1207.0808
Stellar intensity inteferometry: prospects for sub-milliarcsecond optical imaging
Dravins et al
Review interferometric method by arrays of air Chrenkov telescopes, and outlines observational programs that should become realistic already in the rather near future.
1207.0809
A filament of dark matter between two clusters of galaxies
Dietrich, Werner, Clowe, Finoguenov, Kitching, MIller, Simionescu
Galaxy clusters live a the intersection of LSS filaments, traced by galaxy redshift surveys, WHIM in low-z filaments. Report detection of DM filament connecting components of Abell 222/223 from WL signal, with non-parameteric mass reconstruction, and in parametric model fits. Filament coincident with over density of galaxies and diffuse, soft X-ray emission; contributes mass comparable to an additional galaxy cluster to the total mass of the supercluster. Place upper limit of 0.09 on hot gas fraction in the filament.
1207.0813
Search of sub-parsec massive binary black holes through line diagnosis II
Montouri et al
MgII/CIV flux ratio can be unusually small in massive BH binaries at sub-parsec separations, due to erosion of the broad line region around the active, secondary black hole, by the tidal field of primary. Show this with SPH simulation.
* Why are the elemental ratios important? What does it physically mean?
1207.0816
The pseudo-evolution of halo mass
Diemer, More, Kravtsov
Defining halo mass by spherical mass over density can lead to spurious evolution in the halo mass, even if its physical density profile remains constant over time. This pseudo-evolution in mass is caused y the evolution of the reference density with redshift, and has little connection with the actual physical accretion of mass: from z=1 to 0, it increases halo masses significantly across a wide range of halo masses and over densities. Pseudo-evolution accounts for almost the entire mass evolution of haloes with M200 <= 1e12 solar masses, while for larger haloes, it still accounts for ~50% of their overall mass evolution. Estimate the magnitude of pseudo-evolution, assuming density profiles remain static in physical coordinates, and show that this simple model predicts the pseudo-evolution of simulated haloes to a few percent accuracy. Discuss impact on halo mass function. Non-evolution of the low-mass end of the halo mass is the result of a fortuitous cancellation between pseudo-evolution and absorption of small haloes into larger hosts. Evolution of low-mass end of the c-M relation in sims entirely due to pseudo-evolution of mass. Discuss the implications of results for interpretation of evolution of various scaling relations between observable properties of galaxies, galaxy clusters, and their halo masses.
1207.0831
Multiwavelength campaign on Mrk 509: Reverberation of the Fe Kalpha line
Ponti et al
Mrk 509: Seyfert 1 galaxy, shows a clear neutral Fe Kalpha emission line that can be decomposed into a narrow component plus a resolved component. Linear correlation between the intensity of the resolved line component and the flux variations on time scales of few days to years. The resolved Fe Kalpha reverberates the hard X-ray continuum without any measurable lag: resolved Fe component must be located within a few light days-week (1e3 rg) from the BH. Lack or redshifted wing indicates lower limit of >40 rg for its distance from the BH. Fe line could be emitted from the inner regions of GLR, within the 80 light days indicated by the Hbeta line measurements. Detection of weak ionized Fe K emission as well; can be modeled with a blend of two narrow FeXXV and FeXXVI emission lines, or with a single relativistic line in an ionized disk, down to a few rg from the BH. Weakening/disappearing of the medium and high velocity high ionization Fe K wind features found in previous XMM-Newtom observations: campaign made possible the first reverberation measurement of the resolved component of the Fe Kalpha line, inferring a location for the bulk of its emission.
1207.0839
Distribution function approach to redshift space distortions. Part IV: perturbation theory applied to dark matter
Vlah, Seljak, McDonald, Okumura, Baldauf
Perterbative approach to RSD using the phase space distribution function approach, and apply it to the DM z-space power spectrum and its moments. RSD can be written as a sum over density weighted velocity moments correlators. Use PT to determine auto and cross correlators, compare them to N-body simulations; show which can work with standard PT and which need higher order corrections which cannot be modeled in PT. Most of these additional terms are related to the small scale velocity dispersion effects (FoG) which affect some, but not all, of the terms in this expansion, and can be approximately modeled using a simple physically motivated ansatz such as the halo model. ... In contrast to previous models, this approach systematically includes all of the terms at a given order in PT and provides a physical interpretation for the small scale dispersion values. Investigate SRD power spectrum as a function of mu, focusing on the lowest order of mu and multipole moments which dominate the observable RSD power spectrum.
1207.0856
The unusual smoothness of the extragalactic unresolved radio background
Holder
If radio background is coming from cosmological sources, there should be some clustering due to the LSS. The rms temperature variations in cosmic radio background appear to be more than 10x smaller (in temperature) than the fluctuations in the CIB. It is therefore extremely unlikely that this background comes from galaxies, galaxy clusters, or any sources that trace DM haloes at z<5, unless typical sources are smooth on arc minute scales, requiring typical sizes of several Mpc.
1207.0891
GASKAP -- The Galactic ASKAP survey
Dickey et al
Survey of MW disk and Magellanic system in 21cm HI line and 3 18cm OH molecule lines. Molecular thermal emission, absorption, and maser lines, in galactic plane |b|<10deg at all declinations south of delta=+40 deg, plus all area of Magellanic stream and clouds (total 13k sq deg). Goals: galaxy evolution, SF, stellar wind kinematics, thermal phases of ISM, gas in disk and halo, dynamical and thermal states of gas at various positions along the Magellanic Stream.
1207.1074
Mind the gap: tightening the mass-reichness relation with magnitude gaps
Hearin, Zentner, Newman, Berlind
Improve optical tracers of cluster mass b exploiting measurements of the magnitude gap (m12), the difference between ther-band absolute magnitude of the two brightest cluster members. Find that in a mock sample of galaxy groups and clusters constructed from Bolshoi simulation, the mass-richness relation scatter decreases by 15-20 % with magnitude gap information is included. [how is it included?] Find: SDSS groups with small gaps are richer than large gap groups. Show that m12 contains information about cluster mass that supplements the information provided by group richness and luminosity of the brightest cluster galaxy L_bcg.
[Thu **/33] Jul 5
1206.5807
The Zurich Environmental Study (ZENS) of galaxies in Groups along the cosmic web. I. Which environment affects galaxy evolution?
Carollo et al
The ZENS is designed to compare dependence of z=0 galaxy structural and stellar populations diagnostics at constant stellar mass on four measures of the environment: mass of host group halos, projected distance from the center of the halo, the rank of galaxies as centrals or satellites, and the filamentary LSS density on which the groups reside. Contains 1630 galaxies in 1e12.5-14 Msun at z~0.06. Novel approach to quantify environments of galaxies: describe a Nth nearest neighbor approach to determine LSS density field. 40% of groups do not have "centrals", and 10-20% of groups may be dynamically young; central galaxies are not regulated b their environment, but exclusively by their stellar mass; 1e10 Msun in relaxed and unrelaxed groups as well as centrals have similar size, color and SFR distributions, but at lower galaxy masses satellites are 0.1mag bluer in unrelaxed groups. Physical processes occuring in dynamically relaxed group halos are important to quench SF in low mass satellites.
1206.5852
A simple model for the density profiles of isolated dark matter haloes
Visbal, Loeb, Hernquist
Explore the possibility that, density profiles of elliptical galaxies and CDM haloes can be understood in terms of the same physical process: collisionless gravitational collapse. Study the collapse of a cold Plummer sphere: N-body sim with purely radial orbits; results in a final state characterized by a profile slightly steeper than r^-2 at small radii, and r^-4 at large radii; can be understood from simple analytic arguments. Repeat simulation with non-radial orbits: results in a shallower inner density profile, similar to elliptical galaxies and CDM haloes. Outer CDM halo density profile is not "universal", but depends on cosmological environment.
2306.5020
Carollo et al
The ZENS is designed to compare dependence of z=0 galaxy structural and stellar populations diagnostics at constant stellar mass on four measures of the environment: mass of host group halos, projected distance from the center of the halo, the rank of galaxies as centrals or satellites, and the filamentary LSS density on which the groups reside. Contains 1630 galaxies in 1e12.5-14 Msun at z~0.06. Novel approach to quantify environments of galaxies: describe a Nth nearest neighbor approach to determine LSS density field. 40% of groups do not have "centrals", and 10-20% of groups may be dynamically young; central galaxies are not regulated b their environment, but exclusively by their stellar mass; 1e10 Msun in relaxed and unrelaxed groups as well as centrals have similar size, color and SFR distributions, but at lower galaxy masses satellites are 0.1mag bluer in unrelaxed groups. Physical processes occuring in dynamically relaxed group halos are important to quench SF in low mass satellites.
1206.5852
A simple model for the density profiles of isolated dark matter haloes
Visbal, Loeb, Hernquist
Explore the possibility that, density profiles of elliptical galaxies and CDM haloes can be understood in terms of the same physical process: collisionless gravitational collapse. Study the collapse of a cold Plummer sphere: N-body sim with purely radial orbits; results in a final state characterized by a profile slightly steeper than r^-2 at small radii, and r^-4 at large radii; can be understood from simple analytic arguments. Repeat simulation with non-radial orbits: results in a shallower inner density profile, similar to elliptical galaxies and CDM haloes. Outer CDM halo density profile is not "universal", but depends on cosmological environment.
2306.5020
Galaxy Zoo: quantifying morphological indicators of galaxy interaction
Casteels et al
Study morphological signatures of interaction between similar-mass galaxy pairs in SDSS. Many observable features correlate with projected pair separations.
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