In: Physics
Emission lines from the hydrogen Hβ line (rest wavelength of 486.1 nm) are observed in the spectrum of a spiral galaxy at redshift z = 0.9. The galaxy's disk is observed to be inclined at an angle of 45 degrees to the line of sight. The central wavelength of the line is observed to be shifted by 0.5 nm to the red on one side of the galaxy, and by 0.5 nm to the blue on the other side of the galaxy. What is the rotation speed of the galaxy? Hint: you must also account that the redshift expands wavelength differences (Δλmeasured = (1+z)Δλemitted)
given the
Emission lines from the hydrogen H line
rest wavelength = 486.1 nm
The spectrum of spiral galaxy at redshift z = 0.9