A First Measurement of Circumgalactic Dust Reddening from Only 4.6 deg 2 of the Rubin Observatory’s Data Preview 1
Year: 2026
Type: article
Abstract: We present the first measurement of circumgalactic dust reddening from the Vera C. Rubin Observatory, using only 4.6 deg 2 of ComCam Data Preview 1—roughly 0.03% of the final LSST footprint. Using photometric redshifts, we stack background-galaxy colors around foreground-galaxy positions and detect a chromatic reddening profile from r ⊥ ≃ 10 kpc to 1 Mpc. Interpreting average E ( g − z ) with a Milky Way extinction curve, we find A V = ( 1.3 ± 0.4 ) × 1 0 − 1 ( r ⊥ / 20 kpc ) − 1.8 ± 0.4 within 120 kpc. The amplitude and radial dependence agree with earlier Sloan Digital Sky Survey, KiDS, and Dark Energy Survey results despite the ∼1000× smaller survey area and a foreground sample extending 3–6 mag fainter and 1–2 dex lower in stellar mass. The innermost 10–15 kpc bin reaches A V ≃ 0.3 mag, comparable to high-latitude extinction through the Milky Way disk near the solar circle; the steep power-law slope implies a dust distribution that does not simply trace the halo-gas profile. Splitting by rest-frame g − r shows stronger extinction around red foreground galaxies (rest-frame g − r > 0.5), although the blue subsample is too noisy to establish a significant color dependence. This red sample, with median halo mass 5 × 10 11 M ⊙ , shows substantially more reddening within 50 kpc than previously measured around more massive luminous red galaxies and implies a dust-to-stellar-mass ratio of ∼2%, nearly saturating the dust budget allowed by stellar metal yields. These pathfinder data demonstrate LSST’s promise for high-precision galaxy–dust measurements across galaxy mass, environment, and redshift.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
Awards: G1229526393, NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab): Management and Operations of Vera C. Rubin Observatory, Construction of Vera C. Rubin Observatory under the Major Research Equipment and Facilities Construction (MREFC) Account, Final Design, Construction and Operations of Vera C. Rubin Observatory, SEARCHING FOR STRONGLY INTERACTING DARK SECTORS WITH ELECTRON BEAMS, G2371548206, G262532246, CAREER: The Disk/Halo Link: Synthesizing Gaseous Tracer Samples in the Milky Way, G303061748, G4235786860, G4654690619, NSF's National Optical-Infrared Astronomy Research Laboratory (NOIRLab) as a Federally Funded Research and Development Center (FFRDC), G495301720, G498139845, G5570207115, G6671297155, G8382000481, G969889393, G97770923
OpenAlex ID: W7213459398