ИСТИНА

Pulsar timing was suggested for detection of low-frequency gravitational waves (10 −9 Hz< f gw < 10 −7 Hz) by Sazhin in 1978 and independently by Detweiler in 1979. Pulsar timing can be used for detection of different types of signal. In particular, it can be used for detection of monochromatic narrow-band signal, that is generated by a scalar field. Such scalar field is described in Chmelnitsky&Rubakov and suggested to be a possible candidate to warm dark matter. A classic scalar field with mass 10 −23 − 10 −22 eV is considered as warm dark matter. It acts as an ideal liquid with ostillating pressure, and these ostillations cause the ostillations of gravitational potential at frequency m, which can be detected using pulsar timing. The effect of these ostillations on pulsar timing is comparable to the effect of a monochromatic gravitational wave with characteristic strain h_c ≈ 2 · 10 ^{ −15}* ( 10 ^ {−23} eV / m) ^ 2 and frequency f = 5 · 10 { −9 } Hz (m / 10 ^{−23} eV). But unlike usual gravitational-wave background, in case of warm dark matter the signal will be narrow-band and monochromatic and the angle correlation coefficients will not depend on angular distance bteween pulsars. The most important noise, arising during the observations, is clock noise, caused by errors in time standart. Both signal and clock noise have monopolar correlations, and it is this type of noise we are studying in this project.