Central stellar depletion in the Draco dwarf from Subaru photometry
Abstract
Dark matter subhaloes are a fundamental prediction of the standard cosmological model, but their low-mass population remains difficult to constrain observationally. Recent work has shown that interactions between subhaloes and dwarf spheroidal galaxies can induce large-scale, out-of-equilibrium fluctuations in their stellar surface density fields, identifiable through Fourier-based statistics. We apply this formalism to deep Subaru photometry of the Draco dwarf, extending previous tests to ≳𝒪(104) resolved stars. We use artificial-star tests to assign completeness weights to individual stars and incorporate them into a discrete likelihood-based framework. Relative to a cored axisymmetric Plummer model, Draco shows radial corrugations that appear in the filtered normalised residuals as a central stellar depletion surrounded by a ring-like excess. The same feature appears in Fourier space as a low-frequency peak with a signal-to-noise ratio S/N=6.0. Independently, fitting the surface density Σ with an αβγ model yields dΣ/dR>0 at >99.9% confidence -- i.e., a profile that decreases towards the centre. Although these signatures cannot yet be regarded as robust evidence for dark subhaloes, they suggest that central stellar depletion in dwarf galaxies may reflect genuine physical structure rather than crowding alone.
Related
- A combined HST and JWST analysis of the stellar population in Draco II
- A combined HST and JWST analysis of the stellar population in Draco II
- Stellar Loci X: Selection of Nitrogen-Rich Giants Using GALEX NUV and Synthetic SDSS Photometry
- Size, Albedo, and Taxonomy of Asteroid (1201) Strenua from Stellar Occultation and ATLAS Photometry
- The JWST Ultramassive Galaxy Sample -- I. Overview, Photometry, and Stellar Kinematics: Selecting Optimal Template Subsets via Non-Negative Matrix Factorization
BibTeX
@misc{vitral2026central,
title = {{Central stellar depletion in the Draco dwarf from Subaru photometry}},
author = {Eduardo Vitral and Kyosuke S. Sato and Jorge Peñarrubia and Sakurako Okamoto and Veronika Dornan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10941},
eprint = {2610.10941},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10941},
}
RIS
TY - UNPB
TI - Central stellar depletion in the Draco dwarf from Subaru photometry
AU - Eduardo Vitral
AU - Kyosuke S. Sato
AU - Jorge Peñarrubia
AU - Sakurako Okamoto
AU - Veronika Dornan
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10941
UR - https://arxiv.org/abs/2610.10941
AB - Dark matter subhaloes are a fundamental prediction of the standard cosmological model, but their low-mass population remains difficult to constrain observationally. Recent work has shown that interactions between subhaloes and dwarf spheroidal galaxies can induce large-scale, out-of-equilibrium fluctuations in their stellar surface density fields, identifiable through Fourier-based statistics. We apply this formalism to deep Subaru photometry of the Draco dwarf, extending previous tests to ≳𝒪(10^4) resolved stars. We use artificial-star tests to assign completeness weights to individual stars and incorporate them into a discrete likelihood-based framework. Relative to a cored axisymmetric Plummer model, Draco shows radial corrugations that appear in the filtered normalised residuals as a central stellar depletion surrounded by a ring-like excess. The same feature appears in Fourier space as a low-frequency peak with a signal-to-noise ratio S/N=6.0. Independently, fitting the surface density Σ with an αβγ model yields dΣ/dR>0 at >99.9% confidence -- i.e., a profile that decreases towards the centre. Although these signatures cannot yet be regarded as robust evidence for dark subhaloes, they suggest that central stellar depletion in dwarf galaxies may reflect genuine physical structure rather than crowding alone.
ER -