Tuesday. My one suitcase from SF has not arrived, and I haven't got it delivered to me yet. It appears to be lost.
UCB Astro talk
Ultracompact binaries containing two stellar remnants
Paul Groot
* binary of dead stars (very compact)
Compact, period as short as 5 minutes--important gravitational wave sources that are steady, mergers, progenitors of Type Ia and .Ia (what's the difference?). Also a unique possibility to study the influence of chemical composition on accretion disk, nova and dwarf nova outburst physics. (why?)
* Type Ia and .Ia: I don't know if that's a typo.
1106.3568
The birth of a relativistic outflow in the unusual gamma-ray transient Swirt J164449.3+573451
Zauderer et al.
* an individual case of AGN turning on.
AGN = long-term accretion in to central supermassive BHs which produce relativistic jets with t>1e6 years. Transient accretion onto SMBH by eg tidal disruption of a stray star may offer a uinque opportunity to observe and study the birth of a relativistic jet. Once such transient was possibly discovered. Radio transient associated with gamma-ray transient. Measurements on the first month of evolution. Observation positionally coincides with nucleus of an inactive galaxy--an indirect evidence for a newly formed relativistic flow. Tidal disruption of a star naturally explains the high energy properties, radio luminosity and the inferred rate. Radio searches may uncover similar events out to z~6.
* ready for a radio transient survey?
1106.3648
X-ray reverberation in NLS1
Miller, Turner
* what does the reverberation do?
* NLS1 = Narrow-line Seyfert 1 galaxies = show both narrow and broad emission lines, strong in UV and X-ray; variable (~50% in months). AGN seen perpendicular to the accretion disk (the nuclei can be seen, which gives the broad emission line).
Reverberation from scattering material around the BG in AGN is expected to produce a characteristic signature in a Fourier analysis of the time delays between directly-viewed continuum emission and the scattered light. NLS1 are highly variable at x-ray: candidates for reverberation observation. Shows expected time-delay signature. x10 to x100s of gravitational radii scattering. Alternative interpretation of time delay, from x1 gravitational radius from BG, is strongly disfavoured.
* Miller discovered the polarization in the broad emission line in type 2 Seyferts, thus showing that type 1 and 2 are essentially the same object, seen at different angles.
1106.3667
WMAP extragalactic point sources as potential space VLBI calibrators
Gereb, Frey
* point catalog of WMAP used for calibration
Compiled a new catalogue of bright and compact extragalactic radio sources; explored sources sorted out, calculated spectral indicies. 37 new suitable targets unstudied in 86 GHz before (25% addition to previous list). Useful as phase-reference calibrators for ASTRO-G at 43GHz, allowing better sensitivity.
1106.4005
Direct stau production at hadron colliders in cosmologically motivated scenarios
Lindert, Steffen, Trenkel
* what's a "stau"? A slepton which is the hypothetical superpartner of a tau lepton.
* I guess it's a DM particle candidate.
Calculate dominant cross section contributions for stau pair production at hadron colliders within the MSSM. b-quark annihilation and gluon fusion can enhance the crosssections by more than x10 wrt the Drell-Yan predictions (whatever), which is not included in the Monte Carlo simulations yet. New strategies to determine the mass and width of the heavy CP-even Higgs boson H0. Predictions given for LHC and Tevatron. Long-lived status that have exceptionally small thermal relic abundance.
1105.0790
CMB acoustic scale in the entropic-like accelerating universe
Casadio, Gruppuso
* what is an entropic-like accelerating universe?
Generalize it, and show that their BG equations can be made equivalent to a model with a DE component with w_X = -1+2g/3. Can recover standard dust and radiation equations too. Acoustic scale l_A is related to the peak positions in the pattern of the CMB anisostropies, and is also computed and yields the stringent bound gamma << 1.
* that sound hard to detect.
1010.3723
Self-similar solutions of Triaxial DM halos
Lithwick, Dalal
* Yay! A good paper.
Collapse and internal structure of DM halos. Generated from initially scale-free perturbations. Gravitational collapse is self-similar. In the 1980s 1D case was solved. Generalize their results for 3D equations. Solve equations numerically and analyze similarity solutions in detail--internal density profiles of the collapsed halos. Decompose the total density into subprofiles of particles that collapse coevally, and ID two effects as the main determinants of the internal density structure of halos: (1) Adiabatic contraction and (2) the shape of subprofile shortly after collapse. (2) largely reflects the triaxiality of the subprofile. Develop simple model that describes the results of the 3D simulations. Companion paper applies this model to more realisitic cosmological fluctuations, and explain the origin of the nearly universal NFW-like density profiles ound in N-body simulations.
* what does it mean: "gravitational collapse is self-similar"?
* The concentration tells you approximately when the halo formed. low concentration = halo formed recently.
1011.2781
Measuring the galaxy cluster bulk flow from WMAP data
Osborne, Mak, Church, Pierpaoli
* cluster bulk flow? from WMAP? must be kSZ effect.
Isolate the kSZ signal; use two filters to optimize detection. (1) no spectral dependence, and (2) spectral properties of the kinetic and thermal SZ signals to remove the tSZ bias. Measure monopole and dipole spherical harmonic coefficients of the kSZ signal, as well as the l=2-5 modes, at the location of 736 ROSAT-observed galaxy clusters. No significant power in the kSZ signal at these multipoles with either filter, consistent with LCDM. x3 more sensitive then the 2009 detection. There is a tSZ dipole that can be mistaken as bulk motion of 2000-4000 km/s. Unbiased filter can have S/N that is x10 lower.
1011.6110
Finding a spherically symmetric cosmology from observations in observational coordinates--advantages and challenges
Araujo, Stoeger
* symmetric cosmology?
Challenge: determine the large-scale space-time metric from observation. Spherically symmetric, inhomogeneous space-time framework is the first step for minimum-assumption cosmology of showing that the s-t is indeed FLRW. Past: 3+1 coordinate framework, and observational coordinate framework. This paper: investigate stability of solutions, and the use of data in the OC field equations including time evolution. Compare both approaches wrt singularity problem at maximum of angular diameter distance, solution stability, and the use of data in field equations (what do they mean by that?). Enables comparison of the relative advantages of the two equivalent solution frameworks. Both formulations and integration procedures should lead to the same results. However, OC shows certain advantages, particularly in avoiding of coordinate singularities at the maximum of the angular-diameter distance, and in the stability of the solutions obtained.
* I guess OC (observational coordinate framework) is good for calculations.
1101.1525
Parity violation in the CMB from pseudoscalar inflaton
Sorbo
* a pseudoscalar inflaton -- not a scalar, eh?
* axion: a hypothetical elementary particle posulated by the Peccei-Quinn theory to resolve the strong CP problem in QCD. If it exists and have low mass within a certain range, they are a possible DM particle candidate.
* strong CP problem?: why QCD does not seem to break the CP-symmetry.
* CP-symmetry breaking?: the combination of charge conjugation symmetry and parity symmetry is violated. (symmetry in the laws of physics) CP symmetry breaking plays an important role in cosmology to explain the dominance of matter over antimatter in the present universe, and in the study of weak interactions in particle physics.
If the inflaton is a pseudoscalar, then it naturally interacts with gauge fields via an axion-like coupling to the EM field (I think, because they say F\mu\nu). Through this field, the rolling inflaton produces quanta of the gauge field, and source the tensor components of the metric perturbations. Such asymmetry manifests itself in the form of non-vanishing TB and EB correlation functions in CMB. Compute this amplitude of the parity-violating tensor modes. Current data and future detection.
1104.1167
Light-cone averaging in cosmology: formalism and applications
Gasperini, Marozzi, Nugier, Veneziano
* gauge invariance: property of a field theory in which diffeent configurations of the underlying fundamental but unobservable fields result in identical observable quantities. A theory with such a property is called a gauge theory. A transformation from one such field configuration to another is called a gauge transformation. All changes induced by a gauge transformation have to cancel each other out when written in terms of observable quantities. All forces arise from the constraints imposed by local gauge symmetries.
Defining comological averages in a general gauge invariant formalism, which are relevant for observations on light-like signals. This involves either null hypersurfaces or compact surfaces given by their intersection with hypersurfaces. Commutation rules for derivatives of these ligh-cone averages are given. Introduce adapted "geodesic light-cone" coordinates, and give explicit expressions for averaging the redshift to luminosity-distance relation and the so-called "redshift drift" in a generic inhomogeneous Universe.
* It's obvious that I don't understand the details of this abstract.
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