On the Galactic Center being the main source of Galactic Cosmic Rays as evidenced by recent cosmic ray and gamma ray observations Yiqing Guo, Zhaoyang Feng, Qiang Yuan, Cheng Liu, Hongbo Hu ICRC2011--BeiJing

The united model to explain the cosmic ray spectra structure P+CMB->P’+π GZK cut-off P+CMB->P’+e + +e - Ankle(3EeV) Knee(4PeV) CR + ph->CR’ +e + +e - 1. GZK(~50EeV): P+CMB->P’+π Extragalactic cosmic ray 2. ANKLE(~3EeV): P+CMB->P’+e + +e - Extragalactic cosmic ray 3. KNEE(~4PeV): CR + ph(~eV)->CR’ +e + +e - ? Need: (1)Only one set of parameters (1)Only one set of parameters (2)Cosmic Rays come from one (2)Cosmic Rays come from one dominant source dominant source (3)High density background (3)High density background photon photonSources: (1) young SNRs (1) young SNRs (2) Galactic Center (2) Galactic Center Hu et al., ApJ 700:L170– L173, 2009

CR + photon on the source ->CR’+ Shock front 1) At early time of accelleration ， the temperature of background photon is high ， the energy and density also very high ， so proton can get the reaction threshold firstly 。 After reaction,the positron and electron produced and knee for proton is also formed ； 2) At later time ， the temperature decline ， also for the energy and density. At this time the heavy nucleon gain the reaction threshold energy and reaction with background gamm ， so the knee for heavy nucleon is higher ； e+e-e+e-e+e-e+e- 3) The positron and electron can be cooling off through radiation and react with background photon ， only the one below TeV can escape. proton CR :Fe Background photon e+e-e+e-e+e-e+e- e+e-e+e-e+e-e+e- Shock front Background photon e+e-e+e-e+e-e+e-

Knee Structure explanation T p ~10000K T He ~7000K T Fe ~2000K Hu et al., ApJL 700 (2009) L170–L173 B.Wang et al.,Science China,G53, （ 2010 ） Dumped sharp”knee” Naturally explanation B Component

Hu et al., ApJ 700:L170–L173, 2009 The Lepton excess can be well explained the sharp knee and its B Component, the Lepton excess can be natural explained.

Can Galactic Center be the dominant source of Cosmic Rays? Hu et al. proposed the SNRs-Pusar system as this kind of source. However, it is not observed. The sharp knee may indicate a single source of the CRs. Nearby or far away. Instead of the pulsar-SN system, the Galactic center may also be the potential source. (1)Evidence for GC activity in the past (2)Background radiation field may be high (especially in active phase) (3)Powerful enough

Cartoon Picture

Fermi Bubbles Su Meng et al, ApJ. 724, 2010, Luminosity of Fermi Bubbles is 4.0*10 37 ergs/s. 2.Assuming most of CRs come from GC, the power of GCR is about ergs/s with spectra of E -2 to E The power of GCR above knee is ~10 39 ergs/s, which convert mostly to leptons and produce Fermi Bubbles. So, the luminosity of positron and electron produced at GC are consistent with Fermi Bubble observation.

The high energy e+e- can scatter the galactic interstellar radiation field(ISRF): OPT, FIR, CMB Fermi Bubble Spectra The ISRF from GALPROP The calculated spectrum of IC scattering gamma rays and synchrotron radiation are consistent with the Fermi bubbles and WMAP haze.

511keV line emission Georg W. et al.: Nature, 451, 2008, 10. (3)The total number of CRs is ~ (4) Considering the diffusion efficient D~10 28 cm 2 s -1, the ISM nuclei in bulge is 1/cm 3, so the produced positron is ~ (5) The cooling time is 10 7 yrs, so the positron production rate is ~10 44 s -1,Which is consistent with observation.

Conclusion and Discussion Hu’s model can well explain the sharp knee and Lepton excess by using one set of parameter. Galactic Center is potential source of CRs. The Fermi Bubbles spectral can be well explained by e+e- scatering ISRF photons. The 511keV line emission can also be explained if the GC is the dominant CRs source.

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