Compact radio galaxies with a GHz-peaked spectrum (GPS) and/or compact-symmetric-object (CSO) morphology (GPS/CSOs) are increasingly detected in the X-ray domain. Their radio and X-ray emissions are affected by significant absorption. However, the locations of the X-ray and radio absorbers are still debated. We investigated the relationship between the column densities of the total (N_H) and neutral (N_HI) hydrogen to statistically constrain the picture. We compiled a sample of GPS/CSOs including both literature data and new radio data that we acquired with the Westerbork Synthesis Radio Telescope for sources whose X-ray emission was either established or under investigation. In this sample, we compared the X-ray and radio hydrogen column densities, and found that N_H and N_HI display a significant positive correlation, with N_HI \propto N_H^b, where b=0.47 and b=0.35, depending on the subsample. The N_H-N_HI correlation suggests that the X-ray and radio absorbers are either co-spatial or different components of a continuous structure. The correlation displays a large intrinsic spread that we suggest to originate from fluctuations, around a mean value, of the ratio between the spin temperature and the covering factor of the radio absorber, T_s/C_f.

Correlation between X-ray and radio absorption in compact radio galaxies

L. Ostorero;A. Diaferio;
2017-01-01

Abstract

Compact radio galaxies with a GHz-peaked spectrum (GPS) and/or compact-symmetric-object (CSO) morphology (GPS/CSOs) are increasingly detected in the X-ray domain. Their radio and X-ray emissions are affected by significant absorption. However, the locations of the X-ray and radio absorbers are still debated. We investigated the relationship between the column densities of the total (N_H) and neutral (N_HI) hydrogen to statistically constrain the picture. We compiled a sample of GPS/CSOs including both literature data and new radio data that we acquired with the Westerbork Synthesis Radio Telescope for sources whose X-ray emission was either established or under investigation. In this sample, we compared the X-ray and radio hydrogen column densities, and found that N_H and N_HI display a significant positive correlation, with N_HI \propto N_H^b, where b=0.47 and b=0.35, depending on the subsample. The N_H-N_HI correlation suggests that the X-ray and radio absorbers are either co-spatial or different components of a continuous structure. The correlation displays a large intrinsic spread that we suggest to originate from fluctuations, around a mean value, of the ratio between the spin temperature and the covering factor of the radio absorber, T_s/C_f.
849
1
34
52
https://arxiv.org/abs/1709.08404
http://iopscience.iop.org/article/10.3847/1538-4357/aa8ef6
http://adsabs.harvard.edu/abs/2017ApJ...849...34O
Ostorero, L.; Morganti, R.; Diaferio, A.; Siemiginowska, A.; Stawarz, L.; Moderski, R.; Labiano, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1656172
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