• journal_club

# Paper

“Jet Signatures in the Spectra of Accreting Black Holes” by Riordan, Pe’er, and McKinney

http://arxiv.org/pdf/1510.08860v1.pdf

# Summary

Simulate accretion about X-ray binaries using GRMHD (general relativistic magneto-hydrodynamics). Use two competing RIAF (radiatively inefficient accretion flow) models, MAD (magnetically arrested disk) and SANE (standard and normal evolution). Look for signatures of jet emission.

# Models

MAD assumes thin disks can drag magnetic fields into the horizon. SANE relies on a thicker disk.

For each of the above two models, 9 combinations of parameters are used. The parameters are the photon-to-electron temperature ratios in the disk (R_d) and the jet (R_j).

# Figures

Figures 1 and 2 show a snapshot of the electron density and magnetic field using the MAD and SANE models, respectively.

Figures 3, 4, and 5 show the simulated spectra using MAD, for R_d = R_j, R_d < R_j, and R_d > R_j, respectively.

Figures 6, 7, and 8 show the same as above using SANE.

Figure 9 shows light curves produced in the MAD simulation, at different wavelengths.

Figure 10 shows the power spectral density corresponding to the light curves in Figure 9.

Figure 11 shows light curves produced in the MAD simulation during a global magnetic field inversion, at different wavelengths.

# Controversies

Degeneracy of models. Figures 5 and 8 show that MAD is jet dominated, while SANE is disk dominated, for the same parameters.

# Results

Signatures of jet emission:

1. Significant peak in gamma rays around 1e23 Hz.
2. Break in the optical/UV spectrum transitioning between disk and jet dominated.
3. Pronounced peak around 1e15 Hz indicates jet dominates at higher frequencies (I’m not sure I believe this).