NuSTAR/XMM-Newton monitoring of the Seyfert 1 galaxy HE 1143-1810. Testing the two-corona scenario
Abstract
Aims: We test the two-corona accretion scenario for active galactic nuclei in the case of the "bare" Seyfert 1 galaxy HE 1143-1810.
Methods: We perform a detailed study of the broad-band UV-X-ray spectral properties and of the short-term variability of HE 1143-1810. We present results of a joint XMM-Newton and NuSTAR monitoring of the source, consisting of 5 × 20 ks observations, each separated by 2 days, performed in December 2017.
Results: The source is variable in flux among the different observations, and a correlation is observed between the UV and X-ray emission. Moderate spectral variability is observed in the soft band. The time-averaged X-ray spectrum exhibits a cut-off at ∼100 keV consistent with thermal Comptonization. We detect an iron Kα line consistent with being constant during the campaign and originating from a mildly ionized medium. The line is accompanied by a moderate, ionized reflection component. A soft excess is clearly present below 2 keV and is well described by thermal Comptonization in a "warm" corona with a temperature of ∼0.5 keV and a Thomson optical depth of ∼17 - 18. For the hot hard X-ray emitting corona, we obtain a temperature of ∼20 keV and an optical depth of ∼4 assuming a spherical geometry. A fit assuming a jet-emitting disc (JED) for the hot corona also provides a nice description of the broad-band spectrum. In this case, the data are consistent with an accretion rate varying between ∼0.7 and ∼0.9 in Eddington units and a transition between the outer standard disc and the inner JED at ∼20 gravitational radii.
Conclusions: The broad-band high-energy data agree with an accretion flow model consisting of two phases: an outer standard accretion disc with a warm upper layer, responsible for the optical-UV emission and the soft X-ray excess, and an inner slim JED playing the role of a hard X-ray emitting hot corona.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2020
- DOI:
- 10.1051/0004-6361/201936486
- arXiv:
- arXiv:1912.08720
- Bibcode:
- 2020A&A...634A..92U
- Keywords:
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- galaxies: active;
- galaxies: Seyfert;
- X-rays: galaxies;
- X-rays: individuals: HE 1143-1810;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- accepted for publication in A&