The JWST Resolved Stellar Populations Early Release Science Program. VIII. The Spatially Resolved Star Formation History of WLM

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Bibliographic Details
Main Authors:	Cohen, Roger E., McQuinn, Kristen B. W., Savino, Alessandro, Newman, Max J. B., Weisz, Daniel R., Dolphin, Andrew E., Boyer, Martha L., Correnti, Matteo, Geha, Marla C., Gennaro, Mario, Gilbert, Karoline M., Kallivayalil, Nitya, Warfield, Jack T., Williams, Benjamin F., Brooks, Alyson M., Cole, Andrew A., Skillman, Evan D., Garling, Christopher T., Kalirai, Jason S., Anderson, Jay
Format:	Preprint
Published:	2025
Subjects:	Astrophysics of Galaxies
Online Access:	Acceder al recurso
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_version_	1866913698979774464
author	Cohen, Roger E. McQuinn, Kristen B. W. Savino, Alessandro Newman, Max J. B. Weisz, Daniel R. Dolphin, Andrew E. Boyer, Martha L. Correnti, Matteo Geha, Marla C. Gennaro, Mario Gilbert, Karoline M. Kallivayalil, Nitya Warfield, Jack T. Williams, Benjamin F. Brooks, Alyson M. Cole, Andrew A. Skillman, Evan D. Garling, Christopher T. Kalirai, Jason S. Anderson, Jay
author_facet	Cohen, Roger E. McQuinn, Kristen B. W. Savino, Alessandro Newman, Max J. B. Weisz, Daniel R. Dolphin, Andrew E. Boyer, Martha L. Correnti, Matteo Geha, Marla C. Gennaro, Mario Gilbert, Karoline M. Kallivayalil, Nitya Warfield, Jack T. Williams, Benjamin F. Brooks, Alyson M. Cole, Andrew A. Skillman, Evan D. Garling, Christopher T. Kalirai, Jason S. Anderson, Jay
contents	We measure radial stellar age gradients in the relatively isolated gas-rich dwarf irregular WLM, combining JWST NIRCam and NIRISS imaging with six archival Hubble fields over semi-major axis equivalent distances of 0$\lesssim$R$_{SMA}$$\lesssim$4 kpc ($\lesssim$3R$_{hl}$). Fitting lifetime star formation histories (SFHs) to resolved color-magnitude diagrams (CMDs), radial age gradients are quantified using $τ_{90}$ and $τ_{50}$, the lookback times to form 90\% and 50\% of the cumulative stellar mass. We find that globally, the outskirts of WLM are older on average, with ($δ$$τ_{90}$, $δ$$τ_{50}$)/$δ$R$_{SMA}=$(0.82$^{+0.10}_{-0.10}$, 1.60$^{+0.23}_{-0.22}$) Gyr/kpc (stat.), in good agreement with simulations. However, we also detect an azimuthal dependence of radial stellar age gradients, finding that stars on the leading edge of WLM (relative to its proper motion) are both younger and have a flatter age gradient compared to the trailing edge. This difference persists over 0.6$\lesssim$R$_{SMA}$$\lesssim$3.2 kpc ($\sim$0.5$-$2.5R$_{hl}$) and lookback times up to $\sim$8 Gyr, and is robust to assumed stellar evolutionary model. Our results are consistent with star formation triggered by ram pressure stripping from a circumgalactic and/or intergalactic medium, suggested by recent HI observations. If confirmed, processes typifying dense environments, such as ram pressure stripping, may be more relevant to the evolution of isolated galaxies than previously thought.
format	Preprint
id	arxiv_https___arxiv_org_abs_2502_13887
institution	arXiv
publishDate	2025
record_format	arxiv
spellingShingle	The JWST Resolved Stellar Populations Early Release Science Program. VIII. The Spatially Resolved Star Formation History of WLM Cohen, Roger E. McQuinn, Kristen B. W. Savino, Alessandro Newman, Max J. B. Weisz, Daniel R. Dolphin, Andrew E. Boyer, Martha L. Correnti, Matteo Geha, Marla C. Gennaro, Mario Gilbert, Karoline M. Kallivayalil, Nitya Warfield, Jack T. Williams, Benjamin F. Brooks, Alyson M. Cole, Andrew A. Skillman, Evan D. Garling, Christopher T. Kalirai, Jason S. Anderson, Jay Astrophysics of Galaxies We measure radial stellar age gradients in the relatively isolated gas-rich dwarf irregular WLM, combining JWST NIRCam and NIRISS imaging with six archival Hubble fields over semi-major axis equivalent distances of 0$\lesssim$R$_{SMA}$$\lesssim$4 kpc ($\lesssim$3R$_{hl}$). Fitting lifetime star formation histories (SFHs) to resolved color-magnitude diagrams (CMDs), radial age gradients are quantified using $τ_{90}$ and $τ_{50}$, the lookback times to form 90\% and 50\% of the cumulative stellar mass. We find that globally, the outskirts of WLM are older on average, with ($δ$$τ_{90}$, $δ$$τ_{50}$)/$δ$R$_{SMA}=$(0.82$^{+0.10}_{-0.10}$, 1.60$^{+0.23}_{-0.22}$) Gyr/kpc (stat.), in good agreement with simulations. However, we also detect an azimuthal dependence of radial stellar age gradients, finding that stars on the leading edge of WLM (relative to its proper motion) are both younger and have a flatter age gradient compared to the trailing edge. This difference persists over 0.6$\lesssim$R$_{SMA}$$\lesssim$3.2 kpc ($\sim$0.5$-$2.5R$_{hl}$) and lookback times up to $\sim$8 Gyr, and is robust to assumed stellar evolutionary model. Our results are consistent with star formation triggered by ram pressure stripping from a circumgalactic and/or intergalactic medium, suggested by recent HI observations. If confirmed, processes typifying dense environments, such as ram pressure stripping, may be more relevant to the evolution of isolated galaxies than previously thought.
title	The JWST Resolved Stellar Populations Early Release Science Program. VIII. The Spatially Resolved Star Formation History of WLM
topic	Astrophysics of Galaxies
url	https://arxiv.org/abs/2502.13887