Day 31

Monday, but I'm going to hang out with my parents in Seoul today.


1106.5790
Stable heating of cluster cooling flows by cosmic-ray streaming
Fujita, Ohira


* Alfven waves: a type of magnetohydrodynamic wave.  Alfven wave in a plasma is a low-frequency (*not* ion cyclotron frequency) traveling oscillation of the ions and the magnetic field.  Ion mass provides the inertia; magnetic field line tension provides the restoring force.  Wave propagates in the direction of the magnetic field (transverse waves are called magnetosonic waves).  Motion of the ions and perturbation of the magnietic field are the same direction and transverse to the direction of propagation, respectively.  The wave is dispersionless.  For illustration see:
 http://www.physics.carleton.ca/~watson/Physics/Astrophysics/4201_Stellar/4201_thesun2.html?id=0


CRs generated by AGN, and move out with Alfven waves, which become excited by the CR streaming and becomes non-linear.  Large Alfven velocity can heat the entire core if magnetic fields are large enough.  Without thermal conduction, CR streaming can stably heat both high and low temperature clusters for a long (?) time, preventing massive cooling flows.  If there is conduction, heating is stabilized further--CR is insensitive to the change of intracluster medium, and the heating term density dependence is similar to that of radiative cooling.


* CR can excite Alfven waves which can then heat the cluster.  
* It assumes there is a magnetic field to begin with.  What is the origin of the magnetic field?  
* Radio signal is a signature of magnetic field (movement of e- causes synchrotron radiation), which is the origin of the expected cooling flow (radiation cooling).


1106.5791
Detected fluctuations in SDSS LRG magnitudes: Bulk flow signature or systematic?
Abate, Feldman


There is a signature for large scale bulk flow in the SDSS LRG (z>0.08) at v_b>4000 km/s, which doesn't make sense--it's too large.  Signature taken from the fluctuations of the magnitudes of distant LRG's.  Direction of flow agrees with previous studies by different authors: alpha_b = 180, delta_b = -50.  Need more data.


* Well, if the bulk flow anomaly is based on photometry, then must check photometry.  Maybe there is a large scale calibration issue (galactic extinction, etc).  


1106.5836
Searching for fast radio transients with SKA phase 1
Colegate, Clarke


SKA low-cost radio transit search optimization: can be done with existing specs; use incoherent combination of antenna signals for highest event rate per beam.  Low frequency aperture arrays effective for extragalactic searches.  Dishes more effective for directions of increased scatter broadening, such as near the galactic plane.