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The Survey of Nearby Nuclei with the Space Telescope Imaging Spectrograph: Emission-Line Nuclei at Hubble Space Telescope Resolution

Shields, Joseph C. and Rix, Hans-Walter and Sarzi, Marc and Barth, Aaron J. and Filippenko, Alexei V. and Ho, Luis C. and McIntosh, Daniel H. and Rudnick, Gregory and Sargent, Wallace L. W. (2007) The Survey of Nearby Nuclei with the Space Telescope Imaging Spectrograph: Emission-Line Nuclei at Hubble Space Telescope Resolution. Astrophysical Journal, 654 (1). pp. 125-137. ISSN 0004-637X.

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We present results from a program of optical spectroscopy for 23 nearby galaxies with emission-line nuclei. This investigation takes advantage of the spatial resolution of the Hubble Space Telescope to study the structure and energetics of the central ~10-20 pc, and the resulting data have value for quantifying central black hole masses, star formation histories, and nebular properties. This paper provides a description of the experimental design, and new findings from the study of emission lines. The sample targets span a range of nebular spectroscopic class, from H II to Seyfert nuclei. This data set and the resulting measurements are unique in terms of the sample size, the range of nebular class, and the investigation of physical scales extending down to parsecs. The line ratios indicative of nebular ionization show only modest variations over order-of-magnitude differences in radius, and demonstrate in a systematic way that geometrical dilution of the radiation field from a central source cannot be assumed as a primary driver of ionization structure. Comparisons between large- and small-aperture measurements for the H II/LINER transition objects provide a new test that challenges conventional wisdom concerning the composite nature of these systems. We also list a number of other quantitative results that are of interest for understanding galaxy nuclei, including (1) the spatial distribution/degree of concentration of Hα emission as a function of nebular type; (2) the radial variation in electron density as a function of nebular type; and (3) quantitative broad Hα estimates obtained at a second epoch for these low-luminosity nuclei. The resulting measurements provide a new basis for comparing the nuclei of other galaxies with that of the Milky Way. We find that the Galactic center is representative across a wide span of properties as a low-luminosity emission-line nucleus.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rix, Hans-Walter0000-0003-4996-9069
Barth, Aaron J.0000-0002-3026-0562
Filippenko, Alexei V.0000-0003-3460-0103
Ho, Luis C.0000-0001-6947-5846
Rudnick, Gregory0000-0001-5851-1856
Additional Information:© 2007 American Astronomical Society. Print publication: Issue 1 (2007 January 1); received 2004 August 14; accepted for publication 2006 September 8. We thank the referee for constructive comments. Support for this research was provided by NASA through grant GO-7361 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
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Subject Keywords:galaxies: active; galaxies: nuclei; Galaxy: center; Galaxy: nucleus
Issue or Number:1
Record Number:CaltechAUTHORS:20100212-114511057
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Official Citation:The Survey of Nearby Nuclei with the Space Telescope Imaging Spectrograph: Emission-Line Nuclei at Hubble Space Telescope Resolution Joseph C. Shields, Hans-Walter Rix, Marc Sarzi, Aaron J. Barth, Alexei V. Filippenko, Luis C. Ho, Daniel H. McIntosh, Gregory Rudnick, and Wallace L. W. Sargent 2007 ApJ 654 125-137 doi: 10.1086/509059
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17469
Deposited By: Jason Perez
Deposited On:12 Feb 2010 22:35
Last Modified:09 Mar 2020 13:18

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