DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA
Abstract
Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-linemore »
- Authors:
-
- Department of Physics and Astronomy, James Madison University, Harrisonburg, VA 22807 (United States)
- Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States)
- Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
- Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575 (United States)
- Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
- Publication Date:
- OSTI Identifier:
- 22521828
- Resource Type:
- Journal Article
- Journal Name:
- Astrophysical Journal
- Additional Journal Information:
- Journal Volume: 814; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COMPARATIVE EVALUATIONS; DENSITY; EMISSION SPECTRA; EXCITATION; GALAXIES; GALAXY NUCLEI; LUMINOSITY; POTENTIALS; QUASARS; RESOLUTION; SENSITIVITY; SPACE; STARS; TELESCOPES
Citation Formats
Constantin, Anca, Castillo, Christopher A., Shields, Joseph C., Ho, Luis C., Barth, Aaron J., and Filippenko, Alexei V. DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA. United States: N. p., 2015.
Web. doi:10.1088/0004-637X/814/2/149.
Constantin, Anca, Castillo, Christopher A., Shields, Joseph C., Ho, Luis C., Barth, Aaron J., & Filippenko, Alexei V. DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA. United States. https://doi.org/10.1088/0004-637X/814/2/149
Constantin, Anca, Castillo, Christopher A., Shields, Joseph C., Ho, Luis C., Barth, Aaron J., and Filippenko, Alexei V. 2015.
"DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA". United States. https://doi.org/10.1088/0004-637X/814/2/149.
@article{osti_22521828,
title = {DISSECTING THE POWER SOURCES OF LOW-LUMINOSITY EMISSION-LINE GALAXY NUCLEI VIA COMPARISON OF HST-STIS AND GROUND-BASED SPECTRA},
author = {Constantin, Anca and Castillo, Christopher A. and Shields, Joseph C. and Ho, Luis C. and Barth, Aaron J. and Filippenko, Alexei V.},
abstractNote = {Using a sample of ∼100 nearby line-emitting galaxy nuclei, we have built the currently definitive atlas of spectroscopic measurements of Hα and neighboring emission lines at subarcsecond scales. We employ these data in a quantitative comparison of the nebular emission in Hubble Space Telescope (HST) and ground-based apertures, which offer an order-of-magnitude difference in contrast, and provide new statistical constraints on the degree to which transition objects and low-ionization nuclear emission-line regions (LINERs) are powered by an accreting black hole at ≲10 pc. We show that while the small-aperture observations clearly resolve the nebular emission, the aperture dependence in the line ratios is generally weak, and this can be explained by gradients in the density of the line-emitting gas: the higher densities in the more nuclear regions potentially flatten the excitation gradients, suppressing the forbidden emission. The transition objects show a threefold increase in the incidence of broad Hα emission in the high-resolution data, as well as the strongest density gradients, supporting the composite model for these systems as accreting sources surrounded by star-forming activity. The narrow-line LINERs appear to be the weaker counterparts of the Type 1 LINERs, where the low accretion rates cause the disappearance of the broad-line component. The enhanced sensitivity of the HST observations reveals a 30% increase in the incidence of accretion-powered systems at z ≈ 0. A comparison of the strength of the broad-line emission detected at different epochs implies potential broad-line variability on a decade-long timescale, with at least a factor of three in amplitude.},
doi = {10.1088/0004-637X/814/2/149},
url = {https://www.osti.gov/biblio/22521828},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 814,
place = {United States},
year = {Tue Dec 01 00:00:00 EST 2015},
month = {Tue Dec 01 00:00:00 EST 2015}
}