Enabling multi-messenger science with pulsar timing arrays

West Virginia University Research Corporation, Morgantown WV

Investigators

Abstract

Humanity is starting a new phase of exploration of the Universe. In the past two years gravitational waves have been directly detected, but so far, the most massive binaries in the Universe---supermassive black hole binaries (SMBHBs)---still hide from us, although there are traces of their influence in electromagnetic signals from the material around them. A targeted survey to find them in the electromagnetic band by the Very Large Array (VLA) and Very Long Baseline Array (VLBA) will be used to refine models for their gravitational wave emission. Using the 12-15 years of data collected with NANOGrav, the world's leading pulsar timing array, combined with the models from VLA and VLBI, a systematic search will be made to either detect SMBHB systems for the first time, or to constrain their evolutionary processes in the event of a non-detection. This work will be a template for future "multi-messenger" searches that combine the domains of the electromagnetic and gravity to detect and study SMBHBs. Undergraduate students will take part in this research, which will give them excellent training in STEM. An innovative approach to STEM outreach, web-based presentations based on this research, in the form of "science advertisements" will be made to engage the public in the dawning era of gravitational astronomy. This research aims to detect gravitational and electromagnetic waves from binary and/or coalesced supermassive black holes (SMBHBs). A targeted search will be made using NANOGrav, a pulsar timing array, combined with a survey with the VLA and VLBA, radio interferometers, of nearby galaxy mergers that are prime candidates for current SMBHB hosts. The electromagnetic search component will provide added constraints on the systems and will work to raise NANOGrav's sensitivity to any resident SMBHBs. This "multi-messenger" search for nano-hertz frequency gravitational wave sources will make specific and unique statements about SMBHB evolution based on orbital constraints or detections obtained by the VLA, VLBI, and NANOGrav data. This survey will allow an in-depth study of the candidate targets using these complementary electromagnetic and gravitational wave search methods and will provide strict limits on the efficiency of binary evolution in post-merger galaxy systems. NANOGrav's sensitivity is improving and this research may lead to a detection and if not will serve as a template for future "multi-messenger" searches. 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.