Speaker
Description
Axion-like particles (ALPs) can account for the observed dark matter (DM) of the Universe and if their masses are at the eV scale, they can decay into
infrared, optical and ultraviolet photons
{with a decay lifetime larger than the age of the Universe}.
We analyze multi-wavelength data obtained from the central region of Messier 87 (M87) galaxy
by several telescopes, such as, Swift, Astrosat, Kanata, Spitzer and
International Ultraviolet Explorer
in the infrared to ultraviolet frequencies
($\sim 2\times10^{14} \, {\rm Hz} - 3\times10^{15}$ Hz),
to constrain the narrow emission lines indicative of the eV scale ALP DM decay.
We derive constraints on the ALP coupling to two photons ($g_{a\gamma\gamma}$) for ALP mass range $2 \, {\rm eV} < m_a < 20 \, {\rm eV}$,
assuming ALPs form the DM in the M87 halo.
We find that our bounds on ALP-two-photon coupling
can become stronger than the existing ones by an order of magnitude in the ALP
mass range $8 \, {\rm eV} < m_a < 20 \, {\rm eV}$.
