The Dynamic Central Environment of NGC 3516 Revealed by XRISM

Résumé fourni par la source

Abstract We present a detailed, time-resolved analysis of the Fe K band of the Seyfert 1.5 galaxy NGC 3516 observed with XRISM. The 249 ks observation spanning ∼310 ks in elapsed time reveals an exceptionally rich and time-variable absorption spectrum. Six distinct absorption components are detected across multiple ionization states, spanning more than an order of magnitude in ionization parameter and a wide range of systemic velocities, from a potential inflow (+4300 km s −1 ) to an ultrafast outflow (−9800 km s −1 ), the latter detected at >3 σ for the first time in this source. Despite their diversity, the components exhibit relatively small broadening (≲420 km s −1 ), suggesting similar internal dynamics within a medium that has a complex structure. Time-resolved spectroscopy reveals pronounced variability in three highly ionized absorbers, with Fe xxv –Fe xxvi features that appear and disappear on timescales of tens of kiloseconds. This behavior likely reflects a combination of geometrical transits of clumpy gas and ionization-state changes driven by continuum variability. An additional temporary absorption feature in the red wing of the Fe K α line, consistent with Fe xxv absorption, indicates a possible transient ultrafast inflow at ∼15,000 km s −1 (∼5% c ). Finally, the continuum light curve exhibits a tentative ∼40 ks oscillatory pattern, accompanied by correlated shifts of a weak, narrow Fe K α emission feature, suggesting dynamic coupling between the continuum and the line-emitting region. Together, these results reveal an environment dominated by rapidly evolving, multiphase gas flows, where accretion, ejection, and ionization processes are tightly coupled on subparsec scales.

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