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  2. Redshift - Wikipedia

    en.wikipedia.org/wiki/Redshift

    The redshift observed in astronomy can be measured because the emission and absorption spectra for atoms are distinctive and well known, calibrated from spectroscopic experiments in laboratories on Earth. When the redshift of various absorption and emission lines from a single astronomical object is measured, z is found

  3. Redshift survey - Wikipedia

    en.wikipedia.org/wiki/Redshift_survey

    In astronomy, a redshift survey is a survey of a section of the sky to measure the redshift of astronomical objects: usually galaxies, but sometimes other objects such as galaxy clusters or quasars. Using Hubble's law, the redshift can be used to estimate the distance of an object from Earth. By combining redshift with angular position data, a ...

  4. List of common astronomy symbols - Wikipedia

    en.wikipedia.org/wiki/List_of_common_astronomy...

    This is a compilation of symbols commonly used in astronomy, particularly professional astronomy. Age (stellar) τ - age ... z - redshift; Distance description

  5. Hubble's law - Wikipedia

    en.wikipedia.org/wiki/Hubble's_law

    The redshift z is often described as a redshift velocity, which is the recessional velocity that would produce the same redshift if it were caused by a linear Doppler effect (which, however, is not the case, as the velocities involved are too large to use a non-relativistic formula for Doppler shift).

  6. Gravitational redshift - Wikipedia

    en.wikipedia.org/wiki/Gravitational_redshift

    Gravitational redshift can be interpreted as a consequence of the equivalence principle (that gravitational effects are locally equivalent to inertial effects and the redshift is caused by the Doppler effect) [5] or as a consequence of the mass–energy equivalence and conservation of energy ('falling' photons gain energy), [6] [7] though there ...

  7. Distance measure - Wikipedia

    en.wikipedia.org/wiki/Distance_measure

    Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe.They are often used to tie some observable quantity (such as the luminosity of a distant quasar, the redshift of a distant galaxy, or the angular size of the acoustic peaks in the cosmic microwave background (CMB) power spectrum) to another quantity that is ...

  8. Angular diameter distance - Wikipedia

    en.wikipedia.org/wiki/Angular_diameter_distance

    The angular size redshift relation for a Lambda cosmology, with on the vertical scale megaparsecs. The angular size redshift relation describes the relation between the angular size observed on the sky of an object of given physical size, and the object's redshift from Earth (which is related to its distance, d {\displaystyle d} , from Earth).

  9. Cosmic distance ladder - Wikipedia

    en.wikipedia.org/wiki/Cosmic_distance_ladder

    In such cases, the redshift of the host galaxy allows a determination of the Hubble constant. [22] This was the case for GW170817 , which was used to make the first such measurement. [ 25 ] Even if no electromagnetic counterpart can be identified for an ensemble of signals, it is possible to use a statistical method to infer the value of H 0 ...