Day 69

Saturday.  No, wait, Sunday.  I slept away Saturday.  It's 2am now in Zürich.


UCB TAC seminar
3D simulations of solar surface: from limb to secular models
Laurent Piau (CEA-Saclay)


Stagger code: simulates 3D radiation hydrodynamics and magnetic field at the solar surface; addresses ionization effects, compressibility, solves equations of radiation transfer and induction.  Solar model atmospheres computed with OPAL EoS using the most recent solar composition (?).  Models account for the magnetic field.  Offer means of interpreting observations of space borne missions dedicated to solar surface dynamics.  Discuss impact of magnetism on limb darkening profile.  Effects of surface convection = "the surface term" in helio- and astroseismology; it must be understood well, and that can be done through modeling.


1108.4905
The lensing properties of the Einasto profile
Retana-Montenegro, Frutos-Alfaro


* Einasto profile: describes 3d profile rho(r) ~ exp(-Ar^alpha)
* NFW profile:  descries 3d profile
* Sersic profile:  describes surface brightness (projected density)


Derives surface mass density, deflection angle, lens equation, deflection potential, magnification, shear and critical curves of Einasto profile, which is hard because it is non-analytic for general values of the Einasto index.


1108.4688
The impact of massive neutrinos on the abundance of massive clusters
Ichiki, Takada


Spherical top-hat collapse model for a mixed DM model that includes neutrinos of mass 0.05 to 0.1 eV.  Take into account relative differences between the density perturbation amplitudes of radiation, baryon, CDM and neutrinos around the top-hat CDM overdensity, assuming adiabatic initial conditions.  Also solve Boltzmann hierarchy equations to obtain time evolution of neutrino perturbations, including late-time NL gravitational potential.  Presence of massive neutrion slows down the collapse of CDM overdensity: neutrinos cannot fully catch up with the NL CDM perturbation due to its large free-streaming velocity for the ranges of neutrino masses and halo masses considered.  The CDM overdensity collapse time is well monitored by the linear-theory extrapolated overdensity, smoothed for a given halo mass scale, taking into account the suppression effect of the massive neutrinos on the linear growth rate.  Presence of massive neutrinos of 0.05-0.1 eV cause significant decrease in the abundance of massive halos compared to model without the massive neutrinos: 25% for 1e15 Msun, or factor 2 for z=1.


1108.4864
Vesto Slipher and the First Galaxy Redshifts
Thompson


Hubble claimed credit of other astronomers (e.g., Slipher, Lemaitre, Humason...).


1108.4929
Cluster-Cluster lensing and the case of Abell 383
Zitrin, Rephaeli, Sadeh, Medezinski, Umetsu, Sayers, Nonino, Morandi, Molino, Czakon, Golwala


Assess the likelihood of cluster-cluster lensing (CCL).  Describe characteristics of CCLs in optical, X-ray and SZ measurements; calculate their predicted numbers for LCDM parameters and viable range of cluster mass functions and their uncertainties.  Several to a few dozen predicted; depends on lensing triaxiality, through the c-M relation.  Much larger number expected in the WL regime.  A383 is a possible CCL: BG high-z structures magnified as seen in Subaru.


1108.4990
The Principle of Mediocrity
Vilenkin


Combine multiverse with the principle of mediocrity, where many inflationary bubbles with diverse properties are constantly being formed.  Discuss origin of this worldview, possible observational tests, and implications for the beginning and end of the universe.


IPMU seminar (particle physics and string theory)
The monopole-vortex complex: dual gauge symmetry from flavor 
Kenichi Konishi (Pisa U.)


* gauge theory: a type of field theory in which the Lagrangian is invariant under a continuous group of local transformations.
* QED is an abelian gauge theory with the symmetry group U(1) and has one gauge field, the EM field, with the photon being the gauge boson.
* non-Abelian: the standard model is a non-abelian gauge theory with the symmetry group U(1) x SU(2) x SU(3) and has a total of twelve gauge bosons: the photon, three weak bosons, and eight gluons.


1108.2287
On the origin of the Salpeter slope for the initial mass function
Oey


Suggest that intrinsic stellar IMF follows a power-law slope gamma=2, inherited from hierarchical fragmentation of molecular clouds into clumps and clumps into stars.  The logarithmic Salpeter slope gamma=1.35 in clusters is the aggregate slope for all the star-forming clumps contributing to an individual cluster, and is steeper than the intrinsic slope within individual clumps within individual clumps because the smallest star-forming clumps contributing to any given cluster are unable to form the highest-mass stars.