Subject: Re: short paper From: David Cohen Date: Mon, 29 Sep 2008 14:24:01 -0400 To: Roberto C Mancini CC: David Cohen , mrosenbe@mit.edu Roberto, Thanks for including me and Mike on this paper. I've taken the liberty of cc-ing Mike (Hi, Mike! If you want to take a look at the draft to which this email refers, I've put it here: http://astro.swarthmore.edu/~cohen/projects/gas_cell/hedla-v3-imh.pdf). I have several comments and small suggestions, but overall, the paper is very nice as it is. My compliments to Iain. I don't know if you're up against a four page limit or what; some of my suggestions certainly would make the paper longer. First off - to maximize the impact in the astronomical community, I'd suggest posting the paper (once it's in its final form) to the astro-ph section of arXiv. I'll be glad to do the submission if you'd like me to (though they require that LaTeX (or MS Word) versions be submitted, not pdf directly). I like to include my middle initial in my name on author lists because my name is so common. So, "D. H. Cohen" - Mike's middle initial is "R", while you're at it. Intro, 1st par.: In the first sentence, consider adding the adjective "accretion powered" between "source of" and "X-rays." And do you want to supply a couple of references in support of the statement in the second sentence about high resolution astrophysics spectra from Chandra and XMM? I can look them up for you, if you'd like. P.2, first line: we discuss the "X-ray heating flux" here (and later in the paper), but isn't it more germane to refer to the "X-ray ionizing flux"? Heating's something we're trying to minimize and not the effect we're hoping to study. Incidentally, I've been doing some interesting reading about the roles different elements play in the heating-cooling balance in photoionized plasmas. I think it might be possible to achieve significantly lower temperatures in the gas cell by including some helium in the gas fill. This would make the measurement of narrow RRC features (once we do emission spectroscopy) more likely. P.2, Sec 2, 1st par.: I think "helping to assist" sounds a bit awkward (and kind of redundant). How about replacing this phrase with "guiding"? Sec. 2.1: It would be quite valuable to the average reader to have an image from a VisRad simulation here. Not just to demonstrate the modeling, but primarily to show the experimental set up. What do you think? Later in the section, we state that the pinch spectrum is Planckian. A few sentences later, we talk about how the aperture makes the "energy distribution closer to being Planckian." I don't think this is a big deal, but it might avoid some confusion if we explicitly state that the combined direct pinch plus re-emitted spectrum - while each component is assumed to be Planckian - gives a net spectrum with is non-Planckian. Maybe this is obvious, though, to most readers. P.2, 2nd column: Maybe this is nitpicking or maybe it's just a "language gap" between our fields, but to me, the symbol J represents the mean intensity (so, W/cm2/steradian) while I'd use F for flux. Again, looking at Fig. 2, which is great, I think it would be helpful to also have a VisRad image (then the reader could see where each of these components comes from). P.3, 3rd line: again, "heating" -> "ionizing". P.3, sec. 2.2, 1st par.: We've done a bunch of simulations with in-line CRE calculations in Helios (so, not relying on LTE opacity lookup tables). Obviously, we should describe in the paper whatever it is we actually did in the simulations we show here, but I wonder if you have done some comparisons of the LTE vs CRE opacities and find a significant difference in the results of the hydro. I believe that we have, at least under certain assumptions about the drive profile. P.3, right-hand column, first partial paragraph, last sentence: I think it's overly optimistic to claim that the conditions in the neon are "largely uniform." One can see all the shock-compressed neon at the two sides in the simulation output figure. Maybe insert the phrase, "center of the" between "expect the" and "neon region." Next paragraph: When introducing the ionization parameter, you might want to reference Bruce Tarter's original paper on it. End of that same paragraph: While the values of xi we achieve are undeniably lower that we'd like, they're not irrelevant to astrophysical situations. In any real system, there are a wide range of ionization parameters (usually governed primarily by the distance from the hard X-ray continuum source; the compact object). So, even xi~10 has some potential astrophysical applications. P.4, sec. 2.3: seems a little strange to have the word "emission" in the subsection title when we only discuss absorption. Along these lines, do we want to mention that we plan on making simultaneous and complementary emission spectroscopy measurements in the future along a different line of sight? Visrad is misspelled in the fourth reference in the reference list. Finally, there are some typesetting/formatting inconsistencies related to spaces - or not - between numbers and their units. Again, the paper is very nice; thanks for including me on it. I haven't cc'ed the coauthors here, but obviously, feel free to share my comments with Iain and anyone else. David Roberto C Mancini wrote: > David, attached is a pdf file with a short paper for the > proceedings of the hedla meeting that took place in April. > Can you please read it and send me your comments and feedback? > Thank you, Roberto > > Roberto C. Mancini > Department of Physics Phone: 775-784-6595 > College of Science Fax: 775-784-1398 > University of Nevada, Reno E-mail: rcman@unr.edu