A study of globular clusters in a lenticular galaxy in Hydra I from deep HST/ACS photometry
Journal
Date Issued
2022
Author(s)
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Blakeslee, John P.
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Abstract
We take advantage of exquisitely deep optical imaging data from HST/ACS in
the F475W ($g_{F475W}$) and F606W ($V_{F606W}$) bands, to study the properties
of the globular cluster (GC) population in the intermediate mass lenticular
galaxy PGC 087327, in the Hydra I galaxy cluster. We inspect the photometric
(magnitudes and color) and morphometric (compactness, elongation, etc.)
properties of sources lying in an area of $\sim19\times19$ kpc centered on PGC
087327, and compare them with four neighbouring fields over the same HST/ACS
mosaic. This allowed us to identify a list of GC candidates and to inspect
their properties using a background decontamination method. Relative to the
four comparison fields, PGC 087327 shows a robust overdensity of GCs,
$N_{GC}=82\pm9$. At the estimated magnitude of the galaxy, this number implies
a specific frequency of $S_N=1.8\pm0.7$. In spite of the short wavelength
interval available with the $g_{F475W}$ and $V_{F606W}$ passbands, the color
distribution shows a clear bimodality with a blue peak at $\langle
g_{F475W}{-}V_{F606W} \rangle =0.47\pm0.05$ mag and a red peak at $\langle
g_{F475W}{-}V_{F606W}\rangle =0.62\pm0.03$ mag. We also observe the typical
steeper slope of the radial distribution of red GCs relative to blue ones.
Thanks to the unique depth of the available data, we characterize the GC
luminosity function (GCLF) well beyond the expected GCLF turn-over. We find
$g^{TOM}_{F475W} = 26.54\pm0.10$ mag and $V^{TOM}_{F606W} = 26.08 \pm 0.09$
mag, which after calibration yields a distance of $D_{GCLF} = 56.7 \pm
4.3(statistical) \pm 5.2(systematic)$ Mpc.
Volume
666
Start page
A99
Issn Identifier
0004-6361
Rights
open.access
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