dipole anisotropy


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dipole anisotropy

[′dī‚pōl ‚an·ə′sä·trə·pē]
(astronomy)
A deviation of the equivalent blackbody temperature of the cosmic microwave radiation from its average value which is proportional to the cosine of the angle with some given direction, thus resembling the form of radiation from a dipole antenna.
References in periodicals archive ?
The dipole anisotropy, registered by the COBE satellite, is 3.
The EMB dipole anisotropy is explained due to the Tangherlini transformations in the Special Theory of Relativity: the spherical distribution of the earthly origin photons assigned to the EMB experiences the Doppler-like anisotropy toward the rapid motion of the Earth, with a velocity of 365 [+ or -] 18 km/sec, through the weak intergalactic background associated to the Metagalaxy as a whole (so the weak intergalactic background manifests the "preferred" reference frame connected to the entire Metagalaxy, and resting with respect to it).
The dipole anisotropy of the IMB is explained due to the Doppler-effect on the IMB photons: the Earth moves through the IMB with a velocity of 365 [+ or -] 18 km/sec, so the IMB photons registered by an Earth-bound observer (or any observer who is connected to the reference frame of the Earth such as the observers on board of the COBE satellite or the WMAP satellite) bear different energies/frequencies toward and backward this motion that is manifest as the IMB anisotropy in this direction.
On the other hand, the dipole anisotropy of the EMB, being a purely relativistic effect due to the rapid motion of the field's source, the Earth, through the weak intergalactic field, is independent from altitude.
If the origin of a microwave background (EMB) is the Earth, what would be its density and associated dipole anisotropy measured at different altitudes from the surface of the Earth?
The dipole anisotropy of such an earthy microwave background, due to the rapid motion of the Earth relative to the source of a weak intergalactic field which is located in depths of the cosmos, doesn't depend on altitute from the surface of the Earth.
To calculate the accociated dipole anisotropy of the Earth microwave background, which is due to the motion, we should use such a space metric which takes this motion into account.
The dipole anisotropy of the Earth microwave background, due to the rapid motion of the Earth relative to the source of another field which isn't connected to the Earth but is located in depths of the cosmos, doesn't depend on altitute from the surface of the Earth.
The dipole anisotropy is therefore independent of altitude; the anisotropy will be the same be it measured at the altitude of a U2 aeroplane (25 km), the COBE satellite (900 km), or the WMAP satellite located at the L2 point (1.
The discovery of a dipole anisotropy in the CMBR is interpreted as a Doppler shift produced by the Earth's motion (solar barycenter).
For instance, both Miller and Conklin have obtained a non-null result on the two-way path light speed anisotropy and the dipole anisotropy of the CMBR, respectively.