Spatially-Resolved Spectra of the "Teacup" AGN: Tracing the History of a Dying Quasar

TL;DR

This study uses spatially-resolved spectroscopy to analyze the Teacup AGN, revealing a significant decline in luminosity over 46,000 years, indicating the galaxy hosts a dying quasar.

Contribution

It introduces a method of using spatially-resolved photoionization models to trace long-term AGN luminosity changes through EELRs.

Findings

AGN luminosity decreased by over two orders of magnitude

Spatially-resolved spectra reveal the history of AGN activity

Supports the existence of a dying quasar in the Teacup galaxy

Abstract

The Sloan Digital Sky Survey (SDSS) Galaxy Zoo project has revealed a number of spectacular galaxies possessing Extended Emission-Line Regions (EELRs), the most famous being Hanny's Voorwerp galaxy. We present another EELR object discovered in the SDSS endeavor: the Teacup Active Galactic Nucleus (AGN), nicknamed for its EELR, which has a handle like structure protruding 15 kpc into the northeast quadrant of the galaxy. We analyze physical conditions of this galaxy with long-slit ground based spectroscopy from Lowell, Lick, and KPNO observatories. With the Lowell 1.8m Perkin's telescope we took multiple observations at different offset positions, allowing us to recover spatially resolved spectra across the galaxy. Line diagnostics indicate the ionized gas is photoionized primarily by the AGN. Additionally we are able to derive the hydrogen density from the [S II] 6716/6731 ratio. We generated two-component photoionization models for each spatially resolved Lowell spectrum. These models allow us to calculate the AGN bolometric luminosity seen by the gas at different radii from the nuclear center of the Teacup. Our results show a drop in bolometric luminosity by more than two orders of magnitude from the EELR to the nucleus, suggesting that the AGN has decreased in luminosity by this amount in a continuous fashion over 46,000 years, supporting the case for a dying AGN in this galaxy independent of any IR based evidence. We demonstrate that spatially resolved photoionization modeling could be applied to EELRs to investigate long time scale variability.