PHANGS-JWST First Results: Dust embedded star clusters in NGC 7496 selected via 3 3 μ m PAH emission by Jimena Rodriguez et al. on Wednesday 30 November

The earliest stages of star formation occur enshrouded in dust and are not

observable in the optical. Here we leverage the extraordinary new

high-resolution infrared imaging from JWST to begin the study of dust-embedded

star clusters in nearby galaxies throughout the local volume. We present a

technique for identifying dust-embedded clusters in NGC 7496 (18.7 Mpc), the

first galaxy to be observed by the PHANGS-JWST Cycle 1 Treasury Survey. We

select sources that have strong 3.3$\mu$m PAH emission based on a $\rm

F300M-F335M$ color excess, and identify 67 candidate embedded clusters. Only

eight of these are found in the PHANGS-HST optically-selected cluster catalog

and all are young (six have SED-fit ages of $\sim1$ Myr). We find that this

sample of embedded cluster candidates may significantly increase the census of

young clusters in NGC 7496 from the PHANGS-HST catalog -- the number of

clusters younger than $\sim$2 Myr could be increased by a factor of two.

Candidates are preferentially located in dust lanes, and are coincident with

peaks in PHANGS-ALMA CO (2-1) maps. We take a first look at concentration

indices, luminosity functions, SEDs spanning from 2700A to 21$\mu$m, and

stellar masses (estimated to be between $\sim10^4-10^5 M_{\odot}$). The methods

tested here provide a basis for future work to derive accurate constraints on

the physical properties of embedded clusters, characterize the completeness of

cluster samples, and expand analysis to all 19 galaxies in the PHANGS-JWST

sample, which will enable basic unsolved problems in star formation and cluster

evolution to be addressed.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.13426v2