Redshift limit and adding templates

[weidahu]

Dear Sam,

I am playing with Marz to fit the redshift of some JWST spectra. The powerful JWST enables the discovery of amounts of high-redshift galaxies. Marz is very helpful at this and saves lots of time in identifying the redshift. But it seems Marz cannot estimate the redshift of very high-redshift galaxies (z>6), even though the spectrum shows very clear features (see the figure, very significant OIII + Hbeta lines). I am wondering if there is a redshift limit in the code because I noticed that the maximum redshift allowance in the GUI is 5. If so, is there a method to close this limit?

Secondly, I am wondering if it is possible to add some templates, because the JWST data now provides coverage of the rest-frame NIR wavelength.

Any help would be very appreciated.

Best,
Weida

[Samreay]

Hi Weida!

Happy to hear the tool is still useful after all these years! You're right in that there's a redshift limit. The UI limit comes from the way the cross correlation works, which involves rebinning input spectra onto a log-linear wavelenth grid and then calculating the cross correlations against templates.

You can see the redshift bin limits are defined in this config file: https://github.com/Samreay/Marz/blob/gh-pages/js/config.js#L60C29-L60C29

(Note that the two vaules with "Q" at the end are used for quasar templates, and you'll see their ending wavelength goes to up to 10^4.6 as opposed to the normal specta which go up to 10^4.2.

Increading this value will allow templates to match to higher redshifts. If you increase a lot, you might also want to enable finer rebinning (which means uncommenting line 61 and commenting line 62)

The maximum redshift value in the UI is controlled by this setting: https://github.com/Samreay/Marz/blob/gh-pages/js/services.js#L27

And as many templates as youd like can be added to the list in https://github.com/Samreay/Marz/blob/gh-pages/js/templates.js

Now, I can't make those changes in the default version of marz, as it will change the behaviour for existing users, but hopefully it's a simply process to fork the repository and change things as youd like, especially given GitHub pages is how I host the code to turn it into a webpage, and its free!

[weidahu]

Hi Sam,

Thanks a lot for the prompt reply and this great code. I will try to modify it and host it on my laptop.

Best,
Weida