We present ultraviolet (UV) through near-infrared (NIR) photometric and spectroscopic observations of the nearby SN 2024pxl, the third Type Ia supernova (SN Ia) in NGC 6384. SN 2024pxl is a Type Iax supernova (SN Iax) with an intermediate luminosity ($M_r = -16.99\pm0.32$ mag) and an average SN Iax light curve decline rate. SN 2024pxl was discovered $\sim$3 days after first light, and the rising light curve follows a single power law that is inconsistent with significant interaction with a companion star or circumstellar material. Our extensive NIR photometric coverage is comparable to that of the well-observed SNe Iax 2005hk and 2012Z, and we demonstrate that the $J-H$ colors of SNe Iax differ from normal SNe Ia and appear to be more homogeneous as a class. Spectroscopically, we report the earliest-ever NIR spectrum of a SN Iax as measured from maximum light ($t\approx-9$ days): a featureless continuum with similarities to a $\sim$9,000 K blackbody, and the line velocities are consistent with a mixed-ejecta structure, with C, Si, and Fe having similar velocities and velocity evolutions. We find a tentative correlation between the $H$-band break Co II velocity $\sim$20 days post-peak and absolute magnitude, with more luminous SNe Iax showing faster Co II velocities. Our observations suggest that SN 2024pxl resulted from the thermonuclear disruption of a CO white dwarf star that undergoes deflagration burning. less

We analyze 15 years of Fermi-LAT data and produce a detailed model of the Sun's inverse-Compton scattering emission (solar halo), which is powered by interactions between ambient cosmic-ray electrons and positrons with sunlight. By developing a novel analysis method to analyze moving sources, we robustly detect the solar halo at energies between 31.6 MeV and 100 GeV, and angular extensions up to 45$^\circ$ from the Sun, providing new insight into spatial regions where there are no direct measurements of the galactic cosmic-ray flux. The large statistical significance of our signal allows us to sub-divide the data and provide the first $\gamma$-ray probes into the time-variation and azimuthal asymmetry of the solar modulation potential, finding time-dependent changes in solar modulation both parallel and perpendicular to the ecliptic plane. Our results are consistent with (but with independent uncertainties from) local cosmic-ray measurements, unlocking new probes into both astrophysical and beyond-standard-model processes near the solar surface. less

We performed a comprehensive analysis of flux and color variability in a redshift-matched sample of Seyfert galaxies, comprising 23 gamma-ray-detected narrow-line Seyfert 1 galaxies (gNLS1s), 190 non-gamma-ray-detected narrow-line Seyfert 1 galaxies (ngNLS1s), and 10 gamma-ray-detected broad-line Seyfert 1 galaxies (gBLS1s). Utilizing multi-band light curves from the Zwicky Transient Facility (ZTF) in g, r, and i bands, along with mid-infrared (MIR) observations in W1 and W2 bands from the Wide-Field Infrared Survey Explorer (WISE), we observed that gBLS1s exhibit more significant variability than gNLS1s, while ngNLS1s display minimal variability across both optical and MIR wavelengths. The pronounced variability in gBLS1s may be attributed to a more closely aligned jet relative to the observer's line of sight or their comparatively lower accretion rates. In contrast, the subdued variability in ngNLS1s suggests that their flux changes are primarily driven by accretion disk instabilities. A significant correlation between optical and MIR variability amplitudes found here supports the reprocessing scenario, wherein variations in the accretion disk emission are re-emitted by surrounding dust. Furthermore, our long-term color variability analysis revealed a stronger redder-when-brighter (RWB) trend in approximately 35%, 61%, and 80% of gNLS1s, ngNLS1s, and gBLS1s, respectively, in optical wavelength, strengthens the reprocessing scenario with the observed trend of stronger RWB for approximately 68%, 96%, and 30%, respectively, in MIR wavelength. The prevalent RWB trend observed in both optical and MIR wavelengths from the current sample of Seyfert galaxies on the longer time scales is likely associated with accretion disk instabilities. less

We present the results of a three-year X-ray, optical, and radio polarimetric monitoring campaign of the prototypical black hole X-ray binary Cyg X-1, conducted from 2022 to 2024. The X-ray polarization of Cyg X-1 was measured 13 times with the Imaging X-ray Polarimetry Explorer (IXPE), covering both hard and soft spectral states. The X-ray polarization degree (PD) in the hard state was found to be $\approx4.0\%$, roughly twice as high as in the soft state, where it was around $2.2\%$. In both states, a statistically significant increase of PD with the energy was found. Moreover, a linear relation between PD and spectral hardness suggests a gradual and continuous evolution of the polarization properties, rather than an abrupt change of polarization production mechanism between states. The polarization angle (PA) was independent of the spectral state and showed no trend with the photon energy. The X-ray PA is well aligned with the orientation of the radio jet, as well as the optical and radio PAs. We find significant orbital changes of PA in the hard state, which we attribute to scattering of X-ray emission at intrabinary structure. No significant superorbital variability in PD or PA was found at the period $P_{\rm{so}}$ = 294 d. We also find no correlation between the X-ray and optical polarization; if any, there is a long-term anti-correlation between the X-ray PD and the radio PD. less