Monday. Caught up with astro-ph reading over the weekend. Today the painter comes.
1112.1949
What drives the growth of black holes?
Alexander, Hickox
Still lack a coherent picture of the physical drivers of BH growth, the connection between the growth of BHs and their host galaxies, the role of large-scale environment on the fueling of BHs, and the impact of BH-driven outflows on the growth of galaxies. Review progress in addressing these key issues.
1112.1954
Neptune on tiptoes: dynamical histories that preserve the cold classical Kuiper belt
Wolff, Dawson, Murray-Clay
* Kuiper Belt: region of the solar system beyond the planets extending from the orbit of Neptune (30 AU) to approximately 50 AU from the Sun. Consists mainly of small bodies, or remnants from the SS's formation. While the astroid beld is composed primarily of rock, ices, and metal, the Kuiper objects are composed largly of frozen volatiles ("ices") such as methane, ammonia and water. The classical (low-eccentricity) belt is home to at least three dwarf planets -- Pluto, Haumea, and Makemake. Some of the SS's moons, such as Neptune's Triton and Saturn's Phoebe, are also believed to have originated in the region.
Current dynamical structure of the Kuiper belt was shaped by the orbital evolution of the giant planets, especially Neptune, during the era following planet formation, when the giant planets may have undergone planet-planet scattering and/or planetesimal-driven migration. Numerical simulations fail to generate the observed "cold" population. There are several well-defined regimes of secular excitation by Neptune (if it undergoes a period of elevated eccentricity and/or inclination) of the eccentricities and inclinations of the planetesimal disk. Through exploration of parameter space. Neptune's eccentricity and inclination can remain high for a limited amount of time without disrupting the cold classical belt.
1112.1956
Galaxy and Mass Assembly (GAMA): Structural investigation of galaxies via Model Analysis (SIGMA)
Kevin, et al
Present single Sersic 2d modle fits to 167k galaxies modeled independently in the ugrizYJHK bands in SDSS DR7 and UKIDSS-LAS available from the GAMA database. Provide Sersic magnitudes truncated at 10 re which show good agreement with SDSS Petrosian and GAMA photometry for low Sersic index systems (n~4). Split into ETG (n>~2) and LTGs from K band Sersic index and u-r colour relation. The Sersic index of ETGs show a smooth variation with wavelength, increasing from 30% from g through K. LTGs exhibit a more extreme change in Sersic index, increasing by 52% across the same range. ETGs and LTGs exhibit at 38% and 25% decrease respectively in half-light radius from g through K. Trends are shown to arise due to the effects of dust attenuation and stellar population/metallicity gradients within galaxy populations.
1112.1971
A new method to quantify x-ray substructures in clusters of galaxies
Andrade-Santos, Neto, Lagana
Analysis with residual image that is the result of the subtraction of a surface brightness model (based on beta-model or Sersic profile)
1112.1981
The paths of gravity in Galileon cosmology
Appleby, Linder
Explore 3 classes of Galileon models (can explain cosmic acceleration): standard uncoupled, and linearly or derivatively coupled to matter, with expansion history in early time and late time attarctors, as well as linear perturbations. Calculate generalization of Newton's constant, deriving its early and late time behavior. Coupled models are severely constrained by classical instabilities in the early universe.
1112.1991
Employing soft X-rays in experimental astrochemistry
Pilling, Andrade
Presence of soft x-rays is very important for the chemcial evolution fo interstellar medium and other astrophysical environments close to young and bright stars: can penetrate deep in molecular clouds and protostellar disks and trigger chemistry in regions in which UV stellar photons do not reach. The effects of soft x-rays in astrophysical ices are also remarkable because they release secondary electrons in and on the surface fo the ices, which trigger a new set of chemical reactions. Discuss origin and relevance of soft x-rays in astrophysics.
1112.2006
Relaxation-limited evaporation of globular clusters
(Maurice) van Putten
Evaporative evolution of stellar clusters is shown to be relaxation limited when the number of stars satisfies N>>Nc, where Nc~1600. Kelvin-Helmhotz timescale is shorter than Ambartsumian-Spitzer time scale [what is that?].
1112.2064
The cosmic NIR background III: fluctuations, reionization and the effects of minimum mass and self-regulation
Fernandez, Iliev, Komatsu, Shapiro
The universe was reioinized sometime before z~6. Observed through NIRB, which contains information about galaxies which may be too faint to be observed individually. Calculate C_l of the NIRB fluctuations caused by the distribution of these galaxies; C_l will be dominated by galaxies responsible for completing reionization (e.g., z~6). The shape of C_l at high l is sensitive to the amount of non-linear bias of DM haloes hosting galaxies. Can use the shape of C_l to infer typical masses of DM haloes responsible for completing reionization. NL bias enhances the DM halo power spectrum on small scales; find that C_l is steeper for the case with a complete suppression of small sources or partial suppression of SF in small haloes.
1112.2088
Metal-poor hypervelocity star candidates from the SDSS
Li, Luo, Zhao, Ren, Zuo
Hypervelocity stars are believed to be ejected out from the Galactic center through dynamical interacions of (binary) stars with the central massive BH(s). Report 13 metal-poor F-type hypervelocity star candidates selected from SDSS DR7. 7 of them were likely ejected from the GC or the Galactic disk, four neither originated from the GC or disk, and the other two were possibly ejected from either the GD or other regions. Those candidates unlikely originated from the GC or the disk may be explained by other mechanisms, such as the tidal disruption of the MW's dwarf galaxies, or the gravitational interactions with a massive BH at the center of M31 or M32.
1112.2151
Prospects for probing the spacetime of Sgr A* with pulsars
Liu, Wex, Kramer, Cordes, Lazio
* cosmic censorship conjecture: mathematical conjectures about the structure of singularities arising in GR. Singularities that arise in solution to GR are typically hidden within even horizons, and therefore cannot be seen from the rest of spacetime, singularities that are not so hidden are called "naked". The censorship hypothesis conjectures that no naked singularities other than the BB singularity exist in the universe.
Pulsars around SMBH can test "cosmic censorship conjecture" and "no-hair theorem" via pulsar timing. Study prospects: can test 1e-3 frame dragging and 1e-2 test of no-hair theorem within 5 years if Sgr A* is spinning rapidly, for orbital periods below ~0.3 yr [hmm, very close]. A combination of pulsar timing with the astrometric results of stellar orbits would greatly improve the measurement precision of R0, the distance to the Galactic center.
1112.2182
Galactic outflows and evolution of the interstellar medium
Cote, Martel, Drissen, Robert
Present model to self-consistently describe the joint evolution of starburst galaxies and the galactic wind resulting from the evolution. Start with galaxy mass, formation redshift, and adopting a particular form of the SFR, describe the eovlution of the stellar populations in the galaxy, evolution of metallicity and chemical composition of ISM, the propagation of the galactic wind, and the metal-enrichment of the IGM. Main results: (1) for a given star formation efficiency f*, a more extended period of active SF tends to produce a galactic wind that reaches a larger extent. If f* is sufficiently large, the energy deposited by the stars completely expels the ISM. The ISM is eventually replenished by mass loss from SNe and stellar winds. (2) For galaxies with masses above 1e11 Msun, the material ejected in the IGM always falls back onto the galaxy. Hence lower-mass galaxies are the ones responsible for enriching the IGM. (3) Stellar winds play a minor role in the dynamical evolution of the galactic wind, because their energy input is small compared to SNe. However, they contribute significantly to the chemical composition of the galactic wind. Conclude that the history of ISM enrichment plays a determinant role in the chemical composition and extent of the galactic wind, and therefore its ability to enrich the IGM.
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