressed in this central region, potentially indicating a locally elevated Lyman continuum escape fraction facilitated by feedback-driven channels.

astro-ph.GA↗
arXiv2026

The abundance of thin dwarf galaxies: a challenge for cosmological simulations

We study the prevalence of thin galaxies as a function of stellar mass in the range $10^7 < M_{\star} / \rm{M_\odot} < 10^{11}$ using data from the GAMA, DESI, ALFALFA, and Nearby Galaxy catalogs. We use the distribution of projected axis ratios, $q$, to infer the abundance of intrinsically flat galaxies needed to reproduce the observed abundance of highly elongated systems in projection. We find that as many as $40\%$ of galaxies in the mass range $10^9<M_{\star}/\rm{M_\odot}<10^{10}$ are intrinsically flatter than $1$:$5$ (i.e., $c/a<0.2$), a fraction that rises to $\sim 80\%$ for $c/a<0.3$. Although the incidence of thin galaxies decreases towards lower and higher $M_{\star}$, they are still quite common in dwarfs: $\sim 30\%$ and $\sim 65\%$ of $\sim 10^8 ~ \rm{M_\odot}$ galaxies are inferred to be intrinsically flatter than $c/a=0.2$ and $0.3$, respectively. A comparison of these results with several state-of-the-art cosmological hydrodynamical simulations (TNG50, FIREbox, Romulus25) reveals a distinctive lack of thin simulated dwarfs. In particular, there are no $M_{\star} < 10^9 ~ \rm{M_{\odot}}$ simulated galaxies flatter than $c/a=0.2$, in clear contrast with observational samples. This discrepancy likely reflects limitations in resolution and in the treatment of baryonic physics, suggesting that our understanding of the mechanisms regulating the formation of disk galaxies less massive than the Milky Way is still quite incomplete. Our results present a clear challenge to current numerical models of dwarf galaxy formation, which future models should attempt to meet.

astro-ph.GA↗