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The $\gamma$ -ray emission from active galactic nuclei (AGN), including both beamed blazars and misaligned-AGN, dominates the extragalactic $\gamma$ -ray point-source population count and flux. While multiwavelength studies have detected an increasing number of AGN within dwarf galaxies in the local Universe, $\gamma$ -ray emission has so far only been associated with systems hosting supermassive black holes (SMBHs). Dwarf-galaxy AGN are of particular interest because their central black holes fall in the intermediate-mass black hole regime, offering insight into the early evolution of SMBHs. Using 15 years of -LAT data, we present the first search for $\gamma$ -ray emission from dwarf-galaxy AGN. In the sample of 67 x-ray-selected dwarf-galaxy AGN, we find no sources that exceed the -LAT detection threshold. However, a joint-likelihood analysis reveals a modest, trials-corrected population-level excess ( $\sim 2\sigma$ ) above blank-field expectations at very soft photon indices $\mathrm{\Gamma }\gtrsim 3.8$ above 500 MeV. This hint is most pronounced when source contributions are weighed by $M_{\mathrm{IMBH},i}^{\alpha }/d_i^2$ , with $\alpha \simeq 1–1.5$ , suggesting—but not confirming—that $\gamma$ -ray emission could scale with the central black hole mass or a property correlated with it (e.g., accretion rate), but with a markedly softer spectrum than in SMBH-hosted AGN. 

Upcoming near-infrared facilities, including JWST/NIRCam and ELT/MICADO, will dramatically improve the detectability of Galactic Center Cepheids despite the extreme extinction at optical wavelengths. In this work, we study the impact of dark matter annihilation on Cepheid stars in the inner parsec of the Milky Way. We show that at captured dark matter densities of approximately 10^5 GeV/cm^3, blue-loop evolution can be suppressed, preventing the formation of low-mass, short-period Cepheids with masses of 3–6 solar masses and periods of 1–6 days. At slightly higher dark matter densities, Cepheids are suppressed across their entire mass range. A dearth of such variables could provide indirect evidence for dark matter heating. Notably, this effect occurs at lower dark matter densities than those required to affect main-sequence stars. Future surveys will therefore offer a novel and complementary probe of dark matter properties in galactic nuclei. 

Dark photons that are sufficiently light and/or weakly interacting represent a compelling vision of dark matter. Dark photon decay into three photons, which we call the dark photon trident, can be the dominant channel when the dark photon mass falls below the electron pair threshold and can produce a significant flux of x rays. We use 16 years of data from Interrnational Gamma-Ray Astro Physics Laboratory (INTEGRAL)/Spectrometer of INTEGRAL (SPI) to constrain sub-MeV dark photon decay, producing new worlds-best constraints on the kinetic mixing parameter for dark photon masses between 90 and 1022 keV, and comment on the potential for future x-ray observatories to discover the trident decay process. 

Abstract We present the first systematic study of explosive dispersal outflows (EDOs) as potential sources of high-energy emission in the Milky Way. EDOs are energetic outflows produced during dynamical interactions in young, massive star-forming regions, and their physical conditions make them promising environments for cosmic-ray acceleration. Using 16 yr of 0.2–500 GeV Fermi-Large Area Telescope observations, we study theγ-ray properties of seven EDOs. Three EDOs, DR21, G34.26+0.15, and G5.89−0.39, show spatially coincident GeV emission, while the remaining systems yield nondetections. Among the sample, DR21 stands out as the brightest candidate, with a detection significance ≥40σ. Its spectrum is well described by a power law with an exponential cutoff, and the integrated luminosity in the 0.1–500 GeV band isL_γ ≃ 2 × 10³⁵erg s⁻¹. When compared with the outflow’s estimated kinetic energy, the inferred cosmic-ray acceleration efficiency is ≤15%, consistent with values for shocks in dense molecular environments. The energetics and morphology support an association between the DR21 molecular outflow and the observedγ-rays. Our results demonstrate that EDOs span a wide range ofγ-ray luminosities and efficiencies, suggesting they may contribute to the Galactic cosmic-ray budget. This motivates searches for additional EDOs and improved multiwavelength characterization of their environments. 

We analyze 15 years of -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° 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 subdivide 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 astrophysical processes near the solar surface. 

ABSTRACT We use Fermi-LAT data to analyse the faint gamma-ray source located at the centre of the Sagittarius (Sgr) dwarf spheroidal galaxy. In the 4FGL-DR3 catalogue, this source is associated with the globular cluster, M54. We investigate the spectral energy distribution and spatial extension of this source, with the goal of testing two hypotheses: (1) the emission is due to millisecond pulsars within M54, or (2) the emission is due to annihilating dark matter from the Sgr halo. For the pulsar interpretation, we consider a two-component model which describes both the lower-energy magnetospheric emission and possible high-energy emission arising from inverse Compton scattering. We find that this source has a point-like morphology at low energies, consistent with magnetospheric emission, and find no evidence for a higher-energy component. For the dark matter interpretation, we find the signal favours a dark matter mass of mχ = 29.6 ± 5.8 GeV and an annihilation cross section of $$\sigma v = (2.1 \pm 0.59) \times 10^{-26} \, \text{cm}^3$$ s−1 for the $$b \bar{b}$$ channel (or mχ = 8.3 ± 3.8 GeV and $$\sigma v = (0.90 \pm 0.25) \times 10^{-26} \, \text{cm}^3$$ s−1 for the τ+τ− channel), when adopting a J-factor of $$J=10^{19.6} \, \text{GeV}^2 \, \text{cm}^{-5}$$. This parameter space is consistent with gamma-ray constraints from other dwarf galaxies and with dark matter interpretations of the Galactic Centre Gamma-Ray Excess.