AR 17045 (Archival Research)

Sun Jul 14 21:19:01 GMT 2024

Principal Investigator: Missagh Mehdipour
PI Institution: Space Telescope Science Institute
Investigators (xml)

Title: HST spectroscopy of X-ray ultra-fast outflows
Cycle: 30

We propose an archival research program with HST to investigate the UV spectral signatures of X-ray ultra-fast outflows (UFOs) in active galactic nuclei (AGN). The UFOs, with relativistic outflow velocities, are a crucial component of AGN outflows. These energetic winds have adequate kinetic luminosity to play an important role in AGN-galaxy feedback. There are, however, significant gaps in our understanding of UFOs from X-ray studies alone. High-resolution spectroscopy with HST of potential UV counterparts of X-ray UFOs can provide key additional physical information, such as their kinematics and ionization structure, which cannot be ascertained from the X-rays alone. For this archival study with HST we have selected a sample of suitable AGN, composed of two groups, which have previous reports of UFO detection in X-rays. We aim to investigate the multi-ionization-phase 'entrained UFO' model, which would provide a feasible explanation for the currently uncertain formation and structure of these ionized outflows in AGN, bridging small-scale UFOs to large-scale warm-absorber and molecular outflows.