A Black Hole TON618 - Wavelength Spectrum

[nanjo]

Then the answer to your original question is:

"The Lyman-alpha emitted wavelength is 121.567 nm.

You can easily compute the observed wavelength from the redshift value z = 2.219."

If you want the actual number, then $1 + z = \lambda/\lambda_0$ implies that
$$
\lambda = \lambda_0(1+z) = (121.567\ {\rm nm}) (1+2.219) \simeq 391.3\ {\rm nm}
$$

This is irrespective of whether you believe that the observed wavelength is 391.3 nm because the Universe expanded by a factor of 3.319 or not.

Thanks , but I had already acknowledged a misunderstanding. Again, the observed spectrum is what I wanted and did get posts ago.

 

[SlowThinker]

Sorry to resurrect this thread but my question was actually answered by it. I'm wondering, is 391.3 supposed to be the location of the (wide) peak in this image? https://ned.ipac.caltech.edu/spc1/2000/2000ApJS..126..133W/FBQS_J122824.9+312837:S:w2000_sp.png (from https://ned.ipac.caltech.edu/byname?objname=FBQS+J122824.9+312837&hconst=67.8&omegam=0.308&omegav=0.692&wmap=4&corr_z=1, Spectra tab)
It seems the peak is more around 382.0. Earth's own motion won't change it by more than 0.1nm. Am I eyeballing the peak wrong?
Why is the peak so wide, is it the limitation of the instrument, or reality (high temperature, own motion, gravitational red shift, ...)?
Are there other databases of spectra? I can't find JADES-GS-z14-0 .

 

[Ibix]

I'd be very doubtful of eyeballing such a noisy curve.

I don't know much about that source, but line widths can be Doppler broadened. If that's hot gas orbiting rapidly around a black hole the velocities could be high.

 

[phyzguy]

This is a good book to get you started on the spectra of these objects:
https://www.amazon.com/Active-Galactic-Nuclei-Princeton-Astrophysics/dp/0691011516?tag=pfamazon01-20

 

[nanjo]

As a cosmological layman I believe that measurements of the distance extremely distant stellar objects is built upon quite a complex scale ladder which ultimately requires the use of Hubble's Law. First of all, is that belief correct? Secondly, if true, then are there any other methods which would substantiate the values estimated by Hubble's Law for such bodies as TON618?

 

[Ibix]

As a cosmological layman I believe that measurements of the distance extremely distant stellar objects is built upon quite a complex scale ladder which ultimately requires the use of Hubble's Law.

Yes. That's another reason to quote redshifts as the basic measurement, since there's much more uncertainty in the Hubble parameter's values than in the redshift measure.

Secondly, if true, then are there any other methods which would substantiate the values estimated by Hubble's Law for such bodies as TON618?

At that kind of distance, no. Again, this is why cosmologists usually quote and work with the $z$ values instead of distances. There are far fewer assumptions underlying those.

 

[nanjo]

Thanks for the reply Ibix. Moving on to other parameters, I understand that there are numerous and complex methods for estimating the mass and diameter of the the most distant stellar objects. But are there any estimation methods that do NOT require prior knowledge of the distance to such massive and distant bodies as TON618?

 

[Ibix]

Yes. You can see time lags between brightness changes in different parts of the spectrum, in particular between the sharp emission lines of the source and the Doppler-broadened lines of re-emission from orbiting gas. The time difference gives you a size estimate just by multiplying by the speed of light. The amount of Doppler broadening gives you the orbital speed of the gas, and with those two pieces of information you can get the mass.

https://arxiv.org/abs/astro-ph/9911476

 

[mayflowers]

Starting with raw data allows one to proceed in another direction. Using z puts a limit on the next step.

Hi - just here reading first pages of a couple threads with interesting titles, so don't mind me - but this quote of yours is a notion I fully agree with.

Like an information tree. The smaller branches at the very end have less nutrients relative to the main source, but are on the surface of what we see.

I don't think the OP nanjo is looking for an information battle, possibly something completely unrelated, for all I know.