This Week in the Universe: August 17th – August 23rd

Astrophysics and Gravitation:

Neighbouring Solar System Looks a Lot Like Ours

Lo Curto, G., Mayor, M., Benz, W., Bouchy, F., Lovis, C., Moutou, C., Naef, D., Pepe, F., Queloz, D., Santos, N., Segransan, D., & Udry, S. (2010). The HARPS search for southern extra-solar planets XXVII. Astronomy and Astrophysics manuscript no. HD10180

Image Credit: ESO Exo-Planet Press Kit 2010

Not exactly astrophysics, but the observations couldn’t exist without it.  ESO’s HARPS instrument has its latest exoplanet find in the form of at least five planets orbiting the sun-like star, HD 10180, in the Milky Way.  There are also two other possible candidates in the HD 10180 system taking the planet count up to a possible seven, including the lightest possible candidate exoplanet to date.  This is the first time that we’ve been able to observe a solar system so similar to our own.  It’s exciting because it helps confirm much of what we thought about solar system formation (that for a star like ours, the system should look pretty similar to our own).

For more, see ‘Seven planets’ in new solar system, ScienceShot: Neighboring Solar System Resembles Ours, Richest Planetary System Discovered (Press Release), ESO Exoplanet Press Kid [pdf].

Pulsars Still Proving Useful

D. J. Champion, G. B. Hobbs, R. N. Manchester, R. T. Edwards, D. C. Backer, M. Bailes, N. D. R. Bhat, S. Burke-Spolaor, W. Coles, P. B. Demorest, R. D. Ferdman, W. M. Folkner, A. W. Hotan, M. Kramer, A. N. Lommen, D. J. Nice, M. B. Purver, J. M. Sarkissian, I. H. Stairs, W. van Straten, J. P. W. Verbiest, & D. R. B. Yardley (2010). Measuring the mass of solar system planets using pulsar timing Astrophysical Journal arXiv: 1008.3607v1

From the introduction:

The technique of pulsar timing can provide precise measurements of the rotational, astrometric, and orbital parameters of a pulsar by modeling the observed pulse times of arrival (TOAs). The basic timing analysis provides a fittable parametric model of delays associated with variations in the Euclidean distance between the pulsar and the Earth (resulting from Earth’s orbital motion, the proper motion of the pulsar, and its binary motion), dispersive delays in the interstellar medium, and general relativistic time dilation of clocks in the observatory and pulsar frames and along the propagation path.

Basically, signals from pulsars can be used to measure a variety of properties.  Charles Horowitz of Indiana University, Bloomington:

[Using pulsar-timing data,] you don’t even have to see the object, or even know it is there, to feel its gravitational effects.

For more, see Pulsar Signals Could Reveal Solar System Secrets.

Video: Waves in a Molecular Cloud

Berné O, Marcelino N, & Cernicharo J (2010). Waves on the surface of the Orion molecular cloud. Nature, 466 (7309), 947-9 PMID: 20725034

A paper in Nature this week reports the presence of ‘waves’ (Kelvin–Helmholtz instabilities) at the surface of the Orion molecular cloud, where massive stars are forming.  A pretty video of this is made.

For more, see Video: Surf’s Up for Massive Stars.

Missing Black Hole?

B. W. Ritchie, J. S. Clark, I. Negueruela, & N. Langer (2010). A VLT/FLAMES survey for massive binaries in Westerlund 1: II. Dynamical constraints on magnetar progenitor masses from the eclipsing binary W13 Astronomy & Astrophysics arXiv: 1008.2840v1

More from the ESO, astronomers are wondering why a once super massive star in the constellation Ara never became a black hole after exploding as a supernova.  The star in question, believed to once 40 times as massive as our sun is now a magnetar, despite prevailing theory predicting it should have become a black hole.  This is strongly suggestive of the fact that the current theory of gravitational collapse in astrophysics is not quite correct.  This is certainly not the only piece of evidence to suggest this, as there is still no good explanation for why we should see matter collapse into a black hole, in finite time, at all.

For more, see The Mystery of the Absent Black Hole.

Galactic Volcano

Credit: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen)

This image shows the eruption of a galactic “super-volcano” in the massive galaxy M87, as witnessed by NASA’s Chandra X-ray Observatory and NSF’s Very Large Array (VLA).

NASA’s Chandra X-ray Observatory and NSF’s Very Large Array have observed highly energetic jets coming from, what is assumed to be, the black hole inside Messier 87.

From the Press Release:

In the analogy with Eyjafjallajokull, the energetic particles produced in the vicinity of the black hole rise through the X-ray emitting atmosphere of the cluster, lifting up the coolest gas near the center of M87 in their wake, much like the hot volcanic gases drag up the clouds of dark ash. And just like the volcano here on Earth, shockwaves can be seen when the black hole pumps energetic particles into the cluster gas.

Aurora Simionescu of the Kavli Institute:

This analogy shows that even though astronomical phenomena can occur in exotic settings and over vast scales, the physics can be very similar to events on Earth.

Perhaps more importantly, it makes for a pretty picture.

For more, see Galactic Super-volcano in Action.

High Energy Physics and Particles:

Neutrinos Interact with Radioactive Elements?

Ephraim Fischbach,, Peter A. Sturrock,, Jere H. Jenkins,, Daniel Javorsek II,, John B. Buncher,, & John T. Gruenwald (2010). Evidence for Solar Influences on Nuclear Decay Rates Fifth Meeting on CPT and Lorentz Symmetry : 1007.3318

In a series of rather surprising finds, Jenkins, Fischbach et al. have shown that there appears to be a relationship between solar flare activity and radioactive decay rates for certain elements.   Back in 2006, while observing the decay of Manganese-54, Jenkins’ team noticed that the decay rate dropped during a solar flare, corresponding to an increase in solar neutrinos hitting the detector.  These results are now no longer believed to just be due to some apparatus error or environmental factors in the detection system, but actually somehow connected to solar flare activity from the sun.  Neutrinos are the most likely candidate, since we know that they are actually there, but we also know that they don’t really interact with much.  There is nothing in the Standard Model to suggest that neutrinos should effect radioactive elements in a way that could influence decay rates.  There is also talk of some yet unknown particle that may also be produced in the sun that is interacting in these systems, but there is nothing within conventional particle physics to suggest what this may be.  There is still obviously a chance  that neutrinos (or something else) are just interfering with the detection mechanism (although the authors feel they have ruled this out), but there is also an interesting chance that there is some new neutrino physics being observed here.  This is something to keep an eye on.

For more, see The strange case of solar flares and radioactive elements, The strange case of solar flares and radioactive elements (Press Release).

Challenge to Neutron Theory

P. E. Koehler, F. Bečvář, M. Krtička, J. A. Harvey, & K. H. Guber (2010). Anomalous fluctuations of s-wave reduced neutron widths of $^{192,194}$Pt resonances Phys. Rev. Lett. , 105 (7) arXiv: 1007.3675v1

By using neutron beams to measure the strength of neutron resonances, Koehler’s group notes that random matrix theory does not seem to be applicable to neutron structure (with a 99.997% confidence level), noting that the nucleons seem to move in “a coordinated fashion”.

Paul Koehler:

There’s no viable model of nuclear structure that could explain this.

Basically, this is yet again another example of a currently accepted model in particle/nuclear physics not being sufficient to describe the full scope of physical reality.  This is exciting stuff.

For more, see Nuclear theory nudged.

General Relativity, Quantum Gravity, et al.:

Black Holes, Southern Ontario Style

Palenzuela, C., Lehner, L., & Liebling, S. (2010). Dual Jets from Binary Black Holes Science, 329 (5994), 927-930 DOI: 10.1126/science.1191766

The abstract:

The coalescence of supermassive black holes—a natural outcome when galaxies merge—should produce gravitational waves and would likely be associated with energetic electromagnetic events. We have studied the coalescence of such binary black holes within an external magnetic field produced by the expected circumbinary disk surrounding them. Solving the Einstein equations to describe black holes interacting with surrounding plasma, we present numerical evidence for possible jets driven by these systems. Extending the process described by Blandford and Znajek for a single, spinning black hole, the picture that emerges suggests that the electromagnetic field extracts energy from the orbiting black holes, which ultimately merge and settle into the standard Blandford-Znajek scenario. Emissions along these jets could potentially be observable at large distances.

Generally, I would relegate an article on black holes to astrophysics, but this one warrants actually being listed under general relativity.  That is because, if you noticed in the abstract, the authors are actually solving the Einstein equations, which is actually a rarity in work on black hole jets (strange, I know).  This is probably one of the most realistic treatments of black hole mergers done to date (and I swear, me saying that has nothing to do with the fact that it was done by UofT and Perimeter people).

Supporting Material

Snapshots illustrating the Poynting flux structure prior/after the merger takes place: Electromagnetic energy fluxes at times −5.6hrs and 2.3hrs (before/after merger). As the black holes orbit they induce a collimation which is evident by the tubes emanating from the central region. As the merger takes place, these tubes join and the orbiting behavior leaves its imprint in the twisting observed in the tubes.

For more, see A Tale of Two Jets.

Special Maths Acknowledgement:

At the International Congress of Mathematicians in India this week, the 2010 Fields Medallists were announced, along with the Nevanlinna, Gauss, and Chern Prize winners.  Like in previous years, these awards, which are considered to be some of the highest honours a mathematician can receive, acknowledged some great achievements in mathematical physics.

Fields Medalists 2010

• Elon Lindenstrauss – “For his results on measure rigidity in ergodic theory, and their applications to number theory.”
• Ngô Bảo Châu – “For his proof of the Fundamental Lemma in the theory of automorphic forms through the introduction of new algebro-geometric methods.”
• Stanislav Smirnov – “For the proof of conformal invariance of percolation and the planar Ising model in statistical physics.”
• Cédric Villani – “For his proofs of nonlinear Landau damping and convergence to equilibrium for the Boltzmann equation.”

Nevanlinna Prize 2010

• Daniel Spielman – “For smoothed analysis of Linear Programming, algorithms for graph-based codes and applications of graph theory for Numerical Computing.”

Gauss Prize 2010

• Yves Meyer – “For fundamental contributions to number theory, operator theory and harmonic analysis, and his pivotal role in the development of wavelets and multiresolution analysis.”

Chern Prize 2010

• Louis Nirenberg – “For his role in the formulation of the modern theory of non-linear elliptic partial differential equations and for mentoring numerous students and post-docs in this area.”

For more, see Prize Winners 2010, Fields Medals, Other Top Math Prizes, Awarded, Four mathematicians reap Fields Medals, What is the Langlands Programme?.

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