GeV excess in the Galactic center and the Dwarf Galaxies

Presentation on theme: "GeV excess in the Galactic center and the Dwarf Galaxies"— Presentation transcript:

1 GeV excess in the Galactic center and the Dwarf Galaxies
Lei Feng  Purple Mountain Observatory

2 OUTLINE Evidence for the Existence of Dark Matter
Dark Matter Detection. GeV excess in the Galactic center and the dwarf galaxies

3 The Evidence of Dark Matter
Rotation Curve Gravitational lensing The Observation of cosmology Large scale structure …… and so on

4 Rotation Curve

5 Red Region: X Ray Blue Region: Gravitational lensing

6 Large Scale Structure The N-body Simulation of Dark Matter Universe
Structure: Core, Filament and Cosmic Void.

7 Filaments Nature11224

8 What we know about DM particles so far ?
neutral cold (part of it can be warm) weak interaction (with itself and with ordinary matter) ? Maybe! profile (around us 0.3GeV/cm3 V  220 km/s)

9 The methods of detecting Dark Matter

10 The detection of dark matter
Direct detection： PandaX， CDEX， Xenon, CDMS, DAMA, COGENT and so on Indirect detection ： Pamela ,ATIC, Fermi, HESS，AMS02，DAMPE and so on Collider: LHC c c p e+ n g _ 2019/4/21 10

11 Cosmic Ray Propagation

12 Targets to detect dark matter particles
Sun Galaxy Galaxy Cluster Deep extragalactic space and early Universe Baltz et al. 2008

13 Fermi gamma-rays can provide good test of the DM models
Credit: NASA/DOE/Fermi collaboration Galactic center Galactic halo Dwarf galaxies Clusters Extra-galactic diffuse Line search

14 The gamma-ray sky map produced by dark matter annihilation in our Galaxy
The Galaxy center is the best region to detect dark matter. The J-Factor of different dark matter profile models.

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16 The GeV Excess Daylan et al. 2015
这里介绍的工作是基于伽玛射线的研究。目前一般认为银河系中暗物质在银心最为密集，暗物质如湮灭，那么其伽玛射线辐射在银心方向最强，向外逐步衰减。暗物质间接探测的目的之一就是发现与暗物质空间分布度高度相关的伽玛射线信号。Hooper等人发现银心在GeV能区存在超出，该超出的空间分布及能谱都与暗物质模型一致。在最近的一篇文章中他们甚至宣称该暗物质疑似信号的置信度高达40 sigma。但为何没有得到学界公认？因为银心的伽玛射线辐射背景非常的复杂！要宣称物理信号必须考虑背景模板的影响。 Daylan et al. 2015

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18 The template dependence of GEV excess signal

19 GeV excess in Fermi Pass 8 data

20 GeV Excess in the dwarf galaxies?
Shang Li With the publicly-available Pass 8 data of Fermi-LAT we search for −ray emissions from the directions of these eight newly discovered dSph galaxy candidates. No statistically significant −ray signal has been found in the combined analysis of these sources.

21 GeV Excess in the Dwarf Galaxies?
Tuc III: 25 kpc (Li, S. et al. 2016)

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24 The End Thank You