Detalles de publicación
PP 07030
The outer Disks of Early-type Galaxies.I.Surface brightness Profiles of Barred Galaxies.
1. Max Planck Institut f�r Extraterrestrische Physik,Garching, Germany.
2. Instituto de Astrof�sica de Canarias. La Laguna, Tenerife, Spain.
3. Astronomical Institute, University of Groningen, Netherlands
4. Consejo Superior de Investigaciones Cient�ficas, Spain.
We present a study of 66 barred early-type (S0-Sb) disk galaxies, focused on the disk surface brightness profile outside the bar region, with the aim of throwing light on the nature of Freeman Type I and Type II profiles, their origins, and their possible relation to disk truncations. This paper discusses the data and their reduction, outlines our classification system, and presents R-band profiles for all the galaxies in the sample, along with their classifications. In subsequent papers we will explore the structure of outer disks as revealed by these profiles, and investigate their possible origins.
The profiles are derived from a variety of different sources, including the Sloan Digital Sky survey (Data Release 5). For about half of the galaxies we have profiles from more than one telescope; this allows us to check the stability and repeatability of our prifle extraction and classification. The vast majority of the profiles are reliable down to levels of R surface brightness ~27 mag/arcsec*2. In exceptional cases we can trace profiles down to values below 28 mag/arcsec*2. We can typically follow profiles out to at least 1.5 times the traditional optical radius R(25), and for some galaxies we find light extending out to $ 3xR(25). For Type I (single exponential) profiles this
means that we can trace the exponential disk out to 6-7 scale lengths.
We classify the profiles into three main groups: Type I (single exponential),
Type II (down-bending) and Type III (up-bending). The frequencies of these types
are approximately 27%, 42%, and 24% respectively, plus another 6% which are
combinations of Type II and Type III.
We further classify Type II profiles by where the break falls in relation to the bar length, and in terms of postulated mechanisms for breaks at large radii ("classical" truncations versus the influence of the Outer Lindblad Resonance of the bar). We also classify Type III profiles by the probable morphology of the outer light (disk or spheoid). Illustrations are given for all cases
The profiles are derived from a variety of different sources, including the Sloan Digital Sky survey (Data Release 5). For about half of the galaxies we have profiles from more than one telescope; this allows us to check the stability and repeatability of our prifle extraction and classification. The vast majority of the profiles are reliable down to levels of R surface brightness ~27 mag/arcsec*2. In exceptional cases we can trace profiles down to values below 28 mag/arcsec*2. We can typically follow profiles out to at least 1.5 times the traditional optical radius R(25), and for some galaxies we find light extending out to $ 3xR(25). For Type I (single exponential) profiles this
means that we can trace the exponential disk out to 6-7 scale lengths.
We classify the profiles into three main groups: Type I (single exponential),
Type II (down-bending) and Type III (up-bending). The frequencies of these types
are approximately 27%, 42%, and 24% respectively, plus another 6% which are
combinations of Type II and Type III.
We further classify Type II profiles by where the break falls in relation to the bar length, and in terms of postulated mechanisms for breaks at large radii ("classical" truncations versus the influence of the Outer Lindblad Resonance of the bar). We also classify Type III profiles by the probable morphology of the outer light (disk or spheoid). Illustrations are given for all cases