Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shu-Rui Lin
Wentao Luo
Yi-Fu Cai
Qi Guo
Leyao Wei
Bo Wang
Qinxun Li
Can-Po Su
Vitali Halenka
Alexander Rodriguez
Abstract： We report the detection of a 219 $^{+10}_{-28}$ pc-sized dark matter core structure in the center of Milky Way at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE) survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way structure, the Mini Dark Matter Structure (MDMS) fraction ($f_{\rm MDMS}=\Omega_{\rm MDMS}/\Omega_{\rm DM}$) and the core size. We find that this sky map can constrain both $f_{\rm MDMS}$ and the core size simultaneously without strong degeneracy. This discovery provides not only guidance for dark matter particle models, such as self-interacting dark matter (SIDM), but also the baryonic physics of Milky Way.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shu-Rui Lin
Wentao Luo
Yi-Fu Cai
Qi Guo
Leyao Wei
Bo Wang
Qinxun Li
Can-Po Su
Vitali Halenka
Alexander Rodriguez
Abstract： We report the detection of a 219 $^{+10}_{-28}$ pc-sized dark matter core structure in the center of Milky Way at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE) survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way structure, the Mini Dark Matter Structure (MDMS) fraction ($f_{\rm MDMS}=\Omega_{\rm MDMS}/\Omega_{\rm DM}$) and the core size. We find that this sky map can constrain both $f_{\rm MDMS}$ and the core size simultaneously without strong degeneracy. This discovery provides not only guidance for dark matter particle models, such as self-interacting dark matter (SIDM), but also the baryonic physics of Milky Way.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Wentao Luo
Jiajun Zhang
Vitali Halenka
Xiaohu Yang
Surhud More
Chris Miller
Tomomi Sunayama
Lei Liu
Feng Shi
Abstract： We test the Emergent Gravity(EG) theory using the galaxy-galaxy lensing technique based on SDSS DR7 data. In the EG scenario, we do not expect color dependence of the galaxy sample in the 'apparent dark matter' predicted by EG, which is exerted only by the baryonic mass. If the baryonic mass is similar, then the predicted lensing profiles from the baryonic mass should be similar according to the EG, regardless of the color of the galaxy sample. We use the stellar mass of the galaxy as a proxy of its baryonic mass. We divide our galaxy sample into 5 stellar mass bins, and further classify them as red and blue subsamples in each stellar mass bin. If we set halo mass and concentration as free parameters, $\Lambda$CDM is favored by our data in terms of the reduced $\chi^2$ while EG fails to explain the color dependence of ESDs from the galaxy-galaxy lensing measurement.
Peer Review Status:Awaiting Review
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