The column density distribution of hard X-ray radio galaxies

Panessa, F.; Bassani, L.; Landi, R.; Bazzano, A.; Dallacasa, D.; Franca, F. La; Malizia, A.; Venturi, T.; Ubertini, P.

doi:10.1093/mnras/stw1438

Cited by 33 publications

(31 citation statements)

References 132 publications

(93 reference statements)

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“…= 419/426) with best-fit values of photon index Γ=2.11±0.04, reflection parameter R = 0.83±0.36 and slightly overabundance of A F e = 1.16 +1.76 −0.86 . The similar result of reflection in NLS1s was obtained, for example, by Panessa et al (2011) and Vasylenko et al (2015). However, pexmon model includes only "cold" reflection.…”

Section: 'Baseline' Modelssupporting

confidence: 79%

“…NGC 4748 has a quite steep X-ray photon-index Γ = 2.50 ± 0.17 according to the ROSAT/HRI data (Pfefferkorn, Boller & Rafanelli 2001) and Γ = 2.20 ± 0.11 according to the unabsorbed power-law model (Landi et al 2010) based on Swit/XRT spectrum. Panessa et al (2011) obtained a photon index of Γ = 2.01 ± 0.13 and no cut-off at high energies. No Fe-K emission lines and reflection components in the composite Swift/XRT + INTEGRAL/ISGRI spectrum were observed.…”

Section: Introductionmentioning

confidence: 93%

“…Later Ricci et al (2011) and Panessa et al (2011) analyzed partly overlapped samples of 14 NLS1 galaxies detected by INTEGRAL/IBIS in broad-band X-ray range. In both papers there were also obtained steep values of hard photon index Γ ∼ 2.3.…”

Section: Introductionmentioning

confidence: 99%

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The broad-band spectrum of the narrow-line Seyfert 1 NGC 4748: from UV to hard X-ray

Vasylenko

2018

Astrophys Space Sci

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We report the results obtained by a broad-band (0.5-500 keV) data analysis of narrow-line Seyfert 1 galaxy NGC 4748 observed with an XMM-Newton/PN, IN-TEGRAL/ISGRI and SWIFT/BAT telescopes. This galaxy has a soft X-ray excess that is typical for the class of narrow-line Seyfert 1. The question of the origin of soft excess in such objects is still unclear. We tested and compared two spectral models for the soft X-ray spectra based on the different physical scenarios. The first one is based on the Done & Nayakshin model of two-phase accretion disc in a vertical direction, which includes two reflection zones with different ionization levels. According to this model, we found that a highly ionized reflection has the value of ionization ξ ∼ 3000 erg s −1 cm and is mostly responsible for the soft excess. This reflection becomes comparable with a low ionized one (ξ ∼ 30 erg s −1 cm) in moderate X-ray range. However, this model requires also an additional component at soft energies with kT∼300 eV. The second model is an energetically self-consistent model and assumes that a soft excess arises from optically thick thermal Comptonization of the disc emission. Combination of the UV (from XMM/Optical monitor) and X-ray data in the latter model allowed us to determine a mass of the central black hole of 6.9 × 10 6 M ⊙ and Eddington ratio log L/L Edd ≃ −0.57. Also, we were not able to rule out one of competing models using only X-ray spectra of NGC 4748.

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Section: 'Baseline' Modelssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 93%

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The broad-band spectrum of the narrow-line Seyfert 1 NGC 4748: from UV to hard X-ray

Vasylenko

2018

Astrophys Space Sci

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“…The analysis of X/soft gamma-ray data of the entire sample has already been performed (Panessa et al 2016) while the investigation of the radio data is well underway.…”

Section: Preliminary Considerationsmentioning

confidence: 99%

Soft γ-ray selected radio galaxies: favouring giant size discovery

Bassani¹,

Venturi²,

Molina³

et al. 2016

Mon. Not. R. Astron. Soc.

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Using the recent INTEGRAL/IBIS and Swift/BAT surveys we have extracted a sample of 64 confirmed plus 3 candidate radio galaxies selected in the soft gamma-ray band. The sample covers all optical classes and is dominated by objects showing a FR II radio morphology; a large fraction (70%) of the sample is made of "radiative mode" or High Excitation Radio Galaxies (HERG). We have measured the source size on NVSS, FIRST and SUMSS images and have compared our findings with data in the literature obtaining a good match. We surprisingly found that the soft gamma-ray selection favours the detection of large size radio galaxies: 60% of objects in the sample have size greater than 0.4 Mpc while around 22% reach dimension above 0.7 Mpc at which point they are classified as Giant Radio Galaxies or GRGs, the largest and most energetic single entities in the Universe. Their fraction among soft gamma ray selected radio galaxies is significantly larger than typically found in radio surveys, where only a few percent of objects (1-6%) are GRGs. This may partly be due to observational biases affecting radio surveys more than soft gamma ray surveys, thus disfavouring the detection of GRGs at lower frequencies. The main reasons and/or conditions leading to the formation of these large radio structures are still unclear with many parameters such as high jet power, long activity time and surrounding environment all playing a role; the first two may be linked to the type of AGN discussed in this work and partly explain the high fraction of GRGs found in the present sample. Our result suggests that high energy surveys may be a more efficient way than radio surveys to find these peculiar objects.

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“…Among them, some show nuclear activity and are known as active galactic nuclei (AGN). In these cases, the SMBH is fed by an accretion disc and about 10% of the AGN population show strong biconical relativistic jets (see Kellermann et al 1989;Panessa et al 2016, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Restarting activity in the nucleus of PBC J2333.9-2343

Hernández-García¹,

Panessa²,

Giroletti³

et al. 2017

A&A

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Context. The giant radio galaxy PBC J2333.9-2343 shows different characteristics at different wavebands that are difficult to explain within the actual generic schemes of unification of active galactic nuclei (AGN). It is therefore a good candidate host for different phases of nuclear activity. Aims. We aim at disentangling the nature of this AGN by using simultaneous multiwavelength data. Methods. We obtained data in 2015 from the Very Long Baseline Array (VLBA), the San Pedro Mártir telescope, and the XMMNewton observatories. This allows the study of the nuclear parts of the galaxy through its morphology and spectra and the analysis of the spectral energy distribution (SED). We also reanalysed previously-presented optical data from the San Pedro Mártir telescope from 2009 to provide a homogeneous comparison. Results. At X-ray frequencies the source is unabsorbed. The optical spectra are of a type 1.9 AGN, both in 2009 and 2015, although showing a broader component in 2015. The VLBA radio images show an inverted spectrum with a self-absorbed, optically thick compact core (α c = 0.40, where S ν ∝ ν +α ) and a steep-spectrum, optically thin jet (α j,8−15 = −0.5). The SED resembles that of typical blazars and is best represented by an external Compton (EC) model with a viewing angle of approximately 3-6• . The apparent size of the large-scale structure of PBC J2333.9-2343 must correspond to an intrinsic deprojected value of approximately 7 Mpc for θ v < 10• , and to >13 Mpc for θ v < 5• , a value much larger than the biggest giant radio galaxy known, which is 4.5 Mpc. Conclusions. The above arguments suggest that PBC J2333.9-2343 has undergone a new episode of nuclear activity and that the direction of the new jet has changed in the plane of the sky and is now pointing towards us. This changes this source from a radio galaxy to a blazar, a very exceptional case of restarting activity.

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The column density distribution of hard X-ray radio galaxies

Cited by 33 publications

References 132 publications

The broad-band spectrum of the narrow-line Seyfert 1 NGC 4748: from UV to hard X-ray

The broad-band spectrum of the narrow-line Seyfert 1 NGC 4748: from UV to hard X-ray

Soft γ-ray selected radio galaxies: favouring giant size discovery

Restarting activity in the nucleus of PBC J2333.9-2343

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