Detecting warm dark maDetecting warm dark matter by the stochastic gravitational wavestter by the stochastic gravitational waves

NANOGrav has recently reported the detection of a common-spectrum process via the time-of-arrival data of 47 millisecond pulsars[1],which could be interpreted by a stochastic gravitational wave background(SGWB)in the nanohertz frequency band(f∼10−9 Hz)with energy density parameterΩGW∼10−9.Despite the vague quadrupole correlation that obstructs the identification of gravitational waves,this report hints the possibility of some new physics at around or below 100 MeV that can generate nanohertz gravitational waves by,for instance,the first order phase transition(FOPT).