Day 519

Monday.

1309.6643
The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years
Ascaso, ...Squires, et al

Investigate the formation and evolution mechanisms of the BCGs over cosmic time.  At high z~0.9, select the BCGs and most massive cluster galaxies (MMCGs) from the CL1604 supercluster, a complex structure of clusters and groups spanning a wide range in mass.  THese galaxies were compared to low-z~0.1 counterparts drawn from the MCXC catalog and supplemented by SDSS imaging and spectroscopy.  Observed differences in the morphological, color, spectral, and stellar mass properties of the BCGs and MMCGs from low to high redshift: Those housed in the high-z clusters/groups were, in many cases, SF, late-type galaxies, with broadband colors that were bluer than the red sequence, properties that were largely absent at low-z.  The stellar mass was found to increase by a factor of 2.51 pm 0.71, further indicating significant evolution in these galaxies.  The content of stellar mass from spectroscopically confirmed members surrounding the BCGs/MMCGs was compared between the two samples.  Conclude that a combination of major merging (mainly wet or mixed) and in situ SF are the main mechanisms that build stellar mass in BCGs/MMCGs from z~0.9 to z~0.1.  The stellar mass growth of the BCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster.  Through comparisons of structural parameters found that BCGs/MMCGs grow in size on average, by a factor of ~3 and the average Sersic index increases by ~0.45 from z~0.9 to 0.1.  This analysis also supports a picture involving major merging events, though some adiabatic expansion is needed.  These observational results are compared to both SAMs and hydrodynamical simulations to further explore the implications of processes which shape and evolve BCGs/MMCGs over the past ~7 Gyr.

1309.6734
Abundance profiling of extremely metal-poor stars and supernova properties in the early universe
Tominaga, Iwamoto, Nomoto

First stares were Pop III; first chemical enrichment by SN; Chemical evolution of the universe is recorded in abundance patterns of extremely metal-poor (EMP) stars.  Increasing number of the EMP stars are now being discovered.  This allows statistical constraint of SNe of PopIII stars (Pop III SNe).  Investigate the properties of Pop III SNe by comparing their nucleosynthetic yields with the abundance patterns of the EMP stars.  Focus on the most metal-poor stars with [Fe/H] <~ 3.5 and present Pop III SN models that reproduce well their individual abundance patterns.  From these models, derive relations between abundance ratios and properties of Pop III SNe [(C+N)/Fe] vs. an ejected Fe mass, and [(C+N)/Mg] vs. a remnant mass.  Using fitting formulae, distribution of the abundance ratios of EMP stars is converted to those of the properties of Pop III SNe, which can be compared with SNe in the present day.  Large samples of EMP stars obtained by ongoing and planning EMP star surveys and subsequent high-dispersion spectroscopic observations will give a clue to confining properties of Pop III SNe in the early universe.

1309.6768
Probing the circumgalactic medium at high-redshift using composite BOSS spectra of strong Lyman-alpha forest absorbers
Pieri et al

Present composite spectra constructed from a sample of 242k Lya forest absorbers at 2.4<z<3.1 identified in quasar spectra from BOSS SDSS DR9.  Select forest absorbers by their flux in bins 138 km/s wide (approximately the size of the BOSS resolution element).  Split these absorbers into five samples spanning the range of flux -0.05<F<0.45.  Tests on a smaller sample of high-resolution spectra show that the 3 strongest absorption bins would probe circumgalactic regions (projected separation < 300 proper kpc and |Delta v| < 300 km/s) in about 60% of cases for very high S/N.  Within this subset, weakening Lya absorption is associated with decreasing purity of circumgalactic selection once BOSS noise is included.  The weaker two Lya absorption samples are dominated by IGM.  Present composite spectra of these samples and a catalogue of measured absorption features from HI and 13 metal ionization species, all of which is available to the community.  Compare measurements of 7 Ly series transitions in the composite spectra to single line models and obtain further constraints from their associated excess Ly limit opacity.  This analysis provides results consistent with column densities over the range 14.4 <~ Log(N_HI) <~ 16.45.  Compare measurements of metal absorption to a variety of simple single-line, single-phase models for a preliminary interpretation.  Results imply clumping on scales down to ~30 pc and near-solar metallicities in the circumgalactic samples, while high-ionization metal absorption consistent with typical IGM densities and metallicities is visible in all samples.  
1309.6774
MOSE: optical turbulence and atmospherical parameters operational forecast at ESO ground-based sites.  II: atmospherical parameters in the surface layer [0-30]m
Lascaux, Masciadri, Fini

1309.6775
MOSE: optical turbulence and atmosphserical parameters operational forecast at ESO ground-based sites. I: Overview and atmospherical parameters vertical stratification on [0-20] km

[6775]
Feasibility of the forecast of all the most relevant classical atmospherical parameters for astronomical applications (wind speed and direction, temperature, relative humidity) and the optical turbulence (Cn2 and the derived astro-climatic parameters like seeing, isoplanatic angle, wavefront coherence time ...).  Present the results related to the Meso-Nh model ability in reconstructing the surface layer atmospherical parameters (wind speed intensity, wind direction and absolute temperature, [0-30] m a.g.l.).  The model reconstruction of all the atmospherical parameters in the surface layer is satisfactory.   .... The model operational forecast of the surface layer atmospherical parameters is suitable for different applications, among others: thermalization of the dome using the reconstructed temperature, hours in advance, of the beginning of the night; knowing in advance the main direction which the strong winds will come from during the night could allow the astronomer to anticipate the occurrence of a good/bad seeing night, and plane the observations accordingly; preventing adaptive secondary mirrors shake generated by the wind speed.

[6776...they got the order incorrect...]
Investigate the opportunity to implement an automatic system for the forecast of these parameters at these [ESO] sites.  Reconstruct the vertical stratification of the atmospherical parameters along the 20km above ground.  Good performance in reconstructing most of these parameters (and in particular the wind speed) put this tool of investigation at the most suitable for use in astronomical observatories to support AO facilities and to calculate the temporal evolution of the wind speed and the wavefront coherence time at whatever temporal sampling.  Estimates can be available in advance (of order hours) with respect to the time of interest.

1309.6781
Spatial distributions of core-collapse supernovae in infrared-bright galaxies
kangas et al

A more centrally concentrated population of massive stars in IR-bright galaxies; centralization is dominated by a central excess of type Ibc/IIb SNe; possibly due to a top-heavy IMF and/or an enhanced close binary fraction in regions of enhanced SF.  

1309.6783
Beyond consistency test of gravity with redshift-space distortions at quasi-linear scales
Taruya, Koyama, Hiramatsu, Oka

Combine RSD (measure growth of cosmic structure on large scales) with measurement of cosmic expansion history, to be used as cosmological tests of gravity.  An accurate modeling of RSD going beyond linear theory is critical in order to detect or disprove small deviations from GR.  Perturbation theory (PT) heavily relies on GR; here, put forward a new PT prescription [what exactly is it?] for RSD in general modified gravity models.  As a specific application, present theoretical predictions of the redshift-scpae PS in f(R) gravity model, and compare them with N-body sims.  Using the PT template that takes into account the effects of bot modifications of gravity and rSD properly, successfully recover the fiducial model parameter in N-body simulations in an unbiased way.  On the other hand, found it difficult to detect the scale dependence of the growth rate in a model-independent way based on GR templates.

1309.6994
Overview of the SOFIA data cycle system: an integrated set of tools and services for the SOFIA general investigator
Shuping et al

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne astronomical observatory comprised of a 2.5m IR telescope mounted in the aft section of a Boeing 747SP aircraft hat flies at operational altitudes between 37000 and 45000 ft, above 99% of atmospheric water vapor.  DUring routine operations, a host of instruments will be available to the astronomical community including cameras and spectrographs in the near- to far-IR; a sub-mm heterodyne receiver; and an high-speed occultation imager.  One of the challenges for SOFIA (and all observatories in general) is providing a uniform set of tools that enable the non-expert General Investigator (GI) to propose, plan, and obtain observations using a variety of very different instruments in an easy and seamless manner.  The SOFIA Data Cycle System (DCS) is an integrated set of services and user tools for the SOFIA Science and Mission Operations GI Program designed to address this challenge.  ....

1309.7005
Herschel observations and a model for IRAS 08572+3915: a candidate for the most luminous infrared galaxy in the local (z<0.2) universe
Efstathiou, et al

As the title says.  

1309.7044
Robust quantification of galaxy cluster morphology using asymmetry and central concentration
Nurgaliev, ... Vikhlinin, et al

Present a novel quantitative scheme of cluster classification based on the morphological properties that are manifested in X-ray images.  Use: conventional radial surface brightness concentration parameter (c_SB), and a new asymmetry parameter (photon asymmetry: A_phot), developed as a robust substructure statistic for cluster observations with only a few thousand counts.  Demonstrate stability than power ratios or centroid shifts, artificially degrade the X-ray image quality by (a) adding extra BG counts, (b) eliminating a fraction of the counts, (c) increasing the width of the smoothing kernel, and (d) simulating cluster observations at higher z.  The asymmetry statistic presented here as a smaller statistical uncertainty than competing substructure parameters, allowing for low levels of substructure to be measured with confidence.  A_phot is less sensitive to the total number of counts than competing substructure statistics, making it an ideal candidate for quantifying substructure in samples of distant clusters covering wide range of observational S/N.  Additionally, show that the asymmetry-concentration classification separates relaxed, cool core clusters from morphologically-distrubed mergers, in agreement with by-eye classifications.  Code publicly available on github.

1309.7045
Are GRBs the same at high redshift and low redshift?
Littlejohns et al

GRBs at z>6 have propmt durations T()<30s, corresponds to <5s in their rest frames.  Test whether these high-redshift GRBs are consistent with being drawn from the sampe population as those observed at low-z by comparing them to an artificially reds-fhted sample of 114 z<4 bursts.  Use two different methods to compare.  ~1% probability that the high-z GRB samples is drawn from the same population as the bright low-z sample [what is the qualitative difference of the z<4 GRB???]; marginally significant.

1309.7056
Reionization on large scales IV: predictions for the 21 cm signal incorporating the light cone effect
La Plante, .. Trac, Cen, Loeb, et al

Predictions for the 21cm brightness temperature power spectrum during EoR.  Discuss the implications of the "light cone" effect, which incorporates evolution of the 21cm brightness temperature along the LoS.  Model the HI density field and 21 cm signal in large volumes (method calibrated against radiation-hydrodynamic simulations; L=2 Gpc/h).  Inclusion of the light cone effect leads to a relative increase of 2-3 orders of magnitude in the 21cm signal PS on large scales (k<0.1 h/Mpc).  When PS is modified to more closely reflect real-world measurement capabilities, find that the light cone effect leads to a relative decrease of order unity at al scales.  The light cone effect also introduces an anisotropy parallel to the line of sight.  By decomposing the 3d PS into components perpendicular and parallel to the LoS, find that parallel modes contribute about an order of magnitude more power than perpendicular modes.  The anisotropy also strongly depends on the duration of reionization, with shorter durations introducing more anisotropy.  The scales on which the light cone effect is relevant are comparable to the scales where one measures the BAO.  Argue that due to its large comoving scale and introduction of anisotropy, the light cone effect is important when considering RSD and future application to the Alcock-Paczynski test for the determination of cosmo parameters.

1309.7057
A new model of galaxy formation: how sensitive are predicted galaxy luminosities to the choice of SPS model?
Gonzalez-Perez, Lacey, Baugh, ... et al

New release of GALFORM SAM, which exploits a Millennium Simulation-class N-body run performed with WMAP7 cosmology.  Use this new model to study the impact of the choice of SPS model on the predicted evolution of the galaxy LF.  SAM is run using 7 different SPS models.  In each case, obtain the rest-frame luminosity function in the FIR, optical and NIR wavelength ranges.  Find that both the predicted rest-frame UV and optical LF are insensitive to the choice of SPS model.  However, find that the predicted evolution of the rest-frame NIR LF depends strongly on the treatment of the thermally pulsating asymptotic giant branch (TP-AGB) stellar phase in the SPS models, with differences larger than a factor of 2 for model galaxies brighter than K(AB)-5 log h<-22 (about L* for 0<z<1.5).  Results suggest that the observed evolution of the rest-frame NIR LF could help to constrain the modeling of TP-AGB stars.  Have also explored the predicted number counts of galaxies, finding good agreement between the results with different choices of SPS model, except when selecting galaxies with very red optical-NIR colors.  The predicted number counts of these extremely red galaxies appear to be more affected by the treatment of SF in disks than by the treatment of TP-AGB stars in the SPS models.  [can observations at this end be used to constrain the proper model?]

1309.7320
On protecting the planet against cosmic attack: ultrafast real-time estimate of the astroid's radial velocity
Zakharchenko, Kovalenko

A new method for the LoS velocity estimation of a high-speed NEO suggested: method is based on use of fractional, one-half order derivative of a Doppler signal.  The algorithm suggested is much simpler and more economical than the classical one, and it appears preferable for use in orbital weapon systems of threat response.  Application of fractional differentiation to quick evaluation of mean frequency location of the reflected Doppler signal is justified.  The method allows an assessment of the mean frequency in the time domain without spectral analysis.  An algorithm structure for the real-time estimation is presented.  The velocity resolution estimates are made for typical steroids in the X-band.  It is shown that the wait time can be shortened by orders of magnitude compared with similar value in the case of a standard spectral processing.

1309.7263
Can very compact and very massive neutron stars both exist?
Drago, Lavagno, Pagliara

NS with >2Msun requires a stiff EoS at high densities; while the necessary appearance also at high densities of new degrees of freedom, such as hyperons and Delta resonances, can lead to strong sofening of the EoS with resulting maximum masses of ~1.5 Msun and radii smaller than ~10 km.  Hints for the existence of compact stellar obects with very small radii have been found in recent statistical analysis of quiescent low-pmass X-ray binaries in globular clusters.  Propose an interpretation of these two apparently contradicting measurements, large masses and small radii, in terms of two separate families of compact stars: hadronic stars, whose EoS is soft, can be compact, while quark stars, whose equation of state is stiff, can be very massive.  An early appearance of Delta resonances is crucial to guarantee the stability of the branch of hadronic stars.  Proposal can be tested by measurements of radii with an error of ~1km, which is within reach of the planned LOFT satellite, and it would be further strengthened by the discovery of compact stars heavier than ~2Msun.