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The mass and spin of the extreme Narrow Line Seyfert 1 Galaxy 1H 0707-495 and its implications for the trigger for relativistic jets (2016)
Journal Article
Done, C., & Jin, C. (2016). The mass and spin of the extreme Narrow Line Seyfert 1 Galaxy 1H 0707-495 and its implications for the trigger for relativistic jets. Monthly Notices of the Royal Astronomical Society, 460(2), 1716-1724. https://doi.org/10.1093/mnras/stw1070

Relativistic reflection models of the X-ray spectrum of the ‘complex’ Narrow Line Seyfert 1 (NLS1) 1H 0707−495 require a high-spin, moderate-inclination, low-mass black hole. With these parameters fixed, the observed optical/UV emission directly dete... Read More about The mass and spin of the extreme Narrow Line Seyfert 1 Galaxy 1H 0707-495 and its implications for the trigger for relativistic jets.

Tracking the energetics of the non-thermal disc–corona–jet in the very high state GX 339 − 4 (2016)
Journal Article
Kubota, A., & Done, C. (2016). Tracking the energetics of the non-thermal disc–corona–jet in the very high state GX 339 − 4. Monthly Notices of the Royal Astronomical Society, 458(4), 4238-4249. https://doi.org/10.1093/mnras/stw585

The dramatic hard–soft spectral transition in black hole binaries is important as it is associated with the collapse of the jet and with the strongest low-frequency quasi-periodic oscillations (QPOs). These transition spectra (intermediate and very h... Read More about Tracking the energetics of the non-thermal disc–corona–jet in the very high state GX 339 − 4.

Revealing the nature of the QPO and its harmonic in GX 339-4 using frequency-resolved spectroscopy (2016)
Journal Article
Axelsson, M., & Done, C. (2016). Revealing the nature of the QPO and its harmonic in GX 339-4 using frequency-resolved spectroscopy. Monthly Notices of the Royal Astronomical Society, 458(2), 1778-1784. https://doi.org/10.1093/mnras/stw464

We use frequency-resolved spectroscopy to examine the energy spectra of the prominent low-frequency quasi-periodic oscillation (QPO) and its harmonic in GX 339-4. We track the evolution of these spectra as the source makes a transition from a bright... Read More about Revealing the nature of the QPO and its harmonic in GX 339-4 using frequency-resolved spectroscopy.

Limits on pair production and multizone Comptonization: the broad-band X/γ-ray spectrum of XTE J1550–564 revisited (2016)
Journal Article
Hjalmarsdotter, L., Axelsson, M., & Done, C. (2016). Limits on pair production and multizone Comptonization: the broad-band X/γ-ray spectrum of XTE J1550–564 revisited. Monthly Notices of the Royal Astronomical Society, 456(4), 4354-4363. https://doi.org/10.1093/mnras/stv2909

At high luminosities black hole binaries show spectra with a strong disc component accompanied by an equally strong tail where at least some of the electrons are non-thermal. We reanalyse the simultaneous ASCA–RXTE–OSSE data from the 1998 outburst of... Read More about Limits on pair production and multizone Comptonization: the broad-band X/γ-ray spectrum of XTE J1550–564 revisited.

A variable ULX and possible IMBH candidate in M51a (2016)
Journal Article
Earnshaw, H. M., Roberts, T. P., Heil, L. M., Mezcua, M., Walton, D. J., Done, C., …Sutton, A. D. (2016). A variable ULX and possible IMBH candidate in M51a. Monthly Notices of the Royal Astronomical Society, 456(4), 3840-3854. https://doi.org/10.1093/mnras/stv2945

Ultraluminous X-ray source (ULX)-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ULX, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analy... Read More about A variable ULX and possible IMBH candidate in M51a.

Strong constraints on a super-Eddington accretion flow: XMM–Newton observations of an intermediate-mass black hole (2015)
Journal Article
Jin, C., Done, C., & Ward, M. (2016). Strong constraints on a super-Eddington accretion flow: XMM–Newton observations of an intermediate-mass black hole. Monthly Notices of the Royal Astronomical Society, 455(1), 691-702. https://doi.org/10.1093/mnras/stv2319

RX J1140.1+0307 is a Narrow Line Seyfert 1 (NLS1) with one of the lowest black hole masses known in an AGN (M ≤ 106 M⊙). We show results from two new XMM–Newton observations, exhibiting soft 2–10 keV spectra, a strong excess at lower energies, and fa... Read More about Strong constraints on a super-Eddington accretion flow: XMM–Newton observations of an intermediate-mass black hole.

X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR) (2015)
Journal Article
Krawczynski, H., Stern, D., Harrison, F., Kislat, F., Zajczyk, A., Beilicke, M., …Zhang, W. (2016). X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR). Astroparticle Physics, 75, 8-28. https://doi.org/10.1016/j.astropartphys.2015.10.009

This paper describes the Polarization Spectroscopic Telescope Array (PolSTAR), a mission proposed to NASA’s 2014 Small Explorer (SMEX) announcement of opportunity. PolSTAR measures the linear polarization of 3–50 keV (requirement; goal: 2.5–70 keV) X... Read More about X-ray polarimetry with the Polarization Spectroscopic Telescope Array (PolSTAR).

The Accreting Black Hole Swift J1753.5-0127 from Radio to Hard X-Ray (2015)
Journal Article
Tomsick, J., Rahoui, F., Kolehmainen, M., Miller-Jones, J., Fürst, F., Yamaoka, K., …Urata, Y. (2015). The Accreting Black Hole Swift J1753.5-0127 from Radio to Hard X-Ray. Astrophysical Journal, 808(1), https://doi.org/10.1088/0004-637x/808/1/85

We report on multiwavelength measurements of the accreting black hole Swift J1753.5–0127 in the hard state at low luminosity (L ~ 2.7 × 1036 erg s−1 assuming a distance of d = 3 kpc) in 2014 April. The radio emission is optically thick synchrotron, p... Read More about The Accreting Black Hole Swift J1753.5-0127 from Radio to Hard X-Ray.

Reaching the peak of the quasar spectral energy distribution - I. Observations and models (2015)
Journal Article
Collinson, J., Ward, M., Done, C., Landt, H., Elvis, M., & McDowell, J. (2015). Reaching the peak of the quasar spectral energy distribution - I. Observations and models. Monthly Notices of the Royal Astronomical Society, 449(2), 2174-2193. https://doi.org/10.1093/mnras/stv362

We perform a spectral analysis of a sample of 11 medium redshift (1.5 ≲ z ≲ 2.2) quasars. Our sample all have optical spectra from the SDSS, infrared spectra from GNIRS and TripleSpec, and X-ray spectra from XMM–Newton. We first analyse the Balmer br... Read More about Reaching the peak of the quasar spectral energy distribution - I. Observations and models.