TianQin is a proposed space-based gravitational wave detector consisting of three satellites in nearly circular high Earth orbits. As a geocentric mission, it may be susceptible to gravitational perturbations from the Earth–Moon system, potentially including those induced by lunar free oscillations. Here we evaluate the impact of such oscillations on TianQin’s range acceleration between two test masses. The perturbations are computed from the Moon’s normal modes for four seismic velocity models and are incorporated into high-precision orbit simulations. The results indicate that even under extreme excitation of a moment magnitude 7.0 moonquake, the peak range acceleration noise remains at least two orders of magnitude below TianQin’s noise requirement. Therefore, considering only spheroidal normal modes, lunar free oscillations are unlikely to affect TianQin’s sensitivity in its operational frequency band.
We present a multi-observable analysis of the white-light flare (WLF) in NOAA Active Region 13842 during the X9.0-class solar flare of 2024 October 3, the largest flare of Solar Cycle 25 to date. Using Solar Dynamics Observatory (SDO) observations from the Helioseismic and Magnetic Imager (HMI), we utilize three complementary data products derived from the Fe i 6173 Å spectral line (corrected continuum intensity, line-of-sight magnetogram, and line-of-sight Dopplergram) as observables of the WLF and its associated photospheric spectral signatures. We develop a per-pixel transient detection metric that distinguishes flare-induced brightening from secular morphological changes, and apply it to the tracked image stacks. The corrected continuum exhibits a coherent brightening with a mean contrast of 2.5 Δ |B| ≈ 17 G and Δ |V| ≈ 136 m s−1 at the same location, which we interpret as artifacts of flare-induced distortion of the Fe i 6173 Å spectral line rather than physical changes in the photospheric plasma. The three transient footprints overlap with Dice coefficients of 0.34–0.44 against a random expectation of 0.10, with centroid separations of 1.4–1.6 Mm, a few per cent of the footprint extent, and their temporal ordering is resolved at the 45 s cadence. Together with the temporal synchronization of the three signatures, this provides a strong multi-observable confirmation of the WLF.
Holographic dark energy (HDE) with the future event horizon as infrared cut-off is a quantum-gravity motivated alternative to a cosmological constant, but recent analyses of the second data release of the Dark Energy Spectroscopic Instrument (DESI DR2) show that its single parameter c cannot simultaneously satisfy supernova, baryon-acoustic-oscillation (BAO) and cosmic-microwave-background (CMB) constraints. We construct and test a minimal extension in which cold dark matter and dark energy exchange energy through a density-triggered interaction, Q=3Hξ (a)ρ _cρ _DE/(ρ _c+ρ _DE) with ξ (a)=ξ _0a^n/(a^n+a_t^n) , while baryons are separately conserved. The instantaneous coupling vanishes at early times, but its accumulated effect rescales the pre-recombination dark-matter density by a factor ℐ(z_⋆)<1 that must be propagated into the CMB and drag-epoch quantities. With this consistent treatment, cosmic chronometers, DESI DR2 BAO, three supernova compilations and compressed CMB priors give only a lower bound, ξ _0>0.30 (95 per cent), for the full combination, with Δχ ^2=-8.4 relative to HDE, along a degeneracy between the coupling and the present-day matter density. The coupling leaves the holographic parameter essentially unchanged ( c=0.652± 0.020 versus 0.647± 0.018 ), so the phantom state and the Big Rip persist; freeing the switch improves the fit further only at the prior boundaries, where more than half of the present dark matter has been converted from dark energy. Evaluating the CMB shift parameter with the present-day instead of the early-time matter density produces a spurious, apparently highly significant preference for the coupling. Within the HDE family the coupling is mildly preferred, but every holographic model remains disfavoured relative to Λ CDM, and none relieves the Hubble tension.
We present a multiwavelength analysis of the resolved jet in 3C 264 (NGC 3862) using James Webb Space Telescope (JWST) Near-Infrared Camera (NIRCam) imaging, archival Very Large Array (VLA) and Hubble Space Telescope (HST) data, and a combined deep Chandra dataset. JWST/NIRCam detects the jet along the same northeast structure previously traced at radio, optical, and X-ray wavelengths. For the full measured jet, the flux densities are 44.5 mJy at 4.89 GHz, 93.1 μJy in the F070W band, and 201 μJy in the F444W band; the F070W image gives the clearest near-IR morphology. The eight Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observations give 119 ks of exposure and, after correction for the nuclear point-spread function (PSF) wings, yield a 0.5–2 keV jet flux of (8.97± 0.36_stat± 1.52_PSF)× 10^-14 erg cm^-2 s^-1 for an absorbed Γ =2.25 power law. The whole-jet radio–near-IR–X-ray spectral energy distribution (SED) steepens by Δα =0.75^+0.03_-0.03 . At equipartition and without beaming, first-order synchrotron self-Compton (SSC), inverse-Compton scattering of cosmic microwave background photons (IC/CMB), and IC scattering of host-galaxy starlight underpredict the X-rays by at least four orders of magnitude. Our result therefore favors synchrotron emission, although we cannot rule out a strongly beamed IC/CMB model if the fastest optical-knot pattern speed traces the bulk speed of the X-ray-emitting flow.
Outflows driven by active galactic nuclei (AGN) are widely considered a key mechanism for regulating and quenching star formation in massive galaxies. However, direct observational evidence linking outflows to quenching has remained elusive for decades. This article reviews recent findings for massive galaxies at cosmic noon ( z∼ 2 ), based on sensitive James Webb Space Telescope (JWST) observations tracing both star formation histories (through Balmer absorption lines) and neutral outflows (through blueshifted Na i d absorption). Neutral outflows are found in ∼ 25–50% of massive ( log (M_*/M_⊙)> 10 ) galaxies, independent of star formation rate. Outflows from star-forming galaxies are consistent with being powered by star-formation and/or AGN activity, whereas outflows from quiescent systems are generally attributed to current or previous AGN activity. There is growing evidence that recent rapid quenching of star-formation is associated with powerful AGN-driven outflows with mass loading factors η≳ 1–10 . The neutral gas dominates the outflow mass budget but in most cases its velocity is below the halo escape velocity, indicating that this gas may form part of a galactic fountain. Detections of neutral gas inflows and residual cold gas reservoirs in quiescent galaxies suggest that other feedback mechanisms such as AGN heating are required to keep galaxies quenched over long timescales. We highlight the potential of multiphase outflow measurements to constrain feedback models, describe the main systematic uncertainties in mass outflow rate measurements, and discuss how the z∼ 2 results inform our understanding of the formation of the earliest massive quiescent galaxies.
