1201.1285
WorldWide Telescope in research and education
Goodman, Fay, Muench, Pepe, Udomprasert, Wong
The WorldWide Telescope research program, made available to public as free resource in 2008 by Microsoft Research, can be thought of as a scriptable, interactive, richly visual browser of the multi-wavelength Sky seen from Earth, and the Universe. In the web API format, WWT is being used as a service to display professional research data. In desktop format, WWT works in concert with more traditional research applications such as ds9, Aladin and TOPCAT. The WWT Ambassadors Program recruits and trains astrophysically-literate volunteers who use WWT as a teaching tool in online, classroom, and informal educational settings. Early quantitative studies of WWTA indicate that student experiences with WWT enhance science learning dramatically.
1201.1286
Quasar absorption lines from radiative shocks: implications for multiphase outflows and feedback
Faucher-Giguere
Photoionization modeling of certain low-ionization broad absorption lines in quasars implies very compact (Delta R ~ 0.01 pc), galaxy-scale (R kpc) absorbers blueshifted by several 1000 km/s. While these are likely signatures of quasar outflows, the lifetimes of such compact absorbers are too short for them to be direct ejecta from a nuclear wind. Instead, argue that the absorbine clouds must be transient and created in situ. Show that a model in which the cool absorbers form in radiative shocks arising when a quasar blast wave impacts an interstellar cloud along the line of sight successfully explains the key observed properties. Using this radiative shock model, the outflow kinetic luminosities for 3 luminous quasars are estimated to be Edot, k~2-5% L_AGN (with corresponding momentum fluxes Pdot ~ 2-15 L_AGN/c), consistent with feedbakc models of the M-sigma relation. These energetics are similar to those recently inferred of molecular outflows in local ultra-luminous infrared galaxies and in post starburst winds, suggesting that AGN are capable of driving such outflows. Radiative shocks probably affect the multiphase structure of outflows in a range of other systems, including narrower and higher ionization quasar absorption lines, and compact intergalactic absorbers ejected by star formation and AGN activity.
1201.1287
Examining the role of environment in a comprehensive sample of compact groups
Walker, Johnson, Gallagher, Charlton, Hibbard
Compact groups: high number densities [of what?], small velocity dispersions, and an interstellar medium that has not been fully processed, is a local analog to conditions of galaxy interactions in the earlier universe. A color "gap" discovered in mid IR IRAC colorspace of compact group galaxies, not seen in field samples. From sample of 49 compact groups, find that gap exists, lending support to the hypothesis that the compact group environment inhibits moderate sSFRs. Curvature in colorspace distribution consistent with increasing dust temperature as the activity in a galaxy increases. The 49 galaxies have small range of properties, where stochastic effects becomes important. Find that galaxies in different regions of MIR colorspace contain dust with varying temperatures and/or PAH emission.
1201.1290
Strongly SF galaxies in the local universe with nebular He II 4686 emission
Shirazi, Brinchmann
Sample of 2865 sample of emission line galaxies with strong nebular He II emissions in SDSS DR7, investigate the origin of this line in SF galaxies. Show: SF galaxies and galaxies dominated by AGN nucleus form separated branches in the [He II]/Hbeta vs [N II]/Halpha diagnostic diagram. Derive empirical classification scheme. Models can predict He II emission only for instantaneous bursts of 20% solar metallicity or higher, and only for ages of ~4-5 Myr, the period when the extreme-UV continuum is dominated by emission from WR stars, although 50% of the ~200 sample do not have WR features in their spectra. Discuss possible reasons.
1201.1291
Hot and cold galactic gas in the NGC 2563 galaxy group
Rasussen, Bai, Mulchaey, van Gorkom, Jeltema, Zabludoff, Wilcots, Martini, Lee, Roberts
Role of environmentally induced gas stripping in driving galaxy evolution in groups: use Chandra and VLA mosaic of hot and cold interstellar medium within the members of the nearby, x-ray bright NGC group, to study the role of gas stripping and interactions in relatively small host halos. Observations cover nearly all group members to 1.4 R_vir (1.15 Mpc) of the group center. X-ray data consistent with ram pressure stripping of hot gas haloes of early-type galaxies near the group core, but no tails are seen. The H I results suggest moderate HI mass loss from group members compared to similar field galaxies. Six of the 20 HI detected group members show HI evidence of ongoing interactions with other galaxies, consistent with tidal removal of HI. Removal of gas: combination of ram pressure and tidal interactions. Most of HI detections occur on one side of the group--unusual morphological segregation (origin unclear).
1201.1294
The relation between cool cluster cores and Herschel-detected SF in brightest cluster galaxies
Rawle, Edge, Egami, Rex, ... et al
* Hi Marie!
FIR analysis of 68 BCGs at 0.08<z<1.0. Derive total IR luminosities directly from Spitzer and Herschel spanning the peak of dust component (24-500um), calculate the obscured SFR. 22% of the BCGs are detected in the FIR, with SFR=1-150M_sun/yr. The IR luminosity is highly correlated with cluster X-ray gas cooling times for cool-core clusters (gas cooling time 2e11 Lsun), only a small (<0.4 mag) reddening correction required for SFR (Ha) to agree with SFR_FIR. Relatively low Ha extinction (dust obscuration) compare to values reported for the general SF population lens further weight to an alternate (external) origin of the cold gas. Use a stacking analysis of non-cool-core clusters to show that the majority of the fuel of SF in the FIR-bright BCGs is unlikely to originate from normal stellar mass loss.
1201.1296
Satellite galaxy number density profiles in the SDSS
Guo, Cole, Eke, Frenk
Spatial distribution of satellite galaxies around isolated primaries using SDSS spectro and photometric galaxy catalogues. Select isolated primaries from the spectro sample and search for potential satellites in the photometric sample. For specific luminosity primaries, obtain robust statistical results by stacking as many as ~50k galaxy systems. Derive accurate projected number density profiles of satellites down to 4 magnitudes fainter than their primaries. Find the normalized satellite profiles generally have a universal form and can be well fitted by projected NFW profiles. NFW concentration parameter increases with decreasing satellite luminosity while being independent of the luminosity of the primary, except for very bright primaries. The profiles of the faintest satellites show deviations from the NFW form with an excess at small galactocentric projected distances. In addition, quantify how the radial distribution of satellites depends on the colour of the satellites and the colour and concentration of their primaries.
1201.1299
The role of Dwarf Galaxy interactions in shaping the Magellanic system and implications for Magellanic Irregulars
Besla, Kallivayalil, Hernquist, van der Marel, Cox, Keres
Given the LMC SMC velocities, perform cosmo simulations where MCs are currently on their first infall towards our Galaxy. Illustrate that the observed irregular morphology and internal kinematics of the MCs (in gas and stars) are naturally explained by interactions between the LMC and SMC, rather than gravitational interactions with the MW, further supporting the first infall scenario. Demonstrate that the Magellanic stream, a band of H I gas training behind the MCs 150 degrees across the sky, can be accounted for by the action of LMC tides on the SMC before the system was accreted by the MW. Further demonstrate that the off-center, warped stellar bar of the LMC and its one-armed spiral, can be natrually explained by a recent direct collision with the SMC. Such structures are key morphological characteristics of a class of galaxies referred to as Magellanic Irregulars, the majority of which are not associated with massive spiral galaxies. Infer that dwarf-dwarf galaxy interactions are important drivers for the morphological evolution of MIs and can dramatically affect the effeiciency of baryon removal from dwarf galaxies via the formation of extended tidal bridges and tails. Such interactions are important not only for the evolution of dwarf galaxies but also have direct consequences for the buildup of baryons in our own MW, as LMC-mass systems are believed to be the dominant building blocks of MW-type halos.
1201.1303
THe Empirical case for 10 GeV DM
Hooper
Summarize the body of evidence which has accumulatedi n favor of DM in the form of ~10 GeV particles. This evidence include the spectrum and angular distribution of gamma rays from the Galactic Center, the synchrotron emission from the MW's radio filaments, the diffuse synchrotron emission from the Inner Galaxy (WMAP Haze), and low energy signals from the direct detection experiments DAMA/LIBRA, CoGeNT and CRESST-II. [Hmmm.] This collection of observations can be explained by a relatively light DM particle with an annihilation cross section consistent with that predicted for a simple thermal relic, and with a distribution in the halo of the MW consistent with that predicted from simulations. In contrast, Astrophysical explanations for the gamma ray and synchrotron signals have not been successful in accommodating these observations. ...
1201.1305
Dark matter powered stars: constraints from the extragalactic BG light
Maurer, Raue, Kneiske, Elsässer, Hauschildt, Horns
Darks stars can be powered by WIMP dark mater, affecting the IR portion of the spectra. Existing data can rule out some DS parameter sets.
1201.1382
The excursion set mass function of superclusters
Lim, Lee (Jounghun)
* hi Jounghun-san....
Mass function of superclusters derived fully analytically with the help of extended excursion set theory, shown to be in excellent agreement with numerical results from N-body sims. Introduce a multi-dimensional barrier model in which the formation of superclusters occurs when the initial shear eigenvalues that perform non-Markovian random walks enter a clustering zone surrounded by one reflecting and two absorbing barriers. The multi-dimensional barrier heights are determined from the first order Lagrangian perturbation theory and found to be independent of redshift and BG cosmology. With the help of the analytic model for the supercluster mass function, the relative abundance of the rich superclusters is analytically evaluated at a given epoch and found to be sensitive to the growth rate of the cosmic web. Results imply that the relative abundance of the rich superclusters at a given epoch may be useful as a cosmological test of gravity.
1201.1414
Physics of the galactic center cloud G2, on its way towards the SMBH
Burkert, et al
The same article as the Science/Nature paper.
1201.1444
On the inadequacy of N-point correlation functions to describe NL cosmological fields: explicit examples and connection to simulations
Carron, Neyrinck
Demonstrates the fact that the correlation function hierarchy never provides a complete description of a lognormal field, and that it fails to capture information in the NL regime, where other simple observables are left totally unconstrained. Make rough but successful quantitative connection to N-body simulation results that show the spectrum of the log-density field carries more information than the spectrum of the field entering the NL regime.
* what's the difference between the lognormal and log? lognormal is the normal (Gaussian) distribution of ln(x), instead of x. So, is this the difference they are talking about?
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