Strong Limits on Dark Matter Annihilation from the Event Horizon Telescope Observations of M87$^star$. (arXiv:2106.05901v1 [hep-ph])

Strong Limits on Dark Matter Annihilation from the Event Horizon Telescope Observations of M87$^star$. (arXiv:2106.05901v1 [hep-ph])
<a href="http://arxiv.org/find/hep-ph/1/au:+Yuan_G/0/1/0/all/0/1">Guan-Wen Yuan</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Chen_Z/0/1/0/all/0/1">Zhan-Fang Chen</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Shen_Z/0/1/0/all/0/1">Zhao-Qiang Shen</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Guo_W/0/1/0/all/0/1">Wen-Qing Guo</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Ding_R/0/1/0/all/0/1">Ran Ding</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Huang_X/0/1/0/all/0/1">Xiaoyuan Huang</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Yuan_Q/0/1/0/all/0/1">Qiang Yuan</a>

The fast developments of radio astronomy open a new window to explore the
properties of Dark Matter (DM). The recent direct imaging of the supermassive
black hole (SMBH) at the center of M87 radio galaxy by the Event Horizon
Telescope (EHT) collaboration is expected to be very useful to search for
possible new physics. In this work, we illustrate that such results can be used
to detect the possible synchrotron radiation signature produced by DM
annihilation from the innermost region of the SMBH. Assuming the existence of a
spiky DM density profile, we obtain the flux density due to DM annihilation
induced electrons and positrons, and derive new limits on the DM annihilation
cross section via the comparison with the EHT integral flux density at 230 GHz.
Our results show that the parameter space can be probed by the EHT observations
is largely complementary to other experiments. For DM with typical mass regions
of being weakly interacting massive particles, the annihilation cross section
several orders of magnitude below the thermal production level can be excluded
by the EHT observations under the density spike assumption. Future EHT
observations may further improve the sensitivity on the DM searches, and may
also provide a unique opportunity to test the interplay between DM and the
SMBH.

The fast developments of radio astronomy open a new window to explore the
properties of Dark Matter (DM). The recent direct imaging of the supermassive
black hole (SMBH) at the center of M87 radio galaxy by the Event Horizon
Telescope (EHT) collaboration is expected to be very useful to search for
possible new physics. In this work, we illustrate that such results can be used
to detect the possible synchrotron radiation signature produced by DM
annihilation from the innermost region of the SMBH. Assuming the existence of a
spiky DM density profile, we obtain the flux density due to DM annihilation
induced electrons and positrons, and derive new limits on the DM annihilation
cross section via the comparison with the EHT integral flux density at 230 GHz.
Our results show that the parameter space can be probed by the EHT observations
is largely complementary to other experiments. For DM with typical mass regions
of being weakly interacting massive particles, the annihilation cross section
several orders of magnitude below the thermal production level can be excluded
by the EHT observations under the density spike assumption. Future EHT
observations may further improve the sensitivity on the DM searches, and may
also provide a unique opportunity to test the interplay between DM and the
SMBH.

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