The Cosmic BPT Diagram: Confronting Theory with Observations - relevant to us?

• by JeanTate

  The Cosmic BPT Diagram: Confronting Theory with Observations is the title of a recent astro-ph preprint.

  Two bits (sentences) in the abstract struck me as particularly interesting: "We speculate that global spectra of our high redshift galaxies may be dominated by HII regions similar to the extreme clumpy, dense star-forming complexes in the Antennae and M82." (PeterD in particular may find this interesting),

  and "We use our theoretical models to derive a new redshift-dependent classification line that utilizes the standard optical diagnostic line ratios [OIII]/H-beta and [NII]/H-alpha. Our new line can be used to separate star-forming galaxies from AGN between z=0 to z~3.5." Maybe we can apply their "new line" to our own BPT diagrams?

  Posted August 5, 2013 8:19 AM

• by Louise93

  This paper is first-authored by my research supervisor! If you look in the paper, they divide their observational data into four redshift bins, with the lowest redshift one covering redshift of 0 to 0.8. The z = 0.8 lines vary only slightly from the z = 0 lines. I am pretty sure everything will lie inside this redshift range - so you can add the new lines, but in most cases, the standard, z = 0 BPT lines should be fine. I've made a BPT diagram, the trends match what you would expect from a standard local sample 😃

  [plot should be included, but doesn't seem to work....]

  Posted August 5, 2013 11:29 PM

• by ChrisMolloy

  I can see it. Right click on the plot and open in new tab.

  Posted August 6, 2013 10:04 AM

• by JeanTate in response to ChrisMolloy's comment.

  Hmm, I don't 😦

  Posted August 6, 2013 3:10 PM

• by JeanTate in response to Louise93's comment.

  In Quench Sample - BPT diagram I had a go at creating a BPT diagram, and adding various lines.

  You're right, the Kewley et al. (2013) line is essentially the same as a Kewley et al. (2001) I found by googling.

  Posted August 9, 2013 7:57 PM