RUI: Understanding the evolutionary behavior of and radio emission in red quasars

This project will investigate how quasars, which are actively growing supermassive black holes in the centers of galaxies, evolve and influence their host galaxies. The focus of the project will be on a class of quasars that appear red because they are embedded in a dusty environment. These red quasars emit tremendous amounts of energy that expels the dust and injects that energy into their host galaxies, affecting their evolution.

This activity in red quasars may be the key to explaining why some quasars emit light at radio wavelengths while others do not. The work will involve significant contribution from undergraduate research students at Middlebury College. The PI will develop an observational astrophysics course that will train students utilizing Middlebury's campus observatory both in imaging and spectroscopy.

The co-evolution of quasars and their host galaxies is not well understood, and this project will focus on a population of dust-reddened ("red") quasars that are in a transitional phase where feedback mechanisms, which are not well understood, dominate. Luminous quasars are thought to be ignited by major mergers between gas-rich galaxies and the red quasars that will be studied in this work are in an emergent phase, during which their cocoon of dust is blown out.

Red quasars have been shown to have enhanced radio emission, possibly linking the formation of jets to the merger phenomenon or exposing a different form of feedback in these systems, such as dusty radiation-driven winds. To explore these issues, the PI will construct complete samples of red quasars over a broad range in luminosity, redshift, and radio-emitting properties.

These samples will be studied to understand the differences between their radio emission, as a function of luminosity and reddening. The fraction of red quasars compared to the total quasar population will be determined, separating out differences in their radio emission; this fraction represents the fraction of time spent in the "blow-out" phase, which may be different depending on the quasar's radio properties.

The execution of this work will involve photometric selection of red quasar candidates, spectroscopic follow up with near-infrared and optical spectroscopy at large ground-based telescope facilities, and detailed analysis of the spectra to determine fundamental properties of the quasars such as redshift, reddening, intrinsic luminosity, black hole mass, and accretion rate. The outcome of this proposed research will be the construction of statistically complete samples of dust-reddened quasars spanning more than two orders of magnitude in bolometric and radio luminosity.

This project is jointly funded by MPS/AST and the Established Program to Stimulate Competitive Research (EPSCoR).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.