The central engines of 19 liners as viewed by Chandra

Hélène M.L.G. Flohic, Michael Eracleous, George Chartas, Joseph C. Shields, Edward C. Moran

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Using archival Chandra observations of 19 LINERs, we explore the X-ray properties of their inner kiloparsec to determine the origin of their nuclear X-ray emission, to investigate the presence of an AGN, and to identify the power source of the optical emission lines. The relative numbers of LINER types in our sample are similar to those in optical spectroscopic surveys. We find that diffuse, thermal emission is very common and is concentrated within the central few hundred parsecs. The average spectra of the hot gas in spiral and elliptical galaxies are very similar to those of normal galaxies. They can be fitted with a thermal plasma (kT ∼ 0.5 keV) plus a power-law (photon index of 1.3-1.5) model. There are on average three detected point sources in their inner kiloparsec with 1037 ergs s-1 < L0.5-10keV < 1040 ergs s-1. The average cumulative luminosity functions for sources in spiral and elliptical galaxies are identical to those of normal galaxies. In the innermost circle of 2.″5 radius in each galaxy we find an AGN in 12 of the 19 galaxies. The AGNs contribute a median of 60% of the 0.5-10 keV luminosity of the central 2.″'5 region, and they have luminosities of 1037-1039 ergs s-1 (Eddington ratios of 10-8 to 10-5). The ionizing luminosity of the AGNs is not enough to power the observed optical emission lines in this particular sample. Thus, we suggest that the lines are powered either by the mechanical interaction of an AGN jet (or wind) with the circumnuclear gas or by stellar processes, such as photoionization by post-AGB stars from an old or intermediate-age population (in most cases) or by young stars (in a few cases).

Original languageEnglish (US)
Pages (from-to)140-160
Number of pages21
JournalAstrophysical Journal
Volume647
Issue number1 I
DOIs
StatePublished - Aug 10 2006

Fingerprint

linings
liner
engines
engine
luminosity
erg
galaxies
elliptical galaxies
spiral galaxies
light emission
thermal plasmas
asymptotic giant branch stars
high temperature gases
thermal emission
gas
point sources
point source
photoionization
power law
x rays

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Flohic, H. M. L. G., Eracleous, M., Chartas, G., Shields, J. C., & Moran, E. C. (2006). The central engines of 19 liners as viewed by Chandra. Astrophysical Journal, 647(1 I), 140-160. https://doi.org/10.1086/505296
Flohic, Hélène M.L.G. ; Eracleous, Michael ; Chartas, George ; Shields, Joseph C. ; Moran, Edward C. / The central engines of 19 liners as viewed by Chandra. In: Astrophysical Journal. 2006 ; Vol. 647, No. 1 I. pp. 140-160.
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abstract = "Using archival Chandra observations of 19 LINERs, we explore the X-ray properties of their inner kiloparsec to determine the origin of their nuclear X-ray emission, to investigate the presence of an AGN, and to identify the power source of the optical emission lines. The relative numbers of LINER types in our sample are similar to those in optical spectroscopic surveys. We find that diffuse, thermal emission is very common and is concentrated within the central few hundred parsecs. The average spectra of the hot gas in spiral and elliptical galaxies are very similar to those of normal galaxies. They can be fitted with a thermal plasma (kT ∼ 0.5 keV) plus a power-law (photon index of 1.3-1.5) model. There are on average three detected point sources in their inner kiloparsec with 1037 ergs s-1 < L0.5-10keV < 1040 ergs s-1. The average cumulative luminosity functions for sources in spiral and elliptical galaxies are identical to those of normal galaxies. In the innermost circle of 2.″5 radius in each galaxy we find an AGN in 12 of the 19 galaxies. The AGNs contribute a median of 60{\%} of the 0.5-10 keV luminosity of the central 2.″'5 region, and they have luminosities of 1037-1039 ergs s-1 (Eddington ratios of 10-8 to 10-5). The ionizing luminosity of the AGNs is not enough to power the observed optical emission lines in this particular sample. Thus, we suggest that the lines are powered either by the mechanical interaction of an AGN jet (or wind) with the circumnuclear gas or by stellar processes, such as photoionization by post-AGB stars from an old or intermediate-age population (in most cases) or by young stars (in a few cases).",
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Flohic, HMLG, Eracleous, M, Chartas, G, Shields, JC & Moran, EC 2006, 'The central engines of 19 liners as viewed by Chandra', Astrophysical Journal, vol. 647, no. 1 I, pp. 140-160. https://doi.org/10.1086/505296

The central engines of 19 liners as viewed by Chandra. / Flohic, Hélène M.L.G.; Eracleous, Michael; Chartas, George; Shields, Joseph C.; Moran, Edward C.

In: Astrophysical Journal, Vol. 647, No. 1 I, 10.08.2006, p. 140-160.

Research output: Contribution to journalArticle

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Flohic HMLG, Eracleous M, Chartas G, Shields JC, Moran EC. The central engines of 19 liners as viewed by Chandra. Astrophysical Journal. 2006 Aug 10;647(1 I):140-160. https://doi.org/10.1086/505296