Log-Normal as the New Norm? Testing a Log-Normal Model for Multiphase X-Ray Spectra

Presenter: Daniel Owen Kidwell

Faculty Sponsor: DANIEL Q. WANG

School: UMass Amherst

Research Area: Astronomy, Cosmology, and Astrophysics

Session: Poster Session 4, 2:15 PM - 3:00 PM, 165, D11

ABSTRACT

The center of the Milky Way is the closest system that we can probe to deepen our understanding of how galactic nuclei operate. This region hosts some of the most energetic processes in astrophysics including, stellar winds, shocks, magnetic recombination, producing a highly multiphase plasma with a broad temperature distribution. Spectral analysis of these regions is often simplified to isothermal and fit using an APEC plasma model. This approach while convenient, does not capture the complexities of these regions. Our goal is to test a more physically motivated approach to fitting multiphase plasma by utilizing a log-normal model allowing us to use a range of temperatures instead of just one. 

We use hydrodynamic simulations of the stellar winds in the galactic center to simulate observations of multiphase plasma. Using the Python packages PyXSim and SOXS, we create synthetic spectra that are then analyzed in XSPEC. Each is fit with both an isothermal APEC model and our log-normal model to facilitate direct comparison. We expect that this model will perform much better than the APEC model and trace out the spectra more accurately, as well as recover metallicities that agree with simulation input. Testing out models like this that are physically motivated can result in newfound methodologies that further our understanding of these complex systems. Better model fitting can lead to unveiled dynamics and fundamental parameters once shrouded behind a simple generalization.

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