Related papers: Was There a 3.5 keV Line?
We present quantitative statistical evidence for a $\gamma$-ray emission halo surrounding the Galaxy. Maps of the emission are derived. EGRET data were analyzed in a wavelet-based non-parametric hypothesis testing framework, using a model…
Recent observations indicate that a high production rate of positrons (strong 511 keV line) and a significant amount of excess GeV gamma-ray exist in our Galactic bulge. The latter issue can be explained by $\sim 40$ GeV dark matter…
Astronomical data of the several recent years, which present an evidence in favour of abundant antimatter population in our Galaxy, Milky Way, are analysed. The data include: registration of gamma-rays with energy 0.511 MeV, which surely…
We present a spectral analysis of the Seyfert 1.8 ESO 113-G010 observed with XMM-Newton for 4 ks. The spectrum shows a soft excess below 0.7 keV and more interestingly a narrow emission Gaussian line at 5.4 keV (in its rest-frame), most…
The observed angular profile of the 511-keV photon excess from the Milky Way galactic center can allow us to select among combinations of various dark matter and other positron production mechanisms with various models for the dark matter…
Stellar streams around the Milky Way (MW) can provide valuable insights into its history and substructure formation. Previous studies have suggested that several MW streams could have an origin related to that of the disc of satellite…
We propose that a dark matter (DM) spike around the Galactic Center's (GC) supermassive black hole, Sgr A*, could account for most of the bulge's measured 511 keV line intensity while remaining cosmologically compatible. DM annihilation can…
We present spectral and timing results from a long (130 ks) XMM-NEWTON EPIC observation of the nucleus of the Seyfert/LINER galaxy M 81. During the observation the X-ray flux varied by 20%, but there was no significant change in spectral…
The absence of broad [O III] ${\lambda\lambda}$4959,5007 forbidden emission lines is one of the key arguments cited in the published literature for the gas density exceeding the critical density; 7 ${\times}$ 10$^5$ cm$^{-3}$, in the broad…
We detected an emission line feature at 4 keV in the X-ray spectrum of a sky region including the distant radio galaxy 3C220.1(z=0.62) obtained with ASCA. The line energy is 6.1 - 7.0 keV (90% confidence) in the rest frame of 3C220.1.…
We present the first observations of emission lines of CN(2-1), HCO$^{+}$(3-2) and C$_{2}$H(3-2) in the Perseus cluster. We observed at two positions: directly at the central galaxy, NGC 1275 and also at a position about 20$''$ to the east…
We examine the properties of the Fe emission lines that arise near 6.4 keV in the ASCA spectra of AGN. Our emphasis is on the Seyfert 1 galaxies where broad and apparently complex Fe K alpha emission is observed. We consider various origins…
Although about 40% of the soft X-ray background emission in 0.4 to 1 keV range has extragalactic origins and thus is totally blocked by the Galactic absorption in midplane directions, it decreases at most by about 20 % in midplane. Suzaku…
The origins of most stellar streams in the Milky Way are unknown. With improved proper motions provided by Gaia EDR3, we show that the orbits of 23 Galactic stellar streams are highly clustered in orbital phase space. Based on their…
A search for dark matter line-like signals was performed in the vicinity of the Galactic Centre by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis was developed to improve the sensitivity to…
We obtained ALMA spectroscopy and imaging to investigate the origin of the unexpected sub-mm emission toward the most distant quiescent galaxy known to date, ZF-COSMOS-20115 at z=3.717. We show here that this sub-mm emission is produced by…
A mosaic of 7 ROSAT PSPC pointed observations in the direction of (l,b ~ 10,0 deg) reveals deep X-ray shadows in the 0.5-2.0 keV band cast by dense molecular gas. The comparison between the observed on-cloud and off-cloud X-ray fluxes…
We show the existence of a statistically significant, robust detection of a gamma-ray source in the Milky Way Galactic Center that is consistent with a spatially extended signal using about 4 years of Fermi-LAT data. The gamma-ray flux is…
Strong fluorescent Fe line emission at 6.4 keV has been observed from the Sgr B2 giant molecular cloud located in the Galactic Center region. The large equivalent width of this line and the lack of an apparent illuminating nearby object…
It has been known for more than thirty years that the distribution of molecular gas in the innermost 300 parsecs of the Milky Way, the Central Molecular Zone, is strongly asymmetric. Indeed, approximately three quarters of molecular…