The high energy universe at ultra-high resolution: the power and promise of X-ray interferometry

Uttley, Phil; Hartog, Roland den; Bambi, Cosimo; Barret, Didier; Bianchi, Stefano; Bursa, Michal; Cappi, Massimo; Casella, Piergiorgio; Cash, Webster; Costantini, Elisa; Dauser, Thomas; Trigo, Maria Diaz; Gendreau, Keith; Grinberg, Victoria; Herder, Jan-Willem den; Ingram, Adam; Kara, Erin; Markoff, Sera; Mingo, Beatriz; Panessa, Francesca; Poppenhäger, Katja; Różańska, Agata; Svoboda, Jiri; Wijers, Ralph; Willingale, Richard; Wilms, Jörn; Wise, Michael

doi:10.48550/arxiv.1908.03144

Cited by 7 publications

(9 citation statements)

References 58 publications

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“…X-ray torus reprocessing models in general lack a physical scale (i.e., spectra only depend on the optical depth distribution), while current X-ray instruments can only partially resolve reprocessed emission extended on 100 pc scales in a limited number of nearby AGN (Fabbiano et al 2017;Ma et al 2020;Jones et al 2021). More self-consistent multiwavelength studies such as the one presented in this section may prove valuable for indirectly setting the spatial scale of the compact reprocessed emission region, informing the expectations for potential direct size measurements using X-ray interferometry in the future (Uttley et al 2019).…”

Section: Matching Radio Opacity Measurementsmentioning

confidence: 97%

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Baloković,

Cabral,

Brenneman

et al. 2021

Preprint

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Obscuration of the innermost parts of active galactic nuclei (AGN) is observed in the majority of the population both in the nearby universe and at high redshift. However, the nature of the structures causing obscuration, especially in low-luminosity AGN, is poorly understood at present. We present a novel approach to multi-epoch broadband X-ray spectroscopy, anchored in the long-term average spectrum in the hard X-ray band, applied to the nearby, X-ray bright AGN in the galaxy NGC 1052. From spectral features due to X-ray reprocessing in the circumnuclear material, based on a simple, uniform-density torus X-ray reprocessing model, we find a covering factor of 80-100 % and a globally averaged column density in the range (1 − 2) × 10 23 cm −2 . This closely matches the independently measured variable line-of-sight column density range, leading to a straightforward and self-consistent picture of the obscuring torus in NGC 1052, similar to several other AGN in recent literature. Comparing this X-ray-constrained torus model with measurements of spatially resolved sub-parsec absorption from radio observations, we find that it may be possible to account for both X-ray and radio data with a torus model featuring a steep density gradient along the axis of the relativistic jets. This provides a valuable direction for the development of improved physical models for the circumnuclear environment in NGC 1052 and potentially in a wider class of AGN.

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Section: Matching Radio Opacity Measurementsmentioning

confidence: 97%

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Baloković,

Cabral,

Brenneman

et al. 2021

Preprint

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“…et al., 2018, 2020). Whereas size scales of ∼ 10 5 R G are currently inaccessible to all but a few AGN, in the future, X-ray interferometry may eventually make it possible to resolve scales of a few R G in the nearest Seyfert galaxies (Uttley et al, 2019). However, the vast majority of AGNs remain out of reach of current interferometric techniques, thus, other methods are needed to study the innermost regions of AGNs.…”

Section: Dust Reverberation Mappingmentioning

confidence: 99%

Reverberation mapping of Active Galactic Nuclei: from X-ray corona to dusty torus

Cackett,

Bentz,

Kara

2021

Preprint

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The central engines of Active Galactic Nuclei (AGNs) are powered by accreting supermassive black holes, and while AGNs are known to play an important role in galaxy evolution, the key physical processes occur on scales that are too small to be resolved spatially (aside from a few exceptional cases). Reverberation mapping is a powerful technique that overcomes this limitation by using echoes of light to determine the geometry and kinematics of the central regions.Variable ionizing radiation from close to the black hole drives correlated variability in surrounding gas/dust, but with a time delay due to the light travel time between the regions, allowing reverberation mapping to effectively replace spatial resolution with time resolution. Reverberation mapping is used to measure black hole masses and to probe the innermost X-ray emitting region, the UV/optical accretion disk, the broad emission line region and the dusty torus.In this article we provide an overview of the technique and its varied applications.

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“…The following points are driving the design and capabilities of the X-ray interferometer:  The interferometer has to operate in the energy range of 1 to 7 keV for astrophysical reasons (see [1] and [2]). Together with the desired baseline, D, this determines the angular resolution ∆θ = ½λ/D, which is the main performance parameter.…”

Section: The Telephoto Geometrymentioning

confidence: 99%

“…For a potential future ESA mission based on an XRI (X-ray interferometer) [1] and [2], we are developing a series of testbeds to experiment with, develop the enabling technology on, and eventually demonstrate the capabilities of an X-ray interferometry platform. The concept for this grazing-incidence interferometer is based on a design by Willingale [3] and is shown in Figure 1 below.…”

Section: Introductionmentioning

confidence: 99%

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The development of a testbed for the x-ray interferometry mission

Hartog

Uttley

Willingale

et al. 2020

Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray

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An X-ray Interferometer (XRI) has recently been proposed as a theme for ESA's Voyage 2050 planning cycle, with the eventual goal to observe the X-ray sky with an unprecedented angular resolution better than 1 micro arcsec (5 prad) [1]. A scientifically very interesting mission is possible on the basis of a single spacecraft [2], owing to the compact 'telephoto' design proposed earlier by Willingale [3]. Between the practical demonstration of X-ray interferometry at 1 keV by Cash et al. [4] with a 1 mm baseline and 0.1 arcsec effective resolution to a mission flying an interferometer with a baseline of one or more meters, an effective collecting area of square meters and micro arcsec resolution lie many milestones. The first important steps to scale up from a laboratory experiment to a viable mission concept will have to be taken on a scalable and flexible testbed set-up. Such a testbed cannot singularly focus on the optical aspects, but should simultaneously address the thermal and mechanical stability of the interferometer. A particular challenge is the coherent X-ray source, which should provide a wavefront at the entrance of the interferometer that is transversely coherent over a distance at least equal to the baseline, and bright enough.In this paper, we will explore the build-up of a testbed in several stages, with increasing requirements on optical quality and associated thermo-mechanical control and source sophistication, with the intent to guide the technological development of X-ray interferometry from the lab to space in a sequence of achievable milestones.

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The high energy universe at ultra-high resolution: the power and promise of X-ray interferometry

Cited by 7 publications

References 58 publications

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy

Reverberation mapping of Active Galactic Nuclei: from X-ray corona to dusty torus

The development of a testbed for the x-ray interferometry mission

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