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Abstract Tidal disruption events (TDEs) have traditionally been discovered in optical sky surveys through targeted searches of nuclear transients. However, it is expected that some TDEs will occur outside the galaxy nucleus, arising from wandering black holes (BHs) originating in galaxy mergers. Here, we present observations of TDE 2025abcr, the first optical TDE discovered in the outskirts of a host galaxy. The TDE was identified by a custom “off-nuclear” implementation of the machine learning classifiertdescore, which classifies new ZTF transients based on their lightcurves. Follow-up observations confirm that TDE 2025abcr is a TDE-H+He, occurring 9 $\stackrel{\text{″}}{.}$ 5 (9.3 kpc projected distance) from the nucleus of a massive galaxy (M_⋆= 10^11.18±0.03M_⊙) with a central BH mass of 10^8.82±0.65M_⊙. TDE 2025abcr itself was likely disrupted by a much lighter BH (10^6.09±0.53M_⊙, as estimated with peak luminosity scaling relations). The BH was either dynamically ejected from the nucleus or lies at the center of a very faint tidally stripped dwarf galaxy undergoing a minor merger. Late-time observations of TDE 2025abcr could confirm the origin of this apparent “wandering” BH. The rate of highly offset (≳3 kpc) TDEs can be constrained to <10% of the nuclear TDE rate, but our discovery implies that many dozens of similar sources will be detected by the Vera C. Rubin Observatory each year with resolvable offsets. 

Abstract We are searching for hot, constant-color, offset optical flares in the Zwicky Transient Facility data stream that are >10″ from any galaxy in public imaging data from the PanSTARRS survey. Here, we present the first discovery from this search: AT 2024puz, a luminous multiwavelength transient offset by 5 kpc from a ∼10⁸M_⊙galaxy atz= 0.356 with a low–moderate star formation rate (0.01 ± 0.003M_⊙yr⁻¹). It produced luminous 10^44.79±0.04erg s⁻¹optical/UV emission that evolved on a ∼20 day timescale, as well as 10^44.12±0.03erg s⁻¹X-ray emission with a photon-index $\mathrm{\Gamma }=1.73_{-0.09}^{+0.10}$ . No associated radio or millimeter emission was detected. We show that the early time optical emission is likely powered by reprocessing of high-energy, accretion-powered radiation, with a possible contribution from a shock in a dense circumtransient medium. If the shock is dominant at early times, the circumtransient medium has a mass ∼0.1–1M_⊙, a radius 10¹⁵cm, and a density profile shallower than ∼r⁻¹. A near-infrared excess appears at late-times and is suggestive of reprocessing within a wind or other circumtransient medium. The X-rays are most consistent with a central engine. We suggest that AT 2024puz may be associated with an accretion event onto a 50–10⁵M_⊙black hole, where the lower masses are preferred based on the large projected offset from the host galaxy. AT2024puz exhibits properties similar to both luminous, fast, blue optical transients and tidal disruption events, but is intermediate between them in its energetics and evolution timescale. This highlights the need for broader exploration of the landscape of hot optical transients to trace their origins. 

ABSTRACT We study AT2024kmq and AT2024lhc, two tidal disruption events (TDEs) with blue featureless spectra associated with high-mass black holes ($$M_{\rm BH}\sim 10^8\, \mathrm{ M}_\odot$$). Both events show optical precursors consistent with shock dissipation from stream self-intersection. Their X-ray emission is luminous ($$L_{\rm X}\sim 10^{44}\, {\rm erg\, s^{-1}}$$), highly variable (with minimum observed variability time-scales of 1.3 and 4.8 h for factor of ∼3 flux changes), long-lasting (>1 yr), emerging no later than the optical peak, and well characterized by power laws with $$1.7\lt \Gamma \lt 3$$ (where $$f_\nu \propto \nu ^{1-\Gamma }$$). The X-ray properties and radio non-detections support a compact corona ($$\lesssim 10 r_{\rm g}$$) producing Comptonized X-ray emission. Using all published featureless TDEs, we find statistically significant bimodality in the distribution of their peak ultraviolet/optical blackbody luminosities and radii. We assemble a comparison TDE sample with early-time X-ray observations with eROSITA, in which we find different $$M_{\rm BH}$$ distributions in TDEs with different X-ray spectral evolution properties: low-mass black holes ($$M_{\rm BH} \sim 10^6 \mathrm{ M}_\odot$$) remain soft ($$\Gamma \gt 4$$) within $$t\lesssim 2$$ yr, intermediate masses ($$\sim 10^7 \mathrm{ M}_\odot$$) transition from soft to hard at $$\sim$$1 yr, while high masses ($$\sim 10^8 \mathrm{ M}_\odot$$) are hard ($$1.5\lt \Gamma \lesssim 3$$) from the outset. We interpret this result as evidence that the soft-to-hard state transition in TDEs occurs at the critical threshold of $$\dot{M}_{\rm acc} \sim 0.03 \dot{M}_{\rm Edd}$$ (similar to X-ray binaries), using the fact that the transition time-scale predicted by simple disc theory scales with black hole mass as $$t_{\rm tr}\propto M_{\rm BH}^{-3/4}$$. 

Abstract Recent studies suggest that tidal disruption events (TDEs) with off-axis jets may manifest as optically overluminous events. To search for jet signatures at late times, we conducted radio observations of eight such optically overluminous (M_g,peak < −20.8 mag) TDEs with the Very Large Array. We detect radio counterparts in four events. The observed radio luminosities (L_{6 GHz} ∼ 10³⁸–10³⁹erg s⁻¹) are two orders of magnitude lower than those of on-axis jetted TDEs, and we find no evidence for off-axis jets within a rest-frame time of 3 yr. Two of them (AT2022hvp and AT2021aeou) exhibit evolving radio emission, consistent with synchrotron emission from non-relativistic outflows launched near the time of first optical light. Two events (AT2020ysg and AT2020qhs) show no statistically significant variability, which can be attributed to either non-relativistic outflows or pre-existing active galactic nuclei. Compared to a control sample of fainter TDEs withM_g,peak > −20.5 mag observed at similar rest-frame timescales (t_rest ∼ 1.5 yr), our sample shows systematically more luminous radio emission, suggesting that optically overluminous TDEs may launch more powerful prompt non-relativistic outflows. We speculate that strong general relativistic effects near high-mass black holes (M_BH ∼ 10⁸M_⊙) may play a key role. These findings motivate further investigation into the nature of relativistic disruptions around massive black holes and the physical conditions necessary for jet formation. 

Abstract We report on a full-polarization analysis of the first 25 as yet nonrepeating fast radio bursts (FRBs) detected at 1.4 GHz by the 110-antenna Deep Synoptic Array (DSA-110) during commissioning observations. We present details of the data-reduction, calibration, and analysis procedures developed for this novel instrument. Faraday rotation measures (RMs) are searched between ±10⁶rad m⁻²and detected for 20 FRBs, with magnitudes ranging from 4 to 4670 rad m⁻². Fifteen out of 25 FRBs are consistent with 100% polarization, 10 of which have high (≥70%) linear-polarization fractions and two of which have high (≥30%) circular-polarization fractions. Our results disfavor multipath RM scattering as a dominant depolarization mechanism. Polarization-state and possible RM variations are observed in the four FRBs with multiple subcomponents. We combine the DSA-110 sample with polarimetry of previously published FRBs, and compare the polarization properties of FRB subpopulations and FRBs with Galactic pulsars. Although FRB polarization fractions are typically higher than those of Galactic pulsars, and cover a wider range than those of pulsar single pulses, they resemble those of the youngest (characteristic ages <10⁵yr) pulsars. Our results support a scenario wherein FRB emission is intrinsically highly linearly polarized, and propagation effects can result in conversion to circular polarization and depolarization. Young pulsar emission and magnetospheric propagation geometries may form a useful analogy for the origin of FRB polarization. 

Abstract We present the tidal disruption event (TDE) AT2022lri, hosted in a nearby (≈144 Mpc) quiescent galaxy with a low-mass massive black hole (10⁴M_⊙<M_BH< 10⁶M_⊙). AT2022lri belongs to the TDE-H+He subtype. More than 1 Ms of X-ray data were collected with NICER, Swift, and XMM-Newton from 187 to 672 days after peak. The X-ray luminosity gradually declined from 1.5 × 10⁴⁴erg s⁻¹to 1.5 × 10⁴³erg s⁻¹and remains much above the UV and optical luminosity, consistent with a super-Eddington accretion flow viewed face-on. Sporadic strong X-ray dips atop a long-term decline are observed, with a variability timescale of ≈0.5 hr–1 days and amplitude of ≈2–8. When fitted with simple continuum models, the X-ray spectrum is dominated by a thermal disk component with inner temperature going from ∼146 to ∼86 eV. However, there are residual features that peak around 1 keV, which, in some cases, cannot be reproduced by a single broad emission line. We analyzed a subset of time-resolved spectra with two physically motivated models describing a scenario either where ionized absorbers contribute extra absorption and emission lines or where disk reflection plays an important role. Both models provide good and statistically comparable fits, show that the X-ray dips are correlated with drops in the inner disk temperature, and require the existence of subrelativistic (0.1–0.3c) ionized outflows. We propose that the disk temperature fluctuation stems from episodic drops of the mass accretion rate triggered by magnetic instabilities or/and wobbling of the inner accretion disk along the black hole’s spin axis. 

Abstract We present the discovery of SN 2025mkn, a gravitationally lensed Type II supernova. First detected as a blue transient in Zwicky Transient Facility (ZTF), 0 $\stackrel{″}{.}$ 83 from az= 0.42 elliptical galaxy, the follow-up SNIFS/UH2.2 m and LRIS/Keck spectra revealed absorption lines atz= 1.371. Later JWST NIRCam imaging shows that the bright transient is a close pair of point sources separated by $\sim 0\stackrel{″}{.}07$ , and a 30 times fainter counterimage opposite the lens, for which NIRSpec reveals strong Hαemission also atz= 1.371. The lightcurves and spectra are consistent with the Type II supernova source being magnified ≳100 times, with ∼250 required to reconcile its luminosity with that of nearby events such as SN 2023ixf. Lens models are consistent with such high magnifications, and always show that the faint image arrived first (undetected in earlier ZTF imaging), consistent with the later spectral phase of this fainter image. A fourth image is also predicted and possibly detected in the NIRSpec data. Lightcurve-based time-delay measurements are not possible due to the first image being the faintest; however, the resolved NIRSpec spectra offer a future opportunity for time-delay cosmography through supernova phase measurements. 

Abstract Faraday rotation measures (RMs) of fast radio bursts (FRBs) offer the prospect of directly measuring extragalactic magnetic fields. We present an analysis of the RMs of 10 as yet nonrepeating FRBs detected and localized to host galaxies with robust redshift measurements by the 63-antenna prototype of the Deep Synoptic Array (DSA-110). We combine this sample with published RMs of 15 localized FRBs, nine of which are repeating sources. For each FRB in the combined sample, we estimate the host-galaxy dispersion measure (DM) contributions and extragalactic RM. We find compelling evidence that the extragalactic components of FRB RMs are often dominated by contributions from the host-galaxy interstellar medium (ISM). Specifically, we find that both repeating and as yet nonrepeating FRBs show a correlation between the host DM and host RM in the rest frame, and we find an anticorrelation between extragalactic RM (in the observer frame) and redshift for nonrepeaters, as expected if the magnetized plasma is in the host galaxy. Important exceptions to the ISM origin include a dense, magnetized circumburst medium in some repeating FRBs, and the intracluster medium of host or intervening galaxy clusters. We find that the estimated ISM magnetic-field strengths, ${\overline{B}}_{\mid \mid }$ , are characteristically ∼1–2μG larger than those inferred from Galactic radio pulsars. This suggests either increased ISM magnetization in FRB hosts in comparison with the Milky Way, or that FRBs preferentially reside in regions of increased magnetic-field strength within their hosts.