STELLAR TIDAL STREAMS IN SPIRAL GALAXIES OF THE LOCAL VOLUME: A PILOT SURVEY WITH MODEST APERTURE TELESCOPES
- Max Planck Institut fuer Astronomie, Heidelberg (Germany)
- Black Bird Observatory, Mayhill, NM (United States)
- Rancho del Sol Observatory, Modesto, CA (United States)
- Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
- Instituto de Astrofisica de Canarias, La Laguna (Spain)
- Institute of Astronomy, University of Cambridge (United Kingdom)
- Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States)
- The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
- Argelander Institut fuer Astronomie, Universitaet Bonn (Germany)
Within the hierarchical framework for galaxy formation, minor merging and tidal interactions are expected to shape all large galaxies to the present day. As a consequence, most seemingly normal disk galaxies should be surrounded by spatially extended stellar 'tidal features' of low surface brightness. As part of a pilot survey for such interaction signatures, we have carried out ultra deep, wide field imaging of eight isolated spiral galaxies in the Local Volume, with data taken at small (D = 0.1-0.5 m) robotic telescopes that provide exquisite surface brightness sensitivity ({mu}{sub lim}(V) {approx} 28.5 mag arcsec{sup -2}). This initial observational effort has led to the discovery of six previously undetected extensive (to {approx}30 kpc) stellar structures in the halos surrounding these galaxies, likely debris from tidally disrupted satellites. In addition, we confirm and clarify several enormous stellar over-densities previously reported in the literature, but never before interpreted as tidal streams. Even this pilot sample of galaxies exhibits strikingly diverse morphological characteristics of these extended stellar features: great circle-like features that resemble the Sagittarius stream surrounding the Milky Way, remote shells and giant clouds of presumed tidal debris far beyond the main stellar body, as well as jet-like features emerging from galactic disks. Together with presumed remains of already disrupted companions, our observations also capture surviving satellites caught in the act of tidal disruption. A qualitative comparison with available simulations set in a {Lambda}Cold Dark Matter cosmology (that model the stellar halo as the result of satellite disruption evolution) shows that the extraordinary variety of stellar morphologies detected in this pilot survey matches that seen in those simulations. The common existence of these tidal features around 'normal' disk galaxies and the morphological match to the simulations constitutes new evidence that these theoretical models also apply to a large number of other Milky Way-mass disk galaxies in the Local Volume.
- OSTI ID:
- 21443227
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 4 Vol. 140; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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