Date: Wednesday 25-Sep-2024
Time: 11:30-12:30 pm
Location: PSC 1136
Speaker: Jeffrey McKaig (George Mason University)
Title: What controls the strength of optical coronal lines in active galactic nuclei?
Abstract: Forbidden, collisionally excited, optical atomic transitions from high ionization potential (IP~54.8eV) ions, such as Ca4+, Ne4+, Fe6+, Fe10+, Fe13+, Ar9+, and S11+, are known as optical coronal lines (CLs). The spectral energy distribution (SED) of active galactic nuclei (AGN) typically extend to hundreds of electron volts and above, and thus causes CLs to be “smoking guns” of AGN activity. However, optical CLs are often not detected in AGN using large scale optical surveys such as the SDSS. In this talk, I will present photoionization calculations using the spectral synthesis code Cloudy which determine possible reasons for the rarity of optical CLs in AGN. I will discuss the effects that metallicity, dust content, and ionizing SED slope have on the observability of these lines and how lower IP lines (e.g., [O III] 5007A) behave in the presence of CLs. Additionally, I will show optical CLs can be produced up to hundreds of parsecs from the nucleus, without the need for another ionizing source such as shocks.
Guidelines and format for the CTC Lunch seminars.
Past CTC Lunch seminars.
For other questions, contact the CTC Lunch host: Matt Nixon
SPECIAL ACCOMMODATIONS:
Special accommodations for individuals with disabilities can be made by calling (301) 405-3001. It would be appreciated if we are notified at least one week in advance.
