X-Ray Imaging of the Jet From the Supermassive Black Hole M87

The supermassive black hole, M87, has long been a target of interest for the study of black hole physics and relativistic jets across the electromagnetic spectrum. In April 2017, the Event Horizon Telescope and many ground- and space-based observatories undertook a campaign to study nearby supermassive black holes, including M87, at many wavelengths. With the inclusion of phased ALMA, the EHT data should have sufficient resolution to image the event horizon of the black hole. As part of this campaign, we observed M87 with the Chandra X-ray Observatory for a total of 26.24 ks over two exposures, enabling us to study M87 at high energy. We report the results of imaging and spectroscopy of the X-ray jet, focusing on the X-ray nucleus, which includes emission from both the core and a bright knot in the jet called HST-1. We present a deconvolved image to explore the relative intensity of the core and HST-1. Our analysis of this deconvolved image suggests that HST-1 was significantly fainter than the core. We found no evidence of strong variability in the X-ray brightness during our observation, but compared to the historically recorded spectra of the core, we discovered a slight decrease in the photon index (to Γ=2.05+0.06/-0.07, compared to a typical value of Γ=2.25+/-0.10 in the recent past). M87 was also fainter than in recent observations (LX~1.25x1041 erg s-1). In light of the historical variability of HST-1, we explore the possibility that the lower photon index may be due to a smaller HST-1 contribution to the nuclear emission.