The elusive stellar halo of the Triangulum Galaxy

Abstract

The stellar halos of large galaxies represent a vital probe of the processes of galaxy evolution. They are the remnants of the initial bouts of star formation during the collapse of the proto-galactic cloud, coupled with imprint of ancient and on-going accretion events. Previously, we have reported the tentative detection of a possible, faint, extended stellar halo in the Local Group spiral, the Triangulum Galaxy (M33). However, the presence of substructure surrounding M33 made interpretation of this feature difficult. Here, we employ the final data set from the Pan-Andromeda Archaeological Survey (PAndAS), combined with an improved calibration and a newly derived contamination model for the region to revisit this claim. With an array of new fitting algorithms, fully accounting for contamination and the substantial substructure beyond the prominent stellar disk in M33, we reanalyse the surrounds to separate the signal of the stellar halo and the outer halo substructure. Using more robust search algorithms, we do not detect a large scale smooth stellar halo and place a limit on the maximum surface brightness of such a feature of ${\mu }_V$ = 35.5 mags per square arcsec, or a total halo luminosity of $L<10^6{L}_{\odot }$.

arXiv comment17 pages, 23 figures, accepted for publication in MNRAS

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Cited by in corpus (9)

• Orbits of Massive Satellite Galaxies: I. A Close Look at the Large Magellanic Cloud and a New Orbital History for M33
• The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) I. Ultraviolet to Infrared Photometry of 22 Million Stars in M33
• The outer halo globular cluster system of M31 - III. Relationship to the stellar halo
• Stellar halos from The Dragonfly Edge-on Galaxies Survey
• The TREX Survey: Kinematical Complexity Throughout M33's Stellar Disk and Evidence for a Stellar Halo
• A deep narrowband survey for planetary nebulae at the outskirts of M33
• Resolved Stellar Populations as Tracers of Outskirts
• Simulations of the accreted stellar halos of low-mass field galaxies
• The Astrophysical Distance Scale: V. A 2% Distance to the Local Group Spiral M33 via the JAGB Method, Tip of the Red Giant Branch, and Leavitt Law