A panoramic VISTA of the stellar halo of NGC 253

Abstract

Outskirts of large galaxies contain important information about the galaxy formation and assembly process, and resolved star count studies can probe the extremely low surface brightness of the outer halos. We use images obtained with the VISTA telescope to construct spatially resolved J vs Z-J colour-magnitude diagrams (CMDs) of NGC 253, a nearly edge-on disk galaxy in the Sculptor group. The very deep photometry, down to J ~ 23.5, and the wide area covered allows us to trace the red giant branch (RGB) and asymptotic giant branch (AGB) stars that belong to the outer disk and the halo of NGC 253, out to 50 kpc along the galaxy minor axis. We confirm the existence of an extra planar stellar component of the disk, with a very prominent southern shelf and a symmetrical feature on the north side. The only additional visible sub-structure is an overdensity in the north-west part of the halo at about 28 kpc from the plane and extending over ~ 20 kpc parallel with the disk of the galaxy. From the stellar count profile along the major axis we measure the transition from the disk to the halo at a radial distance of about 25 kpc, where a clear break appears in the number density profile. The isodensity contours show that the inner halo is a flattened structure that blends with a more extended, diffuse, rounder outer halo. Such external structure can be traced to the very edge of our image out to 50 kpc from the disk plane. The number density profile of the stars in the stellar halo follows a power law with index -1.6, as function of radius. The CMD shows a very homogeneous stellar population across the whole field; by comparison with theoretical isochrones we conclude that the RGB stars are ~ 8 Gyr old or more, while the AGB stars trace a population of about 2 x 10^8 Mo, formed from ~ 0.5 to a few Gyr ago. Surprisingly, part of this latter population appears scattered over a wide area.

To appear on Astronomy and Astrophysics

References in corpus (11)

• Two Stellar Components in the Halo of the Milky Way
• The ACS Nearby Galaxy Survey Treasury
• The accretion origin of the Milky Way's stellar halo
• The Haunted Halos of Andromeda and Triangulum: A panorama of galaxy formation in action
• The Dual Origin of Stellar Halos
• The large-scale structure of the halo of the Andromeda Galaxy Part I: global stellar density, morphology and metallicity properties
• The ghost of a dwarf galaxy: fossils of the hierarchical formation of the nearby spiral galaxy NGC 5907
• Discovery of a Giant Stellar Tidal Stream Around the Disk Galaxy NGC 4013
• An HST/ACS investigation of the spatial and chemical structure and sub-structure of NGC 891, a Milky Way analogue
• XMM-Newton observations of the diffuse X-ray emission in the starburst galaxy NGC 253
• Unearthing Foundations of a Cosmic Cathedral: Searching the Stars for M33's Halo

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