ESP39607
We propose to investigate a 4.8 keV absorption feature in the z=0.201 AGN ESP39607, recently detected in two NuSTAR observations (>4sigma combined significance) and identified as a potential sustained ultra-fast inflow (UFI). The feature, likely arising from Fe XXV and/or Fe XXVI Ka transitions, suggests inflow velocities of 0.15-0.20c and has persisted across two epochs (2023 and 2024). With XRISM, we aim to: 1) confirm the feature at >6sigma, and 2) conduct detailed spectroscopy to determine its origin and physical properties. This would provide the clearest evidence of a UFI to date, as previous detections never exceeded 3-3.5sigma. The year-long persistence of the feature offers a rare and time-sensitive opportunity to capture this phenomenon before it potentially fades.
obsid = 202035010 / Unique Observation/Sequence Number
object = ESP39607 / Object name
pi_name = PECA ALESSANDRO / Proposal Principal Investigator Name
ra = 11.5862396399668 / Right Ascension (Pointing Position) (deg)
dec = -40.0970633799726 / Declination (Pointing Position) (deg)
roll_angle = 256.370968130705 / Roll Angle (deg)
start_time = 2026-01-05T23:13:04 / Start Time of the Observation
stop_time = 2026-01-08T04:30:04 / Stop Time of the Observation
exposure = 112122.59196 / Effective Total Observation Exposure (s)
public_date= 2027-01-17 / Public Date