X-ray Spectral Index Variation

Sweep the X-ray photon index γ ∈ {1.4, 1.6, 1.8, 2.0, 2.2, 2.4} at fixed bolometric luminosity. Flat spectra (low γ) push photons to higher energies; steep spectra (high γ) drop off quickly above a few keV.

import jax.numpy as jnp
import matplotlib.pyplot as plt
import numpy as np

from tengri.analysis.plotting import setup_style
from tengri.xray import xray_agn_corona

setup_style()

# Wavelength grid spans 0.1 keV (124 A) to 1000 keV (0.0124 A).
# E[keV] = 12.398 / lambda[A].
wavelength = jnp.logspace(np.log10(0.0124), np.log10(124.0), 512)  # Angstrom
wave_keV = 12.398 / np.array(wavelength)

fig, ax = plt.subplots(figsize=(8, 6))

# Photon index sweep
gamma_values = [1.4, 1.6, 1.8, 2.0, 2.2, 2.4]
L_bol = 1e45  # erg/s (fixed)
n_curves = len(gamma_values)

colors = plt.cm.viridis(np.linspace(0.0, 0.85, n_curves))

for gamma, color in zip(gamma_values, colors):
    l_xray = xray_agn_corona(wavelength, L_agn_bol=L_bol, gamma=gamma, E_cut=300.0, alpha_ox=-1.4)
    ax.loglog(wave_keV, np.array(l_xray), lw=2.0, color=color, label=f"γ = {gamma}")

ax.set_xlabel("Energy [keV]")
ax.set_ylabel(r"$L_\nu$ [erg s$^{-1}$ Hz$^{-1}$]")
ax.set_title(
    r"AGN X-ray Corona: Photon Index $\gamma$ Variation"
    "\n"
    r"(L$_{\mathrm{bol}}=10^{45}$ erg/s)"
)
ax.set_xlim(0.1, 1000)
ax.set_ylim(1e21, 5e24)
ax.legend(fontsize=11, frameon=False)
ax.grid(True, alpha=0.3, which="both")

fig.tight_layout()
plt.savefig("plot_xray_gamma_sweep.png", dpi=150, bbox_inches="tight")
plt.show()