The Gamma-ray Milky Way above 10 GeV: Distinguishing Sources from Diffuse Emission

Observations of the Milky Way by the SPI/INTEGRAL satellite have confirmed the presence of a strong 511 keV gamma ray line emission from the bulge, which requires an intense source of positrons in the galactic center. These observations are hard to account for by conventional astrophysical scenarios, whereas other proposals, such as light DM, face stringent constraints from the diffuse gamma ray background. Here we suggest that light superconducting strings could be the source of the observed 511 keV emission. The associated particle physics, at the ~ 1 TeV scale, is within the reach of planned accelerator experiments, while the distinguishing spatial distribution, proportional to the galactic magnetic field, could be mapped by SPI or by future, more sensitive satellite missions.

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On the delay times of merging double neutron stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3312 ◽

2020 ◽

Vol 500 (2) ◽

pp. 1755-1771

Author(s):

Laura Greggio ◽

Paolo Simonetti ◽

Francesca Matteucci

Keyword(s):

Neutron Stars ◽

Binary Systems ◽

Milky Way ◽

Gamma Ray ◽

Chemical Properties ◽

Redshift Distribution ◽

Strong Constraint ◽

Delay Times ◽

Best Fitting ◽

Short Grbs

ABSTRACT The merging rate of double neutron stars (DNS) has a great impact on many astrophysical issues, including the interpretation of gravitational waves signals, of the short gamma-ray bursts (GRBs), and of the chemical properties of stars in galaxies. Such rate depends on the distribution of the delay times (DDT) of the merging events. In this paper, we derive a theoretical DDT of merging DNS following from the characteristics of the clock controlling their evolution. We show that the shape of the DDT is governed by a few key parameters, primarily the lower limit and the slope of the distribution of the separation of the DNS systems at birth. With a parametric approach, we investigate on the observational constraints on the DDT from the cosmic rate of short GRBs and the europium-to-iron ratio in Milky Way stars, taken as tracer of the products of the explosion. We find that the local rate of DNS merging requires that $\sim \! 1 {{\ \rm per\ cent}}$ of neutron stars progenitors live in binary systems which end their evolution as merging DNS within a Hubble time. The redshift distribution of short GRBs does not yet provide a strong constraint on the shape of the DDT, although the best-fitting models have a shallow DDT. The chemical pattern in Milky Way stars requires an additional source of europium besides the products from merging DNS, which weakens the related requirement on the DDT. At present both constraints can be matched with the same DDT for merging DNS.

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Analysis of the very inner Milky Way dark matter distribution and gamma-ray signals

Physical Review D ◽

10.1103/physrevd.94.121301 ◽

2016 ◽

Vol 94 (12) ◽

Cited By ~ 7

Author(s):

V. Gammaldi ◽

V. Avila-Reese ◽

O. Valenzuela ◽

A. X. Gonzalez-Morales

Keyword(s):

Dark Matter ◽

Milky Way ◽

Gamma Ray ◽

Matter Distribution ◽

Dark Matter Distribution

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Multiwavelength Milky Way: An Educational Poster

Symposium - International Astronomical Union ◽

10.1017/s0074180900128682 ◽

1998 ◽

Vol 179 ◽

pp. 237-237 ◽

Cited By ~ 1

Author(s):

D. Leisawitz ◽

S.W. Digel ◽

S. Geitz

Keyword(s):

Milky Way ◽

Gamma Ray ◽

Line Emission ◽

Electromagnetic Spectrum ◽

Data Sets ◽

X Ray ◽

Nasa Goddard Space ◽

Broadband Emission ◽

The Galaxy ◽

Effective Use

The Astrophysics Data Facility at NASA Goddard Space Flight Center supports the processing, management, and dissemination of data obtained by past, current, and future NASA and international astrophysics missions, and promotes the effective use of those data by the astrophysics community, educators, and the public. Our Multiwavelength Milky Way poster was printed for broad distribution. It depicts the Galaxy at radio, infrared, optical, X-ray, and gamma-ray wavelengths. In particular, the poster contains images of the Galactic 21-cm and CO (J = 1 → 0) line emission, and IRAS 12, 60, and 100 μm, COBE/DIRBE 1.25, 2.2, and 3.5 μm, Digitized Sky Survey optical wavelength, ROSAT/PSPC 0.25, 0.75, and 1.5 keV X-ray, and CGRO/EGRET E > 100 MeV gamma ray broadband emission. All of the data sets are publicly available. Captions describe the Milky Way and what can be learned about the Galaxy from measurements made in each segment of the electromagnetic spectrum. The poster is intended to be an educational tool, one that will stimulate heightened awareness by laypersons of NASA's contribution to modern astronomy.Through an interface available on the World Wide Web at http://adf.gsfc.nasa.gov/adf/adf.html one may view the images that appear on the poster, read the poster captions, and locate the archived data and references.

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