Hydrodynamic Simulations of the SS 433 -W50 Complex Paul Goodall, Fathallah Alouani Bibi, Katherine Blundell ABSTRACT METHOD RESULTS .. The compelling evidence for a connection between SS 433 and W50 The field-of-view of our simulation has been chosen carefully to match 51 Evolution of the SNR in the Galactic density gradient: Eblast = 10 ergs has provoked much imagination for decades. There are still many unan- that of the Dubner et al., (1998) image (see Fig.1), and we achieve a max- -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 50 Entropy Index S(t) Entropy Index S(t) 50 swered questions; What was the nature of the progenitor of the compact imum spatial resolution ∆x = 0.014pc on the AMR grid. We create the 40 Sim-time: 38062 years. Sim-time: 38962 years. 40 30 30 object in SS 433? What causes the evident re-collimation in SS 433’s jets? local background environment of SS433 and W50, using the Galactic den- 20 20 10 10 How recent is SS 433’s current precession state? What mass and energy sity profile adapted from Dehnen & Binney (1998), according to: 0 0 -10 -10 contributions from a possible supernova explosion are required to produce -20 -20 Rm R z -30 -30 W50? Here we comment on two of our 53 models: (i) featuring the SNR ρ (R, z) = ρ exp − − − (1) -40 -40 ISM o ( ISM ) -50 -50 evolution alone, and (ii) the SNR combined with a simple jet model. " Rd Rd Zd # 50 Entropy Index S(t) Entropy Index S(t)) 50 .. Sim-time: 39762 years. Sim-time: 40462 years. .. 40 40 30 30 where the constant Rm = 4kpc, Rd = 5.4 kpc is the scale length of the 20 20 INTRODUCTION 10 10 stellar disc, and Zd = 40 pc is the scale height from the Galaxy disc. The 0 0 temperature estimates across this region are taken from the observations of -10 -10 .. SS 433 and the conch-shaped W50 nebula are located approximately -20 -20 ◦ Lockman et al., (2007), and the temperature profile is adjusted to maintain -30 -30 2 from the plane of the Milky Way disc (Fig.1), and together they form an -40 -40 -50 -50 hydrostatic equilibrium of the unperturbed background medium. -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 intriguingly complex and turbulent environment. W50 spans over 200pc 50 Entropy Index S(t) Normalised Radio Flux 50 .. 40 Sim-time: 41262 years. Time: ? years. 40 in length and features a circular bubble-like region, which is centred upon 30 30 .. We then introduce a pre-Sedov supernova explosion within a radius 20 20 SS 433’s coordinates to within ∼5 arcmins (Lockman et al. 2007). Addi- 10 10 R0 = fr RSedov of the reference point (x0, y0), by adding an ejecta mass Mej 0 0 tionally, the nebular axis of symmetry is coincident with SS 433’s mean 1/3 -10 -10 3 Mej -20 -20 to this region, where RSedov = and fr < 1. We allow the SNR -30 -30 jet axis. Finally, radio observations confirm that the distances to both ob- 4 π ρ0 & ∼ -40 -40 jects are approximately 5.5 kpc (Blundell Bowler 2004, Lockman et al. to evolve until it reaches 45 pch (thei approximate size of W50’s shell) as -50 -50 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 2007). Thus it is important to investigate the possibility that these two ob- shown in Fig. 2 below: −γ log[ S I = P ρ ] jects share a mutual evolution. It is feasible that the circular region in W50 11.00 11.25 11.50 11.75 12.00 12.25 12.50 12.75 13.00 13.25 13.50 13.75 14.00 14.25 14.50 14.75 15.00 15.25 15.50 15.75 16.00 16.25 16.50 16.75 17.00 17.25 17.50 17.75 18.00 18.25 18.50 Evolution of the SNR in the Galactic density gradient: E = 1051 ergs blast 51 has formed through mass ejection from a supernova explosion, or even -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 Figure.3 - Simulation N 39: Evolution of a 10 erg supernova blast with non-precessing cylindrical jets. 50 Entropy Index S(t) Entropy Index S(t) 50 through a strong stellar wind from SS 433’s companion star or a wind from 40 Sim-time: 0 years. Sim-time: 10000 years. 40 30 30 its disc. The East-West lobes of W50 may have formed via interaction be- 20 20 SUMMARY 10 10 tween the jets and this ejecta. Under certain conditions, it is also possible 0 0 -10 -10 We present the results from two of our simulations. Simulation N 2 is a for jets alone to produce the morphology displayed in W50. The East-West -20 -20 -30 -30 supernova remnant with blast ebergy 1051 ergs evolved to the characteris- asymmetry of the lobes can be attributed to the gradient in ISM density to- -40 -40 -50 -50 wards the Galactic plane (Fig.1). We have developed comprehensive mod- tic size of W50’s central circular shell. Simulation N 39 features our most 50 Entropy Index S(t) Entropy Index S(t) 50 40 Sim-time: 5000 years. Sim-time: 30000 years. 40 primitive jet model (jet-model0) in conjunction with the SNR from simu- els of these scenarios using the latest observational parameters for SS433 30 30 1 20 20 lation N 2. For the SNR evolution alone, we observe a small increase in and W50, and we implement these hydrodynamically using FLASH . 10 10 0 0 ellipticity due to the hydrodynamic evolution of the SNR in the Galactic The location of W50 in the Galaxy -10 -10 13.25 -20 -20 exponential density profile. The SNR bubble also experiences a buoyancy Figure.1a Figure.1b -30 -30 11.825 yˆ -40 -40 effect, by which the focus of the SNR shell displaces from the origin of the 10.40 -50 -50 ˆ -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 explosion (x , y ) as the SNR evolves. Although no precession is included in 8.975 0 0 ~ ˆ δ −γ GD α −−→ log[ S I = P ρ ] GD 7.55 c jet-model0, the resultant nebula from simulation N 39 has dimensions and 11.00 11.25 11.50 11.75 12.00 12.25 12.50 12.75 13.00 13.25 13.50 13.75 14.00 14.25 14.50 14.75 15.00 15.25 15.50 15.75 16.00 16.25 16.50 = 204p θGD z ψα θGD 6.125 51 xˆ Figure.2 - Snapshots of the SNR evolution for model N 2 with E0 = 10 ergs, fr = 0.25 and Mej = 5 M⊙ a morphology comparable to that of W50 from the Dubner et al., (1998) Dec (J2000) 4.70 Galactic Cen 204pc image, and shows evidence of recollimation of the jet-shock upon exiting 3.275 .. Our jet-model00 consists of a simple cylindrical jet with a mass ejec- the SNR shell. Models in-progress include a full description of the jet pre- 1.85 R = Plate Scale −4 −1 1 Degree 5.1 kpctre tion rate of 10 M⊙ yr . The jet temperature, density, energy and pressure 0.425 96 Parsecs cession and of the accretion disc wind. -1.0 −3 are initialised for the jet injection-zone cells, which are set to the max- References 19.40 19.33 19.26 19.19 19.12 19.05 18.98 18.91 18.84 18.77 18.70 n0 =1cm RA (J200) References imum resolution of the grid. Jet-model0 does not include precession or • Abell, G. O., Margon,B., 1979,Nature , 279, 701 • Begelman, M. C., Sarazin, C. L., Hatchet, S. P., McKee, C. F., Arons, J., 1980, ApJ , 238 , 722-730 Figure.1 - (a) The location of W50 within the Milky Way, created using archival data from the GBT6 Dehnen, W., & Binney, J., 1998,MNRAS , 294 , 429 • Blundell, K. M., et al 2001,ApJL ,562 , L79 • Blundell & Bowler (2004) Blundell, K. M., & Bowler, M. G.,, 2004, ApJL , 616 L159 • Blundell, K. M., & Bowler, M. G., Schmidtobreick, L., 2007,A&A ,474 , 903B • Brinkmann, W., Aschenbach, B., Kawai, N., 1996,A&A , 312, 306 survey. (b) The orientation of W50 in our model as transformed from Dubner et al, (1998). An example orbital motion, and the jets have a velocity only along the x-axis, thus • Brinkmann, W., Kotani, T., & Kawai, N., 2005,AAP ,431, 575 • Chevalier, R. A., & Gardner, J. 1974,ApJ, 192, 457 • Dubner, G. M., Holdaway, M., Goss, W. M., & Mirabel, I. F. 1998,ApJ ,116 , 1842 • Fabrika, S., 2004, Astro.&Space Phys. Rev. , 12 , 1-99 of the Galactic density profile used in our model is indicated by the dashed contour lines, corresponding to • Fryxell, B., Olson, K., Ricker, P., Timmes, F. X., Zingale, M., Lamb, D. Q., MacNeice, P., Rosner, R., Truran, J. W., Tufo, H., 2000, ApJ , 131 , 273-334 −3 −3 vx = vjet = 0.26 c.