All Outputs (357)

Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop (2018)
Journal Article
Noda, H., & Done, C. (2018). Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop. Monthly Notices of the Royal Astronomical Society, 480(3), 3898-3906. https://doi.org/10.1093/mnras/sty2032

We model the broadband (optical/UV and X-ray) continuum spectrum of the “changing-look” active galactic nucleus (AGN) Mrk 1018 as it fades from Seyfert 1 to 1.9 in ∼8 years. The brightest spectrum, with Eddington ratio L/LEdd ∼ 0.08, has a typical ty... Read More about Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop.

A physical model of the broadband continuum of AGN and its implications for the UV/X relation and optical variability (2018)
Journal Article
Kubota, A., & Done, C. (2018). A physical model of the broadband continuum of AGN and its implications for the UV/X relation and optical variability. Monthly Notices of the Royal Astronomical Society, 480(1), 1247-1262. https://doi.org/10.1093/mnras/sty1890

We develop a new spectral model for the broad-band spectral energy distribution (SED) of active galactic nuclei (AGN). This includes an outer standard disc, an inner warm Comptonizing region to produce the soft X-ray excess and a hot corona. We tie t... Read More about A physical model of the broadband continuum of AGN and its implications for the UV/X relation and optical variability.

Breaking the spectral degeneracies in black hole binaries with fast timing data: the hard state of Cygnus X-1 (2018)
Journal Article
Axelsson, M., & Done, C. (2018). Breaking the spectral degeneracies in black hole binaries with fast timing data: the hard state of Cygnus X-1. Monthly Notices of the Royal Astronomical Society, 480(1), 751-758. https://doi.org/10.1093/mnras/sty1801

The spectra of black hole binaries in the low/hard state are complex, with evidence for multiple different Comptonization regions contributing to the hard X-rays in addition to a cool disc component. We show this explicitly for some of the best RXTE... Read More about Breaking the spectral degeneracies in black hole binaries with fast timing data: the hard state of Cygnus X-1.

X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei (2018)
Journal Article
Mizumoto, M., Done, C., Hagino, K., Ebisawa, K., Tsujimoto, M., & Odaka, H. (2018). X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 478(1), 971-982. https://doi.org/10.1093/mnras/sty1114

X-rays illuminating the accretion disc in active galactic nuclei give rise to an iron K line and its associated reflection spectrum which are lagged behind the continuum variability by the light-travel time from the source to the disc. The measured l... Read More about X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei.

Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi* (2018)
Journal Article
Collaboration, H., Aharonian, F., Akamatsu, H., Akimoto, F., Allen, S. W., Angelini, L., Audard, M., Awaki, H., Axelsson, M., Bamba, A., Bautz, M. W., Blandford, R., Brenneman, L. W., Brown, G. V., Bulbul, E., Cackett, E. M., Chernyakova, M., Chiao, M. P., Coppi, P. S., Costantini, E., …Raassen, A. (2018). Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi*. Publications of Astronomical Society of Japan, 70(2), Article 12. https://doi.org/10.1093/pasj/psx156

The Hitomi Soft X-ray Spectrometer spectrum of the Perseus cluster, with ∼5 eV resolution in the 2–9 keV band, offers an unprecedented benchmark of the atomic modeling and database for hot collisional plasmas. It reveals both successes and challenges... Read More about Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi*.

Hitomi (ASTRO-H) X-ray Astronomy Satellite (2018)
Journal Article
Takahashi, T., Kokubun, M., Mitsuda, K., Kelley, R. L., Ohashi, T., Aharonian, F., Akamatsu, H., Akimoto, F., Allen, S. W., Anabuki, N., Angelini, L., Arnaud, K. A., Asai, M., Audard, M., Awaki, H., Axelsson, M., Azzarello, P., Baluta, C., Bamba, A., Bando, N., …Zoghbi, A. (2018). Hitomi (ASTRO-H) X-ray Astronomy Satellite. Journal of Astronomical Telescopes, Instruments, and Systems, 4(02), Article 021402. https://doi.org/10.1117/1.jatis.4.2.021402

The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  > ... Read More about Hitomi (ASTRO-H) X-ray Astronomy Satellite.

Monte-Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries (2018)
Journal Article
Tomaru, R., Done, C., Odaka, H., Watanabe, S., & Takahashi, T. (2018). Monte-Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries. Monthly Notices of the Royal Astronomical Society, 476(2), 1776-1784. https://doi.org/10.1093/mnras/sty336

Blue–shifted absorption lines from highly ionised iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray... Read More about Monte-Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries.

Search for gravitational redshifted absorption lines in LMXB Serpens X-1 (2017)
Journal Article
Yoneda, H., Done, C., Paerels, F., Takahashi, T., & Watanabe, S. (2018). Search for gravitational redshifted absorption lines in LMXB Serpens X-1. Monthly Notices of the Royal Astronomical Society, 475(2), 2194-2203. https://doi.org/10.1093/mnras/stx3328

The equation of state for ultradense matter can be tested from observations of the ratio of mass to radius of neutron stars. This could be measured precisely from the redshift of a narrow line produced on the surface. X-rays bursts have been intensiv... Read More about Search for gravitational redshifted absorption lines in LMXB Serpens X-1.

The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342 (2017)
Journal Article
Kynoch, D., Landt, H., Ward, M. J., Done, C., Gardner, E., Boisson, C., Arrieta-Lobo, M., Zech, A., Steenbrugge, K., & Pereira Santaella, M. (2018). The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342. Monthly Notices of the Royal Astronomical Society, 475(1), 404-423. https://doi.org/10.1093/mnras/stx3161

The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of γ-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum radio... Read More about The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342.

In search of a new era of UK X-ray astronomy (2017)
Journal Article
Gandhi, P., Degenaar, N., Done, C., & Watson, M. G. (2017). In search of a new era of UK X-ray astronomy. Astronomy and Geophysics, 58(6), 6.24-6.28. https://doi.org/10.1093/astrogeo/atx214

X-ray astronomy is our gateway to the hot universe. More than half of the baryons in the cosmos are too hot to be visible at shorter wavelengths. Studying the extreme environments of black hole and neutron star vicinities also requires X-ray data. Wi... Read More about In search of a new era of UK X-ray astronomy.

Evidence for higher black hole spin in radio-loud quasars (2017)
Journal Article
Schulze, A., Done, C., Lu, Y., Zhang, F., & Inoue, Y. (2017). Evidence for higher black hole spin in radio-loud quasars. Astrophysical Journal, 849(1), Article 4. https://doi.org/10.3847/1538-4357/aa9181

One of the major unsolved questions concerning the understanding of the active galactic nucleus population is the origin of the dichotomy between radio-quiet and radio-loud quasars. The most promising explanation is provided by the spin paradigm, whi... Read More about Evidence for higher black hole spin in radio-loud quasars.

What powers the most relativistic jets? – II. Flat-spectrum radio quasars (2017)
Journal Article
Gardner, E., & Done, C. (2018). What powers the most relativistic jets? – II. Flat-spectrum radio quasars. Monthly Notices of the Royal Astronomical Society, 473(2), 2639-2654. https://doi.org/10.1093/mnras/stx2516

Flat Spectrum Radio Quasars (FSRQs) are the most powerful relativistic jets seen from supermassive black holes (BHs) accreting via a radiatively efficient thin disc. Their high energy emission is well modelled by highly relativistic electrons in the... Read More about What powers the most relativistic jets? – II. Flat-spectrum radio quasars.

Thermal winds in stellar mass black hole and neutron star binary systems (2017)
Journal Article
Done, C., Tomaru, R., & Takahashi, T. (2018). Thermal winds in stellar mass black hole and neutron star binary systems. Monthly Notices of the Royal Astronomical Society, 473(1), 838-848. https://doi.org/10.1093/mnras/stx2400

Black hole binaries show equatorial disc winds at high luminosities, which apparently disappear during the spectral transition to the low/hard state. This is also where the radio jet appears, motivating speculation that both wind and jet are driven b... Read More about Thermal winds in stellar mass black hole and neutron star binary systems.

Modelling the energy dependence of black hole binary flows (2017)
Journal Article
Mahmoud, R. D., & Done, C. (2018). Modelling the energy dependence of black hole binary flows. Monthly Notices of the Royal Astronomical Society, 473(2), 2084-2097. https://doi.org/10.1093/mnras/stx2359

We build a full spectral-timing model for the low/hard state of black hole binaries assuming that the spectrum of the X-ray hot flow can be produced by two Comptonization zones. Slow fluctuations generated at the largest radii/softest spectral region... Read More about Modelling the energy dependence of black hole binary flows.

Determining the torus covering factors for a sample of type 1 AGN in the local Universe (2017)
Journal Article
Ezhikode, S. H., Gandhi, P., Done, C., Ward, M., Dewangan, G. C., Misra, R., & Philip, N. S. (2017). Determining the torus covering factors for a sample of type 1 AGN in the local Universe. Monthly Notices of the Royal Astronomical Society, 472(3), 3492-3511. https://doi.org/10.1093/mnras/stx2160

In the unified scheme of active galactic nuclei, a dusty torus absorbs and then reprocesses a fraction of the intrinsic luminosity which is emitted at longer wavelengths. Thus, subject to radiative transfer corrections, the fraction of the sky covere... Read More about Determining the torus covering factors for a sample of type 1 AGN in the local Universe.

Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow (2017)
Journal Article
Jin, C., Done, C., Ward, M., & Gardner, E. (2017). Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow. Monthly Notices of the Royal Astronomical Society, 471(1), 706-721. https://doi.org/10.1093/mnras/stx1634

We present a detailed multiwavelength study of an unobscured, highly super-Eddington Type-1 QSO RX J0439.6-5311. We combine the latest XMM–Newton observation with all archival data from infrared to hard X-rays. The optical spectrum is very similar to... Read More about Super-Eddington QSO RX J0439.6-5311 – II. Multiwavelength constraints on the global structure of the accretion flow.

Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing (2017)
Journal Article
Edelson, R., Gelbord, J., Cackett, E., Connolly, S., Done, C., Fausnaugh, M., …Zheng, W. (2017). Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing. Astrophysical Journal, 840(1), Article 41. https://doi.org/10.3847/1538-4357/aa6890

Swift monitoring of NGC 4151 with an ~6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3–50 keV) and six in the ultraviolet (UV)/optical (1900–5500 Å). The three hardest X-ray... Read More about Swift Monitoring of NGC 4151: Evidence for a Second X-Ray/UV Reprocessing.

The origin of the UV/optical lags in NGC 5548 (2017)
Journal Article
Gardner, E., & Done, C. (2017). The origin of the UV/optical lags in NGC 5548. Monthly Notices of the Royal Astronomical Society, 470(3), 3591-3605. https://doi.org/10.1093/mnras/stx946

The new multiwavelength monitoring campaign on NGC 5548 shows clearly that the variability of the ultraviolet (UV)/optical light curves lags by progressively longer times at longer wavelengths, as expected from reprocessing off an optically thick dis... Read More about The origin of the UV/optical lags in NGC 5548.

Super-Eddington QSO RX J0439.6−5311 – I. Origin of the soft X-ray excess and structure of the inner accretion flow (2017)
Journal Article
Jin, C., Done, C., & Ward, M. (2017). Super-Eddington QSO RX J0439.6−5311 – I. Origin of the soft X-ray excess and structure of the inner accretion flow. Monthly Notices of the Royal Astronomical Society, 468(3), 3663-3681. https://doi.org/10.1093/mnras/stx718

We report the results from a recent 133 ks XMM–Newton observation of a highly super-Eddington narrow-line Type-1 quasi-stellar object RX J0439.6−5311. This source has one of the steepest active galactic nuclei hard X-ray slopes, in addition to a prom... Read More about Super-Eddington QSO RX J0439.6−5311 – I. Origin of the soft X-ray excess and structure of the inner accretion flow.

Revisiting the extremely fast disc wind in a gravitationally lensed quasar APM 08279+5255 (2017)
Journal Article
Hagino, K., Done, C., Odaka, H., Watanabe, S., & Takahashi, T. (2017). Revisiting the extremely fast disc wind in a gravitationally lensed quasar APM 08279+5255. Monthly Notices of the Royal Astronomical Society, 468(2), 1442-1452. https://doi.org/10.1093/mnras/stx559

The gravitationally lensed quasar APM 08279+5255 has the fastest claimed wind from any active galactic nucleus, with velocities of 0.6–0.7c, requiring magnetic acceleration as special relativistic effects limit all radiatively driven winds to v < 0.3... Read More about Revisiting the extremely fast disc wind in a gravitationally lensed quasar APM 08279+5255.