photoD with Rubin's Data Preview 1: first stellar photometric distances and deficit of faint blue stars. Stellar distances with Rubin's DP1

TL;DR

This paper uses Rubin's Data Preview 1 to estimate stellar distances and densities in the Milky Way halo, revealing a steeper density profile than previously modeled, which impacts future Galactic studies.

Contribution

It demonstrates the utility of Rubin's Data Preview 1 for stellar density profiling and identifies a steeper halo density profile than canonical models.

Findings

Significant deficit of blue main sequence turn-off stars at faint magnitudes.

Steeper halo density profile at 10-50 kpc than the standard 1/r^3.

Results align with earlier observations of luminous stellar populations.

Abstract

Aims: We investigate the utility of Rubin's Data Preview 1 for estimating stellar number density profile in the Milky Way halo. Methods: Stellar broad-band near-UV to near-IR $ugrizy$ photometry released in Rubin's Data Preview 1 is used to estimate distance and metallicity for blue main sequence stars brighter than $r=24$ in three $\sim$1.1. sq.~deg. fields at southern Galactic latitudes. Results: Compared to TRILEGAL simulations of the Galaxy's stellar content by (Dal Tio, 2022), we find a significant deficit of blue main sequence turn-off stars with $22 < r < 24$. We interpret this discrepancy as a signature of a much steeper halo number density profile at galactocentric distances $10-50$ kpc than the cannonical $\sim1/r^3$ profile assumed in TRILEGAL simulations. Conclusions: This interpretation is consistent with earlier suggestions based on observations of more luminous, but much less numerous, evolved stellar populations, and a few pencil beam surveys of blue main sequence stars in the northern sky. These results bode well for the future Galactic halo exploration with Rubin's Legacy Survey of Space and Time.