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egsid
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Hello, everyone it seems to me that people understand how to do this problem but I am struggling to solve it.
A quasar with redshift 0.3 is gravitationally lensed into two images by an elliptical galaxy at redshift 0.18. There are two images of the quasar which are separated from the center of the galaxy by 1.10 arcsecs and 1.60 arcsecs on opposite sides. One of the quasar images flares up in intensity by 1 mag. and 16.7 days later the second quasar image flares by the same amount and with the same time profile. Assume the quasar is directly behind the galaxy and that the light paths are straight lines from the quasar to the point nearest the galaxy, then bend, and then are again straight from the point nearest the galaxy to the Earth. From this information, calculate Hubble Constant.
I think this is what is my problem.
I think maybe v = H0*d is the relevant equation. The angles given may help determine what d is which in some combination will help determine Hubble constant?
So I drew my diagram and labeled it with the relevant details. I thought you had to calculate the velocity of the quasar and galaxy so I used the equation 1+z = sqrt((c+v)/(c-v)) to find them. Obviously the time delay is 16.7 days but I don't know how to use this to calculate the Hubble Constant. Also, I don't know if the fact that the intensity "flares up in intensity by 1 mag." is relevant.
Thanks
Homework Statement
A quasar with redshift 0.3 is gravitationally lensed into two images by an elliptical galaxy at redshift 0.18. There are two images of the quasar which are separated from the center of the galaxy by 1.10 arcsecs and 1.60 arcsecs on opposite sides. One of the quasar images flares up in intensity by 1 mag. and 16.7 days later the second quasar image flares by the same amount and with the same time profile. Assume the quasar is directly behind the galaxy and that the light paths are straight lines from the quasar to the point nearest the galaxy, then bend, and then are again straight from the point nearest the galaxy to the Earth. From this information, calculate Hubble Constant.
Homework Equations
I think this is what is my problem.
I think maybe v = H0*d is the relevant equation. The angles given may help determine what d is which in some combination will help determine Hubble constant?
The Attempt at a Solution
So I drew my diagram and labeled it with the relevant details. I thought you had to calculate the velocity of the quasar and galaxy so I used the equation 1+z = sqrt((c+v)/(c-v)) to find them. Obviously the time delay is 16.7 days but I don't know how to use this to calculate the Hubble Constant. Also, I don't know if the fact that the intensity "flares up in intensity by 1 mag." is relevant.
Thanks
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