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Probing the Geometry and Physics of the Emission Region of Active Galactic Nuclei Using Hard X-Ray Observations. Natasha Woods Mentors: Marco Ajello & Masaaki Hayashida. Outline. AGN & Unified Model Testing the Unified Model Results Conclusions. Introduction. AGN - PowerPoint PPT Presentation
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Probing the Geometry and Physics of the Emission Region of Active Galactic Nuclei Using Hard X-Ray Observations
Natasha WoodsMentors: Marco Ajello & Masaaki Hayashida
Outline
• AGN & Unified Model• Testing the Unified Model• Results• Conclusions
Introduction
• AGN–Majority of energy output unrelated to stellar
processes– Compact regions, galaxy center, exceedingly
luminous• Classification– Radio luminosity– Spectral properties
Unified Model for AGN
• All AGN are intrinsically the same
• Perceived differences due to viewing orientation
• SMBH, accretion disk, molecular torus, corona
Seyfert Galaxies
Evidence For & Against the Unified Model
• Polarized broad emission lines in Sy2
• Sy1 <---> Sy2• Electron temperature • Fraction of absorbed
sources
X-ray Spectra
• X-Rays• IC Radiation• Direct, Transmitted,
Reflected
Reflection Component
• IC reflection peak ~30keV, softening spectra (whiteboard)
• Sy1 should have a larger reflection component and photon index than Sy2
High Energy Cut-off
• Corona's electrons expected to be thermal• Cut-offs for Sy1 and Sy2 should be compatible,
corona's properties are independent of orientation
Relevance
• ~100% CXB• Constrain cosmological models and black hole
physics
Sample Population
• ~200 sources• Swift-BAT hard X-ray Survey• 5 sigma significance level• 3 years exposure• Unbiased, blind search
Models for Spectra
•Simple power law model (SPL) fit to individual spectra in Xspec11
Photon Index Histograms
Gaussian and Weighted Averages• Gaussian poorly
fit some data• Weighted
Averages– based on errors– no model
Stacked Spectra
• S/N, mean properties• SPL and PEXRAV fit to spectra
Results: SPL Histograms• (KS p-values)
Results: SPL & PEXRAV Stacked Spectra
• PEXRAV>SPL• Photon
Indices• Reflection • Energy Cut-
off
Conclusion
• Photon Index Sy1 > Sy2• PEXRAV > SPL• Reflection compatible, large errors• Energy Cut-offs different• Future
Acknowledgements