Outputs (7)

SPITZER IRAC observations of IR excess in Holmberg IX X-1: A circumbinary disk or a variable jet? (2016)
Journal Article
Dudik, R., Berghea, C., Roberts, T., Grise, F., Singh, A., Pagano, R., & Winter, L. (2016). SPITZER IRAC observations of IR excess in Holmberg IX X-1: A circumbinary disk or a variable jet?. Astrophysical Journal, 831(1), Article 88. https://doi.org/10.3847/0004-637x/831/1/88

We present Spitzer Infrared Array Camera photometric observations of the ultraluminous X-ray source (ULX, X-1) in Holmberg IX. We construct a spectral energy distribution (SED) for Holmberg IX X-1 based on published optical, UV, and X-ray data combin... Read More about SPITZER IRAC observations of IR excess in Holmberg IX X-1: A circumbinary disk or a variable jet?.

A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift (2016)
Journal Article
Walton, D., Fürst, F., Bachetti, M., Barret, D., Brightman, M., Fabian, A., …Webb, N. (2016). A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift. Astrophysical Journal Letters, 827(1), Article L13. https://doi.org/10.3847/2041-8205/827/1/l13

We report the detection of a 78.1 ± 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 (${L}_{{\rm{X,peak}}}\sim 5\times {10}^{40}$ erg s−1), discovered during an extensive monitoring program with Swift. T... Read More about A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift.

The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1 (2016)
Journal Article
Luangtip, W., Roberts, T., & Done, C. (2016). The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1. Monthly Notices of the Royal Astronomical Society, 460(4), 4417-4432. https://doi.org/10.1093/mnras/stw1282

We present a new analysis of X-ray spectra of the archetypal ultraluminous X-ray source (ULX) Holmberg IX X-1 obtained by the Swift, XMM–Newton and NuSTAR observatories. This ULX is a persistent source, with a typical luminosity of ∼1040 erg s−1, tha... Read More about The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1.

ULX behaviour: The ultraluminous state, winds and interesting anomalies (2016)
Journal Article
Roberts, T., Middleton, M., Sutton, A., Mezcua, M., Walton, D., & Heil, L. (2016). ULX behaviour: The ultraluminous state, winds and interesting anomalies. Astronomical Notes, 377(4-5), 534-540. https://doi.org/10.1002/asna.201612343

Recent evidence – in particular the hard X-ray spectra obtained by NuSTAR, and the large amplitude hard X-ray variability observed when ULXs show soft spectra - reveals that common ultraluminous X-ray source (ULX) behaviour is inconsistent with known... Read More about ULX behaviour: The ultraluminous state, winds and interesting anomalies.

Keck/MOSFIRE spectroscopy of five ULX counterparts (2016)
Journal Article
Heida, M., Jonker, P., Torres, M., Roberts, T., Walton, D., Moon, D., …Harrison, F. (2016). Keck/MOSFIRE spectroscopy of five ULX counterparts. Monthly Notices of the Royal Astronomical Society, 459(1), 771-778. https://doi.org/10.1093/mnras/stw695

We present H-band spectra of the candidate counterparts of five ultraluminous X-ray sources (ULXs; two in NGC 925, two in NGC 4136 and Holmberg II X-1) obtained with Keck/MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration). The candidate co... Read More about Keck/MOSFIRE spectroscopy of five ULX counterparts.

The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates? (2016)
Journal Article
Pintore, F., Zampieri, L., Sutton, A., Roberts, T., Middleton, M., & Gladstone, J. (2016). The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates?. Monthly Notices of the Royal Astronomical Society, 459(1), 455-466. https://doi.org/10.1093/mnras/stw669

A sub-set of the brightest ultraluminous X-ray sources (ULXs), with X-ray luminosities well above 1040 erg s−1, typically have energy spectra which can be well described as hard power laws, and short-term variability in excess of ∼10 per cent. This c... Read More about The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates?.

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.