My Research

Galactic Center, colliding winds, and gamma-ray binaries

Galactic Center

Within the central parsec (about 3 light years) of the Milky Way are a host of interesting astrophysical sources: a supermassive black hole (SMBH) weighing in at around 4 millions suns, over 100 massive stars with powerful stellar winds, streams of gas flows that could be on an eventual collision course with the SMBH, and an outer disk that is only dwarfed in mass by the SMBH. The major goal of my current project is to develop hydrodynamic models that contain all of the aforementioned components, which should be the most complete picture of our Galaxy's inner parsec.

From the simualtions, we synthesize X-ray and infrared observables to comapre to the wealth of these data available. Discrepancies between the model and data then lead to adjustments in the model, which in turn teaches us about the Galactic Center.

Colliding Wind Binaries

Massive stars (approximately 10 solar masses and above) how powerful outflows of their outer layers called stellar winds. Compared to the Sun, the rate at which material is ejected form the star (called the mass-loss rate) can be 10 orders of magnitude greater (so 10,000,000,000 times), and even higher in extreme cases. These stellar winds can also reach very fast speeds, for example 3000 km/s (across the continental US in less than a second and a half); this is well into the supersonic regime for these materials. If a massive star is in a binary system, for which there is increasing evidence, then the stellar winds from these two stars collide violently in what is called a colliding wind binary.

Based on the speed of the stellar winds, the shock that occurs when the supersonic winds collide can heat the wind material to 10s of millions of K (same as 10M °Celcius), and therefore emit thermal X-rays. (For comparison, we humans at about 300K emit mostly in the infrared, and the sun at 6000K emits mainly in the visible, so this X-ray emitting material is quite hot.)

My research involves creating hydrodynamic simulations of the two winds of the massive stars, which reveal how their interaction depends on a host of stellar, wind, and orbital properties, and then subsequently synthesize the X-ray emission to compare with observations. Changing each stellar, orbital, and/or wind parameter has anywhere from a negligible to a major effect on the X-ray results, and so can provide a strong tool for deciphering as much information as possible that the X-rays are telling us about the system. Combining this with information -- both observational and modeling -- from other wavelengths then will hopefully provide us with a complete picture of the colliding wind binary.

Gamma-ray Binaries

The systems contain a usually unidentified compact object (either a black hole or a neutron star) and a massive star. The inclusion of the compact object invokes relativistic phenomena, either the speed of the neutron-star wind or the black hole's jet, and therefore lead to the production of photons in the gamma-ray regime (the highest energy range there is). These objects get their name, in fact, because their emission peaks in the gamma-ray range (above 1 MeV in nu*F_nu).

I am interested in creating hydrodynamic models of these systems and then synthesizing observables, but not necessarily gamma-rays. For example, in PSR B1259, its pulsar dispersion measure can tell us about the disk of the massive star and how we are oriented relative to the orbiting stars, and in LS5039 the thermal X-ray emission (which is not seen) provides constraints on the strength of the pulsar.

Recent Papers

Hamaguchi, K; Corcoran, MF; Sharma,N; Takahashi, H; Pittard, J; Russell, CMP; Grefenstette, BW; Wik, DR; Gull, TR; Richardson, ND; Madura, TI; & Moffat, AFJ, Particle Acceleration in eta Car, a Massive Colliding Wind Binary System, Nature Astronomy, submitted

Richardson, ND; Russell, CMP; St-Jean, L; Moffat, AFJ; St-Louis, N; Shenar, T; Pablo, H; Hill, GM; Ramiaramanantsoa, T; Corcoran, MiF; Hamuguchi, K; Eversberg, T; Miszalski, B; Chené, A-N; Waldron, W; Kotze, EJ; Kotze, MM; Luckas, P; Cacella, P; Heathcote, B; Powles, J; Bohlsen, T; Locke, M; Handler, G; Kuschnig, R; Pigulski, A; Popowicz, A; Wade, GA; & Weiss, W, 2017, The variability of the BRITE-est Wolf-Rayet binary, 2 Velorum I. Photometric and spectroscopic evidence for colliding winds, Monthly Notices of the Royal Astronomical Society, Volume 471, Issue 3, pp. 2715-2729

Corcoran, MF; Liburd, J; Morris, D; Russell, CMP; Hamaguchi, K; Gull, TR; Madura, TI; Teodoro, M; Moffat, AFJ; Richardson, ND; Hillier, DJ; Damineli, A; & Groh, JH, 2017, The 2014 X-ray Minimum of eta Carinae as Seen by Swift, The Astrophysical Journal, Volume 838, Issue 1, Article 45, pp. 1-12

Russell, CMP; Wang, QD; & Cuadra, J, 2017, Modelling the thermal X-ray emission around the Galactic Centre from colliding Wolf-Rayet winds, Monthly Notices of the Royal Astronomical Society, Volume 464, Issue 4, pp. 4958-4965

Richardson, ND; Madura, TI; St-Jean, L; Moffat, AFJ; Gull, TR; Russell, CMP; Damineli, A; Teodoro, M; Corcoran, MF; Walter, F; Clementel, N; Groh, JH; Hamaguchi, K; & Hillier, DJ, 2016 To v_infinity and Beyond! The P Cygni absorption variability of He I across the 2014.6 periastron passage of the very massive binary eta Carinae, Monthly Notices of the Royal Astronomical Society, Volume 461, Issue 3, pp. 2540-2558

Hamaguchi, K; Oskinova, L; Russell, CMP; Petre, R; Enoto, T; Morihana, K; & Ishida, M, 2016, Discovery of Rapidly Moving Partial X-ray Absorbers within Gamma Cassiopeiae, The Astrophysical Journal, Volume 832, Issue 2, Article 140, pp. 1-11

Russell, CMP; Corcoran, MF; Hamaguchi, K; Madura, TI; Owocki, SP; & Hillier, DJ, 2016, Modelling the Central Constant Emission X-ray component of eta Carinae, Monthly Notices of the Royal Astronomical Society, Volume 458, Issue 3, pp. 2275-2287

Teodoro, M; Damineli, A; Heathcote, B; Richardson, ND; Moffat, AFJ; St-Jean, L; Russell, CMP; Gull, TR; Madura, TI; Pollard, KR; Walter, F; Coimbra, A; Prates, R; Fernandez-Lajus, E; Gamen, RC; Hickel, G; Henrique, W; Navarete, F; Andrade, T; Jablonski, F; Luckas, P; Locke, M; Powles, J; Bohlsen, T; Corcoran, MF; Hamaguchi, K; Groh, JH; Hillier, DJ; & Weigelt, G, 2016, He II λ4686 Emission from the Massive Binary System in eta Car: Constraints to the Orbital Elements and the Nature of the Periodic Minima, The Astrophysical Journal, Volume 819, Issue 2, Article 131, pp. 1-24

Hamaguchi, K; Corcoran, MF; Gull, T; Takahashi, H; Grefenstette, B; Yuasa, T; Stuhlinger, M; Russell, CMP; Moffat, AFJ; Madura, TI; Richardson, ND; Groh, JH; Pittard, JM; & Owocki, SP, 2016, Eta Carinae's Thermal X-ray Tail Measured with XMM-Newton and NuSTAR, The Astrophysical Journal, Volume 817, Issue 1, Article 23, pp. 1-9

Corcoran, MF; Nichols, JS; Pablo, H; Shenar, T; Pollock, AMT; Waldron, WL; Moffat, AFJ; Richardson, ND; Russell, CMP; Hamaguchi, K; Huenemoerder, DP; Oskinova, L; Hamann, W-R; Nazé, Y; Ignace, R; Evans, NR; Lomax, JR; Hoffman, JL; Gayley, K; Owocki, SP; Leutenegger, M; Gull, TR; Hole, KT; Lauer, J; & Iping, RC, 2015, A Coordinated X-ray and Optical Campaign on the Nearest Massive Eclipsing Binary, delta Ori Aa: I. Overview of the X-ray Spectrum, The Astrophysical Journal, Volume 809, Issue 2, Article 132, pp. 1-15

Nichols, J; Huenemoerder, DP; Corcoran, MF; Waldron, W; Nazé, Y; Pollock, AMT; Moffat, AFJ; Lauer, J; Shenar, T; Russell, CMP; Richardson, ND; Pablo, H; Evans, NR; Hamaguchi, K; Gull, TR; Hamann, W-R; Oskinova, L; Ignace, R; Hoffman, JL; Hole, KT; & Lomax, JR, 2015, A Coordinated X-ray and Optical Campaign on the Nearest Massive Eclipsing Binary, delta Ori Aa: II. X-ray Variability, The Astrophysical Journal, Volume 809, Issue 2, Article 133, pp. 1-21

Pablo, H; Richardson, ND; Moffat, AFJ; Corcoran, MF; Shenar, T; Benvenuto, O; Fuller, J; Nazé, Y; Hoffman, JL; Miroshnichenko, A; Maíz Apellániz, J; Evans, N; Eversberg, T; Gayley, K; Gull, T; Hamaguchi, K; Hamann, W-R; Henrichs, H; Hole, T; Ignace, R; Iping, R; Lauer, J; Leutenegger, M; Lomax, J; Nichols, J; Oskinova, L; Owocki, S; Pollock, A; Russell, CMP; Waldron, W; Buil, C; Garrel, T; Graham, K; Heathcote, B; Lemoult, T; Li, D; Mauclaire, B; Potter, M; Ribeiro, J; Matthews, J; Cameron, C; Guenther, D; Kuschnig, R; Rowe, J; Rucinski, S; Sasselov, D; & Weiss, W, 2015, A Coordinated X-ray and Optical Campaign on the Nearest Massive Eclipsing Binary, delta Ori Aa: III. Analysis of Optical Photometric (MOST) and Spectroscopic (Ground Based) Variations, The Astrophysical Journal, Volume 809, Issue 2, Article 134, pp. 1-11

CV

Press Releases

 231st Meeting of the American Astronomical Society
Wednesday, January 10, 2017
Scientists take viewers to the center of the Milky Way
In coordination with Chandra Press Office
Links: NASA article, Chandra article, the video, and the talk

Grants (as PI)

 Chandra Theory Grant, Cycle 18: 3D Hydrodynamic & Radiative Transfer Models of HETG Line Profiles from Colliding Winds
Co-I's: K. Hamaguchi, M. F. Corcoran, T. I. Madura, S. P. Owocki, and T. R. Kallman

Eudcation

 Ph.D. in Physics: University of Delaware, 2013
Dissertation: Using 3D Dynamic Models to Reproduce X-ray Properties of Colliding Wind Binaries
Advisor: Stanley P. Owocki

 B.S. in Physics: University of Delaware, 2005
Concentration in Astronomy and Astrohpysics
Minors in Mathermatics and Computer Science

Employment

 Sep 2017 - present: Pontificia Universidad Católica de Chile, Instituto de Astrofísica
FONDECYT Postdoctorado Fellowship: The inner parsec of the Galactic center.
Advisor: Jorge Cuadra

 Nov 2014 - Aug 2017: NASA Goddard Space Flight Center, X-ray Astrophysics Laboratory.
NASA Postdoctoral Program Fellowship: 3D Hydrodynamic & Radiative Transfer Models of TeV-emitting Compact-Object + Massive-Star Binaries
Advisor: Timothy R. Kallman

 Apr 2014-Oct 2014: University of Delaware
Supported by various observational grants to perform modeling work in support of these grants.
Advisor: Stanley P. Owocki

 Apr 2013 - Mar 2014: Hokkai-Gakuen University, Sapporo, Japan
Japan Society for the Promotion of Science (JSPS) Obei-Tanki Fellowship: 3D Hydrodynamic Modeling of X-rays and Gamma-rays from Massive Stars
Advisor: Atsuo T. Okazaki

Get in touch

  • Email

    crussell AT udel DOT edu
  • Social

  • Address

    Instituto de Astrofísica
    Pontificia Universidad Católica de Chile
    4860 Avenida Vicuña Mackenna
    Macul, 8970117
    Santiago, Chile