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The center of our Galaxy is a known strong source of electron-positron 511-keV annihilation radiation. Thus far, however, there have been no reliable detections of annihilation radiation outside of the central radian of our Galaxy. One of…

Hadron emission from supernova remnant (SNR)-molecular cloud (MC) association systems has been widely regarded as a probe of the shock-accelerated cosmic-ray protons. Here, we report on the detection of a {\gamma}-ray emission source, with…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Bing Liu , Yang Chen , Xiao Zhang , Gao-Yuan Zhang , Yi Xing , Thomas G. Pannuti

The electron-positron annihilation gamma-ray signal at 511 keV in the Milky Way is investigated towards a possible dark matter interpretation. If all bulge positrons were created by dark matter particle annihilation, the satellite galaxies…

High Energy Astrophysical Phenomena · Physics 2017-07-24 Thomas Siegert

Diffuse 511 keV line emission, from the annihilation of cold positrons, has been observed in the direction of the Galactic Centre for more than 30 years. The latest high-resolution maps of this emission produced by the SPI instrument on…

Astrophysics · Physics 2009-11-13 Reba M. Bandyopadhyay , Joseph Silk , James E. Taylor , Thomas J. Maccarone

We report the results obtained from XMM-Newton observations of the TeV-detected supernova remnant (SNR) HESS J1534-571. We focus on the nature of the cosmic-ray particle content in the SNR, which is revealed by its $\gamma$-ray emission. No…

High Energy Astrophysical Phenomena · Physics 2023-11-08 N. T. Nguyen-Dang , G. Pühlhofer , M. Sasaki , A. Bamba , V. Doroshenko , A. Santangelo

The 511 keV positron annihilation emission remains a mysterious component of the high energy emission of our Galaxy. Its study was one of the key scientific objective of the SPI spectrometer on-board the INTEGRAL satellite. In fact, a lot…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Laurent Bouchet , Jean-Pierre Roques , Elisabeth Jourdain

INTEGRAL/SPI has recently observed a strong and extended emission resulting from electron-positron annihilation located in the Galactic center region, consistent with the Galactic bulge geometry, without any counterpart at high gamma-ray…

Astrophysics · Physics 2007-05-23 Stephane Schanne , Michel Casse , Bertrand Cordier , Jacques Paul

Young supernova remnants show a characteristic ejecta-dominated X-ray emission that allows us to probe the products of the explosive nucleosynthesis processes and to ascertain important information about the physics of the supernova…

High Energy Astrophysical Phenomena · Physics 2015-06-03 M. Miceli , S. Sciortino , E. Troja , S. Orlando

The supernova remnant (SNR) G51.26+0.11 was recently discovered and little is known about its properties and environment. Using data from the \emph{Fermi} Large Area Telescope we study the GeV emission seen in the direction of G51.26+0.11…

High Energy Astrophysical Phenomena · Physics 2021-11-17 Miguel Araya

One of the most essential but uncertain processes for producing cosmic-rays (CRs) and their spectra is how accelerated particles escape into the interstellar space. We propose that the CR electron spectra at >~TeV energy can provide a…

High Energy Astrophysical Phenomena · Physics 2015-04-23 Norita Kawanaka , Kunihito Ioka , Yutaka Ohira , Kazumi Kashiyama

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…

High Energy Astrophysical Phenomena · Physics 2016-02-29 Man Ho Chan

Models of Galactic 1.275 MeV emission produced by the decay of the radionuclide $^{22}$Na have been computed. Several frequency-spatial distributions of novae have been investigated using recent results of nova rates and spatial…

Astrophysics · Physics 2009-10-31 P. Jean , M. Hernanz , J. Gomez-Gomar , J. Jose

G1.9+0.3 is the youngest known Galactic supernova remnant (SNR), with an estimated supernova (SN) explosion date of about 1900, and most likely located near the Galactic Center. Only the outermost ejecta layers with free-expansion…

High Energy Astrophysical Phenomena · Physics 2015-06-16 K. J. Borkowski , S. P. Reynolds , U. Hwang , D. A. Green , R. Petre , K. Krishnamurthy , R. Willett

Galactic supernova remnants (SNRs) are thought to accelerate cosmic rays (CRs) to several PeV energies, but this has yet to be confirmed as general behavior. Although several sources show ~100 TeV gamma rays, their hadronic origin is…

High Energy Astrophysical Phenomena · Physics 2025-12-10 Emily Simon , Rebecca Diesing , Damiano Caprioli , Stephen Sclafani

We present the first systematic investigation of the [NeV] (14um/24um) and [SIII] (18um/33um) infrared line flux ratios, traditionally used to estimate the density of the ionized gas, in a sample of 41 Type 1 and Type 2 active galactic…

Astrophysics · Physics 2009-06-23 R. P. Dudik , J. C. Weingartner , S. Satyapal , J. Fischer , C. C. Dudley , B. O'Halloran

We investigate the extinction curves of young galaxies in which dust is supplied from Type II supernovae (SNe II) and/or pair instability supernovae (PISNe). We adopt Nozawa et al. (2003) for compositions and size distribution of grains…

At times later than 200 days, Type Ia SN light curves are dominated by the kinetic energy deposition from positrons created in the decay of $^{56}$Co. In this paper, the transport of positrons after emission are simulated, for deflagration…

Astrophysics · Physics 2009-10-30 Peter A. Milne , Lih-Sin The , Mark D. Leising

We generate bolometric light curves for a variety of type Ia supernova models at late times, simulating gamma-ray and positron transport for various assumptions about the magnetic field and ionization of the ejecta. These calculated light…

Astrophysics · Physics 2009-10-31 P. A. Milne , L. -S. The , M. D. Leising

Measurement and astrophysical interpretation of characteristic gamma-ray lines from nucleosynthesis was one of the prominent science goals of the INTEGRAL mission and in particular its spectrometer SPI. Emission from 26Al and from 60Fe…

Instrumentation and Methods for Astrophysics · Physics 2021-12-10 Roland Diehl , Martin G. H. Krause , Karsten Kretschmer , Michael Lang , Moritz M. M. Pleintinger , Thomas Siegert , Wei Wang , Laurent Bouchet , Pierrick Martin

The annihilation of positrons in the Galaxy's interstellar medium produces characteristic gamma-rays with a line at 511 keV. This emission has been observed with the spectrometer SPI on INTEGRAL, confirming a puzzling morphology with bright…