1206.4688
Keck/NIRC2 imaging of the warped, asymmetric debris disk around HD 32297
Currie et al
A disk model for a single dust belt including a phase function with two components and a 5-10 AU pericenter offset explains the disk's warped structure, and reproduces some of the surface brightness profile's shape but more poorly reproduces the disk's brightness asymmetry. Agreement between mm peak emission consistent with over density of very small, sub-blowout-sized dust and large, 0.1-1mm-sized grains at ~45AU tracing the same parent population of planetesimals. ...
1206.4692
Evolutionary connection between QSOs and SMGs: molecular gas in far-infrared luminous QSOs at z~2.5
Simpson Smail, et al
Two FIR-luminous QSOs, selected to have SMBH masses similar to those thought to reside in SMGs (sub-mm galaxies) at z~2.5, to study systems in transition from ULIRG phase to a sub-mm faint, unobscured, QSO. The 2 have similar dynamical but lower gas masses than SMGs by ~50pm23% (warm/dense gas). QSOs lack the extended, cool reservoir of gas seen in SMGs, suggests that they are at a different evolutionary stage. Consistent with the hypothesis that FIR bright QSOs represent a short (1Myr) but ubiquitous phase in the transformation of dust obscured, gas-rich, starburst-dominated SMGs into unobscured, gas-poor, QSOs.
1206.4693
Molecular and atomic line surveys of galaxies I: the dense, star-forming phase as a beacon
Geach, Papadopoulos
Predict the space density of molecular gas reservoirs in the Universe; place lower limits on CO, HCN, CII lines in blind z-surveys in submm-cm spectral regime. Model (A) HCN SLEDs (spectral line energy distribution) of local LIRGs, (b) SFR/M_dense(H_2), (c) model for the IR luminosity density. CO SLED calculated from HCN SEDs. Include CII as cooling lines. Then, ALMA could potentially detect very distant (z~10-12) CII emitters in the >ULIRGs at a rate of 0.1~1 per hour, SKA: z>3 low CO emitters at 40-70/hour. CII lines can detect metal-poor systems with extensive reservoirs of CO-dark molecular gas.
1206.4694
Disrupting primordial planet signatures: the close encounter of two single-planet ecosystems in the Galactic disc
Veras, Moeckel
During their MS lifetimes, majority of Galactic stars must endure at least one stellar intruder passing within a few hundred AU. Observations of planet-star separations near or beyond this distance suggest that these close encounters may fundamentally shape orbital architectures, and hence obscure primordial orbital features. Investigate resulting change in orbital ellipticity and semi major axis from fast close encounter of one planet systems. Derive analytical limit. Find each wide-orbit planet has a few percent chance of escape, and an eccentricity that will typically change by at least 0.1. Tight-orbit exoplanets are likely to be disrupted.
1206.4697
Evidence for asymmetric distribution of circumstellar material around Type Ia Supernovae
Förster et al
Find EW distribution of NaI and CaII absorption lines differ significantly between + and - nebular velocity shifts (v_neb), with generally stronger absorption for SNe Ia with v_neb > 0. Similar results for distribution of colors. Results suggest that (1) a significant part of these differences in color should be attributed to extinction (2) Extinction caused by asymmetric distribution of circumstellar material, and (3) the CSM absorption is generally stronger on the side of the ejecta opposite to where the ignition occurs. Argue that asymmetry of CSM originated after explosion by stronger ionizing flux on the side of the ejecta where ignition occurs, probably due to a stronger shock breakout and/or more exposed radioactive material on one side of the ejecta.
1206.4699
Moleculare and atomic line surveys of galaxies II: unbiased estimates of their star formation mode
Papadopoulos, Geach
Use ISM emission model of Paper I to examine the utility of key line ratios in surveys of SF 'mode' traced by M_dense(H_2)/M_total(H_2) = xi_SF, a sensitive, extinction-free discriminators of rapid starburst/merger-driven vs. secular quiescent/disk-like stellar mass assembly, with the most promising diagnostic to be applied in the near-future being CO/[Ci]. These lines accessible across 0<z<2 (covers bulk of galaxy evolution) with ALMA. With SKA, can discover H_2-rich galaxies with very low xi_SF.
1206.4702
The comic infrared background experiment (CIBER): the wide-field imagers
Bock, Sullivan, Arai, Battle, Cooray, ... et al
Developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic BG light in search for fluctuations from z>6 galaxies during the epoch of reionization. For CIBER, designed to observe the extragalactic BG light above the Earth's atmosphere during a suborbital sounding rocket flight. 4 sqdeg FoV (for 10 arcmin fluctuation detection) and 7"x7" pixels (remove lower z galaxies--reduce the low-z galaxy clustering FG below instrumental sensitivity [?]). At wavelengths where the EM spectrum of reionization extragalactic BG is thought to peak, and complements fluctuations measurements by AKARI and Spitzer at longer wavelengths.
1206.4705
Deriving the comic ray spectrum from gamma-ray observations
Kachelreiss, Ostapchenko
Fundamental problem of CR physics: determination of the average properties of Galactic CRs outside the Solar System. PAMELA (80 GeV-230 GeV) consistent with Fermi-LAT (1-2 GeV) spectra from molecular clouds.
1206.4718
Kepler-36: A pair of planets with neighboring orbits and dissimilar densities
Carter, Agol, et al
Find exoplanet system with 2 close-orbit planets (10% difference in orbital distance), but one being a super-Earth, and the other being more like a Neptune.
1206.4722
Detection of pulsar beams deflected by the black hole in Sgr A*: effects of black hole spin
Nampalliwar, Price, Creighton, Jenet
Calculate the odds of observability of rotating SMBH from pulsar timing analysis of deflected pulses.
1206.4724
The dependence of neutrino mechanism of chore-collapse supernovae on the equation of state
Couch
Study the dependence of the delayed neutrino-heating mechanism for core-collapse SNe on the equation of state [aka "as the title says"]. 1d and 2d simulations; test 3 different EoS commonly used in core-collapse simulations. ...
1206.4734
Models of the contribution of blazars to the anisotropy of the extragalactic diffuse gamma-ray background
Harding, Abazajian
Relation between the measured anisotropies in the extragalactic diffuse gamma-ray background (DGRB) and its spectral intensity, and their potential origin from the unresolved blazar population. Find: blazars can account for the observed anisotropy of the DGRB consistent with their observed source-count distribution, but are in turn constrined in contributing significantly to the observed DGRB intensity. Best fit: boasars contribute 4.3+4.1-1.1% (1 sigma) of the DGRB intensity above 1GeV. [some limitation on the "LDDE model".] ...
1206.4735
Measurement of the intracluster light at z~1
Burke, Collins, Stott, Hilton
Significant fraction of light in clusters are in ICL, which extends 100s of kpc from the core. ICL reveal details of evolutionary histories and processes occurring within galaxy clusters, but low surface brightness makes it hard to detect. Measure fraction of ICL with deep J-band (1.2 um) on VLT. Look at 6 X-ray selected clusters at 0.8<z<1.2; find ICL below surface brightness of 22 mag/arcsec2 constitutes 1-4% of the total cluster light within radius R500; broadly consistent with simulations; ICL light increase by 2-4x since z~1. Find: fraction of total cluster light contained within BCG: 2.0-6.3% (larger than the fraction of the ICL component), different from nearby clusters. Suggests evolution in cluster cores involves substantial stripping activity at late times, in addition to the early build up of the BCG stellar mass through merging.
1206.4758
Tentative wiggle in the cosmic ray electron/positron spectrum at $/sim$ 100GeV: a dark matter annihilation signal in accordance with the 130 GeV $\gamma-$ray line?
Feng, Yuan, Fan
130 GeV gamma-ray line signal identified--DM annihilation signal? Wiggles at 100 GeV seen in ATIC and PAMELA, could be result of annihilation of 140 GeV DM particles into e-/e+ with weighted cross section <sigma v>~1e-26 to 1e-25 cm^3/s. Need more accurate measurements.
1206.4828
A comparison between the stellar and dynamical masses of six globular clusters
Sollima, Belazzini, Lee
Stellar mass are on average smaller than those predicted by canonical integrated stellar evolution models because of the shallower slope of their mass function. Also systematically smaller than the dynamical mass by ~40% (but possibly systematics). Modest amount of DM?
1206.4887
Late time anisotropy as a n imprint of cosmological backreaction
Marozzi, Uzan
Backreaction effects of the large scale structure on the background dynamics have been claimed to lead a renormalization of the background dynamics that may account for the late time acceleration of the cosmic expansion [?]. ... Isotropy of the Hubble flow may allow to constrain the backreaction approach to DE.
1206.4889
Estimating the frequency of extremely energetic solar events, based on solar, stellar, lunar, and terrestrial records
Schrijver, Beer, ...
Proxy records of flare energies based on SEP [??] in principle may offer the longest time base to study infrequent large events. Nitrate concentrations in polar ice cores does not may reliably to SEP events. Concentrations of select radionuclides also not so reliable--calibration depends on multiple poorly known properties and processes (cannot determine the flare energy frequency distribution). Combine solar flare (direct) observations with stellar flare observations [for frequency study, I suppose]. Use Kepler for stellar studies.
1206.4895
Cusp-core transformations in dwarf galaxies: observational predictions
Teyssier, Pontzen, Dubois, Read
DM core in the central kpc of many dwarf galaxies has been a long standing problem in galaxy formation theories based on standard CDM. SPH and strong-feedback sims show that it's possible to form extended cores using baryonic processes related to a more realistic treatment of the ISM. Use AMR with stronger SNe feedback in RAMSES, show that it is also possible to form prominent DM core within the well-controlled framework of an isolated, initially cuspy, 1e10 Msun DM halo. Inner profile a pseudo-isothermal profile, core radius of 800 pc. Observational predictions: (i) bursty SF history with peak to trough ratio of 5-10, and duty cycle comparable to the local dynamical time; (ii) stellar distribution that is hot with v/sigma=1. Compare the observational properties of model galaxy with recent measurement of the isolated dwarf WLM; show spatial and kinematical distribution of stars and HI gas are in agreement with observations, supporting the fundamental role played by stellar feedback in shaping both the stellar and DM distribution.
No comments:
Post a Comment