Variability of the X-ray obscuring wind in Mrk 335 with XMM-Newton/RGS

TL;DR

This study investigates the short-term variability and structure of the X-ray obscuring wind in Mrk 335, revealing multi-phase, dynamic winds at broad-line region scales through high-resolution spectral analysis.

Contribution

It provides the first detailed, time-resolved analysis of multi-phase X-ray winds in Mrk 335, demonstrating rapid variability and wind restructuring on day timescales.

Findings

Detected three distinct photoionised wind phases with varying velocities.

Observed rapid changes in column density and ionisation during flares.

Constrained the wind location to broad-line region scales (~10^3-10^5 R_g).

Abstract

Transient X-ray obscuration in Seyfert 1 galaxies is thought to arise from clumpy accretion-disk winds near the broad-line region (BLR), but the wind structure and its short-timescale variability are difficult to measure because high-resolution spectra are often suppressed during deep low states. We analyse a coordinated XMM-Newton/NuSTAR campaign on Mrk 335 in June 2021, complemented by long-term Swift monitoring, which captured the source in an intermediate-flux state that preserves strong RGS absorption features. We first model the broadband spectral energy distribution to determine the ionising continuum and then perform self-consistent photoionisation modelling of the RGS spectra. The stacked RGS spectrum requires three photoionised absorbers with time-averaged log xi approx 3.63, 3.10, and 2.01 and outflow velocities |v_out| approx 5820, 3210, and 2140 km/s. Their properties are broadly consistent with the three-phase obscurer reported in the 2009 intermediate state, indicating recurring multi-phase obscuration over decade timescales. Using five consecutive RGS observations, we track the wind evolution on day timescales and find strong variability in column density and ionisation in all phases, together with smaller but coherent changes in outflow velocity. During a flare, the low-ionisation phase shows an extreme drop in N_H, and the subsequent epoch exhibits an increase in outflow velocity in all phases, consistent with rapid restructuring and possible radiative acceleration in a clumpy wind. The high-ionisation phase responds most directly to changes in the ionising luminosity, while the lowest-ionisation phase shows at most a delayed response. Order-of-magnitude constraints place the obscurer at BLR scales (approx 10^3-10^5 R_g), and simple continuity arguments suggest kinetic power that can reach the percent level of L_bol for plausible estimates of geometry and clumpiness.