Day 576

Monday.

1401.0548
Fermi-LAT detection of gravitational lens delayed gamma-ray flares from Blazar B0218+357
Cheung et al

A known double-image lensed system, showing a clear gamma-ray measurement of delay between flares from a blazar.  Peak fluxes consistently observed to reach >20-50 times its previous average flux.  Delay of 11.46 pm 0.16 days (1sigma) from cross-correlation function., ~1 day greater than previous measurements.  Decompose individual sequences of superposing gamma-ray flares/delayed emissions.  Find flux ratios consistent with ~1; systematically smaller than those from radio observations.  Flux doubling timescales of 3=6 hours observed, implying extremely compact gamma-ray emitting regions.

1401.0601
Calculating the Habitable Zone of multiple star systems (http://astro.twam.info/hz)
Mueller, Haghighipour

Calculating HZ of multiple star systems from spectral weight factors, calculating contribution of each star (based on SED) to the total flux received at the top of the atmosphere of an Earth-like planet, and use HZ of the Sun to determine the boundaries of HZ.

1401.0706
A clear and measurable signature in the galaxy velocity field
Hellwing, … Frenk, … Cole et al

The velocity field of the DM and galaxies reflects the continued action of gravity through cosmic history.  Show that the low-order moments of the pairwise velocity distribution, v_12, are a powerful diagnostic of the laws of gravity on cosmological scales.  The projected LoS galaxy parities velocity dispersion, sigma_12(r), is very sensitive to the presence of modified gravity.  Use N-body sims to compute the pairwise velocity distribution, and its projected LoS dispersion for a class of modified gravity theories:  f(R) and  Galileon (cubic and quartic).  Deviation from GR at 5 to 10 sigma level shown.  Examine strategies for detecting these deviations in galaxy redshift and peculiar velocity surveys.  

1401.0737
A physical understanding of how reionization suppresses accretion onto dwarf halos
Noh, McQuinn

Develop a physically motivating theory for how the interplay between gravity, pressure, cooling and self-shielding set the z-dependent mass scale at which haloes can accrete intergalactic gas.  This theory provides a physical explanation for the halo mass scale that can accrete unshocked intergalactic gas, which has been explained with ad hoc criteria tuned to reproduce the results of a few simulations.  Furthermore, it provides an intuitive explanation for how this mass scale depends on the reionization redshift, the amplitude of the ionizing background, and the redshift.  Show that accretion is inhibited onto more massive halos that had been [previously] thought because previous studies had focused on the gas fraction of halos rather than the instantaneous mass that can accrete gas.  A halo as massive as 1e11 Msun cannot accrete intergalactic gas at z=0, even through typically its progenitors were able to accrete gas at higher redshifts.  Describe a simple algorithm that can be implemented in SAMs, and compare this algorithm implemented on top of a halo merger tree to the results in the simulations.  

1401.0745
Is there a maximum star formation rate in high-redshift galaxies?
Barger et al

From GOOD-N field observations in FIR/submm/radio, get spectro-z for ~65% of radio sources; determine SFRs of the sub millimeter sources based on there radio powers and their sub millimeter and find that they agree well.  The radio data are deep enough to detect SF galaxies with SFRs > 2000 Msun /yr to z~6.  Find galaxies with SFRs up to ~6k Msun/yr over 1.5<z<6, but see evidence for a turn-down in the SFR distribution function above 2000 Msun/yr.

1401.1193
A WISE measurement of the ISW effect
Ferraro, Sherwin, Spergel

ISW measures the decay of the gravitational potential due to cosmic acceleration and is thus a direct probe of DE.  Measure cross-power of galaxies and AGN from WISE with CMB from WMAP9 to provide an independent measurement of the ISW amplitude.  Cross-correlations with the recently released Planck lensing potential maps are used to calibrate the bias and contamination fraction of the sources, thus avoiding systematic effects that could be present when using auto-spectra to measure bias.  Find amplitude of cross power of A=1.24 from galaxies and A=0.88 for AGN, fully consistent with the LCDM prediction of A=1.  ISW S/N is 2.7 and 1.2, respectively, giving a combined significance close to 3 sigma.  Comparing the amplitudes of galaxy and AGN cross-correlations, which arise from different redshifts, find no evidence for z evolution in DE properties, consistent with cosmological constant.

1401.1208
The dynamics of isolated Local Group galaxies
Kirby, Bullock, Boylan-Kolchin, Kaplinghat, Cohen

Measure velocities of 862 individual red giant stars in 7 isolated dwarf galaxies in the Local Group.  None of the isolated galaxies is denser than the densest LG satellite galaxy.  Furthermore, the isolated dwarf galaxies have no obvious distinction in the velocity dispersion-HLR plane from the satellite galaxies of the MW and M31.  The similarity of the isolated and satellite galaxies' dynamics and structural parameters imposes limitations on environmental solutions to the too-big-to-fail problem, wherein there are fewer dense dwarf satellite galaxies than would be expected from CDM simulations.  This data set also has many other applications for dwarf galaxy evolution, including the transformation of dwarf irregular into dwarf spheroidal galaxies, to be explored in future work.

1401.1209
What is the physical origin of strong Lya emission?  I.  Demographics of Lya emitter structures
Shibuya, et al

Present structure analysis for 426 LAEs at z~2.2 observed with HST.  Merger fraction and average ellipticity of LAE's stellar component are 10-30% and 0.4-0.6, respectively, that are comparable with previous study results.  Successfully identify that some LAEs have a spatial offset between Lya and stellar-continuum emission peaks, d_Lya, by ~2.5-4 kpc beyond statistical errors.  To uncover the physical origin of strong Lya emission found in LAEs, investigate Lya EW dependences of merger fraction, d_Lya, and ellipticity in the range EW(Lya)=20-250A.  Contrary to expectations,, find that merger fraction does not significantly increase with Lya EW.  Reveal an anti-correlation between d_Lya and EW(Lya).  There is a trend that the LAEs with a large Lya EW have a small ellipticity, consistent with recent theoretical claims that Lya photons can more easily escape from face-on disks having a small ellipticity, due to less inter-stellar gas along the LoS, although KS test indicates that this trend is not statistically significant.  Results of Lya-EW dependence generally support the idea that an EI column density is a key quantity determining Lya emissivity.

1401.1216
Dependence of the outer density profiles of halos on their mass accretion rate
Diemer, Kravtsov

Present systematic study of density profiles of halos forming in LCDM cosmology, focusing on the outer regions of halos, 0.1<r/Rvir<9.  Show that the median and mean density profiles of halo samples of a given peak height exhibit significant deviations from the universal analytic profiles (NFW, Einasto), at radii r>0.5 R200m.  In particular, the logarithmic slope of medan density profiles of massive or rapidly accreting halos steepens more sharply than predicted, with the steepening becoming more pronounced with increasing mass accretion rate.  The steepest profile occurs at r~R200m, and its absolute value increases with increasing peak height or mass accretion rate, reaching slopes of --4 and steeper.  Find that the outermost density profiles at r>R200m are remarkably self-similar when radii are rescaled by R200m.  This self-similarlity indicates that radii defined wrt the mean density are preferred for describing the structure and evolution of the outer profiles.  However, they under density profiles are most self-similar when radii are rescaled by R200c, a radius enclosing a fixed over density wrt the critical density of the universe.  Propose a new fitting formula that describes the profiles at all radii out to r~9 Rvir, including the transition region around r~R200m where the steepening occurs.  The formula fits the median and mean density profiles of halo samples selected by their peak height or mass accretion rate with accuracy <10% at all redshifts and masses studied, 0<z<4 and Mvir>1.7e10 Msun/h.  Discuss observational signatures of the density profile features described above, and show that the steepening of the outer profile should be detectable in future WL analysis of massive clusters.

1401.1246
Constraining Halo Occupation Distribution and cosmic growth rate using multiple power spectrum
Hikage

Propose a new method of measuring HOD together with cosmic growth rate using multipole components of galaxy power spectrum P_l(k).  The NL z-space distortion due to the random motion of satellite galaxies (FoG) generates high-l multipole anisotropy in galaxy clustering such as the l=4 (hexadecapole) and l=6 (tetra-hexadecapole), which are sensitive to the fraction and the velocity dispersion of satellite galaxies.  Using simulated samples following the HOD of LRG, find that the input HOD is successfully reproduced using P_l(k) even when directly fitting the central and satellite HOD values at different bins of mass without assuming any functional form.  Also show that the measurements of the cosmic growth rate as well as the satellite fraction and velocity dispersions are significantly improved by adding the small-scale information of high-l multipoles.

1401.1317
Magnetic fields and haloes in spiral galaxies
Krause

B-field patter which is spiral along the disk and X-shape in the halo [profile?], sometimes accompanied by strong vertical fields above and below the central region of the disk; strength of B-fields comparable.  The total and turbulent B-field strength is (weakly) increasing with SF, though there are indications that stronger SF reducers the B-field regularity globally.  B-field thought to be amplified by dynamo action; During the galaxy's formation and evolution, the turbulent dynamo amplifies the field strength to energy equipartition with the turbulent gas, while the large-scale (mean-field) dynamo mainly orders the B-field.  Hence, the large-scale B-field pattern evolves with time.  SN explosions causes further continuous injection of turbulent B-fields.  Assuming that small-scale field injection is situated only within the spiral arm region (where SF mostly occurs) lead to a large-scale field structure in which the B-field regularity is stronger in the inter arm region as observed in several nearby spiral galaxies.  The detection of similar scale heights in several spiral galaxies of different Hubble type SF implies a relation between the galactic wind, the total B-field strength and the SF in the galaxy.  A galactic wind may be essential for an effective dynamo action.  Strong tidal interaction, however, seems to disturb the balance leading to deviating and locally different scale heights as observed in M82 and NGC 4631.

1401.1342
The AGN content of deep radio surveys and radio emission in radio-quiet AGN.  Why every astronomer should care about deep radio fields
Padovani, et al

The main messages to non-radio astronomers is that radio surveys are reaching such faint limits that, while previously they were mainly useful for radio quasars and radio galaxies, they are now detecting mostly SFing galaxies and radio-quiet AGN, i.e., the bulk of the extragalactic sources studied in the IR, optical, and X-ray bands.

1401.1371
Circular polarization of the CMB: a probe of the first stars
De, Tashiro

Faraday conversion (FC) ude to SN remnants of the First stars (Pop III stars), in presence of B-field and scattering of photons with relativistic electrons.  Amplitude of l(l+1) Clvv / 2pi > 0.001 in units of micro kelvin squared for l>100, with the age of the Pop III SN remnant to be 10k years and frequency of CMB observation as 30 GHz.  

1401.1389
The cosmological parameters 2014
Lahav, Liddle

For Review of Particl Physics 2014 (aka the Particle Data Book).  Topics include: parameterizing the universe; extensions to the standard model; probes; brining observations together, outlook.

1401.1499
The atmospheres of Earth-like planets after giant impact events
Lupu et al

Explore the atmospheric chemistry, photochemistry, and spectral signatures of post-giant-impact terrestrial planets enveloped by thick atmospheres consisting predominantly of CO2, and H2O.  Self-consistent computation for atmospheres in equilibrium with hot surfaces with composition reflecting either the bulk silicate Earth (crust, mantle, atmosphere and oceans) or Earth'c continental crust.  Account for all opacity sources including collision-induced absorption.  Find that these atmospheres are dominated by H2O and CO2, while the formation of CH4, and NH3 is quenched due to short dynamical timescales.  Other important constituents are HF, HCl, NaCl, and SO2.  These are apparent in the emerging spectra, and can be indicative that an impact has occurred .  THe use of comprehensive opacities results in spectra that are a factor of 2 lower in surface brightness in the spectral windows than predicted by previous models.  The estimated luminosities show that the hottest post-giant-imact planets will be detectable with near-IR coronagraphs on the planned 30m-class telescopes.  The 1-4um region will be most favorable for such detections, freeing bright features and better contrast between the planet and potential debris disk.  Derive cooling timescales on the order of 1e5-6 Myrs, based on the modeled effective temperatures.  THis leads to the possibility of discovering tens of such planets in future surveys.

1401.1501
The SLUGGS survey: breaking degeneracies between dark matter, anisotropy and the IMF using globular cluster subpopulations in the giant elliptical NGC 5846
Napolitano, et al

Study the mass and anisotropy distribution of NGC 5846 using stars, as well as the red and blue GC subpopulations.  Use different phase space distributions of the two GC subpopulations to unambiguously constrain the mass of the galaxy and the anisotropy of the GC system.  Red GCs show the same spatial distribution and behavior and the starlight, whereas blue GCs have a shallower density profile, a larger velocity dispersion and a lower kurtosis, all of which suggest a different orbital distribution.  Use a dispersion-kurtosis Jeans analysis and find that the solutions of separate analyses for the two GC subpopulations overlap in halo parameter space.  The solution coverless on a massive DM halo, consistent with expectations from LCDM and WAMP7 cosmology in terms of M_DM~10e13.3 Msun and concentration c ~ 8.  This is the first example of this method; improves the uncertainties on the halo parameter determinations by 2x and opens new avenues for the use of elliptical galaxy dynamics as tests of predictions from cosmological simulations.  The implied stellar M/L ratio derived from the dynamical modeling is fully consistent with a Salpeter IMF and rules out a bottom light IMF.  The different GC subpopulations show markedly distinct orbital distributions at large radii, with red GCs having an anisotropy parameter beta~0.4 outside r ~ 3R_e, and the blue GCs having beta~0.15 at the same radii, while centrally ~1R_e they are both isotropic.  Discuss implications of findings within the 2-phase formation scenario for early-type galaxies.

1401.1510
Sub-millimeter galaxies as progenitors of compact quiescent galaxies
Toft et al

At z=2 (3 Gyrs after BB), half of the most massive galaxies were already old, quiescent systems with little to no residual SF and extremely compact with stellar mass densities at least an order of magnitude larger than in low z ellipticals, their descendants.  Dense stellar populations suggest formation within intense, compact starbursts 1-2 Gyr 1-2 Gyr earlier (3<z<6).  Simulations show that gas-rich major mergers can give rise to such starbursts which produce dense remnants.  Sub-millimeter galaxies (SMGs) are prime examples of intense, gas-rich, SBs.  With a new representative spectroscopic sample of compact quiescent galaxies at z=2 and a statistically well-understood sample of SMGs, show that z=3-6 SMGs are consistent with being the progenitors of z=2 quiescent galaxies, matching their formation redshifts and their distributions of sizes, stellar masses and internal velocities.  Assuming an evolutionary connection, their space densities also match if the mean duty cycle of SMG starbursts is 42 (+40/-29) Myr (consistent with independent estimates), which indicates that the bulk of stars in these massive galaxies were formed in a major, early surge of star formation.  These results suggests a coherent picture of the formation history of the most massive galaxies in the universe, from their initial burst of violent SF through their appearance as high stellar-density galaxy cores and their ultimate fate as giant ellipticals.


1401.1728
Variability in Ultra-luminous X-ray sources
Webb

Variable ULX's are thought to be accreting BHs for the most part.

1401.1814
The astronomical reach of fundamental physics
Burrows, Ostriker

Derive by dimensional and physical analysis the characteristic masses and sizes of important objects in the Universe in terms of just a few fundamental constants.  This exercise illustrates the unifying power of physics and the profound connections between the small and the large in the Cosmos we inhabit.  Focus on the minimum and maximum masses of normal stars, the corresponding quantities for neutron stars, the maximum mass of a rocky planet, the maximum mass of a WD, and the mass of a typical galaxy.  To zeroth order, show that all these masses can be expressed in terms of either the Planck mass or the Chandrasekhar mass, in combination with various dimensionless quantities.  With these examples, expose the deep interrelationships imposed by Nature between disparate realms of the Universe and the amazing consequences of the unifying character of physical law.

1401.1817
Galaxy and mass assembly (GAMA): ugrizYJHK S\'ersic luminosity functions and the cosmic spectral energy distribution by Hubble type
Kelvin, et al

Report morphological classification of 3727 galaxies from GAMA with M_r<-17.4 mag and 0.025<z<0.06 (2.1e5 Mpc^3) into E, S0-Sa, SBo-SBa, Sab-Scd, SBab-SBcd, Sd-Irr an little blue spheroid classes.  Approximately 70% of galaxies in sample are disk dominated systems, with the remaining ~30% spheroid dominated.  Establish the robustness of classifications, and use them to derive morphological-type luminosity functions and luminosity densities in the ugrizYJHK passbands, improving on prior studies that split by global color or light profile shape alone.  Find the the total galaxy luminosity function is best described by a double-Schechter function while the constituent morphological-type luminosity functions are well described by a single-Schechter function.  These data are also used to derive the SFR densities for each Hubble class, and the attenuated and unattenuated (corrected for dust) cosmic SEDs, i.e., the instantaneous energy production budget.  While the observed optical/NIR energy budget is dominated by 58:42 by galaxies with a significant spheroidal component, the actual energy projection rate is reversed, i.e., the combined disk dominated populations generate ~1.3x as much energy as the spheroid dominated populations.  On the grandest scale, this implies that chemical evolution in the local universe is currently confined to mid-type spiral classes like our MW.

1401.1830
60Fe-60Ni chronology of core formation in Mars
Tang, Dauphas

The timescales of accretion, core formation, and magmatic differentiations in planetary bodies can be constrained using extinct radionuclide systems.  Ni becomes more siderophile [dissolves into (solid) Fe readily, causing them to sink deeper into the Earth's Fe-rich core] with decreasing pressure, which is reflected in the progressively higher Fe/Ni ratios in the mantles of Earth, Mars and Vesta.  Mars formed rapidly and its mantle has a high Fe/Ni ratio, so the 60Fe-60Ni decay system (2.62 Myr half-life) is well suited to establish the timescale of core formation in this object.  Report new measurements of 60Ni/58Ni ratios in bulk SNC/martian meteorites and chondrites [meteorites that have not been modified due to melting or differentiation of the parent body].  The difference in epsilon-60Ni ratios in between SNC meteorites and the building blocks of Mars assumed to be chondritic (55% ordinary chondrites +45% enstatite chondrites) is +0.028pm0.023 (95% CL).  Using a model of growth of planetary embryo, this translate into a time for Mars to have reached ~44% of its present size of 1.9=0.8+1.7 Myr with a strict lower limit of 1.2 Myr after solar system formation, which agrees with a previous estimate based on 182Hf-182W systematics.  The presence of Mars when planetesimals were still being formed may have influenced the formation of chondrules through bow shocks or by inducing collisions between dynamically excited planetesimals.  Constraints on the growth of large planetary bodies are scarce and this is a major development in our understanding of the chronology of Mars.  

1401.1867
Nonparametric 3d map of the IGM using the Lyman-alpha forest
Cisewski et al

Visualizing the high-z Universe is difficult due to the dearth of available data; however, Lyman-alpha forest provides a means to map the IGM at redshifts no accessible to large galaxy surveys.  large-scale structure surveys, such as BOSS, have collected WSO spectra that enable the reconstruction of HI density fluctuations.  The at a fall on a collection of lines defined by the LoS of the QSO, and a major issue with producing a 3d reconstruction is determining how to model the regions between the LoS.  Present a method that produces a 3d map of this relatively uncharted portion of the Universe by employing local polynomial smoothing, a nonparametric methodology.  The performance of the method is analyzed on simulated data that mimics the varying number of LoS expected in real data, and then is applied to a sample region selected from BOSS.  Evaluation of the reconstruction is assessed by considering various features of the predicted 3d maps including visual comparison of slices, PDFs, counts of local minima and maxima, and standardized correlation functions.  This 3d reconstruction allows for an investigation of the topology of this portion of the Universe using persistent homology.

1401.2060
Subhaloes gone Notts: Subhaloes as tracers of the dark matter halo shape
Hoffmann, .. Gaztanaga, … et al

Study the shapes of sub halo distributions from 4 DM only simulations of MW hype halos (Springel et al 2008).  The sub haloes have been identified by ten sub halo finders at up to 5 different resolution levels (Onions+ 2012).  Comparing the shapes derived from the sub halo distributions at high resolution to those of the underlying DM fields, find the former to be more triaxial if the analysis is restricted to massive sub haloes.  For 3 of the 4 analyzed halos the increased triviality of the distributions of massive sub haloes can be explained by a systematic effect caused by the low number of objects.  Subhaloes of the fourth halo show indications for anisotropic accretion via their strong triaxial distribution and orbit alignment wrt the DM field.  At low resolution levels the shape measurements of the sub halo distributions consisting of the 13 most massive objects identified by the different sub halo finders are strongly scattered.  Comparing the shape of the observed MW satellite distribution to those of high-res sub halo samples from simulations, find an agreement for samples of bright satellites, but significant deviations if faint satellites are included in the analysis.  These deviations might result from observational incompleteness.

1401.2087
The XXL survey: detection of the Sunyaev-Zel'dovich effect of the redsfhit 1.9 galaxy cluster XLSSU J021744.1-034536 with CARMA
Mantz et al

Photo-z determined SZ cluster at z=1.9pm0.2, the most distant for which the SZ effect has been measured.  Estimate a mass M500~1-2e14 Msun from X-ray flux and SZ signal.

1401.2134
10 simple rules for the care and feeding of scientific data
Goodman, et al

As the title says.

1401.2159
The impact of rotation on the line profiles of Wolf-Rayet stars
Shenar et al

Model emission line width of rotating WR stars.  The rotational velocities are difficult to measure, due to their expanding atmospheres, but some WR stars have peculiarly broad and round emission lines.  Assume a rotational velocity field consisting of an inner co-rotating domain and an outer domain, where the angular momentum is conserved.  Find that rotation can reproduce the unique spectra, but the inferred rotational velocities at the stellar surface are large (~200 km/s) and the inferred co-rataion radii (~10 stellar radii) suggest the existence of very strong photospheric magnetic fields (~20 kG).

1401.2274
Discovery of four doubly imaged quasar lines from the Sloan Digital Sky Survey
Inada, Oguri, Rusu, Kayo, Morokuma

As the title says.  From SDSS, with follow-up observations.

1401.2392
Superhabitable worlds
Heller, Armstrong

Superhabitable == worlds that offer more benign environments to life ethan Earth does.  Illustrate how tidal heating can render terrestrial or icy worlds habitable beyond the stellar HZ. [what does "more habitable than Earth" mean?  wouldn't that narrow the range of habitable zone?]