An Analysis Framework for Understanding the Origin of Nuclear Activity in Low-power Radio Galaxies

Using large samples containing nearly 2300 active galaxies of low radio luminosity (1.4 GHz luminosity between 2 × 1023 and 3 × 1025 W Hz−1, essentially low-excitation radio galaxies) at z 0.3, we present a self-contained analysis of the dependence of the nuclear radio activity on both intrinsic and...

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Bibliographic Details
Published in:The Astronomical journal 2018-05, Vol.155 (5), p.188
Main Authors: Lin, Yen-Ting, Huang, Hung-Jin, Chen, Yen-Chi
Format: Article
Language:English
Subjects:
Active galaxies
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
Cooling effects
COOLING TIME
Dark matter
Dependence
Deposition
ENTROPY
EXCITATION
Galactic halos
Galaxies
galaxies: active
galaxies: clusters: general
galaxies: elliptical and lenticular, cD
GALAXY CLUSTERS
Gas cooling
GHZ RANGE 01-100
Halos
LUMINOSITY
MASS
NONLUMINOUS MATTER
Principal components analysis
Radio astronomy
radio continuum: galaxies
RADIO GALAXIES
Regression analysis
SATELLITES
Statistical analysis
Statistical methods
Stellar mass
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Summary:Using large samples containing nearly 2300 active galaxies of low radio luminosity (1.4 GHz luminosity between 2 × 1023 and 3 × 1025 W Hz−1, essentially low-excitation radio galaxies) at z 0.3, we present a self-contained analysis of the dependence of the nuclear radio activity on both intrinsic and extrinsic properties of galaxies, with the goal of identifying the best predictors of the nuclear radio activity. While confirming the established result that stellar mass must play a key role on the triggering of radio activities, we point out that for the central, most massive galaxies, the radio activity also shows a strong dependence on halo mass, which is not likely due to enhanced interaction rates in denser regions in massive, cluster-scale halos. We thus further investigate the effects of various properties of the intracluster medium (ICM) in massive clusters on the radio activities, employing two standard statistical tools, principle component analysis and logistic regression. It is found that ICM entropy, local cooling time, and pressure are the most effective in predicting the radio activity, pointing to the accretion of gas cooling out of a hot atmosphere to be the likely origin in triggering such activities in galaxies residing in massive dark matter halos. Our analysis framework enables us to logically discern the mechanisms responsible for the radio activity separately for central and satellite galaxies.
ISSN:0004-6256
1538-3881
1538-3881
DOI:10.3847/1538-3881/aab5b4