The Neutron Star Crust and Surface (INT, 2007)

2009-05-17T17:46:00.000-07:00

Joule heating in magnetized NS

2007-07-18T10:29:00.000-07:00

Joule heating in the crustal layers due to Ohmic decay was thought to affect only the late photon cooling era in old NS (10^7 yr), and to be an efficient mechanism to maintain the surface temperature as high as 10^{4-5} K for a long time (Miralles & Urpin, 1998). Now we have revisited the problem and found that for strongly magnetized NS (B~10^14 G) Joule heating can be important much earlier in the evolution. The magnetic field decay energy could modify or even control the cooling of a magnetized NS, rather independently from the stellar structure or matter composition. We have performed first 2D simulations keeping the geometry of the magnetic field fixed. Coupled magneto-thermal evolution calculations are needed.

Crosstalk: Mini Workshop on Type I X-ray bursts.

2007-07-12T16:07:00.001-07:00

Barry Davids (TRIUMF). Experimental Efforts to Determine the 15O(a,g)19Ne Reaction Rate.
To Astronomers: The 15O(a,g) reaction rate has not been measured, but upper limits are x100 above the theoretical lower limit. With present instrumentation, we can get within x10 the theoretical lower limit; to do better, we will likely need new instrumentation, to produce a high intensity 15O beam, to produce a direct measurement. This would permit pinning down the 15O(a,g)19Ne reaction rate, which is a present choke-point in the rp-process (active in type I x-ray bursts).
To Nuclear Theorists: We need reliable theoretical predictions for reaction rates, benchmarked with observables.

Chris Ruiz (TRIUMF). Nuclear Astrophysics of neutron-deficient nuclei - experimental approaches at ISAC.
To Astrophysicists: We rely on astrophysical modellers to tell us: which reactions are of astrophysical importance? It takes many years (~5 years, say) to develop a specific reaction experimental setup, so the reactions you tell us to measure must be critically important, not merely of some curiosity.

Ed Brown (MSU/JINA). The X-ray Burst-Crust Connection.
For nuclear theorists: Pay attention to all phenomena predicted by your models. It is not enough to see that it produces consistency with one phenomenon; you must also work out the implications for other phenomena as well.

Andrew Cumming (McGill). Constraints on the rp-process from X-ray bursts.
For nuclear experimentalists: There are many possible influences on the phenomena, so nuclear reaction rates are important for understanding them, but there are astronomical influences as well. At present, our uncertainties are not hung up on a single waiting point; however, our level of uncertainty does depend, for example, on
astrophysical causes, such as turbulence or spreading in the burning layer.

Randy Cooper (Harvard/CfA). Nuclear Reactions During the Onset of Type I X-ray Bursts.
The uncertainty in the Hot CNO breakout reaction rates, and in parti15O(a,g)19Ne rate is an important uncertainty in type-I x-ray burst ignition models.

Crosstalk

2007-07-10T12:21:00.000-07:00

Zach Medin. Condensed Matter Surfaces of Neutron Stars: Applications and Tangents.
Under certain conditions the atmosphere of a neutron star is negligibly thin and a condensed matter surface forms. This is applicable for neutron stars with large surface magnetic fields and moderate surface temperatures.
For observational astronomers: Condensed matter surfaces could be used, e.g., to explain the featureless spectrum of RX J1856.5-3754, and are also a key ingredient in vacuum gap pulsar emission models.
For nuclear theorists: The strong magnetic fields of neutron stars have an important effect on matter even at low pressure/density.

Arrivals and Departures

2007-07-06T17:40:00.000-07:00

Below is the list of arrivals and departures of those in residence at the INT, which occurred as of Monday July 9, in comparison with this previous posting.

Arrivals: Deborah Aguilera (Alicante) Ed Brown (MSU; returning), Randall Cooper (Harvard; returning), Barry Davids (TRIUMF), Huaiyu Duan (UCSD), Pawel Haensel (Copernicus), Alex Potekhin (Ioffe), Achim Schwenk (TRIUMF; returning)

Remaining: Andrew Cumming (McGill), Lirio Aparicio (UNAM), Michael Forbes (UW), Janusz Gil (Kepler Institute), Jillian Anne Henderson (UNAM), Charles Horowitz (Indiana U), Zachary Medin (Cornell), George Melikidze (University of Zielona Gora), Dany Page (UNAM), George Pavlov (PSU), Madappa Prakash (Ohio), Bob Rutledge (McGill), Nicolai Sandulescu (Institute of Atomic Physics)

Departures: Liliana Caballero (Indiana U), Sanjib Gupta (LANL), Jim Lattimer (SUNY), Kseniya Levenfish (Ioffe), Peter Moller (LANL), Jorge Piekarewicz (Florida State), Sergey Postnikov (Ohio), Sanjay Reddy (LANL), Alex Turbiner (UNAM), Roberto Turolla (INFN Padova).

Next Week's Talks

2007-07-05T17:04:00.000-07:00

Monday, July 9
10:30. C421. Zach Medin (Cornell)
Condensed Matter Surfaces of Neutron Stars: Applications and Tangents

Tuesday, July 10
10:30. C421. A. Potekhin (Ioffe)
Thermal structure of magnetized neutron star envelopes

Wednesday, July 11
10:30. C421. Pawel Haensel (Copernicus)
Deep crustal heating in accreting neutron stars

Thursday, July 12.
Mini-Workshop: Nuclear Reactions in Type I X-ray Bursts. C421.
10:30. Barry Davids (TRIUMF). Experimental Efforts to Determine the 15O(a,g)19Ne Reaction Rate
11:15. Chris Ruiz (TRIUMF). Nuclear Astrophysics of neutron-deficient nuclei - experimental
2:00. Ed Brown (MSU, JINA). The X-ray Burst—Crust Connection
2:30. Andrew Cumming (McGill). Constraints on the rp-process from X-ray Bursts
3:00. Randall Cooper (Harvard/CfA). Nuclear Reactions During the Onset of Type I X-ray Bursts
3:30-5:00 Coffee & Discussion

Friday, July 12.
10:30. C421. Madappa Prakash (Ohio U.)
Discussion: Hot Topics in The Neutron Star Crust and Surface

Crosstalk

2007-07-05T10:47:00.000-07:00

O.L. Caballero. Transport Properties of Dense Plasmas. We are calculating transport properties of the ions in the Neutron star crust using MD simulations. In our model the ions interact via a Yukawa potential. We obtained the thermal conductivity, diffusion coefficient and shear viscosity for a density range between 10^9 to 10^13 gm/cm^3. We expect to match results coming from quantum calculations by Prakash and Postnikov for the dilute gas. In the future we expect to generate results for the nuclear pasta phase.

Neutrino Emission due to Cooper Pair Breaking and Formation (PBF): Clarification

2007-07-05T10:13:00.000-07:00

One of the conclusions of my talk during the workshop was that the PBF rate in the vector channel is highly suppressed by a factor of V_F^4 (about 10_as described in the paper by Leinson and Perez (2006). Sedrakian and collaborators have revisted the problem. They also find the rate is suppressed relative to the calculation by Flowers, Sutherland and Ruderman by a factor of about 4 *10^-3 at densities of relevance to the crust.

Crosstalk

2007-07-05T09:43:00.000-07:00

From Friday, June 29th:

Jean in' t Zand. Observations of Rare and Peculiar X-ray Bursts.
Many of the details of X-ray bursts are not understood, and many of these may have nuclear physics explanations.

Randy Cooper. Generation of Type 1 X-ray Burst Oscillations.
For nuclear theorists: These oscillations are exciting for nuclear theorists, because they can constrain neutron star compactness, and so contain information about the nuclear EOS, in a way which is complementary and independent of methods heard this week.

Erik Kuulkers. INTEGRAL Galactic Bulge Monitoring Program.
For nuclear theorists: the high energy sky changes from time to time.

Fang Peng. Weak Hydrogen-Powered Explosions on Accreting Neutron Stars.
For Nuclear theorists: X-ray burst modeling depends on the heating from the crust.
For Astronomical observers: Observations of the following phenomena would be useful in constraining burst models: X-ray bursts in low-luminosity sources, search for long bursts, weak H flashes, or peculiar bursts, need high resolution light curves.

Andrew Cumming. Nuclear Burning on Accreting Nuetron Stars.
For nuclear theorists: people working the proton rich side, particularly on rp-processes, we need to understand the timescales for the different processes in rp-process burning. Also on the neutron rich side, we need to understand the crustal processes which produce the heat flux at the base of the crust, to help us explain KS 1731-260.

A problem: H and He is clearly burning stably at 0.1-0.2 of the Eddington accretion rate (i.e., at low temperature in the atmosphere); but we expect to only burn stably at accretion rates at the Eddington rate (at a much higher temperature in the atmosphere). How is it able to burn stably at such a low accretion rate?

Sudip Bhattacharyya. Probing Neutron Star Physics Using Thermonuclear X-ray Bursts. For nuclear theorists: produce mass-radius relationships using only up-to-date physics for neutron stars, strange stars and hybrid stars (quark cores, normal matter in the atmosphere/crust). In other words, please specify which models have outlived their assumptions.

That's the question

2007-07-04T11:05:00.000-07:00

If you suddenly find yourself awake at night and
frantically try to remember what that crucial question
(or quest in my opinion) was, well, now you can
here it over and over again, and you'll never
forget: Bob's quest.
Enjoy!

July 4th Party

2007-07-03T13:07:00.002-07:00

Prakash and Dany Page invite program participants to a July 4th party at their place:

July 4th Party and BBQ.
3pm-
Madappa Prakash and Dany Page
4227 Dayton Ave.
(Intersecton of 42nd St. & Fremont Ave, leads to Daton Ave).
Ph: (206) ~~632-5055~~ CORRECTION 634 0515.
Please feel free to bring: whatever you like, though basic BBQ meats and beer will be present (check with Dany and Prakash).

Directions.
Bus #44 on 45th St. is useful, but it will follow the Sunday schedule due to the holiday.

Crosstalk

2007-07-02T17:24:00.000-07:00

J. Henderson - Solving the Mysteries of Ultra-Magnetized Neutron Stars - Heat Transport inside the Crust.
The addition of a toroidal component to the crustal field can sufficiently reduce the radius of the hot emitting areas on the NS surface to possibly explain some observations (i.e. "The Magnificent Seven").
To Observational Astronomers: Keep doing what you're doing.

Alexandros Gezerlis - Neutron Star Matter Superfluidity: from BCS to QMC.
Microscopic simulations of the 1S0 zero-temperature neutron-matter pairing gap show it to be larger than that calculated within all the previous formalisms.
To Observational Astronomers: to quote Chuck Horowitz, "Astronomers should ask nuclear physicists two questions: (1) Are your results model dependent, and (2) What are your theoretical error bars?"

Talks This Week

2007-07-02T10:09:00.000-07:00

Monday July 2
10:30. C421. J. Henderson (UAM). Solving the Mysteries of Ultra-Magnetized Neutron Stars?
and A. Gezerlis (LANL). Neutron Star Matter Superfluidity: from BCS to QMC. Each 30 min + 15 min for questions.

Tuesday, July 3
10:30. C421. P. Moller (LANL) Large-scale calculations of nuclear-structure data for simulation data bases
and Sanjib Gupta (LANL). Composition dependence of Neutron Star Deep Crust Crustal Heating.

Wednesday, July 4
Holiday. INT Closed.

Thursday, July 5
10:30. C421. Sergey Postnikov (Ohio). Thermal and Transport Properties of a Non-Relativistic Quantum System
and Liliana Caballero (Indiana U). Transport Properties of Dense Plasmas

Friday, July 6
10:30. C421. George Melikidze (University of Zielona Gora). Partially Screened Polar Gap and its Observational Consequences
and Janusz Gil (J. Kepler Institute of Astronomy). X-ray Pulsar Radiation from Hot Polar Caps Heated by Back-Flow Bombardment.

Arrivals and Departures

2007-07-02T09:33:00.000-07:00

Below is the list of arrivals and departures of those in residence at the INT, which occurred as of Monday July 2, in comparison with this previous posting.

Arrivals: Lirio Aparicio (UNAM), Liliana Caballero (Indiana U), Andrew Cumming (McGill), Alex Gezerlis (LANL), Janusz Gil (Kepler Institute), Sanjib Gupta (LANL), Jillian Anne Henderson (UNAM), Charles Horowitz (Indiana U), Jim Lattimer (SUNY Stony Brook), Kseniya Levenfish (Ioffe), Zachary Medin (Cornell), George Mlikidze (University of Zielona Gora), Peter Moller (LANL), George Pavlov (PSU), Jorge Piekarewicz (Florida State), Sergey Postnikov (Ohio), Madappa Prakash (Ohio), Sanjay Reddy (LANL), Nikolai Sandulescu (Institute of Atomic Physics), Alex Turbiner (UNAM), Roberto Turolla (INFN Padova).

Departures: Werner Becker, Chris Fryer, Aimee Hungerford, Jerome Margueron, Vyatcheslav Zavlin, Joseph Carlson.

Crosstalk

2007-06-28T19:42:00.000-07:00

E. Cackett: Crustal cooling in accretion heated neutron stars.
Quasi persistent sources provide a rare opportunity to observe crustal cooling ... and we think we've measured the thermal relaxation time of the crust in 2 sources.

A. Steiner: Symmetry energy, crust thickness and KS 1731.
The physics of neutron star crusts is very thorny, the theorist have much work to do, yet we are a vibrant community which is making progress! Keep the observations coming, contact us with questions or concerns anytime. Don't give in to dark energy.

N. Sandulescu: Nuclear Superfluidity and Cooling Time of Neutron Star Crust.
No conclusions but in summary: Pairing in the crust can significantly change the thermal diffusion time.

C. Heinke: Constraints on Neutron Star Physics from Transiently.
Accreting Neutron Stars in Quiescence.
Messages:

Zero-B hydrogen-atmosphere models are trustworthy.

M,R constraints from neutron stars in globular clusters are sound and getting interesting

Cooling rates for soft x-ray transients are strictest constraints and disallow minimal cooling.

Questions:

What range of nuclear EOS are considered reasonable.

K. Levenfish: Thermal steady-states of neutron stars in soft X-ray transients vs deep crustal heating.
Proton superfluidity is strong in the core and neutron superfluidity weak.

E. Brown: Crust electron captures: Implications for superbursts and transient lightcurves.
For the nuclear physicists:
Transport properties: what is the thermal conductivity of pasta (and sauce) - are there reasonable upper and lower limits. Need better understanding of the crust/core interface.

For the astrophysicists
Need larger sample of superburst and burst at low accretion rates. Synthesis of disparate observations: isolated cooling neutron stars, magnetars, X-ray bursters, X-ray transients share the same nuclear physics.

S. Reddy. Weak interactions in superfluids and cooling rates in the inner crust.
Neutrino rates in matter can differ by factors of a few but if larger factors are proposed - be skeptical - ask lots of questions.

Forget about about PBF in the vector channel.

J. Dey: Stellar and terrestial observations from the mean field large colour QCD models.
For astrophysicists: Observations are good.
For nuclear model people: u r doing well.
For phenomenologist like us the message is: look for discrepancies and try simple QCD models.

Tomorrow's Talks

2007-06-28T17:43:00.000-07:00

9:00. Jean in' t Zand. Observations of Rare and Peculiar X-ray Bursts.
10:00. Randy Cooper. Generation of Type 1 X-ray Burst Oscillations.
11:00. Erik Kuulkers. INTEGRAL Galactic Bulge Monitoring Program
12:00. Fang Peng. Weak Hydrogen-Powered Explosions on Accreting Neutron Stars.
2:00. Andrew Cumming. Nuclear Burning on Accreting Nuetron Stars.
3:00. Sudip Bhattacharyya. Probing Neutron Star Physics Using Thermonuclear X-ray Bursts.
4:00. Discussion.
Conference Close.

Tomorrow's Talks

2007-06-27T18:35:00.000-07:00

9:00. Ed Cackett. Crustal Cooling in Accretion Heated Neutron Stars.
10:00. Andrew Steiner. Symmetry Energy, Crust Thicknesses, and KS 1731-260.
11:00. Nikolai Sandulescu. Nuclear Superfluidity and Cooling Time of Neutron-Star Crust.
11:30. Craig Heinke. Constraints on Neutron Star Physics from Transiently Accreting Neutron Stars in Quiescence.
12:00. Kseniya Levenfish. Thermal Steady-States of Neutron Stars in SXTs vs. Deep Crustal Heating.
2:00. Ed Brown. Crust Electron Captures: Implications for Superbursts and Transient Lightcurves.
3:00. Sanjay Reddy. Weak Interactions in Superfluids and Cooling Rates in the Inner Crust.
3:30. Jishnu Dey. Stellar and Terrestrial Observations from the Mean Field Large Colour QCD Models.
4:30. Discussion.

Crosstalk

2007-06-27T11:47:00.000-07:00

Vicky Kaspi. Magnetars. For nuclear theorists: Magnetars may have relevance to the EOS.

Anna Watts. Magnetar Seismology. For nuclear theorists: If we really are seeing NS starquakes, then we have a fantastic new probe of crust physics. Also, I would like to know:
* How and when the Crust yields
* The Shear Modulus of your favorite crust models
* What precisely is going on at the crust/core boundary.

Jeremy Heyl. QED Can Explain the Non-Thermal Emission from SGRs and AXPs.
For Nuclear Theorists: Does nuclear material have a gap? I don't care whether it's 0.5 or 2 MeV.
* Is the proton superconductor Type I or Type II? If Type II, do currents along vortices make it act like Type I?
* Where is the quark-hadron phase transition? Sure the quark phase has lots of structure, but it may be completely irrelevant.

For Observational Astronomers:
* Should I really believe these lines, periods, Pdots, error bars?
* Rare systems are great! Get me more? How about some eclipsing binaries in globular clusters, or really young cooling neutron stars.
* Coordinated timing campaigns as BATSE did for accreting neutron stars.

Roberto Turolla. X-ray Spectra from Magnetar Candidates.
For nuclear theorists: It would be a great help to have a detailed model of the corona of the magnetosphere.

Silvia Zane. SGRs Long Term Spectral Variability.
For Nuclear Theorists: I would like to understand better the effect of a strong magnetic field on the interior of the neutron star.

Equation of State from Heavy Ion Collisions

2007-06-27T06:28:00.000-07:00

"If Bill Lynch were here..." - Madappa Prakash

There is much effort going in to determining the equation of state of matter (and the density dependence of the symmetry energy) in the heavy-ion community (of which Bill is an integral part). Heavy-ion collisions can potentially determine the EOS up to possibly a few times saturation density and Bill's famous Science paper is here. I (along with others) spoke a bit about this in Catania (EXOCT'07), but will not have time to do so here. For those of you who are interested, there is a simple and brief discussion about heavy-ion collisions in Jim and Prakash's recent contribution to the Hans Bethe volume.

- Andrew Steiner

a glossary for neutron star physics

2007-06-26T23:24:00.000-07:00

I find that it is a very nice idea to bring together neutron star observers, astrophysicists and nuclear physicists. It is a very rare opportunity to discuss
but I think that it may be even better to try to write up a short glossary of the present terminology used in the field. This is of course constantly renewing, mainly for the observational part, new objects are discovered, new classes show up, ... But it could be of interest for our communication to define the 20-30 items mostly used and have 5 lines of description. It would fix the 2007 terminology and could be renewed every year.
In practice, the idea would be that each of the participants contribute to 1 item during the workshop, then we collect all the items, built a glossary, and that's done !

Tomorrow's Talks

2007-06-26T21:21:00.000-07:00

9:00. Vicky Kaspi. Magnetars
10:00. Anna Watts. Magnetar Seismology
11:00. Jeremy Heyl. QED Can Explain the Non-Thermal Emission from SGRs and AXPs.
11:30. Roberto Turolla. X-ray Spectra from Magnetar Candidates.
12:00. Silvia Zane. SGRs Long Term Spectral Variability.
12:30. David Eichler. What Can We Learn about Magnetar Crusts from the QPO Component of their Flare Emission? (Withdrawn).

My notes on a wiki

2007-06-26T14:07:00.001-07:00

Hi,

I have been taking notes on the talks on my wiki at the following URL

http://tabitha.phas.ubc.ca/wiki/index.php/INT_-_Neutron_Star_Crust_and_Surface

that others might find useful.

Jeremy

Crosstalk

2007-06-26T10:51:00.000-07:00

Chuck Horowitz: Neutron Rich Matter and Neutron Star Crusts.
To observational astronomers: Astronomers should ask nuclear physicists two questions: (1) Are your results model dependent. and (2) What are your theoretical error bars?

Jorge Piekarewicz:The Impact of Terrestrial Facilities on the Structure of the Neutron Star Crust
To observational astronomers: The new facilities (like RHIB) will constrain the low density EOS. We need nice neutron star M-R measurements to constrain the high-density EOS, and the observational astronomy approaches are the only ones I know which can produce these constraints.

Jim Lattimer: Observational Constraints on the Neutron Star Crust and their Implications for the Dense Matter Equation of State.
We desparately need a radius measurement, even without a mass measurement, because it can provide a reasonable constraint on the EOS.

K. Sato: Nuclear "Pasta" Phases by Quantum Molecular Dynamics.

To observational astronomers: It would be very valuable to have observational constraints on what densities the pasta phase occurs [ed.: it is noted that this will be difficult, since it is not yet clear what observable can provide a unique signature of the pasta phase.]

Bennet Link. The Dynamics of Vortex Pinning in the Neutron Star Crust.
To observational astronomers: Please identify rotational and seismic modes (observationally!).
To Nuclear Theorists: fully solve the vortex/nucleus interaction problem.

Steve Price. Time-correlated Structure in Spin Fluctuations of an Isolated Neutron Star.
To nuclear theorists: In the future, we will assume some physical value for the torque, and be able to constrain the value of the reduce the moment of inertia. This should constrain the ratio of the core moment of inertia to that of the crust.

Alex Turbiner. One-Two Electrons Atomic-Molecular Systems in a Strong Magnetic Field.
To observational astronomers: At B-fields between 1e12 and 4.4e13 G of two-electron systems, all basic transitions, dissociations and ionization energies have energies between 100-1000 eV.

Marcello Baldo. Microscopic Theory of the Neutron Star Inner Crust.
To observational astronomers: We can calculate in a reliable way the Equation of State of the crust (pressure vs. density); however, the more detailed physics (such as the shear modulus) is still not well known.

Jerome Margueron. Equation of State in the Inner Crust of Neutron Matter: Discussion of the Finite Size Effects. What is interesting in thisese models is the impact on predictions regarding cooling processes (see talk by N. Sandulecu).

Chris Fryer. After the Shock, Magnetic Fields and Fallback on Newly Formed Neutron Stars.
To observational astronomers: Anything you can tell me about Cas A (is it a magnetar?) will help me constrain SNe models. To nuclear physicists: are there any effects of fallback on nucleosynthetic yields?

Aimee Hungerford. Neutrino Scattering in Proto-Neutron Stars.
To observational astronomers: Self-regulation was a bit of surprise to us, but it seems one cannot learn very much about the interior equation of state from neutrino observations.

Blogging and Relevancy

2007-06-26T07:26:00.001-07:00

I'd like to point out that, so far, there haven't been any posts by anyone other than myself -- some for information, some for commentary.

But I've heard about 4-5 different people say "We should have a discussion about XX" on various subjects. While it's reasonable to want to have the discussion live-time, this is actually the perfect form to start such discussions. As I've written before, this blog is open to any topic of any type related to the workshop. Twenty-two of the conference goers -- about half -- have signed on.

Update: All program participants and conference attendees should have received (by email) an invitation to be able to post. If you have not, send me an email.

Today's Talks

2007-06-26T07:10:00.000-07:00

Today's Talks for the workshop conference:

9:00. Chuck Horowitz. Neutron Rich Matter and Neutron Star Crusts

10:00. Jorge Piekarewicz. The Impact of Terrestrial Facilities on the Structure of the Neutron Star Crust

11:00. Jim Lattimer. Observational Constraints on the Neutron Star Crust and their Implications for the Dense Matter Equation of State.

12:00. Katsuhiko Sato. Nuclear "Pasta" Phases by Quantum Molecular Dynamics.

2:00. Bennet Link. The Dynamics of Vortex Pinning in the Neutron Star Crust.

2:30. Steve Price. Time-correlated Structure in Spin Fluctuations of an Isolated Neutron Star.

3:00. Alex Turbiner. One-Two Electrons Atomic-Molecular Systems in a Strong Magnetic Field.

4:00. Marcello Baldo. Microscopic Theory of the Neutron Star Inner Crust.

4:30. Jerome Margueron. Equation of State in the Inner Crust of Neutron Matter: Discussion of the Finite Size Effects.

5:00. Chris Fryer. After the Shock, Magnetic Fields and Fallback on Newly Formed Neutron Stars.

5:30. Aimee Hungerford. Neutrino Scattering in Proto-Neutron Stars.

Crosstalk

2007-06-25T16:50:00.000-07:00

Throughout the conference, I am asking all observational astronomers, "What single most important fact do you want our nuclear theorist colleagues to take away from your talk?". Also, I am asking all nuclear theorists the similar question, what observational astronomers should take away from their talks.

This is the compendium of responses from the first day.

David Kaplan:
To nuclear theorists: Things are a lot more complicated than we thought five or ten years ago, but we are making progress and learning a lot.

Slava Zavlin: X-ray emission from the young pulsar J1357-6429 and similar objects.
To nuclear theorists: Be cautious in interpreting numbers from observations. There are many systematic uncertainties.

Dong Lai: Surfaces of Magnetic Neutron Stars.
To nuclear theorists: There is a lot of interesting physics to be explored regarding the condensed surfaces of neutron stars.

Eric Gotthelf: CCO pulsars as anti-magnetars: Evidence of Neutron stars Weakly Magnetized at Birth.
To nuclear physicists: Emission mechanisms for CCOs, magnetars and INSs are something which we don't understand, and what we need to know, to explain these classes of NSs jointly.

H.-J. Schulze: Pairing Gaps in Neutron Star Matter.
To observational astronomers:
Polarization effects suppress the BCS gaps. This will impact cooling, and observations of glitches.

Achim Schwenk: Superfluidity in neutron stars.
To observational astronomers:
1. There are many developments attempting S-wave pairing.
2. Neutrons may not be superfluid in the core.
3. Nuclear Theory is now trying to do calculations without model dependence, but including systematic uncertainties.
4. I would like to know what observational constraints exist on pairing in superfluid neutrons.

Enrico Vigezzi. Pairing Calculations Beyond Mean Field in the Inner Crust.
To observational astronomers:
1. Listen to the next talk (Barranco).
2. The specific heat in superfluid neutrons can be influenced due to the presence of nuclear clusters, by 1-2 orders of magnitude.
3. Be cautious about the local density approximation.

F. Barranco: Microscopic Calculations of Vortex-Nucleus Interaction.
To observational astronomers:
1. The pinning energy is not negative at > 0.03 fm-3 as previously thought; it is apparently positive.
2. Consequences in terms of glitch properties will be discussed by Bennet Link tomorrow. But, pinning is simply much less likely, only very weakly, and in a much smaller volume. Bennet will argue that pinning is very difficult to ever occur in this scenario. In other words, pinning would have nothing to do with glitches in the crust.

Joe Carlson. Pairing gaps in low-density neutron matter and cold atoms
To observational astronomers:
A question: The laboratory experiments using cold atoms will solve the problem of low density s-wave pairing caps -- is that useful in an astrophysical setting?

Monday's Talks

2007-06-22T14:03:00.000-07:00

Monday is the first day of the workshop conference, The Neutron Star Crust and Surface: Observations and Models. There will be nine speakers, including 3 reviews.

9:00am. David Kaplan. Nearby, Thermally Emitting Neutron Stars

10:00am. Slava Zavlin. X-ray emission from the young pulsar J1357-6429 and similar objects

11:00am. Dong Lai. Surfaces of Magnetic Neutron Stars

12:00pm. Eric Gotthelf. CCO Pulsars as Anti-magnetars: Evidence of Neutron Stars Weakly Magnetized at Birth

2:00pm. H-J. Shulze. Pairing Gaps in Neutron Star Matter

3:00pm. F. Barranco. Microscopic Calculation of Vortex-Nucleus Interaction

4:00pm. Achim Schwenk. Superfluidity in neutron stars

4:30pm. E. Vigezzi. Pairing calculations beyond Mean Field in the Inner Crust

5:00pm J. Carlson. Pairing gaps in low-density neutron matter and cold atoms

Conference Location

2007-06-21T16:57:00.000-07:00

The location of the Workshop Conference, "The Neutron Star Crust and Surface: Observations and Models", next week is mapped here and here, the red-circled auditorium, which is one of the three wings of the Physics and Astronomy Building on the University of Washington Campus.

Tommorrow's Talks

2007-06-21T12:05:00.000-07:00

Friday. 10:30 am. Slava Zavlin (MSFC). "Thermal X-ray Emission from Isolated Neutron Stars". C421.

July 12: Nuclear Reactions in Type-I X-ray Bursts

2007-06-21T09:45:00.000-07:00

Nuclear Reactions in Type I X-ray Bursts
Mini-workshop at the INT Program The Neutron Star Crust and Surface
July 12
Room C421, Physics and Astronomy Building, University of Washington.

Thermonuclear burning in the atmospheres of neutron stars
accreting H- and He- rich matter from companions in X-ray binaries
determines the chemical makeup of the neutron star atmospheres and crusts. A quantitative understanding of these thermonuclear processes -- in particular, the breakout from the CNO cycles and the subsequent rapid proton capture process -- is needed to ascertain the properties of the atmosphere and crust. This mini-workshop will focus on completed and future nuclear physics experiments, and how their results impact processes in the neutron star crust and atmosphere.

The workshop will be centered around short talks scheduled on a timetable, but with the intention of expanding into the rest of the day, in both formal and informal discussions.

Speakers:
10:30-11:00 Barry Davids (TRIUMF)
11:15-11:45 Chris Ruiz (TRIUMF)
2:00-2:30 Ed Brown (MSU, JINA)
2:30-3:00 Andrew Cumming (McGill)
3:00-3:30 Randall Cooper (Harvard/CfA)
3:30-5:00 Coffee & Discussion

==ABSTRACTS===
Barry Davids (TRIUMF)
Experimental Efforts to Determine the 15O(a,g)19Ne Reaction Rate

I will review worldwide efforts to ascertain the rate of this nuclear
reaction, which apparently plays a critical role in the ignition of Type-I
X-Ray Bursts. As direct measurements are not yet possible,
indirect measurements have been the only option. I will present these
experiments in a manner I hope will be comprehensible to observational
astronomers and theoretical astrophysicists.

Chris Ruiz (TRIUMF)
Nuclear Astrophysics of neutron-deficient nuclei - experimental
approaches at ISAC

To give observational astronomers and theoreticians a taste of what experiments in Nuclear Astrophysics consist of, I will present an overview of the DRAGON and TUDA facilities at TRIUMF-ISAC. I will discuss how these measurements pertain to reactions and observables in novae and x-ray bursts, highlighting the considerable challenges in making these crucial measurements, and developing the accelerated beams. I will also describe future endeavors to measure Q-values of (p,$\gamma$) reactions taking
place in the &\nu$-rp process using the TITAN facility.

Ed Brown (MSU, JINA)
The X-ray Burst—Crust Connection

The crust of an accreting neutron star is composed of the ashes of X-ray bursts. The heating from electron captures in the crust depends sensitively on the composition of these ashes. In turn, the heating in the crust influences the ignition of bursts for which H is not consumed steadily by the HCNO cycle, for example, superbursts and X-ray bursts from low mass accretion rate systems. I will describe the relation between the burst composition and the crustal heating, and speculate on what may happen in the inner crust.

Andrew Cumming (McGill)
Constraints on the rp-process from X-ray Bursts

I discuss the ways in which X-ray burst observations potentially constrain the rp-process. In particular I will show comparison of model X-ray burst lightcurves with observations of GS 1826-24, and then discuss current constraints on the amount of carbon needed to power superbursts, which is critically dependent on the duration of the rp-process path.

Randall Cooper (Harvard/CfA)
Nuclear Reactions During the Onset of Type I X-ray Bursts

I will review our current understanding of the physics of the
onset of type I X-ray bursts, with an emphasis on the pertinent nuclear
reactions. In particular, I will discuss the roles that both the hot CNO
cycles and their breakout reactions 15O(a,g)19Ne and 18Ne(a,p)21Na play in
the stability of thermonuclear burning and the
rising phase of X-ray bursts.

Tommorrow's Talks

2007-06-20T14:10:00.000-07:00

Thursday, 10:30am. Werner Becker (MPE) "X-ray Emission Properties of Old Pulsars". C421.

Tommorrow's Talks

2007-06-19T17:30:00.000-07:00

Wednesday, 10:30am. Bob Rutledge (McGill) "Calvera: An Isolated Compact Object of Indeterminate Type". C421.

Open Thread: Conference-Related Topics

2007-06-19T09:56:00.000-07:00

Next week (June 25-29), we are hosting the workshop conference, "The Neutron Star Crust and Surface: Observations and Models." [Link.] We have 54 confirmed attendees, 12 review talks, and 31 special topics talks scheduled.

But are you going to hear what you want to hear about? You can examine the abstract list, and hope -- but even better, use the comment section of this thread to lay down subjects that you would like to hear speakers address. Or lay-in about what isn't going to be addressed, but should have been. Or talk about how thrilled you are the Mariners have a home week June 25-29.

Pre- Conference-related discussion.

Tommorrow's Talks

2007-06-18T13:53:00.000-07:00

Tuesday, 10:30 am. Dany Page (UNAM) "Cooling of Neutron Stars: Pairing vs. Magnetic Fields". C421.

Lunch Discussion: eROSITA

2007-06-18T13:24:00.000-07:00

Werner Becker and Salva Zavlin talked about eROSITA (extended ROentgen Survey with an Imaging Telescope Array), a new 0.2-12 keV all-sky-survey which is a joint mission of MPE and IKI, approved a few months ago. The mission will use XMM-type optics (15" on-axis resolution, 20" FOV average; 2500 cm^2) with advanced pn detectors, and survey the full sky over 4 years, with a slated launch in 2011. MPE will provide the optics (7 separate mirror modules) and detectors, IKI will provide the bus and platform, which will also contain a Lobster-style all sky monitor.

Arrivals and Departures

2007-06-18T11:13:00.000-07:00

Arrivals: Dany Page (UNAM), Bob Rutledge (McGill), Werner Becker (MPE), Chris Fryer (LANL), Aimee Hungerford (LANL), Jerome Margueron (Institute de Physique Nucleaire d'Orsay), Vyatcheslav Zavlin (MSFC), Joseph Carlson (LANL; Thursday).

Departures: None.

UPDATE: Arrivals: Michael Forbes, in residence at INT (UW).

The Neutron Star Crust and Surface 2007

2007-06-17T08:08:00.000-07:00

Welcome to the blog on The Neutron Star Crust and Surface Program, held at the Institute for Nuclear Physics at the University of Washington, Seattle, June 18-July 25th 2007.

This is a bit of an experiment -- is a blog a good forum for documenting a research workshop? Does it improve communication among participants, and between participants and people outside? Leave a comment about what you came here to see, and what you will be looking for here.