Day 190

Tuesday.  I have a astro-ph pile up.  Wrote a long e-mail to YK this morning about A, which is why I'm reading astro-ph now (11am)...  First German class of the semester today (A1.2).  Too bad I'll be missing the 2nd class, will have dinner with A & P instead!  Looking forward to a nice dinner at home.


1201.5891
Accretion geometry of the low-mass X-ray binary Aquila X-1 in the Soft and Hard states
Sakurai, Yamada, Torii, Noda, Nakazawa, Makishima


* Comptonization: change in radiation spectrum due to scattering by electrons.  Relevant for high T, low density plasma, having large optical thickness in Thomson scattering.


NS low-mass X-ray binary Aquila X-1 observed 7 times in the decaying phase of an outburst.  Constrain the flux-dependent accretion geometry; spectrum successfully explained by an optically-thick disk emission plus a Comptonized blackbody component.  Characteristics of the hard state successfully explained by the same two continuum components but with rather different parameters including much stronger thermal Comptonization, of which the seed photon source was identified with BB emission from the NS surface [!].  As a result, the accretion flow in the hard state is inferred to take a form of an optically-thick and geometrically-thin disk down to a radius of 21pm4 km for the NS, and then in turn into an optically-thin nearly-spherical hot flow.


1201.5892
Subhaloes in self-interacting galactic dark matter haloes
Vogelsberger, Zavala, Loeb


Present N-body sim with a new class of self-interacting DM models which do not violate any astrophysical constraints.  Take MW-like DM halo from Aquarius and re-simulate it for a few representative cases for this new model.  Find: the main halo only develops a small core (~1 kpc) followed by a density profile identical to that of CDM outside that radius.  Subhalo mass function nor the radial number density of subhaloes altered.  Significant change in the inner density structure of subhaloes resulting in the formation of a large density core.  So the inner circular veloctiy profiles of the most massive subhaloes differen significantly from te CM predictions.  Demonstrate that they are compatible with the observational data of the brightest MW dSphs.  No subhaloes that are more concentrated than that inferred from the kinematics of the MW dSphs.  Conclude that these models offer anin teresting alternative to the CDM model that can reduce the recently reported tension between the brightest MW satellites and the dense subhalos found in CDM simulations.


1201.5899
Entropy production in collisionless systems. II. Arbitray phase-space occupation numbers
Barnes, Williams


* violent relaxation: the rapid evolution of a star cluster or galaxy that has formed in a configuration far from equilibrium. During violent relaxation, the orbits of individual stars change dramatically because of changes in the gravitational potential of the system. It is thought to play an important part in shaping elliptical galaxies during the first billion years of their evolution.

Analysis of two thermodynamic techniques for determining equilibria of self-gravitating systems.  (1) Lynden-Bell entropy maximization analysis (violent relaxation).  (2) extends entropy production extremization of self-gravitating systems, also without the use of the Stirling approximation.  ...  Derive entropy production expressions for both families, give the extremum conditions for entropy production.  Analysis indicates that extremizing entropy production rate results in systems that have maximum entropy, in both LB and MB (Maxwell-Boltzmann) statistics.  Both thermodynamic approaches lead to the same equilibrium structures.

1201.5918
The effect of major mergers on age and metallicity across the fundamental plane
Porter, Somerville, Croton, Covington, Graves, Faber, Primack


Other's attempt to determine SFH of elliptical galaxies by tracking correlations between the stellar pop params (age, metallicity) and the structural parameters that enter the fundamental plane (size and velocity dispersion).  These studies have found that velocity dispersion, rather than effective radius or dynamical mass, is the main predictor of the galaxy's stellar age and metallicity.  Apply an analytic model that predicts the structural properties of remnants formed in major mergers to progenitor disk galaxies with properties taken from two different SAMs.  Predict the effective radius, velocity dispersion, luminosity, age and metallicity of the merger remnants, enabling comparison to observations.  Find tight correlation between age and velocity dispersion, find a stronger dependence of age and metallicity on effective radius than observations report.  The correlations arise as a result of the dependence of gas fraction, age, and metallicity on the stellar mass in the progenitor disk galaxies.  These dependences induce a rotation in the radius-velocity plane [??] between the correlations with effective radius and circular velocity ....  The differences between this result and observations suggest that major mergers alone cannot produce the observed lack of correlation between effective radius and stellar population parameters.  Simulations show subsequent minor mergers introduce scatter in the effective radius, while leaving the velocity dispersion essentially unchanged, could bring sims closer to observations.  


1201.5926
Observational tests of inflation with a field derivative coupling to gravity
Tsujikawa


A field kinetic coupling with the EInstein tensor leads to a gravitationally enhanced friction during inflation, by which even steep potentials with theoretically natural model parameters can drive cosmic acceleration.  In the presence of this non-minimal derivative coupling, we place observational constraints on a number of representative inflationary models such as chaotic inflation, inflation with exponential potentials, natural inflation, and hybrid inflation.  Show that most of the models can be made compatible with the current observational data mainly due to the suppressed tensor-to-scalar ratio.


1201.5955
Constraining inflation with future galaxy redshift surveys
Huang, Verde, Vernizzi


Future galaxy surveys will bring a large number of Fourier modes of the distribution of the LSS of this Universe.  These modes are complementary to those of the CMB and cam be used to set constraints on the models of the early universe, such as inflation.  Using MCMC, compare power of CMB with that of combination of CMB and galaxy survey data, to constrain the power spectrum of primordial fluctuations generated during inflation.  Combine Planck with Euclid as example, consider models of slow-roll inflation, show that the inclusion of LSS improves the constraints by halving the error bars on the scalar spectral index and its running.  Attempt to reconstruct the inflationary single-field potential, a similar conclusion can be reached.  Then study models with features in the power spectrum.  Consider ringing features produced by a break in the potential and oscillations such as in axion monodromy.  Adding LSS improves the constraints on features by more than a factor of two.  In axion monodromy, show that there are oscillations with small amplitude and frequency in momentum space that are undetected by CMB alone but can be measured by including galaxy surveys in the analysis.


1201.6010
Planetary nebula kinematics in NGC 1316: a young Sombrero
McNeil-Moylan, Freeman, Arnaboldi, Gerahard


Present 796 PNe in NGC 1316, use PNe and existing kinematics to explore the rotation of this merger remnant and constrain dynamical models.  The 2d velocity field indicates dynamically-important rotation that rises in the outer parts, possibly due to the outward transfer of angular momentum during the merger.  The modeling indicates a high DM content, particularly in the outer parts, that is consistent with previous estimates from dynamical models, lensing and stellar population models.  The exceptionally large sample of PNe velocities makes it possible to explore the kinematics of NGC 1316 in detail.  Comparing the results to other early-type galaxies, NGC 1316 represents a transition phase from a major-merger event to a bulge-dominated galaxy.


1201.6031
Interstellar gas within ~10pc of Sgr A*
Ferriere


3d picture of interstellar gas out to about 10pc of the dynamical center of our Galaxy (Sgr A*).  Compile different gaseous components identified near Sgr A*, and retain all information relating to their spatial configuration and/or physical state.  3d representation of interstellar gas describes component in terms of its precise location and morphology, and its thermodynamic properties.  5 basic components: (1) a central cavity with roughly equal amounts of warm ionized and atomic gases, (2) a ring of mainly molecular gas, (3) a SNe remnant filled with hot ionized gas, (4) a radio halo of warm ionized gas and relativistic particles, and (5) a belt of massive molecular clouds.  While the halo gas fills 80% of the studied volume, the molecular components enclose 98% of the interstellar mass.


1201.6074
Star formation in the early universe: beyond the tip of the iceberg
Tanvir et al


HST imaging (late-time) of 6 Swift GRBs at 5<z<9.5.  Data include very deep observations of the field of the most distant spectroscopically confirmed burst at z=8.2.  Place limits on the luminosities of their host galaxies.  One seemed to have excess flux (corresponding to a host galaxy), the others didn't.  All hosts lie below L* at their respective redshifts, with SFR < 4 Msun/yr in all cases.  Stacking the 5 fields with WFC3-IR data, conclude a mean SFR 90% confidence.  Not yet possible to make stronger statements now, but studies hold great potential in the future.


1201.6108
The cosmic history of the spin of DM haloes within the LSS
Trowland, Lewis, Bland-Hawthorn


N-body sims to investigate the evolution of the orientation and magnitude of DM halo angular momentum within the LSS since z=3.  Evolution of the alignment of halo spins with filaments and with each other, as well as the spin parameter, which is a measure of magnitude of angular momentum.  Found: angular momentum vectors of DM haloes at high z have weak tendency to be orthogonal to filaments and high mass haloes have stronger orthogonal alignment than low mass haloes.  Since z=1, the spins of low mass haloes have become weakly aligned parallel to filaments, whereas high mass haloes keep their orthogonal alignment.  This recent parallel alignment of low mass casts doubt on tidal torque theory as the sole mechanism for the build up of angular momentum.  Find a significant alignment of neighboring DM haloes only at very small separations, r<0.3 Mpc.h, which is driven by substructure.  A correlation of the spin parameter with halo mass is confirmed at high z.  [do they mean observationally?]


1201.6230
UV extinction towards a quiescent molecular cloud in the SMC
Apellaniz, Rubio


The mean UV extinction law for the SMC is taken as a template for low-metallicity galaxies, but the current derivation is based on only 5 stars.  Should increase the number of targets, to assess dependence on parameters such as metallicity and SF activity.  Obtain HST STIS slitless UV spectroscopy of 25"x25" FoV, combine with ground-based NIR and visible photometry of the stars in the field.  Use CHORIZOS to derive the visible-NIR extinction values of each star.  The unextinguished SEDs obtained in this way were then used to derive the UV extinction law for the 4 most extinguished stars.  Results: extinction law vary significantly star-by-star.


1201.6245
Comparison of Fe and Ni opacity calculations for a better understanding of pulsating stellar envelopes
Gilles et al


* Rosseland mean value opacity: Use a temperature derivative of Planck distribution (normalized) as the weighting function, when defining the average opacity.  The Rosseland opacity is derived in the diffusion approximation to the radiative transport equation; valid whenever the radiation field is isotropic over distances comparable to or less than a radiation mean free path, such as in local thermal equilibrium.  
* Planck opacity: use Planck BB radation energy distribution as the weighting function.


Opacity: important ingredient of the evolution of stars. Opacity coefficient calculations complicated by the plasma containing partially ionized heavy ions that contribute to the opacity dominated by H and Ne.  The astrophysical community has greatly benefited from the work of the contributions of Los Alamos, Livermore, and the Opacity Project, but unexplained differences up to 50% in the radiative forces and the Rosseland mean values for Fe have been noticed for conditions corresponding to stellar envelopes.  Such uncertainty has a real impact on the understanding of pulsating stellar envelopes on the excitation of modes and on the identification of the mode frequencies.  Temperature and density conditions equivalent to those found in stars can now be produced in laboratory experiments for various atomic species.  Recently, spectra of Ni and Fe plasmas have been measured for temperatures between 15 and 40 eV and densities of ~3 mg/cm^3.  Present the set of opacity calculations performed by 8 different groups for conditions relevant to the experiment and to astrophysical stellar envelope conditions.

Day 189

Saturday.  Wasted away the morning, want to be productive in the afternoon.  Wonder if I can do it.  ... I couldn't.  Same for Sunday (except for some GREAT3 reading).


Monday.  Wrote to Yookyung last night, to Aaron this morning.  


1201.5640
On the magnetic flux problem in star formation
Braithwaite


Strong magnetic fields play a crucial role in the removal of angular momentum from collapsing clouds and protostellar discs, and are necessary for the formation of disc winds as well as jets from the inner disc.  Strong large-scale poloidal magnetic fields are observed in protostellar discs at all radii down to ~10 Rsun.  But by the time the star is visible virtually all of the original magnetic flux has vanished.  Explore mechanisms for removing this flux during the formation of the protostar once it is magnetically disconnected from the parent cloud, looking at both radiative and convective protostars.  Includes numerical investigation of buoyant magnetic field removal from convective stars.  Find: if the star goes through a fully convective phase, all remaining flux can easily be removed from the protostar, essentially on an Alfven timescale.  On the other hand if the protostar has no fully convective phase then some flux can be retained, the quantity depending on the net magnetic helicity, which is probably small.  Only some fraction of the flux is visible at the stellar surface.  Look at how the same mechanisms could prevent flux from accreting onto the star, meaning that mass would only accrete as fast as it is able to slip past the flux.


1201.5641
Absorption signatures of warm-hot gas at low redshift: Broad Lya absorbers
Tepper-Garcia, Richter, Schaye, Booth, Vecchia, Theuns


Investigate the physical state of HI absorbing gas at low z (~0.25) using hydrosims, focusing on broad (>40km/s) Lya absorbers (BLAs), believed to originate in shock-heated gas in the Warm-Hot Intergalactic medium (WHIM).  The fiducial model, which includes radiative cooling by heaving elements and feedback by SNe and AGN, predicts that by z=0.25 nearly 60% of the gas mass ends up at densities and temperatures characteristic of the WHIM and find that half of this fraction is due to outflows.  The standard HI observables (distribution of HI column densities N_HI, distribution of Doppler parameters b_HI, b_HI-NHI correlation) and the BLA line number density predicted by simulations are in good agreement with observations.  BLAs arase in gas that is hotter, more highly ionised and more enriched than the gas giving rise to typical Lya forest absorbers.  Although the majority of the BLAs arise in warm-hot (log(T/K)~5) gas at low (log Delta < 1.5) densities, their line width correlates only weakly with the gas temperature, and is thus a poor indicator of the thermal state of the gas.  Detectable BLAs account for only a small fraction of the true baryon content of the WHIM at low redshift.  In order to detect the bulk of the mass in this gas phase, a sensitivity at least one order magnitude better than achieved by current UV spectrographs is required.  Argue that BLAs mostly trace gas that has been shock-heated and enriched by outflows and that they therefore provide an important window on a poorly understood feedback process.


1201.5642
On the detection of ionizing radiation arising from SF galaxies at z~3-4: looking for analogs for "Stellar Reionizers"
Vanzella, ... Grogin, Koekemoer, Newman, et al


Use spatially resolved, multi-band photometry in the GOODS-S field to constrain the nature of candidate Lyman continuum (LyC) emitters at redshift z~3.7 identified using imaging below the Lyman limit.  In 18 candidates, the light centroid of the candidate LyC emission is offset from that of the LBG by up to 1.5".  Fit the SED of the LyC candidates to spectral populations synthesis models to measure photo-z and stellar population parameters.  Also discuss the differences in the UV colors between the LBG and the LyC candidates, and how to estimate the escape fraction of ionizing radiation (f_esc) in cases, where the lyC emission is spatially offset from the host galaxy.  In all but one case, conclude that the candidate LyC emission is most likely due to lower redshift interlopers.  Argue that the majority of similar measurements reported in the literature need further investigation before it can be firmly concluded that LyC emission is detected.  Only a single surviving LyC candidate is a LBG at z=3.795, which shows the bluest (B-V) color among LBGs at similar redshift, a stellar mass of 2e9 Msun, weak interstellar absorption lines and a flat UV spectral slope with no Lya in emission.  Estimate f_esc in the range 25-100%, depending on the dust and intergalactic attenuation.


1201.5644
First cosmological constraints on the proton-to-electron mass ratio from observations of rotational transitions of methanol
Ellingsen, Voronkov, Breen, Lovell


Used Australia telescope compact array to measure the absorption from the 12.2 GHz transition of methanol towards the z=0.89 lensing galaxy in the PKS B 1830-211 gravitational lens system.  Comparison of the velocity of the main absorption feature with the published absorption spectrum from the (different) transition of methanol shows that they differ by -0.6 pm 1.6 km/s.  Can use these observations to constrain the changes in the proton-to-electron mass ration from z=0.89 to present to 0.8pm2.1e-7.  This result is consistent, and of similar precision to recent observations at z=0.68 achieved through comparison of a variety of rotational and inversion transitions, and approximately a factor of 2 better than previous constraints obtained in this source.  Future observations that incorporate additional rotational methanol transitions can improve results by factor of 5-10.


1201.5662
Temperature structure and mass-temperature scatter in galaxy clusters
Ventimiglia, Voit, Rasia


The T_HBR (the ratio of hardband to broadband spectral-fit temperatures) is a substructure indicator, that is found to be modestly correlated to the scatter in the M-T_X relation.


1201.5697
"Evaporation" of a flavor-mixed particle from a gravitational potential
Medvedev


Demonstrate that a stable particle with flavor mixing, confined in a gravitational potential can gradually and irreversibly escape ("evaporate") from it.  Effect due to mass eigenstate conversions which occur in interactions (scattering) of mass states with other particles even when the energy exchange between them is vanishing.  The evaporation and conversion are quantum effects not related to flavor oscillations, particle decay, quantum tunneling or other well-known processes.  These effects should have implications for cosmology: (1) cosmic neutrino background distortion and (2) softening of central cusps in DM haloes and smearing out or destruction of dwarf haloes.


1201.5742
Expected constraints on the galactic magnetic field using PLANCK data
Fauvet et al


Simulation shows that PLANCK should be able to recover the main properties of the Galactic magnetic field.    An accurate reconstruction of the matter distribution would require an improved modelling of the ISM and the usage of extra data sets such as the rotation measurements of pulsars [???].


1201.5746
The cluster and large scale environments of quasars at z<0.9
Harris


Thesis: to study (1) the large scale environment over a large z range (2) the evolution as well as any change in environment with quasar luminosity and z, and (3) the orientation of quasar with respect to a galaxy cluster.  Deficit of quasars lying close to cluster centers for 0.4<z<0.8 (preference for less dense environments).  Position [?] of quasars as a function of absolute quasar magnitude does not change, nor the preferred orientation between the quasar and the cluster major axis for bright or faint quasars.  Fe II emission discussed.


1201.5784
How to make an ultra-faint dwarf spheroidal galaxy: tidal stirring of disky dwarfs with shallow DM density profiles
Lokas, Kazantzidis, Mayer


Use n-body sims, reproduce tidal interactions between MW-sized host galaxies and rotationally supported dwarfs embedded in 1e9 Msun DM haloes.  UFDs can be produced via the tidal stirring of disky dwarfs on relatively tight orbits, consistent with a redshift of accretion by the host galaxy of z~1, and with intermediate values for the halo inner density slopes.  The inferred slopes in agreement other sims.  Similarities in basic observational parameters.  Tidal stirring of rotationally supported dwarfs is a viable mechanism for the formation of UFDs in the LG environment.


1201.5785
Do stellar winds play a decisive role in feeding AGN?
Davies, Burtscher, Dodds-Eden, de Xivry


Existence of starburst-AGN connection is undisputed, but no consensus on what the connection is.  Begin by noting that mechanisms that drive gas inwards in disk galaxies are generally inefficient at removing angular momentum, leading to stalled inflows.  Thus, a tiered series of such processes is required to bring gas to the smallest scales, each of which on its own may not correlate with the presence of an AGN.  Similarly, each may be associated with a starburst event, making it important to discriminate between 'circumnuclear' and 'nuclear' star formation.  Show that stellar feedback on scales of tens of parsecs plays a critical role in first hindering and then helping accretion.  Argue: only after the initial turbulent phases of a starburst that gas from slow stellar winds can accrete efficiently to smaller scales.  Implies that the properties of the obscuring torus are directly coupled to SF and that the torus must be a complex dynamical entity.  


1201.5794
Connecting the cosmic web to the spin of dark haloes: implications for galaxy formation
Codis, Pichon, Devriendt, Slyz, Pogosyan, Dubois, Sousbie


Detect clear mass transition: the spin of DM haloes above a critical mass tends to be perpendicular to the closest filament, and aligned with the intermediate axis of the tidal tensor, whereas the spin of low-mass haloes is more likely to be aligned with the closest filament.  The critical mass of 5e12 (Msun) is redshift dependent and scales as (1+z)^-2.5.  Interpretation in terms of large-scale cosmic flows: most low-mass haloes are formed through the winding of flows embedded in misaligned walls; they acquire a spin parallel to the axis of the resulting filaments forming at the intersection of these walls.  On the other hand, more massive haloes are typically the products of later mergers along such filaments, and thus acquire a spin perpendicular to this direction when their orbital angular momentum is converted into spin.  Show that this scenario is consistent with both the measured excess probabilities of alignment wrt the eigen-directions of the tidal tensor, and halo merger histories.  On a more qualitative level, it also seems compatible with 3d visualization of the structure of the cosmic web as traced by "smoothed" DM simulations or gas tracer particles.  Provides extra support to the disk forming paradigm by Pichon+2011, as it extends it by characterizing the geometry of secondary infall at high z.


1201.5888
THe evolution of massive black holes and their spins in their galactic hosts
Barausse


Study the mass and spin evolution of massive BHs within a semi-analytical galaxy-formation model that follows the evolution of DM haloes among merger trees, as well as that of the baryonic components (hot gas, stellar and gaseous bulges, and stellar and gaseous galactic disks).  Allows us to study the mass and spin evolution of massive black holes in a self-consistent way, by taking into account the effect of the gas present in galactic nuclei both during the accretion phases and during mergers.  Also present predictions, as a function of redshift, for the fraction of gas-rich BH mergers, in which the spins prior to the merger are aligned due to the gravito-magnetic torques exerted by the circumbinary disk, as opposed to gas-poor mergers, in which the orientation of the spins before the merger is roughly isotropic.  Predictions may be tested with e.g., eLISA.

Day 188

Friday, already.  Talked about the Arizona wine with Aaron on the bus on my way back home.  Peter's talk on the Excellence Cluster was excellent, I hope Bonn/Cologne gets the 36M Euro for the next 5 years.  It's a much better plan than the Korean one, I'd say!


1201.5374
How to detect gravitational waves through the cross-correlation of the galaxy distribution with the CMB polarization
Alizadeh, Hirata


CMB Thompson scatters off of reionization free electrons, inducing a correlation between the distribution of galaxies and the polarization pattern of the CMB, the magnitude of which is proportional to the quadrupole moment of radiation at the time of scattering.  Since the quadrupole moment generated by gravitational waves (GWs) gives rise to a different polarization pattern than that produced by scalar modes, one can put constraints on the strength of GWs on large scales by cross-correlating the small scale galaxy distribution and CMB polarization.  Use this method together with Fisher analysis to predict how well future surveys can measure the tensor-to-scalar ratio r.  Find that with a future CMB experiment with detector noise Delta_P = 2 mu K-arcmin and a beam width theta_FWHM=2' and a future galaxy survey with limiting magnitude I < 25.6 one can measure the tensor-to-scalar ratio with an error sigma_r~0.09.  To measure r~0.01, however, one needs 0.5muK-radian and theta_FWHM=1'.  Also investigate a few systematic effects, non of which turn out to add any bias to the estimators, but increase the error bars by adding to the cosmic variance.  The incomplete sky coverage has the most dramatic effect on the constraints for r on large sky cuts, with a reduction in signal-to-noise smaller than one would expect from the naive estimate (S/N)^2 propto f_sky.  Specifically, find a degradation factor of f_deg=0.32 for a sky cut of |b| > 10 deg (f_sky=0.83) and f_deg = 0.05 for a sky cut of |b|>20 deg (f_sky=0.66).  Nonetheless, given that the method has different systematics than the more conventional method of observing the large scale B modes directly, it may be used as an important check in the case of a detection.


1201.5375
A new window on primordial non-Gaussianity
Pajer, Zaldarriaga


Very little known about primordial curvature perturbations on scales smaller than about a Mpc. Measurements of the mu-type distortion of the CMB spectrum provide the unique opportunity to probe these scales over the unexplored range from 50 to 1e4 Mpc^-1.  This is a very clean probe, in that it relies only on well-understood linear evolution.  Point out that correlations between mu-distortion and temperature anisotropies can be used to test Gaussianity at these very small scales.  In particular the mu-T cross correlation is proportional to the very squeezed limit of the primordial bispectrum and hence measures fNL^loc{ss}, while mu-mu is proportional to the primordial trispectrum and measures tauNL.  Present a Fisher matrix forecast of the observational constraints.


* what is the mu-type distortion of the CMB spectrum?  mu stands for chemical potential.  talking about mu-distortion caused by Silk damping as the signal.


1201.5376
The chemical signature of relic star cluster in the Sextans Dwarf spheroidal galaxy-implications for near-field cosmology
Karlsson, Bland-Hawthorn, Freemen, Silk


Found a possibly dissolved star cluster of extremely poor metallicity of [Fe/H]=-2.7.  In the future with large surveys, might be able to put firm constraints on the dwarf-galaxy origin of MW's stellar halo.  Also argue that the average star cluster mass in the majority of the newly discovered ultra-faint dwarf galaxies was notably lower than it is in the Galaxy today and possibly lower than in the more luminous, classical dwarf spheroidal galaxies.  Moreover, the slope of the cumulative metallicity function in dwarf spheroidals falls below that of the ultra-faints, which increases with increasing metallicity as predicted from the stochastic chemical evolution model.  These two findings, together with a possible difference in the ratio suggest that the ultra-faint dwarf galaxy population, or a significant fraction thereof, and the dsph population, were formed in different environments and would thus be distinct in origin.


1201.5377
UV properties of galactic globular clusters with GALEX I. the color-magnitude diagrams
Schiavon, et al


Present GALEX data for 44 galactic globular clusters.  Color-magnitude diagrams presented.  Blue and intermediate-blue horizontal branch is the dominant feature of the UV color-magnitude diagrams of old Galactic globular clusters. Sample large enough to display the variaty of horizontal branch shapes found in old stellar populations.  Other stellar types that are obviously detected are blue stragglers and post core-He burning stars.  The main features of UV color-magnitude diagrams of Galactic globular clusters are briefly discussed.  Establish the locus of post-core He burning stars n the UV color-magnitude diagram and present a catalog of candidate AGB-manque, post early-AGB, and post-AGB stars within the cluster sample.  

Day 187

Wednesday.   Take today off with Yoko to go have fun in Düsseldorf.  

Thursday.   Saw Yoko off, have 1 hr till next train arrives.  Have 2 days of astro-ph to read.


1201.4859
The SF history of Leo T from HST imaging
Weisz, ... de Jong, .. Dalcanton, ...  Bell, et al


SFH of the faintest SF galaxy Leo T with WFPC2.  Color-magnitude diagram of Leo T is 2 mag below the oldest MS turnoff, permit excellent constraints on SF at all ages.  Assume 3 different stellar evolution models: (1,2) solar-scaled metallicity (Padova and BaSTI) and (3) alpha-enhanced metallicities.  The resulting SFHs are consistent at all ages (SFH robust).  50% of total stellar mass formed z>1 (7.6 Gyr ago).  After this, the SFH is roughly constant until 25Myr ago, when it shows an abrupt drop, but could be due to IMF effect (unable to distinguish between the two).  HST provides improved age resolution and reduced uncertainties at all epochs.  Leo T does not resemble other faint dwarf galaxies from the Local Group, but strongly resembles gas-rich dwarf galaxies (irregular or transition), suggesting that gas-rich dwarf galaxies may share common modes of SF over a large range of stellar mass (1e5-9 Msun).


1201.4863
Optimizing automated classification of periodic variable stars in new synoptic surveys
Long, El Karoui, Rice, Richards, Bloom


Classification of periodic variable stars necessary as survey scales grow.  Machine learning, statistics to construct classifiers on multi-epoch sources for automatic classification.  But different surveys will yield different features (metrics) from the light curve; survey-dependent mismatch in feature will typically lead to degraded classifier performance.  Show how and why feature distributions change, using OGLE and Hipparcos light curves.  Apply "noisification" method which attempts to empirically match distributions of features between the labeled sources used to construct the classifier and the unlabeled sources wished to be clarified.  Results from simulated and real-world light curves show noisification can significantly improve classifier performance, from 27% to 7%.  Recommend use for Gaia and LSST.


1201.4864
Spikes in the SED and ripples in the outskirts of galaxies
Chakrabarti


Describe a new method that quantitatively characterize galactic satellites from analysis of distrubances in outer gas disks, without optical information of the satellite ("Tidal Analysis").  Apply to local spirals with known optical companions (e.g., M51/NGC 1512), which have companions 1/100 to 1/3 mass of the primary galaxy.  Present preliminary results on the SEDs and images calculated along the time sequence of dynamical simulations using the 3D self-consistent MC radiative transfer code RADISHE.  Explore SF prescriptions and how they affect the emergent SEDs and images.  Goal: identify SED colors that are primarily affected by the galaxy's interaction history, and not significantly affected by the choice of SF prescription.  If successful, may be able to utilize the emergent UV-IR SED of the primary galaxy to understand its recent interaction history.


1201.4873
Magnetically-levitating disks around SMBH
Gaburov, Johansen, Levin


Report on the formation of magnetically-levitating accretion disks around SMBH.  Structure of disks calculated by numerically modelling tidal disruption of magnetized interstellar gas clouds.  Find: resulting disks entirely supported by the pressure of the magnetic fields against the component of gravitational force directed perpendicular to the disks.  The magnetic field shows ordered LS geometry that remains stable for the duration of numerical experiments extending over 10% of disk lifetime.  Strong magnetic pressure allows high accretion and inhibits disk fragmentation: in combination with the repeated feeding of magnetized molecular clouds to a SMBH yields a possible solution to the long-standing puzzle of BH growth in the centers of galaxies.


1201.4878
A consistent comparison of bias models using observational data
Papageorgiou, Plionis, Basilakos, Ragone-Figueroa


Investigate 5 different models for the DM halo bias, by comparing their cosmological evolution using optical QSO and galaxy bias data at different redshifts, consistently scaled to the WMAP7 cosmology.  Assuming each halo hosts one extragalactic mass tracer, use a chisq minimization procedure to determine the free parameters of the bias models; statistically quantiyf ability to represent the observational data.  Find the best model(s).  The average DM halo mass that hosts optical QSOs are M_h=2.7e12 Msun/h, while the corresponding value for optical galaxies is M_h=6.3e11Msun/h.


1201.4889
Standard candles from the Gaia perspective
Eyer et al


ESA Gaia mission will bring a new era to the domain of standard candles.  Astrometric precision, whole-sky coverage, and the combination of photometric, spectrophotometric and spectroscopic measurements.  Fundamental outcome: DPAC (Gaia Data Analysis and Processing Consortium), which will contain a variable source classification and specific properties for stars of specific variability types.  Review what will be produced for Cepheids, RR Lyrae, Long Period Variable stars and eclipsing binaries.


1201.4989
NIR/Optcial selected local mergers: spatial density and sSFR enhancement
Xu


Dependence of local merger rate and the sSFR enhancement on 4 fundamental observables: (1) stellar mass (2) mass ratio (3) separation (4) environment.


1201.4910
The HST/ACS coma cluster survey. VIII. Barred disk galaxies in the core of the Coma cluster
Marinova et al


Use HST images to study bars in massive disk galaxies (S0s) and in dwarf galaxies in the Coma core; to constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts.  (1) Fraction and properties of bars in 32 bright S0 galaxies that dominate the cluster core.  About 60%.  (2) Compare the S0 bar fraction across different environments (Coma core, A901/902, Virgo).  Find bar fraction among bright S0 galaxies does not show a statistically significant variation across environments spanning 2 orders of magnitude in galaxy number density (n~300-10000 gal/Mpc^3).  S0 bar fraction not significantly enhanced in rich clusters because S0s in rich clusters are less prone to bar instabilities (they are dynamically hot and gas poor due to ram pressure stripping and accelerated SF).  Additionally, high-speed encounters in rich clusters may be less effective than slow, strong encounters in inducing bars.  (3) Analyze a sample of 333 faint dwarf galaxies in Coma core; only 13 with bar and/or spiral structure.  Paucity of disk structures in Coma dwarfs suggest that either disks are not common in these galaxies, or that any disks present are too hot to develop instabilities.


1201.4947
Constraints on obscured SF in host galaixes of gamma-ray bursts
Hatsukade, et al


Observe 4 host galaxies of GRBs in 16-cm continuum using Australia Telescope compact array.  Radio not detected in any of the host galaxies.  Derive upper SF rates, ~30-45 Msun/yr; 10 times less than from UV/optical observations (no significant dust-obscured SF).  Results imply that dark GRBs do not always occur in galaxies enshrouded by dust.  Suggest cause of dark GRB is the intrinsic faintness of the optical afterglow (dust extinction not observed).  High column density observed in afterglow, the likely cause of the dark GRB (extinction in the LoS).


1201.4950
Are nuclear star clusters the precursors of massive black holes?
Neumayer, Walcher


Present upper limits for BH masses in extremely late type spiral galaxies.  Confirm: has BH with M<1e6 Msun, if any.  Derive new upper limits for nuclear star cluster (NC) masses in massive galaxies with known BH masses.  Use new upper limits and literature compilation to study the low mass end of the global-to-nucleus relation.  Find: (1) the M_BH-sigma relation cannot flatten at low masses, but may steepen.  (2) The M_BH-M_bulge relation may flatten in contrast.  (3) The M_BH-Sersic n relation is able to account for the large scatter in BH masses in low-mass disk galaxies; outliers seem to be dwarf ellipticals.  When plotting M_BH-M_NC, find 3 different regimes, implying a sequence of NC dominated transitioning into BH dominated, by which the BH grow faster and destroy the NC when M_BH is >100 M_NC.  Nuclear star clusters may thus be the precursors of massive BH in galaxy nuclei.


1201.4970
The structure of HI in galactic disks: simulations vs observations
Acreman, et al


Generate synthetic HI galactic plane surveys from spiral galaxy simulations which include stellar feedback processes.  Compared to a model without feedback, find a increased scale height of HI emission (in better agreement with observations) and more realistic spatial structure (including SNe blown bubbles).  The synthetic data show HI self-absorption with a morphology similar to that seen in observations.  The density and temperature of the material responsible for HI self-absorption is consistent with observationally determined values, and is found to be only weakly dependent on absorption strength and SF efficiency.


* what is self-absorption?


1201.4998
Revealing velocity dispersion as the best indicator of a galaxy's color, compared to stellar mass, surface mass density or morphology
Wake, van Dokkum, Franx


Using SDSS nearby galaxies, investigate whether stellar mass, central velocity dispersion, surface mass density, or Sersic n parameter is best correlated with a galaxy's rest-frame color.  Specifically, determine how the mean color of galaxies varies with one parameters when another is fixed.  When stellar mass is fixed, see that strong trends remain with all other parameters.  Residual trends are weaker when surface mass density, n, or velocity dispersion are fixed.  Overall, velocity dispersion is the best indicator of a galaxy's typical color, showing the largest residual color dependence when any of the other 3 parameters are fixed, and stellar mass is the poorest.  Other studies have indicated that both the halo and BH properties are better correlated with velocity dispersion than with stellar mass, surface mass density or Sersic n.  Therefore, results are consistent with a picture where a galaxy's star formation history and present SFR are determined to some significant degree by the current properties and assembly history of its dark matter halo and/or the feedback from its central SMBH.


1201.5018
Looking for the Wind in the Dust
Gallagher, Everett, Keating, Hill, Deo


The blue-shifted broad emission lines and/or broad absorption lines seen in many luminous quasars are evidence for a broad line region in which radiation driving plays an important role.  Consider the case for a similar role for radiation driving beyond the dust sublimation radius by focussing on the IR regime where the relationship between luminosity and the prominence of the 3-5 micron bump may be key.  [?]  Apply 3d hydrodynamic wind model of Everett to predict the IR SED of quasars.  The presence of the 3-5 micron bump and strong, broad silicate features can be reproduced with this dynamical wind model when radiation driving on dust is taken into account.


1201.5101
Slicing the Torus: obscuring structures in quasars
Elvis


Quasars and AGNs are often obscured by dust and gas.  It is normally assumed that the obscuration occurs in an oblate "obscuring torus", that begins at the radius at which the most refractive dust can remain solid.  The most famous form of this torus is a donut-shaped region of molecular gas with a large scale-height.  While this model accounts for many phenomena at once, it does not hold up to detailed tests.  In stead the obscuration in AGNs must occur on a wide range of scales and be due to a minimum of 3 physically distinct absorbers.  Slicing the "torus" into these 3 regions will allow interesting physics of the AGN to be extracted.


1201.5112
Astrophysical models of r-Process nucleosynthesis: An update
Qian


Update on astrophysical models for nucleosynthesis via rapid neutron capture (r process) given.  A neutrino-induced r process in SNe He shells may have operated up to metallicities of 1e-3 times the solar value.  Another r-process source, possibly neutron star mergers, is required for higher metallicities.


1201.5114
Observations of dark and luminous matter: the radial distribution of satellite galaxies around massive red galaxies
Tal, Wake, van Dokkum


Study the projected radial distribution of satellite galaxies around more than 28k LRGs at z=0.34 and trace the vravitational potential of LRG groups in the range 7< 
[...abstract messed up...]


whereas baryons account for more than 50% of the mass at smaller radii.  Calculate the total dark-to-baryonic mass ratio and show that it is consistent with measurements from WL for environments dominated by massive early type galaxies.  Divide the satellite galaxies into 3 luminosity bins, and show that the satellite light profiles of all brightness levels are consistent with each other outside of roughly 25 kpc.  At smaller radii find evidence for a mid mass segregation with an increasing fraction of bright satellites close to the central LRG.


1201.5116
Cooling and heating functions of photoionized gas
Gnedin, Hollon


Cooling functions of cosmic gas are crucial ingredient for any study of gas dynamics and thermodynamics in the interstellar and intergalactic medium.  As such, they have been studied extensively in the past under the assumption of collisional ionization equilibrium.  However, for a wide range of applications, the local radiation field introduces a non-negligible, often dominant, modification to the cooling and heating functions.  In the most general case, these modifications cannot be described in simple terms, and would require a detailed calculation with a large set of chemical species using a radiative transfer code (e.g., "Cloudy").  Show, however, that for a sufficiently general variation in the spectral shape and intensity of the incident radiation field, the cooling and heating functions can be approximated as depending only on (1) the photo-dissociation rate of molecular H, (2) the H photo-ionization rate, and (3) the photo-ionization rate of OVIII; more complex and more accurate approximations also exist.  Such dependence is easy to tabulate and implement in cosmological or galactic-scale simulations, thus economically accounting for an important but rarely-included factor in the evolution of cosmic gas.  Also show a few examples where the radiation environment has a large effect, the most spectacular of which is a quasar that suppresses gas cooling in its host halo without any mechanical or non-radiative thermal feedback.


Astronomical Colloquium (MPIfR 0.02, Fri. 11am)
The early evolution of protostellar disks: fragmentation, episodic accretion, planet formation and other unexpected effects
Eduard Vorobyov


Review the recent progress in understanding the early stages of protostellar disk evolution when the disk is deeply embedded in the parent core: disks prone to gravitational instability and fragmentation--triggering episodic accretion onto the star; formation of gas giants and brown dwarfs on wide orbits and ejection of brown dwarfs and very-low-mass stars into the intracluster medium; flattening of the mass accretion--stellar mass relation the crystallization of amorphous silicates in the depths of massive fragments.  Show how episodic accretion can resolve the long standing luminosity problem, where young stars are systematically underluminous compared to what standard theories of SF predict.

Day 186

Tuesday.  JC swap today.  Not much on the list.  (edit) A lot of high-quality papers today!  Enough to fill the JC.


1201.4385
Prograde and regrograde black holes: whose jet is more powerful?
Tchekhovskoy, McKinney


Study prograde and retrograde disc accretion on rapidly spinning BHs via global 3d time-dependent non-radiative GR magnetohydrodynamic simulations.  Discs contain more large-scale vertical magnetic flux than the accreting gas can push into the BH; BH becomes saturated with flux, and strong centrally concentrated large-scale magnetic fields form that obsstruct the accretion and lead to a magnetically arrested disk.  Show that the efficiency with which such accretion systems generate steady outflows depends only on the dimensionless BH spin a, and accretion disk angular thickness h/r.  Prograde BHs with thick discs generate jets and outflows several times more efficiently than retrograde BHs, for the same absolute value of spin.  Both orientations can reach high values of outflow efficiency, eta~100%, with higher efficiency values for thicker discs.


1201.4386
The assembly history of disk galaxies: II. Probing the emerging Tully-Fisher relation during 1<z<1.7
Miller, Ellis, Sullivan, Bundy, Newman, Treu


New measurements of the resolved spectra of 70 morphologically-selected star-forming galaxies with i_AB<24.1 in the redshift range 1<z<1.7.  Using ACS images, successfully recover rotation curves using the extended emission line distribution of OII to 2.2 times the disk scale radius for a sample of 42 galaxies.  Combining these measures with stellar masses derived from HST and ground-based near-infrared photometry enables constructing the stellar mass Tully-Fisher relation in the time interval between z~1 and z>2.  Find a well-defined TF relation with up to 60% increase in scatter and only a modest zero-point shift, Delta M* -0.06pm0.02 dex at z~1.7, compared to local observation.  Sample is incomplete.  Discuss implicaton of typical SF disk galaxies evolve to arrive on a well-defined TF relation with a short period of cosmic history.


1201.4387
The stellar IMF, core mass function, and the last-crossing distribution
Hopkins


Derive stellar IMF as a consequence of turbulent density fluctuations, using an argument similar to Press Schechter 1974 for Gaussian random fields.  This solution does not resolve the 'cloud in cloud' problem, nor does it extend to large scales that dominate the velocity/density fluctuations.  In principle, these can change the results at the order-of-magnitude level.  Here, use results from Hopkins 2011 to generalize the excursion set formalism and derive the exact solution in this regime.  Argue that the stellar IMF and core mass function (CMF) should be associated with the last-crossing distribution; i.e., the mass spectrum of bound objects defined on the smallest scale on which they are self-gravitating.  This differens from the first-crossing distribution (mass function on the largest self-gravitating scale) which si defined cosmologically and which H11 show corresponds to the GMC mass function in disks.  Derive an analytic equation for the last-crossing distribution that can be used for an arbitrary collapse threshold in ISM and cosmological studies.  Show that the same model that predicts the GMC mass function and large-scale structure of galaxy disks also predicts the CMF (and by extrapolation IMF) in good agreement with observations.  The only adjustable parameter in the model is the turbulent velocity power spectrum, which in the range p~5/3-2 gives similar results.  Also use this to justify why the approximate solution in HC08 is reasonable (up to a normalization) over the CMF/IMF mass range; however there are significant corrections at intermediate and high masses.  Discuss how the exact solution here can be embedded into time-dependent models that follow density fluctuations, fragmentation, successive generations of star formation.


1201.4394
Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations
Santini, et al


Compare average SF activity in x-ray selected AGN hosts with mass-matched control inactive galaxies, including SF and quiescent sources, at 0.5<z<2.5.  Recent observations carried out by Herschel in GOODS-S, GOODS-N and COSMOS allow unbiased estimate of the far-IR luminosity, and hence the SF properties of the two samples.  Accurate AGN host stellar masses are measured by decomposing their total emission into the stellar and nuclear components.  Find a higher average SF activity in AGN hosts with respect to non-AGNs.  The level of SF enhancement is modest (~0.26 dex at 3 sigma) at low X-ray luminosities, and more pronounced (0.56 dex) in the hosts of luminous AGNs.  However, when comparing to SF galaxies only, AGN hosts are broadly consistent with the locus of their 'main sequence'.  Investigate the relative far-IR luminosity distributions on active and inactive galaxies, and find a higher fraction of PACS detected, hence normal and highly SF systems among AGN hosts.  Although different interpretation are possible, explain the findings as a consequence of a twofold AGN growth path: (1) faint AGNs evolve through secular processes, with instantaneous AGN accretion not thighly linked to the current total SF in the host galaxy, while the luminous AGNs co-evolve with their hosts through periods of enhanced AGN activity and SF, possibly through major mergers.  An increased SF activity with respect to in active galaxies of similar mass is expected in the latter.  The modeslt SF offsets measured in low lum. AGN hosts either (a) generated by non-synchronous accretion and SF histories in a merger scenario, or (b) due to possible connections between instantaneous SF and accretion that can be induced by smaller scale (non-major merger) mechanisms.  Far IR luminosity distributions favour the latter scenario.


1201.4398
Reconstructing the near-IR BG fluctuations from known galaxy populations using multiband measurements of luminosity functions
Helgason, Ricotti,, Kashlinsky


Model fluctuations in the CIB arising from known galaxy populations using 230 measuremd UV, optical and NIR luminosity functions from a variety of surveys spanning a wide range of redshifts.  Compare best-fit Schechter parameters across the literature and find clear indication of evolution with redshift.  Provide fitting ofmulae for the multi-band evolution of the LFs; calculate the total emission redshifted into the near-IR bands in the observer frame and recover the galaxy number counts in the 0.45-4.5 micron range.  Empirical approach in conjunction witha a halo model describing the clustering of galaxies allows computation of fluctuations of the unresolved CIB and compare the models to current measurements.  Find that fluctuations from known galaxy populations are unable to account for more than 20 % of CIB clustering signal seen in Spitzer and AKARI at angular scales out to at least 5 arcmin.  This holds true even if the LFs are extrapolated with the steepest faint-end slope allowed by data out to faint magnitudes.  A rapid increase in the number of low-z dwarf galaxies just beyond the detection thresholds of current surveys would violate the shot noise levels seen in the data.  Also show that removing resolved sources to progressively fainter magnitude limits isolates CIB fluctuations arising from higher z.  This approach suggests that known galaxy populations are not responsible for the bulk of the fluctuation signal seen in the measurements.


1201.4401
What makes a galaxy radio-loud?
Ortega-Minakata, et al


* LINER: low-ionization nuclear emission-line region (O, O+, N+, S+).  AGN or SF region emission, unknown.  LINERs often referred to as AGN.
* Quasar: powered by an accretion disk around a SMBH of a galactic nucleus.


Compare SED of radio-loud and radio-quiet AGNs in 3 different samples observed with SDSS: RLAGNs, LLAGNs (low-luminosity) and IG-AGNs (isolated galaxies).  All have similar optical spectral characteristics.  Median SED of RLAGNs is consistent with the characteristic SED of quasars, while that of the LL AGNs and IG-AGNs are consistent with the SED of LINERs, with a low luminosity in the IG-AGNs than LL AGNs.  Infer the masses of the BHs from the bulge masses: increase from the IG-AGN to LLAGNs are highest for the LR AGNs.   All AGNs show accretion rates near or slightly below 10% of the Eddington limit, the differences in luminosity being solely due to different BH masses.  Results suggests there are two types of AGNs, radio quiet and radio loud, differing only by the mass of their bulges or BHs.  


1201.4405
Probing the intergalactic magnetic field with the anisotropy of the extragalactic gamma-ray background
Venters, Pavlidou


THe IGMF may leave in imprint on the anisotropy properties of the extragalactic gamma-ray background through its effect on EM cascades triggered by interactions between very high energy photons and the extragalactic background light.  A strong IGMF will defect secondary particles produced in these cascades and will thus tend to isotropize lower energy cascade photons, thus inducing a modulation in the anisotropy energy spectrum of the gamma-ray background.  Present a simple calculation of the magnitude of this effect; demonstrate that the two extreme cases (zero IGMF and IGMF strong enough to completely isotropize cascade photons) would be separable by ten years of Fermi observations and reasonable model parameters for the gamma-ray background.  The anisotropy energy spectrum of Fermi gamma-ray BG could thus be used as a probe of the IGMF strength.


1201.4527
Gaussianizing the non-Gaussian lensing convergence field II: the applicability to noisy data
Yu, Zhang, Lin, Cui, Fry


A local monotonic Gaussian transformation can significantly reduce non-Gaussianity in noise-free lensing convergence field--promising for high-order lensing statistics.  Present study of its applicability in lensing data analysis, in particular when shape measurement noise is present(ed) in lensing convergence maps.  (1) shape measurement noise significantly degrades the gaussianization performance and the degradation increases for shallower surveys.  (2) Wiener filter is efficient to reduce the impact of shape measurement noise.  Gaussianization of the Wiener filtered lensing maps is able to suppress skewness, kurtosis ... by factor of 10 or more.  Also works efficiently to reduce the bispectrum well to zero.


1201.4600
The evolution of stellar velocity dispersion during dissipationless galaxy mergers
Stickly Canalizo


Study the evolution of central stellar velocity dispersion (sigma) during dissipationless binary mergers of galaxies in N-body simulations.  Sigma measured using the mass-weighting method, as well as flux-weighting method (similar to observations).  Toy model for dust attenuation introduced in order to study the effect of dust attenuation on measurements of sigma.  Find there are 3 stages in evolution: oscillation, phase mixing, and dynamical equilibrium.  During the oscillation stage, sigma undergoes damped oscillations of increasing frequency.  Amplitude of variation in sigma is smaller and more chaotic (mixing stage).  Upon reaching dynamical equilibrium, sigma assumes a stable value.  Use data on evolution of sigma to characterize the scatter inherent in making measurements of sigma in non-quiescent systems.  Find: sigma does not fall below 70% or exceed 200% of its final quiescent value during merger, and that a random measurement of sigma in such a system is much more likely to fall near the equilibrium value than near an extremum.  Toy model of dust attenuation suggested that dust can systematically reduce observational measurements of sigma and increase the scatter in sigma measurements. 


1201.4752
A new third-order cosmic shear statistics: separating E/B-mode correlations on a finite interval
Krause, Scneider, EIfler


Decompose shear signal into E- and B- modes separately (without leakage of modes into each other) has been a long-standing problem in WL.  At the 2-pt level, this was resolved by the ring statistics, and later COSEBIs; however, extending these concepts to the 3-pt level is not trivial.  Currently used methods to decompose 3pt shear correlation functions into E- and B- modes require knowledge of 3PCF down to arbitrary small scales.  Implies that the 3PCF needs to be modeled on scales smaller than the minimum separation of 2 galaxies and subsequently will be biased towards the model, or in the absence of a model, the statistics is affected by E/B-mode leakage (mixing).  Derive a new 3rd order E/B-mode statistic that performs the decomposition using the 3PCF only on a finite interval, and therby is free of any E/B mode leakage while at the same time relying solely on information from the data.  In addition, relate this 3rd order ring statistics to the convergence field, thereby enabling a fast and convenient calculation of this statistic from numerical simulations.  Note: new statistics should be applicable to corresponding E/B-mode separation problems in the CMB polarization field.


1201.4773
THe dust emission of high-z quasars
Leipski, Meisenheimer


Detection of powerful near-IR emission in high-z (z>5) quasars: demonstrates that very hot dust is present close to the active nucleus.  Currently being investigated.  (T~65K is "unusually high temperature").


1201.4820
First light: a brief review
Wise


The first stars in the universe are thought to be massive, forming in DM haloes with masses around 1e6 solar masses.  Recent simulations suggest that these metal-free (Pop III) stars may form in binary or multiple systems.  Because of their high stellar masses and small host haloes, their feedback ionizes the surrounding 3kpc of intergalactic medium and drives the majority of the gas from the potential well.  The next generation of stars then must form in this gas-poor environment, creating the first galaxies that produce the majority of ionizing radiation during cosmic reionization.  Review the latest developments in the field of Pop III star formation and feedback and its impact on galaxy formation prior to reionization.  Focus on the numerical simulations that have demonstrated this sequence of events, ultimately leading to cosmic reionization.


1201.4827
Evidence for quadratic tidal tensor bias from the halo bispectrum
Baldauf, Seljak, Desjacques, McDonald


Bias: relation between clustering properties of luminous matter (galaxies) and underlying DM distribution: important in interpreting galaxy surveys.  Local bias model: galaxy density is a function of local matter density, infer the matter power spectrum or correlation function from the measured galaxy counterparts.  However, gravitational evolution generates a term quadratic in the tidal tensor and thus non-local in the density field, even if this term is absent in the initial conditions (Lagrangian space).  Because the term is quadratic, it contributes as a loop correction to the power spectrum, so the standard linear bias picture still apples on large scales, however, it contributes at leading order to the bispectrum for which it is significant on all scales.  Such a term could also be present in Lagrangian space if halo formation were influenced by the tidal field.  Measure the corresponding coupling strengths from the matter-matter-halo bispectrum in numerical simulations and find a non-vanishing coefficient for the tidal tensor term.  Find no scale dependence of the bias parameters up to k=-0.1h/Mpc and that the tidal effect is increasing with halo mass.  While the lagrangian bias picture is a better description of the results than the Eulerian bias picture, our results suggest that there might be a tidal tensor bias already in the initial conditions.  Find that the coefficients of the quadratic density term deviate quite strongly from the theoretical predictions based on the spherical collapse model and a universal mass function. Both quadratic density and tidal tensor bias terms must be included in the modeling of galaxy clustering of current and future surveys if one wants to achieve the high precision cosmology promise of these datasets.  

1201.4119
The intracluster magnetic field power spectrum in A2199
Vacca, et al


Investigate the magnetic field power spectrum in the cool core galaxy cluster A2199 by analyzing the polarized emission of the central radio source 3C338.  The polarized radiation from the radio emitting plasma is modified by the Faraday rotation as it passes through the magneto-ionic intracluster medium.  Use VLA observations to produce detailed Faraday rotation measure and fractional polarization images of the radio galaxy.  Simulate Gaussian random 3-dimensional magnetic field models with different power-law power spectra and assume that the field strength decreases radially with the thermal gas density as n_e^eta.  Comparing the synthetic and observed image, constrain the strength and structure of the magnetic field associated with the ICM.  Find the Faraday rotation is consistent with magnetic field power law characterized by index n=2.8 pm 1.3 with a min and max fluctuation scale of 0.7 and 35 kpc.  By including the modeling X-ray cavities coincident with the radio galaxy lobes, find a magnetic field strength of <B>=11.7 micro Gauss at the cluster center.  Further out, the field decreases with the radius following the gas density to the power of eta=0.9.


1201.4125
Continuum reverberation mapping in a z=1.41 radio-loud quasar
Goicoechea, Shalyapin, Gil-Merino, Braga


* Reverberation (or echo) mapping: a time-domain technique to resolve the accretion flow in AGNs.  Relies on the analysis of time-delayed responses of different emitting regions to original fluctuations in an irradiating source.  


Q0957+561: the first discovered gravitationally lensed quasar.  The mirage shows two images of a radio-loud quasar at redshift z=1.41.  The time lag between these two images is well established around one year.  Detect a very prominent variation in the optical brightness of Q0957+561A at the beginning of 2009, allowing prediction of presence of significant intrinsic variation in multi-wavelength light curves of the B image over the first semester of 2010.  To study the predicted brightness fluctuations of the B image, conducted X-ray, NUV, optical and NIR monitoring campaign using both ground-based and space-based facilities.  The continuum NUV-optical light curves revealed evidence of a centrally irradiated, standard accretion disk.  Focus on the radial structure of the standard accretion disk and the nature of the central irradiating source in the distant radio-loud AGN.