Near-infrared and optical observations of galactic warps: A common, unexplained feature of most discs - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




Near-infrared and optical observations of galactic warps: A common, unexplained feature of most discs - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: Context: Warps occurring in galactic discs have been studied extensively inHI and in the optical, but rarely in the near-infrared NIR bands that tracethe older stellar populations.Aims: We provide NIR data of nearby edge-on galaxies, combined with opticalobservations, for direct comparison of the properties of galactic warps as afunction of wavelength, and calculate warp curves for each galaxy and obtainthe characteristic warp parameters. We discuss these properties as possibleconstraints to the different mechanisms that have been proposed for thedevelopment and persistence of galactic warps.Methods: We observed 20 galaxies that were selected from a statisticallycomplete diameter-limited subsample of edge-on disc galaxies. We used the CerroTololo Infrared Imager CIRIM at the CTIO 1.5m Ritchey-Chretien telescope toacquire the NIR data. We used the 1.54m Danish and 0.92m Dutch telescopes atthe European Southern Observatory-s La Silla site for our optical observations.Results: Our results show that 13 of our 20 sample galaxies are warped, withthe warp more pronounced in the optical than at NIR wavelengths. In theremaining seven galaxies, no warp is apparent within the limitations of ourautomated detection method. The transition between the unperturbed inner discand the outer, warped region is rather abrupt. S0 galaxies exhibit very smallor no warps. The magnetic model remains one of a number of interestingformation scenarios.



Author: A. Guijarro, R. F. Peletier, E. Battaner, J. Jiménez-Vicente, R. de Grijs, E. Florido

Source: https://arxiv.org/







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