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Accretion disks in active galactic nuclei (AGN) are promising sites for mergers of stellar-mass black holes (BHs) detectable via gravitational waves (GWs). These environments facilitate both in situ formation and dynamical capture of compact objects and their subsequent mergers. The uncertain origin of GW events detected by LIGO, Virgo, and KAGRA motivates searching for accompanying electromagnetic (EM) signatures. Here, we investigate postmerger EM flares associated with jets launched from merger remnants, as well as from the shocked ambient gas as the jet breaks out of the disk. We find that jet breakout produces luminous gamma-ray emission, detectable with MeV-band telescopes. Cooling emission from a shocked circum-BH minidisk, winds, and background AGN disk peaks in the UV and optical, with durations ranging from about an hour to a month, and can be identified through year-long monitoring of ∼10<SUP>3</SUP> AGNs with luminosities ranging from ∼10<SUP>44</SUP> to ∼10<SUP>45</SUP> erg s<SUP>−1</SUP>. With a single set of parameters, this postmerger jet model produces gamma-ray, hard X-ray, and optical flares similar to those claimed to be associated with GW events. Furthermore, by incorporating a transition from a high- to low-angular-momentum accretion state after the merger, the model avoids excessive BH growth, alleviating tensions with hyper-Eddington accretion scenarios.

X-ray flaring activity from active galactic nuclei (AGNs) may mimic the expected emission from tidal disruption events (TDEs), thus contaminating TDE searches. To compare X-ray emission properties between TDEs and AGNs, we crossmatch publicly available XMM-Newton and Swift-XRT point-source catalogs with the Million Quasars Catalog and optically selected TDEs. We find that AGNs tend to become softer with a similar hardness ratio (HR) value to TDEs during their flaring events. The soft HRs during flaring events in these AGNs are driven by the emergence of a blackbody-like component below ∼2 keV, likely associated with the soft X-ray excess, as well as the continuum emission becoming steeper with the increase of accretion rate. We find that 2.5% of AGNs in XMM-Newton (23 out of 920) and 4.4% of AGNs in Swift-XRT (179 out of 4089) display flares with peak count rate &gt;2σ from the median count rate and peak HR &lt; −0.75. The rate of such flares in XMM-Newton and Swift-XRT is (1.1─2.5) × 10<SUP>−3</SUP> galaxy<SUP>−1</SUP> yr<SUP>−1</SUP> and (0.9─2.0) × 10<SUP>−3</SUP> galaxy<SUP>−1</SUP> yr<SUP>−1</SUP>, respectively. We also estimate the rate of flares with a maximum flux change (peak/min) of &gt;20× over on a rest-frame timescale of 2 yr or more with an HR &lt; −0.75 at peak to be (4.7─11.0) × 10<SUP>−5</SUP> galaxy<SUP>−1</SUP> yr<SUP>−1</SUP> and (3.1─7.1) × 10<SUP>−5</SUP> galaxy<SUP>−1</SUP> yr<SUP>−1</SUP> in XMM-Newton and Swift-XRT, respectively. Finding an optical or infrared counterpart may help to identify these flaring AGNs. We confirm 61% and 79% of flaring sources from XMM-Newton and Swift-XRT, respectively, as AGNs through variability in Zwicky Transient Facility light curves or a Wide-field Infrared Survey Explorer W1 − W2 &gt; 0.8 mag color cut.