3 years ago

Cosmic ray $e^{+} e^{-}$ spectrum excess and peak feature observed by the DAMPE experiment from dark matter.

Hong-bo Jin, Bin Yue, Xin Zhang, Xuelei Chen

The Chinese satellite Wukong, also known as the DArk Matter Particle Explorer (DAMPE), has released its observation data of the cosmic ray (CR) electrons and positrons. The data shows an excess in the energy spectrum up to TeV energy, and possibly a peak-like fine structure at $\sim 1.4 \TeV$. We investigate the scenario that the source of the excess comes from dark matter annihilation or decay. We find that the annihilation or decay of diffuse dark matter particles in the Galactic halo can give excellent ($W^+W^-$ channel) or at least good (double $\tau^+\tau^-$ channel) fits to the broad excess. However, the annihilation cross-section is $10^{-23}\cm^3s^{-1}$, larger than required for getting the correct relic abundance. We then study whether the narrow peak at $\sim 1.4\TeV$ could be explained by a nearby subhalo, which thanks to the smaller distance, could supply $e^+e^-$ within a narrow energy range. We find that in order to produce a peak width less than the energy bin width (0.2 TeV), the source must be located within $r\lsim 0.53~\kpc$. Our global fit models do not produce the peak-like feature, instead at 1.4 TeV the spectrum show either a slope or a cliff-like feature. However, if less than optimal fit is allowed, the peak-like feature could be generated. Furthermore, an excellent fit with peak could be obtained with model B if the background is rescaled. If the dark matter decay and annihilation rates are determined using the broad excess, the required subhalo mass $\sim10^{5}~M_\odot$ for decay model, or $\sim10^{4.5}\Msun$ for annihilation model and a shallower density profile slope $\alpha=1.2$, or $\sim10^{2.5}\Msun$ for the steep density profile $\alpha=1.7$. However, the probability for the existence of a such nearby subhalo as massive as given above is very low.

Publisher URL: http://arxiv.org/abs/1712.00362

DOI: arXiv:1712.00362v3

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.