Kavli Affiliate: Erin Kara
| Summary:
Quasi-periodic eruptions (QPEs) are recurring bursts of X-ray radiation originating from supermassive black holes (SMBHs). They are an unprecedented type of structured, high-amplitude SMBH variability, but the physical origins of their regularity, timescales, energetics, and emission are uncertain. We present new XMM-Newton observations of the QPEs in ZTF19acnskyy/“Ansky”, constituting the deepest observations of individual bursts in any source thus far. The X-ray spectra reveal time-evolving P Cygni profiles comprising blueshifted absorption and redshifted emission from L-shell transitions of Fe XIX-XXIV, with column densities $N_Hsim 10^22-23$ cm$^-2$ and bulk velocities of $|v_w/c|sim 0.2$, indicating relativistic mass ejections during each eruption. We construct a time-dependent analytical model of a wind turning on to self-consistently compute its evolving luminosity and ionization properties, and find that the light curve and spectral lines can be simultaneously produced by a wide-angle outflow with $dotMsim 10^-9-10^-8,M_odot$ s$^-1$ kinetically powering the X-rays with an efficiency of $L_X/dotE_Ksim 0.1$. Each eruption ejects $sim 10^-3,M_odot$ and $gtrsim 10^49$ erg of kinetic energy, setting an upper bound on the QPE lifetime of $lesssim30$ years if the underlying mass reservoir is $sim1 M_odot$, and implying that the bursts may result in detectable multiwavelength signatures of reverberation and feedback. These measurements provide new quantitative constraints on QPE energetics, emission mechanisms, and the mass/energy they recycle into their circumnuclear environments, as well as an observational probe for direct comparison with physical models and hydrodynamical simulations of QPEs.
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