| 1. |
- Abdalla, H., et al.
(author)
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Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation
- 2021
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In: Journal of Cosmology and Astroparticle Physics. - : Institute of Physics Publishing (IOPP). - 1475-7516. ; :2
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Journal article (peer-reviewed)abstract
- The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for gamma-ray astronomy, provides unique capabilities to address significant open questions in astrophysics, cosmology, and fundamental physics. We study some of the salient areas of gamma-ray cosmology that can be explored as part of the Key Science Projects of CTA, through simulated observations of active galactic nuclei (AGN) and of their relativistic jets. Observations of AGN with CTA will enable a measurement of gamma-ray absorption on the extragalactic background light with a statistical uncertainty below 15% up to a redshift z = 2 and to constrain or detect gamma-ray halos up to intergalactic-magnetic-field strengths of at least 0.3 pG. Extragalactic observations with CTA also show promising potential to probe physics beyond the Standard Model. The best limits on Lorentz invariance violation from gamma-ray astronomy will be improved by a factor of at least two to three. CTA will also probe the parameter space in which axion-like particles could constitute a significant fraction, if not all, of dark matter. We conclude on the synergies between CTA and other upcoming facilities that will foster the growth of gamma-ray cosmology.
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| 2. |
- Braito, V., et al.
(author)
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The stratified disc wind of MCG-03-58-007
- 2021
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 500:1, s. 291-300
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Journal article (peer-reviewed)abstract
- Past Suzaku, XMM-Newton, and NuSTAR observations of the nearby (z = 0.03233) bright Seyfert 2 galaxy MCG-03-58-007 revealed the presence of two deep and blue-shifted iron K-shell absorption line profiles. These could be explained with the presence of two phases of a highly ionized, high column density accretion disc wind outflowing with v(out1) similar to-0.1c and v(out2) similar to -0.2c. Here we present two new observations of MCG-03-58-007: one was carried out in 2016 with Chandra and one in 2018 with Swift. Both caught MCG-03-58-007 in a brighter state (F2-10 (keV) similar to 4 x 10(-12) erg cm(-2) s(-1)) confirming the presence of the fast disc wind. The multi-epoch observations of MCG-03-58-007 covering the period from 2010 to 2018 were then analysed. These data show that the lower velocity component outflowing with v(out1) similar to -0.072 +/- 0.002c is persistent and detected in all the observations, although it is variable in column density in the range N-H similar to 3-8 x 102(3) cm(-2). In the 2016 Swift observation we detected again the second faster component outflowing with v(out2) similar to-0.2c, with a column density (N-H = 7.0(-4.1)(+5.6) x 10(23) cm(-2)), similar to that seen during the Suzaku observation. However during the Chandra observation 2 yr earlier, this zone was not present (N-H < 1.5 x 10(23) cm(-2)), suggesting that this faster zone is intermittent. Overall the multi-epochs observations show that the disc wind in MCG-03-58-007 is not only powerful, but also extremely variable, hence placing MCG-03-58-007 among unique disc winds such as the one seen in the famous QSO PDS456. One of the main results of this investigation is the consideration that these winds could be extremely variable, sometime appearing and sometime disappearing; thus to reach solid and firm conclusions about their energetics multiple observations are mandatory.
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| 3. |
- Braito, V, et al.
(author)
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Dramatic Changes in the Observed Velocity of the Accretion Disk Wind in MCG-03-58-007 Are Revealed by XMM-Newton and NuSTAR
- 2022
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 926:2
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Journal article (peer-reviewed)abstract
- Past X-ray observations of the nearby Seyfert 2 MCG-03-58-007 revealed the presence of a powerful and highly variable disk wind, where two possible phases outflowing with vout1/c ∼ −0.07 and vout2/c ∼ −0.2 were observed. Multi-epoch X-ray observations, covering the period from 2010 to 2018, showed that the lower-velocity component is persistent, as it was detected in all the observations, while the faster phase outflowing with vout2/c ∼ −0.2 appeared to be more sporadic. Here we present the analysis of a new monitoring campaign of MCG-03-58-007 performed in 2019 May–June and consisting of four simultaneous XMM-Newton and NuSTAR observations. We confirm that the disk wind in MCG-03-58-007 is persistent, as it is detected in all the observations, and powerful, having a kinetic power that ranges between 0.5% and 10% of the Eddington luminosity. The highly ionized wind (log(ξ/erg cm s−1) ∼ 5) is variable in both the opacity and, remarkably in its velocity. This is the first time where we have observed a substantial variability of the outflowing velocity in a disk wind, which dropped from vout/c ∼ −0.2 (as measured in the first three observations) to vout/c ∼ −0.074 in just 16 days. We conclude that such a dramatic and fast variability of the outflowing velocity could be due to the acceleration of the wind, as recently proposed by Mizumoto et al. Here, the faster wind, seen in the first three observations, is already accelerated to vout/c ∼ −0.2, while in the last observation our line of sight intercepts only the slower, pre-accelerated streamline.
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