How do we measure the Spectral Energy Distribution of quasars?

[quasarLie]

Hello,
What do you think about this article?
https://arxiv.org/abs/1502.05850
Why and how do we mesure the Spectral Energy Distribution for quasars?
Thanks

 

[phyzguy]

Hello,
What do you think about this article?
https://arxiv.org/abs/1502.05850
Why and how do we mesure the Spectral Energy Distribution for quasars?
Thanks

I don't quite understand your question. Why do we measure the SED- because we want to learn about quasars. How - with a spectrograph.

 

[quasarLie]

I don't quite understand your question. Why do we measure the SED- because we want to learn about quasars. How - with a spectrograph.

Okay thank you, and in the article they say that they choose quasars with redshift beween 1.5 and 2.2, what does it mean?? does it means that it is in the infra red?

 

[phyzguy]

Okay thank you, and in the article they say that they choose quasars with redshift beween 1.5 and 2.2, what does it mean?? does it means that it is in the infra red?

All distant astronomical objects are redshifted because of the expansion of the universe. See this article for an explanation. So quoting the redshift is a way of specifying how far away the quasars are. These objects are very far away and we are seeing them as they looked approximately 10 billion years ago.

 

[quasarLie]

All distant astronomical objects are redshifted because of the expansion of the universe. See this article for an explanation. So quoting the redshift is a way of specifying how far away the quasars are. These objects are very far away and we are seeing them as they looked approximately 10 billion years ago.

and why some object emit in radio and other infra red or UV ?? it depends on what?

 

[phyzguy]

and why some object emit in radio and other infra red or UV ?? it depends on what?

It depends on many things. Many astronomical objects emit light close to black-bodies, so what wavelengths they emit depends on how hot they are. But there are many other mechanisms for how bodies emit EM radiation. It's very difficult to learn these things by just asking random questions. It sounds like you need to get a book on introductory astronomy and read through it. I like Shu's "The Physical Universe".