skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE

Abstract

We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dish observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas.more » Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.« less

Authors:
; ;  [1];  [2];  [3];  [4];  [5];  [6];  [7]; ;  [8];  [9]
  1. Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)
  2. Joint ALMA Office, Av. El Golf 40, Piso 18, Las Condes, Santiago (Chile)
  3. Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany)
  4. Nobeyama Radio Observatory, NAOJ, Minamimaki, Minamisaku, Nagano, 384-1305 (Japan)
  5. Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden (Netherlands)
  6. Onsala Space Observatory, SE-43992 Onsala (Sweden)
  7. Harvard-Smithsonian Center for Astrophysics, Submillimeter Array, 645 North A'ohoku Place, Hilo, HI 96720 (United States)
  8. Department of Physics and Astronomy, MSC07 4220, University of New Mexico, Albuquerque, NM 87131 (United States)
  9. Center for Quantum Electronics, Institute of Physics, Vietnam Academy of Science and Technology, 10 DaoTan, ThuLe, BaDinh, Hanoi (Viet Nam)
Publication Date:
OSTI Identifier:
21460109
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 720; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/720/1/666
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ABSORPTION SPECTRA; PHYSICAL PROPERTIES; QUASARS; RADIO GALAXIES; COSMIC RADIO SOURCES; GALAXIES; SORPTION; SPECTRA

Citation Formats

Espada, D., Matsushita, S., Sakamoto, K., Peck, A. B., Henkel, C., Iono, D., Israel, F. P., Muller, S., Petitpas, G., Pihlstroem, Y., Taylor, G. B., and Trung, D. V., E-mail: despada@cfa.harvard.ed. DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE. United States: N. p., 2010. Web. doi:10.1088/0004-637X/720/1/666.
Espada, D., Matsushita, S., Sakamoto, K., Peck, A. B., Henkel, C., Iono, D., Israel, F. P., Muller, S., Petitpas, G., Pihlstroem, Y., Taylor, G. B., & Trung, D. V., E-mail: despada@cfa.harvard.ed. DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE. United States. doi:10.1088/0004-637X/720/1/666.
Espada, D., Matsushita, S., Sakamoto, K., Peck, A. B., Henkel, C., Iono, D., Israel, F. P., Muller, S., Petitpas, G., Pihlstroem, Y., Taylor, G. B., and Trung, D. V., E-mail: despada@cfa.harvard.ed. Wed . "DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE". United States. doi:10.1088/0004-637X/720/1/666.
@article{osti_21460109,
title = {DISENTANGLING THE CIRCUMNUCLEAR ENVIRONS OF CENTAURUS A. II. ON THE NATURE OF THE BROAD ABSORPTION LINE},
author = {Espada, D. and Matsushita, S. and Sakamoto, K. and Peck, A. B. and Henkel, C. and Iono, D. and Israel, F. P. and Muller, S. and Petitpas, G. and Pihlstroem, Y. and Taylor, G. B. and Trung, D. V., E-mail: despada@cfa.harvard.ed},
abstractNote = {We report on atomic gas (H I) and molecular gas (as traced by CO(2-1)) redshifted absorption features toward the nuclear regions of the closest powerful radio galaxy, Centaurus A (NGC 5128). Our H I observations using the Very Long Baseline Array allow us to discern with unprecedented sub-parsec resolution H I absorption profiles toward different positions along the 21 cm continuum jet in the inner 0.''3 (or 5.4 pc). In addition, our CO(2-1) data obtained with the Submillimeter Array probe the bulk of the absorbing molecular gas with little contamination by emission, which was not possible with previous CO single-dish observations. We shed light on the physical properties of the gas in the line of sight with these data, emphasizing the still open debate about the nature of the gas that produces the broad absorption line ({approx}55 km s{sup -1}). First, the broad H I line is more prominent toward the central and brightest 21 cm continuum component than toward a region along the jet at a distance {approx}20 mas (or 0.4 pc) further from the nucleus. This indicates that the broad absorption line arises from gas located close to the nucleus, rather than from diffuse and more distant gas. Second, the different velocity components detected in the CO(2-1) absorption spectrum match well with other molecular lines, such as those of HCO{sup +}(1-0), except the broad absorption line that is detected in HCO{sup +}(1-0) (and most likely related to that of the H I). Dissociation of molecular hydrogen due to the active galactic nucleus seems to be efficient at distances r {approx}< 10 pc, which might contribute to the depth of the broad H I and molecular lines.},
doi = {10.1088/0004-637X/720/1/666},
journal = {Astrophysical Journal},
number = 1,
volume = 720,
place = {United States},
year = {Wed Sep 01 00:00:00 EDT 2010},
month = {Wed Sep 01 00:00:00 EDT 2010}
}