Staff profile

Responsibilities within department

Current: Director of Education;

Previous: Health & Safety committee; Teaching Review committee; Admissions selector; L4 course director; General Problems paper committee chair; Assessment & Feedback Committee; Physics in Society module leader

Teaching activity

Current: L4 Radiative Processes in Astrophysics lecture course; L4 project supervisor.

Previous: L1 Phases of Matter lecture course; L1 Astrobiology lecture course; L1 Thermodynamics lecture course; L1 tutor; L2 tutor; L2 labs; L2 Physics in Society tutor; L3 General Problems class organiser; L3 Planetary Systems lecturer; L4 project moderator; Postgrad lectures on Black Holes.

• Ultraluminous X-ray sources
• The X-ray emission of nearby normal galaxies
• Starburst galaxies
• Low-luminosity active galactic nuclei

Journal Article

• Beuchert, T., Middleton, M. J., Soria, R., Miller-Jones, J. C. . A., Dauser, T., Roberts, T., Sathyaprakash, R., & Markoff, S. (in press). Exploring the case for hard-X-ray beaming in NGC 6946 X-1. Monthly Notices of the Royal Astronomical Society, https://doi.org/10.1093/mnras/stae1975
• Imbrogno, M., Motta, S. E., Amato, R., Israel, G. L., Rodríguez-Castillo, G. A., Brightman, M., Casella, P., Bachetti, M., Fürst, F., Stella, L., Pinto, C., Pintore, F., Tombesi, F., Gúrpide, A., Middleton, M. J., Salvaggio, C., Tiengo, A., Belfiore, A., De Luca, A., Esposito, P., …Salvaterra, R. (2024). Skipping a beat: discovery of persistent quasi-periodic oscillations associated with pulsed fraction drop of the spin signal in M51 ULX-7. Astronomy & Astrophysics, 689, Article A284. https://doi.org/10.1051/0004-6361/202450432
• Barra, F., Pinto, C., Middleton, M., Di Salvo, T., Walton, D. J., Gúrpide, A., & Roberts, T. P. (2024). Examining the nature of the ultraluminous X-ray source Holmberg II X-1. Astronomy & Astrophysics, 682, Article A94. https://doi.org/10.1051/0004-6361/202348471
• Luangtip, W., & Roberts, T. P. (2024). NGC 2403 XMM4: evidence for a super-Eddington neutron star with a possible transient pulsation. Monthly Notices of the Royal Astronomical Society, 528(1), 418-431. https://doi.org/10.1093/mnras/stae023
• Bachetti, M., Middleton, M. J., Pinto, C., Gúrpide, A., Walton, D. J., Brightman, M., Lehmer, B., Roberts, T. P., Vasilopoulos, G., Alford, J., Amato, R., Ambrosi, E., Dai, L., Earnshaw, H. P., El Byad, H., García, J. A., Luca Israel, G., Jaodand, A., Madsen, K., Maitra, C., …Wolter, A. (2023). The high energy X-ray probe ( HEX-P ): studying extreme accretion with ultraluminous X-ray sources. Frontiers in Astronomy and Space Sciences, 10, Article 1289432. https://doi.org/10.3389/fspas.2023.1289432
• Roberts, T. P., Walton, D. J., Mackenzie, A. D. A., Heida, M., & Scaringi, S. (2023). Digging a little deeper: characterizing three new extreme ULX candidates. Monthly Notices of the Royal Astronomical Society, 525(3), 3330-3343. https://doi.org/10.1093/mnras/stad2367
• West, L., Garofali, K., Lehmer, B. D., Prestwich, A., Eufrasio, R., Luangtip, W., Roberts, T. P., & Zezas, A. (2023). The Large Deficit of HMXB Emission from Luminous Infrared Galaxies: The Case of the Circumnuclear Starburst Ring in NGC 7552. Astrophysical Journal, 952(1), Article 22. https://doi.org/10.3847/1538-4357/acd9aa
• MacKenzie, A., Roberts, T., & Walton, D. (2023). The hyperluminous X‐ray source population. Astronomische Nachrichten, 344(4), Article e230028. https://doi.org/10.1002/asna.20230028
• Fürst, F., Walton, D. J., Israel, G. L., Bachetti, M., Barret, D., Brightman, M., Earnshaw, H. P., Fabian, A., Heida, M., Imbrogno, M., Middleton, M. J., Pinto, C., Salvaterra, R., Roberts, T. P., Rodríguez Castillo, G. A., & Webb, N. (2023). Probing the nature of the low state in the extreme ultraluminous X-ray pulsar NGC 5907 ULX1. Astronomy & Astrophysics, 672, Article A140. https://doi.org/10.1051/0004-6361/202245048
• Barra, F., Pinto, C., Walton, D., Kosec, P., D’Aì, A., Di Salvo, T., Del Santo, M., Earnshaw, H., Fabian, A., Fuerst, F., Marino, A., Pintore, F., Robba, A., & Roberts, T. (2022). Unveiling the disc structure in ultraluminous X-ray source NGC 55 ULX-1. Monthly Notices of the Royal Astronomical Society, 516(3), 3972-3983. https://doi.org/10.1093/mnras/stac2453
• Robba, A., Pinto, C., Pintore, F., Rodriguez, G., Ambrosi, E., Barra, F., Cusumano, G., D’Aì, A., Del Santo, M., Kosec, P., Marino, A., Middleton, M., Roberts, T., Salvaggio, C., Soria, R., Wolter, A., & Walton, D. (2022). A transient ultraluminous X-ray source in NGC 55. Monthly Notices of the Royal Astronomical Society, 515(4), 4669-4674. https://doi.org/10.1093/mnras/stac2018
• Sathyaprakash, R., Roberts, T., Grisé, F., Kaaret, P., Ambrosi, E., Done, C., Gladstone, J., Kajava, J., Soria, R., & Zampieri, L. (2022). A multi-wavelength view of distinct accretion regimes in the pulsating ultraluminous X-ray source NGC 1313 X-2. Monthly Notices of the Royal Astronomical Society, 511(4), 5346-5362. https://doi.org/10.1093/mnras/stac402
• Earnshaw, H. P., Brightman, M., Harrison, F. A., Heida, M., Jaodand, A., Middleton, M. J., Roberts, T. P., & Walton, D. J. (2022). The variability behavior of NGC 925 ULX-3. Astrophysical Journal, 934(1), Article 42. https://doi.org/10.3847/1538-4357/ac79b0
• Walton, D., Mackenzie, A., Gully, H., Patel, N., Roberts, T., Earnshaw, H., & Mateos, S. (2022). A multimission catalogue of ultraluminous X-ray source candidates. Monthly Notices of the Royal Astronomical Society, 509(2), 1587-1604. https://doi.org/10.1093/mnras/stab3001
• Khan, N., Middleton, M., Wiktorowicz, G., Dauser, T., Roberts, T., & Wilms, J. (2022). The impact of precession on the observed population of ULXs. Monthly Notices of the Royal Astronomical Society, 509(2), 2493-2506. https://doi.org/10.1093/mnras/stab3049
• Alston, W., Pinto, C., Barret, D., D'Ai, A., Del Santo, M., Earnshaw, H., Fabian, A., Fuerst, F., Kara, E., Kosec, P., Middleton, M., Parker, M., Pintore, F., Robba, A., Roberts, T., Sathyaprakash, R., Walton, D., & Ambrosi, E. (2021). Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1. Monthly Notices of the Royal Astronomical Society, 505(3), 3722-3729. https://doi.org/10.1093/mnras/stab1473
• Robba, A., Pinto, C., Walton, D., Soria, R., Kosec, P., Pintore, F., Roberts, T., Alston, W., Middleton, M., Cusumano, G., Earnshaw, H., Fuerst, F., Sathyaprakash, R., Kyritsis, E., & Fabian, A. (2021). Broadband X-ray spectral variability of the pulsing ULX NGC 1313 X-2. Astronomy & Astrophysics, 652, Article A118. https://doi.org/10.1051/0004-6361/202140884
• Pinto, C., Soria, R., Walton, D., D'Ai, A., Pintore, F., Kosec, P., Alston, W., Fuerst, F., Middleton, M., Roberts, T., Del Santo, M., Barret, D., Ambrosi, E., Robba, A., Earnshaw, H., & Fabian, A. (2021). XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows. Monthly Notices of the Royal Astronomical Society, 505(4), 5058-5074. https://doi.org/10.1093/mnras/stab1648
• Fuerst, F., Walton, D., Heida, M., Bachetti, M., Pinto, C., Middleton, M., Brightman, M., Earnshaw, H., Barret, D., Fabian, A., Kretschmar, P., Pottschmidt, K., Ptak, A., Roberts, T., Stern, D., Webb, N., & Wilms, J. (2021). Long-term pulse period evolution of the ultra-luminous X-ray pulsar NGC 7793 P13. Astronomy & Astrophysics, 651, Article A75. https://doi.org/10.1051/0004-6361/202140625
• Walton, D., Heida, M., Bachetti, M., Fürst, F., Brightman, M., Earnshaw, H., Evans, P., Fabian, A., Grefenstette, B., Harrison, F., Israel, G., Lansbury, G., Middleton, M., Pike, S., Rana, V., Roberts, T., Rodriguez Castillo, G., Salvaterra, R., Song, X., & Stern, D. (2021). A new transient ultraluminous X-ray source in NGC 7090. Monthly Notices of the Royal Astronomical Society, 501(1), 1002-1012. https://doi.org/10.1093/mnras/staa3666
• D'a, ì. A., Pinto, C., Del Santo, M., Pintore, F., Soria, R., Robba, A., Ambrosi, E., Alston, W., Barret, D., Fabian, A., Fürst, F., Kara, E., Kosec, P., Middleton, M., Roberts, T., Rodriguez-Castillo, G., & Walton, D. (2021). The chameleon on the branches: spectral state transition and dips in NGC 247 ULX-1. Monthly Notices of the Royal Astronomical Society, 507(4), 5567-5579. https://doi.org/10.1093/mnras/stab2427
• López, K., Heida, M., Jonker, P., Torres, M., Roberts, T., Walton, D., Moon, D.-S., & Harrison, F. (2020). NIR Counterparts to ULXs (III): Completing the photometric survey and selected spectroscopic results*. Monthly Notices of the Royal Astronomical Society, 497(1), 917-932. https://doi.org/10.1093/mnras/staa1920
• Walton, D., Pinto, C., Nowak, M., Bachetti, M., Sathyaprakash, R., Kara, E., Roberts, T., Soria, R., Brightman, M., Canizares, C., Earnshaw, H., Fürst, F., Heida, M., Middleton, M., Stern, D., Tao, L., Webb, N., Alston, W., Barret, D., Fabian, A., …Kosec, P. (2020). The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM–Newton, Chandra, and NuSTAR. Monthly Notices of the Royal Astronomical Society, 494(4), 6012-6029. https://doi.org/10.1093/mnras/staa1129
• Rodríguez Castillo, G., Israel, G., Belfiore, A., Bernardini, F., Esposito, P., Pintore, F., De Luca, A., Papitto, A., Stella, L., Tiengo, A., Zampieri, L., Bachetti, M., Brightman, M., Casella, P., D’Agostino, D., Dall’Osso, S., Earnshaw, H., Fürst, F., Haberl, F., Harrison, F., …Wolter, A. (2020). Discovery of a 2.8 s Pulsar in a 2 Day Orbit High-mass X-Ray Binary Powering the Ultraluminous X-Ray Source ULX-7 in M51. Astrophysical Journal, 895(1), Article 60. https://doi.org/10.3847/1538-4357/ab8a44
• Pinto, C., Walton, D., Kara, E., Parker, M., Soria, R., Kosec, P., Middleton, M., Alston, W., Fabian, A., Guainazzi, M., Roberts, T., Fuerst, F., Earnshaw, H., Sathyaprakash, R., & Barret, D. (2020). XMM–Newton campaign on ultraluminous X-ray source NGC 1313 X-1: wind versus state variability. Monthly Notices of the Royal Astronomical Society, 492(4), 4646-4665. https://doi.org/10.1093/mnras/staa118
• Earnshaw, H. P., Heida, M., Brightman, M., Fürst, F., Harrison, F. A., Jaodand, A., Middleton, M. J., Roberts, T. P., Sathyaprakash, R., Stern, D., & Walton, D. J. (2020). The (re)appearance of NGC 925 ULX-3, a new transient ULX. Astrophysical Journal, 891(2), Article 153. https://doi.org/10.3847/1538-4357/ab77b8
• Pinto, C., Mehdipour, M., Walton, D., Middleton, M., Roberts, T., Fabian, A., Guainazzi, M., Soria, R., Kosec, P., & Ness, J. .-U. (2020). Thermal stability of winds driven by radiation pressure in super-Eddington accretion discs. Monthly Notices of the Royal Astronomical Society, 491(4), 5702-5716. https://doi.org/10.1093/mnras/stz3392
• Kara, E., Pinto, C., Walton, D., Alston, W., Bachetti, M., Barret, D., Brightman, M., Canizares, C., Earnshaw, H., Fabian, A., Furst, F., Kosec, P., Middleton, M., Roberts, T., Soria, R., Tao, L., & Webb, N. (2020). Discovery of a soft X-ray lag in the Ultraluminous X-ray Source NGC 1313 X-1. Monthly Notices of the Royal Astronomical Society, 491(4), 5172-5178. https://doi.org/10.1093/mnras/stz3318
• Pintore, F., Marelli, M., Salvaterra, R., Israel, G., Rodríguez Castillo, G., Esposito, P., Belfiore, A., De Luca, A., Wolter, A., Mereghetti, S., Stella, L., Rigoselli, M., Earnshaw, H., Pinto, C., Roberts, T., Walton, D., Bernardini, F., Haberl, F., Salvaggio, C., Tiengo, A., …Middleton, M. (2020). The Ultraluminous X-ray sources population of the galaxy NGC 7456. Astrophysical Journal, 890(2), Article 166. https://doi.org/10.3847/1538-4357/ab6ffd
• Song, X., Walton, D., Lansbury, G., Evans, P., Fabian, A., Earnshaw, H., & Roberts, T. (2020). The Hunt for Pulsating Ultraluminous X-ray Sources. Monthly Notices of the Royal Astronomical Society, 491(1), 1260-1277. https://doi.org/10.1093/mnras/stz3036
• López, K., Jonker, P., Heida, M., Torres, M., Roberts, T., Walton, D., Moon, D.-S., & Harrison, F. (2019). Discovery and analysis of a ULX nebula in NGC 3521★. Monthly Notices of the Royal Astronomical Society, 489(1), 1249-1264. https://doi.org/10.1093/mnras/stz2127
• Middleton, M., Fragile, P., Ingram, A., & Roberts, T. (2019). The Lense-Thirring timing-accretion plane for ULXs. Monthly Notices of the Royal Astronomical Society, 489(1), 282-296. https://doi.org/10.1093/mnras/stz2005
• Anderson, G., Miller-Jones, J., Middleton, M., Soria, R., Swartz, D., Urquhart, R., Hurley-Walker, N., Hancock, P., Fender, R., Gandhi, P., Markoff, S., & Roberts, T. (2019). Discovery of a radio transient in M81. Monthly Notices of the Royal Astronomical Society, 489(1), 1181-1196. https://doi.org/10.1093/mnras/stz1303
• Sathyaprakash, R., Roberts, T., & Siwek, M. (2019). Observational limits on the X-ray emission from the bubble nebula surrounding Ho IX X-1. Monthly Notices of the Royal Astronomical Society, 488(4), 4614-4622. https://doi.org/10.1093/mnras/stz2022
• Sathyaprakash, R., Roberts, T., Walton, D., Fuerst, F., Bachetti, M., Pinto, C., Alston, W., Earnshaw, H., Fabian, A., Middleton, M., & Soria, R. (2019). The discovery of weak coherent pulsations in the ultraluminous X-ray source NGC 1313 X-2. Monthly Notices of the Royal Astronomical Society, 488(1), L35-L40. https://doi.org/10.1093/mnrasl/slz086
• Earnshaw, H., Roberts, T., Middleton, M., Walton, D., & Mateos, S. (2019). A new, clean catalogue of extragalactic non-nuclear X-ray sources in nearby galaxies. Monthly Notices of the Royal Astronomical Society, 483(4), 5554-5573. https://doi.org/10.1093/mnras/sty3403
• Brightman, M., Baloković, M., Koss, M., Alexander, D., Annuar, A., Earnshaw, H., Gandhi, P., Harrison, F., Hornschemeier, A., Lehmer, B., Powell, M., Ptak, A., Rangelov, B., Roberts, T., Stern, D., Walton, D., & Zezas, A. (2018). A long hard-X-ray look at the dual active galactic nuclei of M51 with NuSTAR. Astrophysical Journal, 867(2), Article 110. https://doi.org/10.3847/1538-4357/aae1ae
• Earnshaw, H., Roberts, T., & Sathyaprakash, R. (2018). Searching for propeller-phase ULXs in the XMM-Newton Serendipitous Source Catalogue. Monthly Notices of the Royal Astronomical Society, 476(3), 4272-4277. https://doi.org/10.1093/mnras/sty501
• Middleton, M., Fragile, P., Bachetti, M., Brightman, M., Jiang, Y.-F., Ho, W., Roberts, T., Ingram, A., Dauser, T., Pinto, C., Walton, D., Fuerst, F., Fabian, A., & Gehrels, N. (2018). Lense-Thirring precession in ULXs as a possible means to constrain the neutron star equation-of-state. Monthly Notices of the Royal Astronomical Society, 475(1), 154-166. https://doi.org/10.1093/mnras/stx2986
• Kaaret, P., Feng, H., & Roberts, T. P. (2017). Ultraluminous X-Ray Sources. Annual Review of Astronomy and Astrophysics, 55(1), 303-341. https://doi.org/10.1146/annurev-astro-091916-055259
• Siwek, M., Sadowski, A., Narayan, R., Roberts, T., & Soria, R. (2017). Optical and X-ray luminosity of expanding nebulae around ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society, 470(1), 361-371. https://doi.org/10.1093/mnras/stx1185
• López, K., Heida, M., Jonker, P., Torres, M., Roberts, T., Walton, D., Moon, D.-S., & Harrison, F. (2017). A Systematic Search for Near-Infrared Counterparts of Nearby Ultraluminous X-ray sources (II). Monthly Notices of the Royal Astronomical Society, 469(1), 671-682. https://doi.org/10.1093/mnras/stx857
• Pinto, C., Alston, W., Soria, R., Middleton, M., Walton, D., Sutton, A., Fabian, A., Earnshaw, H., Urquhart, R., Kara, E., & Roberts, T. (2017). From ultraluminous X-ray sources to ultraluminous supersoft sources: NGC 55 ULX, the missing link. Monthly Notices of the Royal Astronomical Society, 468(3), 2865-2883. https://doi.org/10.1093/mnras/stx641
• Earnshaw, H., & Roberts, T. (2017). Soft Extragalactic X-Ray Binaries at the Eddington Threshold. Monthly Notices of the Royal Astronomical Society, 467(3), 2690-2705. https://doi.org/10.1093/mnras/stx308
• Sutton, A., Swartz, D., Roberts, T., Middleton, M., Soria, R., & Done, C. (2017). Crossing the Eddington Limit: Examining Disk Spectra at High Accretion Rates. Astrophysical Journal, 836(1), Article 48. https://doi.org/10.3847/1538-4357/836/1/48
• 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
• 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
• Walton, D., Fürst, F., Bachetti, M., Barret, D., Brightman, M., Fabian, A., Gehrels, N., Harrison, F., Heida, M., Middleton, M., Rana, V., Roberts, T., Stern, D., Tao, L., & 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
• 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
• Heida, M., Jonker, P., Torres, M., Roberts, T., Walton, D., Moon, D.-S., Stern, 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
• Roberts, T., Middleton, M., Sutton, A., Mezcua, M., Walton, D., & Heil, L. (2016). ULX behaviour: The ultraluminous state, winds and interesting anomalies. Astronomische Nachrichten, 377(4-5), 534-540. https://doi.org/10.1002/asna.201612343
• Earnshaw, H. M., Roberts, T. P., Heil, L. M., Mezcua, M., Walton, D. J., Done, C., Harrison, F. A., Lansbury, G. B., Middleton, M. J., & 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
• Middleton, M. J., Walton, D. J., Fabian, A., Roberts, T. P., Heil, L., Pinto, C., Anderson, G., & Sutton, A. (2015). Diagnosing the accretion flow in ultraluminous X-ray sources using soft X-ray atomic features. Monthly Notices of the Royal Astronomical Society, 454(3), 3134-3142. https://doi.org/10.1093/mnras/stv2214
• Sutton, A., Roberts, T., & Middleton, M. (2015). X-ray spectral residuals in NGC 5408 X-1: diffuse emission from star formation, or the signature of a super-Eddington wind?. Astrophysical Journal, 814(1), Article 73. https://doi.org/10.1088/0004-637x/814/1/73
• Heida, M., Torres, M., Jonker, P., Servillat, M., Repetto, S., Roberts, T., Walton, D., Moon, D.-S., & Harrison, F. (2015). Discovery of a red supergiant counterpart to RX J004722.4-252051, a ULX in NGC 253. Monthly Notices of the Royal Astronomical Society, 453(4), 3510-3518. https://doi.org/10.1093/mnras/stv1853
• Hernández-García, L., Vaughan, S., Roberts, T., & Middleton, M. (2015). X-ray time lags and non-linear variability in the ultraluminous X-ray sources NGC 5408 X-1 and NGC 6946 X-1. Monthly Notices of the Royal Astronomical Society, 453(3), 2877-2884. https://doi.org/10.1093/mnras/stv1830
• Prestwich, A., Jackson, F., Kaaret, P., Brorby, M., Roberts, T., Saar, S., & Yukita, M. (2015). Ultra-luminous X-Ray Sources in HARO II and the Role of X-Ray Binaries in Feedback in Lyα Emitting Galaxies. Astrophysical Journal, 812(2), Article 166. https://doi.org/10.1088/0004-637x/812/2/166
• Sutton, A., Roberts, T., Gladstone, J., & Walton, D. (2015). The hyperluminous X-ray source candidate in IC 4320: another HLX bites the dust. Monthly Notices of the Royal Astronomical Society, 450(1), 787-793. https://doi.org/10.1093/mnras/stv505
• Mezcua, M., Roberts, T., Lobanov, A., & Sutton, A. (2015). The powerful jet of an off-nuclear intermediate-mass black hole in the spiral galaxy NGC 2276. Monthly Notices of the Royal Astronomical Society, 448(2), 1893-1899. https://doi.org/10.1093/mnras/stv143
• Middleton, M., Heil, L., Pintore, F., Walton, D., & Roberts, T. (2015). A spectral-timing model for ULXs in the supercritical regime. Monthly Notices of the Royal Astronomical Society, 447(4), 3243-3263. https://doi.org/10.1093/mnras/stu2644
• Walton, D., Harrison, F., Bachetti, M., Barret, D., Boggs, S., Christensen, F., Craig, W., Fuerst, F., Grefenstette, B., Hailey, C., Madsen, K., Middleton, M., Rana, V., Roberts, T., Stern, D., Sutton, A., Webb, N., & Zhang, W. (2015). NuSTAR and XMM-Newton observations of the extreme ultraluminous X-ray source NGC 5907 ULX1 : a vanishing act. Astrophysical Journal, 799(2), Article 122. https://doi.org/10.1088/0004-637x/799/2/122
• Luangtip, W., Roberts, T., Mineo, S., Lehmer, B., Alexander, D., Jackson, F., Goulding, A., & Fischer, J. (2015). A deficit of ultraluminous X-ray sources in luminous infrared galaxies. Monthly Notices of the Royal Astronomical Society, 446(1), 470-492. https://doi.org/10.1093/mnras/stu2086
• Sutton, A. D., Done, C., & Roberts, T. P. (2014). Irradiated, colour-temperature-corrected accretion discs in ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society, 444(3), 2415-2427. https://doi.org/10.1093/mnras/stu1597
• Heida, M., Jonker, P., Torres, M., Kool, E., Servillat, M., Roberts, T., Groot, P., Walton, D., Moon, D., & Harrison, F. (2014). Near-infrared counterparts of ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society, 442(2), 1054-1067. https://doi.org/10.1093/mnras/stu928
• Middleton, M., Walton, D., Roberts, T., & Heil, L. (2014). Broad absorption features in wind-dominated ultraluminous X-ray sources?. Monthly Notices of the Royal Astronomical Society, 438(1), L51-L55. https://doi.org/10.1093/mnrasl/slt157
• Mezcua, M., Roberts, T., Sutton, A., & Lobanov, A. (2013). Radio observations of extreme ULXs : revealing the most powerful ULX radio nebula ever or the jet of an intermediate-mass black hole?. Monthly Notices of the Royal Astronomical Society, 436(4), 3128-3134. https://doi.org/10.1093/mnras/stt1794
• Sutton, A., Roberts, T., & Middleton, M. (2013). The ultraluminous state revisited : fractional variability and spectral shape as diagnostics of super-Eddington accretion. Monthly Notices of the Royal Astronomical Society, 435(2), 1758-1775. https://doi.org/10.1093/mnras/stt1419
• Sutton, A., Roberts, T., Gladstone, J., Farrell, S., Reilly, E., Goad, M., & Gehrels, N. (2013). A bright ultraluminous X-ray source in NGC 5907. Monthly Notices of the Royal Astronomical Society, 434(2), 1702-1712. https://doi.org/10.1093/mnras/stt1133
• Walton, D., Miller, J., Harrison, F., Fabian, A., Roberts, T., Middleton, M., & Reis, R. (2013). X-Ray Outflows and Super-Eddington Accretion in the Ultraluminous X-Ray Source Holmberg IX X-1. Astrophysical Journal Letters, 773(1), Article L9. https://doi.org/10.1088/2041-8205/773/1/l9
• Heida, M., Jonker, P., Torres, M., Roberts, T., Miniutti, G., Fabian, A., & Ratti, E. (2013). VLT/FORS2 observations of four high-luminosity ULX candidates. Monthly Notices of the Royal Astronomical Society, 433(1), 681-687. https://doi.org/10.1093/mnras/stt756
• Prestwich, A., Tsantaki, M., Zezas, A., Jackson, F., Roberts, T., Foltz, R., Linden, T., & Kalogera, V. (2013). Ultra-luminous X-ray sources in the most metal poor galaxies. Astrophysical Journal, 769(2), Article 92. https://doi.org/10.1088/0004-637x/769/2/92
• Gladstone, J., Copperwheat, C., Heinke, C., Roberts, T., Cartwright, T., Levan, A., & Goad, M. (2013). Optical Counterparts of the Nearest Ultraluminous X-Ray Sources. Astrophysical Journal Supplement, 206(2), Article 14. https://doi.org/10.1088/0067-0049/206/2/14
• Nebot Gómez-Morán, A., Motch, C., Barcons, X., Carrera, F., Ceballos, M., Cropper, M., Grosso, N., Guillout, P., Hérent, O., Mateos, S., Michel, L., Osborne, J., Pakull, M., Pineau, F.-X., Pye, J., Roberts, T., Rosen, S., Schwope, A., Watson, M., & Webb, N. (2013). The XMM-Newton SSC survey of the Galactic plane. Astronomy & Astrophysics, 553, Article A12. https://doi.org/10.1051/0004-6361/201220308
• Middleton, M. J., Miller-Jones, J. C., Markoff, S., Fender, R., Henze, M., Hurley-Walker, N., Scaife, A. M., Roberts, T. P., Walton, D., Carpenter, J., Macquart, J.-P., Bower, G. C., Gurwell, M., Pietsch, W., Haberl, F., Harris, J., Daniel, M., Miah, J., Done, C., Morgan, J. S., …Grainge, K. (2013). Bright radio emission from an ultraluminous stellar-mass microquasar in M 31. Nature, 493(7431), 187-190. https://doi.org/10.1038/nature11697
• Roberts, T., Fabbiano, G., Luo, B., Kim, D.-W., Strader, J., Middleton, M., Brodie, J., Fragos, T., Gallagher, J., Kalogera, V., King, A., & Zezas, A. (2012). A variable ultraluminous X-ray source in a globular cluster in NGC 4649. Astrophysical Journal, 760(2), Article 135. https://doi.org/10.1088/0004-637x/760/2/135
• Jonker, P., Heida, M., Torres, M., Miller-Jones, J., Fabian, A., Ratti, E., Miniutti, G., Walton, D., & Roberts, T. (2012). The Nature of the Bright ULX X-2 in NGC 3921: A Chandra Position and HST Candidate Counterpart. Astrophysical Journal, 758(1), Article 28. https://doi.org/10.1088/0004-637x/758/1/28
• Gruyters, P., Exter, K., Roberts, T., & Rappaport, S. (2012). A VLT VIMOS IFU study of the ionisation nebula surrounding the supersoft X-ray source CAL 83. Astronomy & Astrophysics, 544, Article A86. https://doi.org/10.1051/0004-6361/201219051
• Sutton, A. D., Roberts, T. P., Walton, D. J., Gladstone, J. C., & Scott, A. E. (2012). The most extreme ultraluminous X-ray sources: evidence for intermediate-mass black holes?. Monthly Notices of the Royal Astronomical Society, 423(2), 1154-1177. https://doi.org/10.1111/j.1365-2966.2012.20944.x
• Jackson, F., Roberts, T., Alexander, D., Gelbord, J., Goulding, A., Ward, M., Wardlow, J., & Watson, M. (2012). On the nature of high X-ray luminosities in Sloan Digital Sky Survey galaxies. Monthly Notices of the Royal Astronomical Society, 422(1), 2-13. https://doi.org/10.1111/j.1365-2966.2011.20164.x
• Middleton, M., Sutton, A., Roberts, T., Jackson, F., & Done, C. (2012). The missing link: a low mass X-ray binary in M31 seen as an ultraluminous X-ray source. Monthly Notices of the Royal Astronomical Society, 420(4), 2969-2977. https://doi.org/10.1111/j.1365-2966.2011.20145.x
• Prestwich, A., Galache, J., Linden, T., Kalogera, V., Zezas, A., Roberts, T., Kilgard, R., Wolter, A., & Trinchieri, G. (2012). Chandra observations of the collisional ring galaxy NGC 922. Astrophysical Journal, 747(2), Article 150. https://doi.org/10.1088/0004-637x/747/2/150
• Rasmussen, J., Bai, X.-N., Mulchaey, J. S., van Gorkom, J., Jeltema, T. E., Zabludoff, A. I., Wilcots, E., Martini, P., Lee, D., & Roberts, T. P. (2012). Hot and cold galactic gas in the NGC 2563 galaxy group. Astrophysical Journal, 747(1), Article 31. https://doi.org/10.1088/0004-637x/747/1/31
• Middleton, M., Cackett, E., Shaw, C., Ramsay, G., Roberts, T., & Wheatley, P. (2012). Identifying a new intermediate polar using XMM-Newton and INTEGRAL. Monthly Notices of the Royal Astronomical Society, 419(1), 336-341. https://doi.org/10.1111/j.1365-2966.2011.19696.x
• Middleton, M., Sutton, A., & Roberts, T. (2011). X-ray spectral evolution in the ultraluminous X-ray source M33 X-8. Monthly Notices of the Royal Astronomical Society, 417(1), 464-471. https://doi.org/10.1111/j.1365-2966.2011.19285.x
• Walton, D., Roberts, T., Mateos, S., & Heard, V. (2011). 2XMM ultraluminous X-ray source candidates in nearby galaxies. Monthly Notices of the Royal Astronomical Society, 416(3), 1844-1861. https://doi.org/10.1111/j.1365-2966.2011.19154.x
• Walton, D., Gladstone, J., Roberts, T., Fabian, A., Caballero-Garcia, M., Done, C., & Middleton, M. (2011). Comparing spectral models for ultraluminous X-ray sources with NGC 4517 ULX1. Monthly Notices of the Royal Astronomical Society, 414(2), 1011-1022. https://doi.org/10.1111/j.1365-2966.2011.18397.x
• Jenkins, L., Brandt, W., Colbert, E., Koribalski, B., Kuntz, K., Levan, A., Ojha, R., Roberts, T., Ward, M., & Zezas, A. (2011). Investigating the Nuclear Activity of Barred Spiral Galaxies: The Case of NGC 1672. Astrophysical Journal, 734(1), Article 33. https://doi.org/10.1088/0004-637x/734/1/33
• Middleton, M., Roberts, T., Done, C., & Jackson, F. (2011). Does NGC 5408 X-1 really contain an intermediate-mass black hole?. Astronomische Nachrichten, 332, 388-391. https://doi.org/10.1002/asna.201011506
• Roberts, T., Gladstone, J., Goulding, A., Swinbank, A., Ward, M., Goad, M., & Levan, A. (2011). (No) dynamical constraints on the mass of the black hole in two ULXs. Astronomische Nachrichten, 332(4), 398-401. https://doi.org/10.1002/asna.201011508
• Walton, D., Gladstone, J., Roberts, T., & Fabian, A. (2011). A large catalogue of ultraluminous X-ray source candidates in nearby galaxies. Astronomische Nachrichten, 332(4), 354-357. https://doi.org/10.1002/asna.201011498
• Sutton, A., Roberts, T., & Walton, D. (2011). Key results from an XMM-Newton and Chandra study of a new sample of extreme ULXs from the 2XMM catalogue. Astronomische Nachrichten, 332(4), 362-366. https://doi.org/10.1002/asna.201011500
• Gladstone, J., Roberts, T., & Done, C. (2011). Unlocking the nature of ultraluminous X-ray sources using their X-ray spectra. Astronomische Nachrichten, 332(4), 345-348. https://doi.org/10.1002/asna.201011496
• Russell, D., Yang, Y.-J., Gladstone, J., Wiersema, K., & Roberts, T. (2011). New observations of ULX supershells, and their implications. Astronomische Nachrichten, 332(4), 371-374. https://doi.org/10.1002/asna.201011502
• Middleton, M., Roberts, T., Done, C., & Jackson, F. (2011). Challenging times: a re-analysis of NGC 5408 X-1. Monthly Notices of the Royal Astronomical Society, 411(1), 644-652. https://doi.org/10.1111/j.1365-2966.2010.17712.x
• Richings, A., Fabbiano, G., Wang, J., & Roberts, T. (2010). The Hot Interstellar Medium of the Interacting Galaxy NGC 4490. Astrophysical Journal, 723(2), 1375-1392. https://doi.org/10.1088/0004-637x/723/2/1375
• Lehmer, B., Alexander, D., Bauer, F., Brandt, W., Goulding, A., Jenkins, L., Ptak, A., & Roberts, T. (2010). A Chandra Perspective on Galaxy-wide X-ray Binary Emission and its Correlation with Star Formation Rate and Stellar Mass: New Results from Luminous Infrared Galaxies. Astrophysical Journal, 724(1), 559-571. https://doi.org/10.1088/0004-637x/724/1/559
• Vierdayanti, K., Done, C., Roberts, T., & Mineshige, S. (2010). X-ray spectral variability in the ultraluminous X-ray source Holmberg IX X-1. Monthly Notices of the Royal Astronomical Society, 403(3), 1206-1212. https://doi.org/10.1111/j.1365-2966.2009.16210.x
• Irwin, J., Brink, T., Bregman, J., & Roberts, T. (2010). Evidence for a Stellar Disruption by an Intermediate-mass Black Hole in an Extragalactic Globular Cluster. Astrophysical Journal Letters, 712(1), L1-L4. https://doi.org/10.1088/2041-8205/712/1/l1
• Zampieri, L., & Roberts, T. (2009). Low-metallicity natal environments and black hole masses in Ultraluminous X-ray Sources. Monthly Notices of the Royal Astronomical Society, 400(2), 677-686. https://doi.org/10.1111/j.1365-2966.2009.15509.x
• Gladstone, J., Roberts, T., & Done, C. (2009). The ultraluminous state. Monthly Notices of the Royal Astronomical Society, 397(4), 1836-1851. https://doi.org/10.1111/j.1365-2966.2009.15123.x
• Heil, L., Vaughan, S., & Roberts, T. (2009). A Systematic Study of Variability in a Sample of Ultraluminous X-ray Sources. Monthly Notices of the Royal Astronomical Society, 397(2), 1061-1072. https://doi.org/10.1111/j.1365-2966.2009.15068.x
• Gladstone, J., & Roberts, T. (2009). The ultraluminous X-ray source population of NGC 4485/4490. Monthly Notices of the Royal Astronomical Society, 397(1), 124-134. https://doi.org/10.1111/j.1365-2966.2009.14937.x
• Berghea, C., Weaver, K., Colbert, E., & Roberts, T. (2008). Testing the Paradigm that Ultra-Luminous X-ray Sources as a Class Represent Accreting Intermediate-Mass Black Holes. Astrophysical Journal, 687(1), 471-487. https://doi.org/10.1086/591722
• Roberts, T., Levan, A., & Goad, M. (2008). New Hubble Space Telescope imaging of the counterparts to six ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society, 387(1), 73-78. https://doi.org/10.1111/j.1365-2966.2008.13293.x
• Barcons, X., Carrera, F., Ceballos, M., Page, M., Bussons-Gordo, J., Corral, A., Ebrero, J., Mateos, S., Tedds, J., Watson, M., Baskill, D., Birkinshaw, M., Boller, T., Borisov, N., Bremer, M., Bromage, G., Brunner, H., Caccianiga, A., Crawford, C., Cropper, M., …Ziaeepour, H. (2007). The XMM-Newton serendipitous survey. IV. Optical identification of the XMM-Newton medium sensitivity survey (XMS). Astronomy & Astrophysics, 476(3), 1191-1203. https://doi.org/10.1051/0004-6361%3A20077606
• Prestwich, A., Kilgard, R., Crowther, P., Carpano, S., Pollock, A., Zezas, A., Saar, S., Roberts, T., & Ward, M. (2007). The Orbital Period of the Wolf-Rayet Binary IC 10 X-1: Dynamic Evidence that the Compact Object Is a Black Hole. Astrophysical Journal Letters, 669(1), L21-L24. https://doi.org/10.1086/523755
• Roberts, T. (2007). X-ray observations of ultraluminous X-ray sources. Astrophysics and Space Science, 311(1-3), 203-212. https://doi.org/10.1007/s10509-007-9547-z
• Warwick, R., Jenkins, L., Read, A., Roberts, T., & Owen, R. (2007). An XMM-Newton view of M101 - III. Diffuse X-ray emission. Monthly Notices of the Royal Astronomical Society, 376(4), 1611-1620. https://doi.org/10.1111/j.1365-2966.2007.11571.x
• Vazquez, G., Hornschemeier, A., Colbert, E., Roberts, T., Ward, M., & Malhotra, S. (2007). Constraints on accretion in ultraluminous X-ray sources from Spitzer IRS observations of NGC 4485/4490: Infrared diagnostic diagrams. Astrophysical Journal Letters, 658(1), L21-L24. https://doi.org/10.1086/513423
• Roberts, T., Kilgard, R., Warwick, R., Goad, M., & Ward, M. (2006). Chandra monitoring observations of the ultraluminous X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 371(4), 1877-1890. https://doi.org/10.1111/j.1365-2966.2006.10821.x
• Stobbart, A., Roberts, T., & Warwick, R. (2006). The X-ray properties of the dwarf Magellanic-type galaxy NGC 55. Monthly Notices of the Royal Astronomical Society, 370(1), 25-42
• Stobbart, A.-M., Roberts, T., & Wilms, J. (2006). XMM-Newton observations of the brightest ultraluminous X-ray sources. Monthly Notices of the Royal Astronomical Society, 368(1), 397-413. https://doi.org/10.1111/j.1365-2966.2006.10112.x
• Goad, M., Roberts, T., Reeves, J., & Uttley, P. (2006). A deep XMM-Newton observation of the ultraluminous X-ray source Holmberg II X-1: the case against a 1000-M-circle dot black hole. Monthly Notices of the Royal Astronomical Society, 365(1), 191-198
• Krauss, M., Kilgard, R., Garcia, M., Roberts, T., & Prestwich, A. (2005). M74 X-1 (CXOU J013651.1+154547): An extremely variable ultraluminous X-ray source. Astrophysical Journal, 630(1), 228-237
• Watson, M., Roberts, T., Akiyama, M., & Ueda, Y. (2005). Discovery of multiple ultra-luminous X-ray sources in the galaxy KUG 0214-057. Astronomy & Astrophysics, 437(3), 899-904
• Roberts, T., Warwick, R., Ward, M., Goad, M., & Jenkins, L. (2005). XMM-Newton EPIC observations of the ultraluminous X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 357(4), 1363-1369
• Jenkins, L., Roberts, T., Warwick, R., Kilgard, R., & Ward, M. (2005). An XMM-Newton view of M101 - II. Global X-ray source properties. Monthly Notices of the Royal Astronomical Society, 357(2), 401-419. https://doi.org/10.1111/j.1365-2966.2005.08645.x
• Jenkins, L., Roberts, T., Ward, M., & Zezas, A. (2005). XMM-Newton observations of the interacting galaxy pairs NGC 7771/0 and NGC 2342/1. Monthly Notices of the Royal Astronomical Society, 357(1), 109-123
• Jenkins, L., Roberts, T., Ward, M., & Zezas, A. (2004). XMM-Newton observations of the starburst merger galaxies NGC 3256 and NGC 3310. Monthly Notices of the Royal Astronomical Society, 352(4), 1335-1346
• Stobbart, A., Roberts, T., & Warwick, R. (2004). A dipping black hole X-ray binary candidate in NGC 55. Monthly Notices of the Royal Astronomical Society, 351(3), 1063-1070
• Roberts, T., Warwick, R., Ward, M., & Goad, M. (2004). Chandra observations of five ultraluminous X-ray sources in nearby galaxies (vol 349, pg 1193, 2004). Monthly Notices of the Royal Astronomical Society, 350(4), 1536-1536. https://doi.org/10.1111/j.1365-2966.2004.07891.x
• Roberts, T., Warwick, R., Ward, M., & Goad, M. (2004). Chandra observations of five ultraluminous X-ray sources in nearby galaxies. Monthly Notices of the Royal Astronomical Society, 349(4), 1193-1210. https://doi.org/10.1111/j.1365-2966.2004.07626.x
• Jenkins, L., Roberts, T., Warwick, R., Kilgard, R., & Ward, M. (2004). An XMM-Newton view of M101 - I. The luminous X-ray source population. Monthly Notices of the Royal Astronomical Society, 349(2), 404-424. https://doi.org/10.1111/j.1365-2966.2004.07546.x
• Roberts, T., Goad, M., Ward, M., & Warwick, R. (2003). The unusual supernova remnant surrounding the ultraluminous X-ray source IC 342 X-1. Monthly Notices of the Royal Astronomical Society, 342(3), 709-714. https://doi.org/10.1046/j.1365-8711.2003.06593.x
• Roberts, T., & Colbert, E. (2003). Chandra reveals a black hole X-ray binary within the ultraluminous supernova remnant MF 16. Monthly Notices of the Royal Astronomical Society, 341(4), L49-L54
• Roberts, T., Warwick, R., Ward, M., & Murray, S. (2002). A Chandra observation of the interacting pair of galaxies NGC 4485/4490. Monthly Notices of the Royal Astronomical Society, 337(2), 677-692. https://doi.org/10.1046/j.1365-8711.2002.05950.x
• Goad, M., Roberts, T., Knigge, C., & Lira, P. (2002). The optical counterpart of the ultraluminous X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 335(3), L67-L70
• Barcons, X., Carrera, F., Watson, M., McMahon, R., Aschenbach, B., Freyberg, M., Page, K., Page, M., Roberts, T., Turner, M., Barret, D., Brunner, H., Ceballos, M., Della Ceca, R., Guillout, P., Hasinger, G., Maccacaro, T., Mateos, S., Motch, C., Negueruela, I., …Worrall, D. (2002). The XMM-Newton serendipitous survey - II. First results from the AXIS high galactic latitude medium sensitivity survey. Astronomy & Astrophysics, 382(2), 522-536. https://doi.org/10.1051/0004-6361%3A20011615
• Schurch, N., Roberts, T., & Warwick, R. (2002). High-resolution X-ray imaging and spectroscopy of the core of NGC 4945 with XMM-Newton and Chandra. Monthly Notices of the Royal Astronomical Society, 335, 241-246
• Roberts, T., Goad, M., Ward, M., Warwick, R., O'Brien, P., Lira, P., & Hands, A. (2001). The identification of an optical counterpart to the super-Eddington X-ray source NGC 5204 X-1. Monthly Notices of the Royal Astronomical Society, 325(2), L7-L11. https://doi.org/10.1046/j.1365-8711.2001.04659.x
• Roberts, T., Schurch, N., & Warwick, R. (2001). Do LINER 2 galaxies harbour low-luminosity active galactic nuclei?. Monthly Notices of the Royal Astronomical Society, 324(3), 737-746
• Watson, M., Augueres, J., Ballet, J., Barcons, X., Barret, D., Boer, M., Boller, T., Bromage, G., Brunner, H., Carrera, F., Cropper, M., Denby, M., Ehle, M., Elvis, M., Fabian, A., Freyberg, M., Guillout, P., Hameury, J., Hasinger, G., Hinshaw, D., …Worrall, D. (2001). The XMM-Newton serendipitous survey I. The role of XMM-Newton Survey Science Centre. Astronomy & Astrophysics, 365(1), L51-L59
• Pietsch, W., Roberts, T., Sako, M., Freyberg, M., Read, A., Borozdin, K., Branduardi-Raymont, G., Cappi, M., Ehle, M., Ferrando, P., Kahn, S., Ponman, T., Ptak, A., Shirey, R., & Ward, M. (2001). XMM-Newton observations of NGC 253: Resolving the emission components in the disk and nuclear area. Astronomy & Astrophysics, 365(1), L174-L180. https://doi.org/10.1051/0004-6361%3A20000068
• Hopwood, M., Evans, A., Roberts, T., Burleigh, M., Odenkirchen, M., Beardmore, A., O'Brien, T., Jeffries, R., Penny, A., & Eyres, S. (2000). A possible detection of diffuse extended X-ray emission in the environment of the globular cluster NGC 6779. Monthly Notices of the Royal Astronomical Society, 316(1), L5-L8
• Roberts, T., & Warwick, R. (2000). A ROSAT High Resolution Imager survey of bright nearby galaxies. Monthly Notices of the Royal Astronomical Society, 315(1), 98-114
• Roberts, T., Warwick, R., & Ohashi, T. (1999). The X-ray properties of the nearby LINER galaxy NGC 4736. Monthly Notices of the Royal Astronomical Society, 304(1), 52-60
• Warwick, R., & Roberts, T. (1998). The extragalactic X-ray background at 0.25 keV. Astronomische Nachrichten, 319(1-2), 59-62
• Roberts, T., & Warwick, R. (1998). Nuclear X-ray sources in nearby galaxies. Astronomische Nachrichten, 319(1-2), 34-34
• Barber, C., Roberts, T., & Warwick, R. (1996). Shadowing of the 0.25-keV extragalactic X-ray background by the disc of NGC 55. Monthly Notices of the Royal Astronomical Society, 282(1), 157-166