Astrophysics (index)about

Redshift

(z, Redshift Parameter)
(change to longer wavelengths due to Doppler affects)

Redshift is a lengthening of Wavelengths, e.g., of Spectral Lines, due to Doppler effects of radial motion of the radiation source away from the observer (i.e., its Recessional Velocity). Given the expansion of the universe, redshift is used as a measure of distance and time, and a redshift due to this is called a Cosmological Redshift.

Smaller redshifts and Blue Shifts (for the analogous shortening of the wavelength from sources moving toward the observer) are also measured to determine Radial Velocity in studies of Peculiar Velocity and of objects orbiting stars such as Extra-Solar Planets and Binary Star companions. Measurements using specially developed Spectrographs can determine radial velocities and radial velocity differences as small as 1 meter per second.

The Redshift Parameter (often just called Redshift) z is:

     observed wavelength - Rest Wavelength
z =  —————————————————————————————————————
              rest wavelength

The relationship between z and the recessional velocity is:

              1 + v/c
1 + z = sqrt( ——————— )
              1 - v/c

Transverse motion and Gravity also produce/affect redshift.


When a body's redshift is determined, assuming the redshift is cosmological allows a distance estimate to be calculated using the redshift and the Hubble Constant (70 kmps/Mpc). Below are some calculated values. "Linear" was calculated using a simple linear approximation (workable for z less than 0.1) and "Relativistic" takes Special Relativity into account (the above formula) and is suitable for all redshifts. "Giga Years" is how far in the past we're viewing the body and is also its distance in billions of light-years.

RedshiftLinearRelativisticLinear's
zVelocity Mpc GYearsVelocity Mpc GYearsexcess
0.013000km/s 43Mpc 0.1GY2985km/s 43Mpc 0.1GY0.50%
0.026000km/s 86Mpc 0.3GY5940km/s 85Mpc 0.3GY1.01%
0.039000km/s 129Mpc 0.4GY8865km/s 127Mpc 0.4GY1.52%
0.0412000km/s 171Mpc 0.6GY11760km/s 168Mpc 0.5GY2.04%
0.0515000km/s 214Mpc 0.7GY14625km/s 209Mpc 0.7GY2.56%
0.0618000km/s 257Mpc 0.8GY17461km/s 249Mpc 0.8GY3.09%
0.0721000km/s 300Mpc 1.0GY20267km/s 290Mpc 0.9GY3.62%
0.0824000km/s 343Mpc 1.1GY23043km/s 329Mpc 1.1GY4.15%
0.0927000km/s 386Mpc 1.3GY25789km/s 368Mpc 1.2GY4.69%
0.130000km/s 429Mpc 1.4GY28507km/s 407Mpc 1.3GY5.24%
0.260000km/s 857Mpc 2.8GY54098km/s 773Mpc 2.5GY10.91%
0.390000km/s 1286Mpc 4.2GY76952km/s 1099Mpc 3.6GY16.96%
0.4120000km/s 1714Mpc 5.6GY97297km/s 1390Mpc 4.5GY23.33%
0.5150000km/s 2143Mpc 7.0GY115385km/s 1648Mpc 5.4GY30.00%
0.6180000km/s 2571Mpc 8.4GY131461km/s 1878Mpc 6.1GY36.92%
0.7210000km/s 3000Mpc 9.8GY145758km/s 2082Mpc 6.8GY44.07%
0.8240000km/s 3429Mpc 11.2GY158491km/s 2264Mpc 7.4GY51.43%
0.9270000km/s 3857Mpc 12.6GY169848km/s 2426Mpc 7.9GY58.97%
1300000km/s 4286Mpc 14.0GY180000km/s 2571Mpc 8.4GY66.67%
1.5450000km/s 6429Mpc 21.0GY217241km/s 3103Mpc 10.1GY107.14%
2600000km/s 8571Mpc 28.0GY240000km/s 3429Mpc 11.2GY150.00%
3900000km/s 12857Mpc 41.9GY264706km/s 3782Mpc 12.3GY240.00%
41200000km/s 17143Mpc 55.9GY276923km/s 3956Mpc 12.9GY333.33%
51500000km/s 21429Mpc 69.9GY283784km/s 4054Mpc 13.2GY428.57%
61800000km/s 25714Mpc 83.9GY288000km/s 4114Mpc 13.4GY525.00%
72100000km/s 30000Mpc 97.8GY290769km/s 4154Mpc 13.5GY622.22%
82400000km/s 34286Mpc 111.8GY292683km/s 4181Mpc 13.6GY720.00%
92700000km/s 38571Mpc 125.8GY294059km/s 4201Mpc 13.7GY818.18%
103000000km/s 42857Mpc 139.8GY295082km/s 4215Mpc 13.7GY916.67%
113300000km/s 47143Mpc 153.8GY295862km/s 4227Mpc 13.8GY1015.38%
123600000km/s 51429Mpc 167.7GY296471km/s 4235Mpc 13.8GY1114.29%
133900000km/s 55714Mpc 181.7GY296954km/s 4242Mpc 13.8GY1213.33%
144200000km/s 60000Mpc 195.7GY297345km/s 4248Mpc 13.9GY1312.50%
154500000km/s 64286Mpc 209.7GY297665km/s 4252Mpc 13.9GY1411.76%
10030000000km/s 428571Mpc 1397.8GY299941km/s 4285Mpc 14.0GY9901.96%

(measure,EMR,Doppler)
http://en.wikipedia.org/wiki/Red_shift

Referenced by:
AEGIS
AIM-CO
Alcock-Paczyński Effect
ALFALFA
Astronomical Quantities
AzTEC-3
Balmer Series
Band Shifting
Balmer-Break Galaxy (BBG)
Brightest Cluster Galaxy (BCG)
Blind Survey
Baryon Oscillation Spectroscopic Survey (BOSS)
Calán/Tololo Survey
Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)
Carbon (C)
Cepheid Variable
Canadian Hydrogen Intensity Mapping Experiment (CHIME)
Cosmic Infrared Background (CIB)
Cluster Radius
Cosmic Microwave Background (CMB)
Carbon Monoxide (CO)
COMAP
Carbon Monoxide Mapping Array (COMA)
COPSS
Cosmic Distance Ladder
Cosmological Time Dilation
Cosmological Zoom Simulation
Cosmic Evolution Survey (COSMOS)
Critical Density (ρc)
Dark Age
DEEP2
Deep Field (DF)
Deep Survey
Dark Energy Spectroscopic Instrument (DESI)
Dropout
Extended Groth Strip (EGS)
Emission Line Galaxy (ELG)
Emission Line
Epoch of Reionization (EOR)
Epoch of Galaxy Formation
Euclid
Faber-Jackson Relation
Faint Infrared Grism Survey (FIGS)
First Galaxies
Galaxy Cluster (CL)
Galaxy Merger
Galaxy Power Spectrum
Gas Fraction Estimation
Gemini Observatory
GISMO
Giant Metrewave Radio Telescope (GMRT)
Gravitational Redshift
Great Attractor
Great Debate
Gunn-Peterson Trough
Galaxy Zoo 2 (GZ2)
Hamburg/ESO Survey (HE)
HERA
Hercules-Corona Borealis Great Wall (Her-CrB GW)
Herschel Redshift Survey (HeRS)
HFLS3
Hot DOG
Hubble Constant (H0)
Hubble Diagram
Hubble Ultra-Deep Field (HUDF)
K Correction
KMOS3D
Lyman-Alpha Emitter (LAE)
Lambda-CDM model (ΛCDM)
Lyman-Break Galaxy (LBG)
Line Broadening
Large Millimeter Telescope (LMT)
Low-Frequency Array (LOFAR)
Luminous Red Galaxy (LRG)
Luminosity Distance (dL)
Luminosity Function (LF)
Lyman-Alpha Forest
Molecular Deep Field
Murchison Widefield Array (MWA)
OIR
Origins Space Telescope (OST)
PAPER
Palomar Four-Filter Survey (PC)
P Cygni Profile
Peak Star-Formation Epoch
PHIBSS
Photometric Redshift
Protogalaxy
Quasar (QSO)
Recombination
Redshift-angular Size Relation
Redshift-magnitude Relation
Redshift Space
Redshift Survey
Rest Wavelength
R-Process
Supernova Cosmology Project (SCP)
Sloan Digital Sky Survey (SDSS)
Star Formation History (SFH)
Star Formation Rate (SFR)
Star-Formation Rate Stellar-Mass Ratio
Spitzer HETDEX Exploratory Large Area Survey (SHELA)
SINS
Submillimeter Galaxy (SMG)
Supernova Legacy Survey (SNLS)
Spectral Line
Sachs-Wolfe Effect (SWE)
3C 273
3C 295
3C 48
Time Dilation
Tomographic Ionized-Carbon Mapping Experiment (TIME)
21cm Experiment
21cm Line
2dF Galaxy Redshift Survey (2dFGRS)
Ultraluminous Infrared Galaxy (ULIRG)
USS Sources
VIRMOS-VLT Deep Survey (VVDS)
WiggleZ

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