NAS's Astro2010 Decacal Survey recommendations

The National Academies of Sciences has released its Astro2010 decadal survey report and recommendations. A PDF of the release presentation is also available on that site. The panel's recommendations influence what programs NASA, NSF and DOE pursue and fund in astronomy and astrophysics for the next decade, so this is a big deal.

So far I've only read the presentation, and looked at Steinn Sigurdsson's comments on his blog [1, 2], so what follows is by no means a complete and final assessment.

My personal take is that its a mix of the good and the bad.

Whats good (from my perspective at least):

• A strong endorsement and emphasis on revitalizing the Explorer class mission program. This had suffered badly under O'Keefe and Griffin.
• A strong recognition of the importance of feedback, and flows of matter and energy into and out of galaxies (the 8th, 9th, and 10th points on slide 9 of the PDF copy of presensation).

Whats bad:

• IXO ranks 4th, behind some wide field IR telescope focussed on Dark Energy (yawn, a couple of billion bucks to get one not-very-interesting number) and LISA. IXO will only get $180m in the next decade, so basically that pushes it back to ~2030? And probably kills its chances in the ESA mission rankings too. Given that Constellation-X (IXO's forerunner prior to the merger with ESA) came 2nd (after JWST) in the previous decadal and IXO thought it had a good chance of coming 1st this time the current ranking is a real blow.
• LISA is somehow ranked as lower risk (and cheaper) than IXO! Seriously?
• Funding for astrophysics doesn't look like it going to get better.
• Unless you're an optical/IR astronomer, or the three gravitational wave astronomers, you're in for a bad decade and a half. X-ray astronomy, UV astronomy, and radio seem to be in trouble.
• From my perspective there is a disconnect between the science priorities for the next decade and the missions endorsed. Feedback and the galaxy/IGM interconnection isn't going to be answered by JWST, WFIRST, LISA or any Explorer mission

Interesting Astrophysics: Apr 06 to Apr 10

It has been a relatively quiet week in terms of papers and preprints that I consider interesting enough to make a note of. Perhaps the most interesting is Martinez and Trimble's "Cosmologists in the dark", largely as it is a historical review rather than a technical paper.

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Galaxies and Starbursts

An ultraviolet study of nearby luminous infrared galaxies: star formation histories and the role of AGN
Sugata Kaviraj, 2009, MNRAS, 394, 1167
Full Text: HTML, PDF (Size: 13559K)

Over half of the far-infrared background light comes from galaxies at z > 1.2
Mark J. Devlin, et al, arXiv:0904.1201 [pdf]

Comments: Accepted to Nature. Maps available at this http URL

Journal-ref: Nature, vol. 458, 737-739 (2009)

BLAST: A Far-Infrared Measurement of the History of Star Formation
Enzo Pascale, et al, arXiv:0904.1206 [ps, pdf, other]

Comments: Submitted to ApJ. Maps available at this http URL

X-ray nuclear activity in nearby galaxies
Wei Ming Zhang, Roberto Soria, Shuang Nan Zhang, Douglas A. Swartz, JiFeng Liu, arXiv:0904.1091 [ps, pdf, other]
Comments: 27 pages, 353 kB, accepted by ApJ

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Cosmology

Cosmologists in the dark
Vicent J. Martinez, Virginia Trimble, arXiv:0904.1126 [ps, pdf, other]
Comments: 10 pages, ASP style (asp2006.sty), invited talk, to be published in the proceedings of the conference "Cosmology across Cultures" (held at Granada, Spain, on 2008, September 8th to 12th), J. A. Belmonte, F. Prada, J. A. Rubino Martin, & A. Alberdi, Eds., ASP, S. Francisco. Comments are welcome

A nice discussion of the history of the last century of cosmology that maintains a fair balance in its critiques. It certainly does a nice job of discussing the problems with Steady State and Quasi Steady State models. The title, which you might think of as a dig at cosmologists, is actually in reference to the quote from T.S. Elliot's "East Coker" (which I'm sure you know, or should know anyway).

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Black Holes and AGN

The Contribution of Active Galactic Nuclei to the Microjansky Radio Population
D.R. Ballantyne, arXiv:0904.0996 [ps, pdf, other]
Comments: 30 pages, 11 figures, accepted by the ApJ

Active Galactic Nuclei with Starbursts: Sources for Ultra High Energy Cosmic Rays
P.L. Biermann, J.K. Becker, L. Caramete, L. Gergely, I.C. Maris, A. Meli, V. de Souza, T. Stanev, arXiv:0904.1507 [ps, pdf, other]
Comments: 4 pages, 1 figure, proceedings of "High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", Heidelberg

Quasar Feedback: More Bang for Your Buck
Philip F. Hopkins, Martin Elvis, arXiv:0904.0649 [ps, pdf, other]
Comments: 7 pages, 2 figures, submitted to MNRAS

Meh. I must be feeling extra cynical today as I really don't think this says anything new other than collecting old results together and packaging them together with a cartoon picture.

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Numerical Astrophysics and Hydrodynamics

The turbulent destruction of clouds – I. A k–ε treatment of turbulence in 2D models of adiabatic shock–cloud interactions
J. M. Pittard, S. A. E. G. Falle, T. W. Hartquist, J. E. Dyson, 2009, MNRAS, 394, 1351
Full Text: HTML, PDF (Size: 52479K)

Numerical approaches to star formation and SuperNovae energy feedback in simulations of galaxy clusters
Martina Giovalli, arXiv:0904.1399 [pdf, other]
Comments: Ph.D. Thesis, 203 pages

Note to self: Might be good. Try to find the time to read this carefully.

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Stars, Supernovae and Planets

The Core-collapse rate from the Supernova Legacy Survey
G. Bazin, et al, arXiv:0904.1066 [ps, pdf, other]
Comments: accepted Astronomy and Astrophysics

On the Mass and Metallicity Distributions of the Parent AGB Stars of O-rich Presolar Stardust Grains
Larry R. Nittler, arXiv:0904.1388 [ps, pdf, other]
Comments: 8 pages, 5 figures; accepted for publication in the Publications of the Astronomical Society of Australia

I found this part of the abstract particularly interesting: "3) The Sun appears to have a moderately low metallicity for its age and/or unusual 17O/16O and 18O/16O ratios for its metallicity. 4) The Solar 17O/18O ratio, while unusual relative to present-day molecular clouds and protostars, was not atypical for the presolar disk and does not require self-pollution of the protosolar molecular cloud by supernova ejecta."

Dark Energy and Straw Men

On today's set of astro-ph preprints is a conference proceedings article by Andreas Albrecht (astro-ph/0710.0867) entitled "The case for an aggressive program of dark energy probes" caught my eye. Specifically the abstract attracted my attention:

The observed cosmic acceleration presents the physics and cosmology communities with amazing opportunities to make exciting, probably even radical advances in these fields. This topic is highly data driven and many of our opportunities depend on us undertaking an ambitious observational program. Here I outline the case for such a program based on both the exciting science related to the cosmic acceleration and the impressive impact that a strong observational program would have. Along the way, I challenge a number of arguments that skeptics use to question the value of a strong observational commitment to this field.

From the abstract I had hoped this would address and rebut the criticisms raised by Simon White earlier this year in "Fundamentalist physics: why Dark Energy is bad for Astronomy" (astro-ph/0704.2291). Unfortunately Albrecht's article does not address any of these substantive criticisms regarding discovery space, scientific method, whether Dark Energy experiments advance our knowledge of astrophysics, or experiment systematics, so for now I am left to believe that White's criticisms remain valid and significant.

Don't misunderstand me - IF we can confirm and constrain the nature of dark energy it may revolutionize our understanding of particle physics, but its role in explaining the Universe of galaxies, stars and planets that we live in is extremely limited. By all means fund dark energy probes out of the DoE and classics physics funding, but significant progress in astrophysics will be stifled if too much astrophysics money is diverted into DE.

Understanding the nature of the dark matter particle would also advance fundamental physics greatly, and dark matter plays a much larger role than dark energy in shaping the nature of the Universe and the specific objects we live in than dark energy does. Yet the discovery of the dark matter wasn't met with a program of dropping successful existing astronomy projects and throwing vast resources at satellites that could only quantify one number about dark matter.

Constellation-X: There is good news and there is bad news

Last week the National Research Council's Space Studies Board finally published its conclusions assessing the feasibility and priorities for space missions in the NASA "Beyond Einstein" program. Basically this was a match-up to select between current political and fashion favorites going after dark energy, and the older-but-surer science missions like Constellation-X (and X-ray observatory, e.g. for understanding black holes, AGN, and anything else extremely hot in the universe) and LISA (gravitational wave detection).

The committee will be charged to address the following tasks:

1. Assess the five proposed Beyond Einstein missions (Constellation-X, Laser Interferometer Space Antenna, Joint Dark Energy Mission, Inflation Probe, and Black Hole Finder probe) and recommend which of these five should be developed and launched first, using a funding wedge that is expected to begin in FY 2009. The criteria for these assessments include:
a. Potential scientific impact within the context of other existing and planned space-based and ground-based missions; and
b. Realism of preliminary technology and management plans, and cost estimates.

2. Assess the Beyond Einstein missions sufficiently so that they can act as input for any future decisions by NASA or the next Astronomy and Astrophysics Decadal Survey on the ordering of the remaining missions. This second task element will assist NASA in its investment strategy for future technology development within the Beyond Einstein Program prior to the results of the Decadal Survey.

You can read the full report online here. Stein Sigurdsson already offered his take on the predictable outcome (a mission focused on dark energy) in a post last week that can be found here. The Constellation-X team is rather more upbeat in its assessment:

Dear Colleagues:

The BEPAC report provides both bad and good news for the Con-X project. Bad news is that Con-X was not chosen as the highest priority (JDEM was recommended as the first BE mission) or even as the 2nd highest priority (LISA was recommended for enhanced technology investment). Good news can be found in the BEPAC endorsement of the Con-X science and technical readiness. Specifically, "Con-X will make the broadest and most diverse contributions to astronomy of any of the candidate Beyond Einstein missions...the general observer program of Con-X will harness the ingenuity of the entire astronomical community", and "Con-X is one of the best studied and tested of the missions presented to the panel...much of this can be attributed to...strong community support". The panel recognized that "Con-X was ranked second only to the James Webb Space Telescope in the 2001 Decadal Survey".

Looking forward, the BEPAC recommends that "Con-X development activities need to continue aggressively in areas such as achieving the mirror angular resolution, cooling technology and x-ray micro-calorimeter arrays to improve the Con-X missions readiness for the next Astronomy and Astrophysics Decadal Survey." We will continue to pursue technology developments in these areas. All of your assistance in preparing the BEPAC presentations provides us with a very good start for the upcoming Decadal Survey. One of our tasks will be to expand upon the BEPAC material, which was very focused on BE science, in order to capitalize on the breadth and diversity of Con-X science (which was recognized by the BEPAC). We anticipate having the next Con-X FST meeting in mid-Feb 2008, following the release of the NASA budget request for FY2009.

Harvey Tananbaum, Nick White, Michael Garcia, Jay Bookbinder, and Ann Hornschemeier, for the Con-X Project Team.

I leave it as an exercise for the reader to compare the Constellation-X assessment with the officially stated goals of the assessment (1a and b above).

Speaking personally, I'm very disappointed in the selection. Getting the equation of state for dark energy is interesting, but very limited in scope, and this selection basically sacrifices the potential of lot of scientific progress and potential for new discoveries in many branches of astrophysics for a very limited advance in one specific area. Indeed, an area that has little practical impact for our understanding the broader nature of the Universe and how we came to be here (see Simon White's essay regarding dark energy and astronomy here).

Constellation-X is, furthermore, the only proposed instrument in the next 10-20 years with the potential to unambiguously answer the most fundamental unknowns regarding starburst-driven winds (my primary area of study): measuring the velocity of the hot and very hot metal-enriched X-ray-emitting gas. If we don't and won't know that for sure, then we'll never be quite sure about interstellar medium and intergalactic medium feedback processes. Forget about getting the full picture on galaxy formation, galactic chemical evolution, mass loss from galaxies, enrichment and heating of the IGM, and so on. But hey, instead we get to know whether a number called W is between -1 and 1. I'm sure the public is eager to know that, I'm positive they'll get very excited about that result.

Now Con-X isn't officially dead yet, but being third in line is a dangerous place to be. In another few years, if there are further assessments to rationalize and prioritize spending, will Con-X survive? And without Con-X, I feel like I might as well pack up and give in. Game over...