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What Are The Effects Of Different Dark Matter Candidates On Compact Binary Systems? (Cosmology)

Ebrahim Hassani and colleagues investigated the effects of different dark matter candidates on the properties of compact binary systems due to the accretion of dark matter particles into them. They found that, the low-mass DM candidates has the potential to change the period of compact binary systems more than the observed values. Their study recently appeared in Arxiv.

As compact binary star systems move inside the halo of our Galaxies, they interact with dark matter particles. The interaction between dark matter particles and baryonic matter causes dark matter particles to lose some part of their kinetic energy. After dark matter particles have lost part of their kinetic energy, they gravitationally bound to stars and stars start to accrete dark matter particles from the halo. The accretion of dark matter particles inside compact binary systems increases the mass of the binary components and then, the total mass of the binary systems increases too. According to Kepler’s third law, increased mass by this way can affect other physical parameters (e.g. semi-major axes and orbital periods) of these systems too.

Thus, Ebrahim Hassani and colleagues now investigated the effects of different dark matter candidates on the properties of known compact binary systems (such as NS-NS, NS-WD, WD-WD, where, NS is neutron star and WD is white dwarf) due to the accretion of dark matter particles into them.

Initially, they considered four DM particles candidates which are axions with mass in the range 10Β―15 βˆ’10Β―12 (𝐺𝑒𝑉.𝑐¯2), Neutrinos with mass in the range 10Β―12 βˆ’ 10Β―10 (𝐺𝑒𝑉.𝑐¯2), SuperWIMPs with mass in the range 10Β―6 βˆ’ 104 (𝐺𝑒𝑉.𝑐¯2), and WIMPs with mass in the range 10Β―1 βˆ’ 105 (𝐺𝑒𝑉.𝑐¯2).

Later, they estimated the periodic change of some known compact binary systems due to the accretion of dark matter particles inside them and then compared the results with the period change of these systems due to dynamical friction and gravitational wave emission.

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Fig. 1: Calculated mass change of different types of compact binary systems and for different DM particle candidates. sub-plots (a)-(d) are for WD-WD type, sub-plots (e)-(h) for WD-NS type and sub-plots (i)-(l) for NS-NS type compact binary systems. In all sub-plots horizontal axes are the mass range of different DM particle candidates and vertical axes are the mass change of the compact binary systems. Only SuperWIMP particles have the potential to change the period of the compact binary systems in the range of the observed period change values for the observed period change values Β© Ebrahim Hassani et al.

They found that, low-mass DM candidates has the potential to change the period of compact binary systems more than the observed values. They also found that intermediate-mass DM candidates has the ability to change the period of compact binary systems as comparable as the observed values. But high-mass DM candidates can not change the period of compact binary systems as much as the observed values.

“Because of lack of knowledge about the exact physical nature of DM we can not speak with confidence that which DM candidate can be the best source of period change in compact binary systems


Moreover, they deduced that, gravitational wave emission from compact binary systems and the accretion of dark matter (DM) particles inside the compact binary systems can be considered as the main reasons of the observed periodic decay or change in these systems.

Finally, from results obtained, they suggested that, DM candidates with mass in the range, π‘šπœ’ ∝ 10Β―1βˆ’105 (𝐺𝑒𝑉.𝑐¯2) are the best DM candidates for this observed period changes.


Reference: Ebrahim Hassani, Amin Rezaei Akbarieh, Yousef Izadi, “The effects of dark matter on compact binary systems”, Arxiv, 2021. https://arxiv.org/abs/2106.05043


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