0811.3139
The case for optical interferometric polarimetry
Elias, Jones, Schmitt, Jorgensen, Ireland, Perraut
Interferometry: Measuring diameters and asymmetries of single stars, imaging the orbits of multiple stars, modeling Be star disks, and modeling AGN nuclei. Polarimetry: Characterizing the atmospheres and shells of red giant/supergiants, envelopes of AGB stars, morphology of Be stars, and short- and long-term behavior of AGNs. Next logical evolutionary step in instrumentation is to combine interferometry with polarimetry: measurements of spatial coherence are performed simultaneously with measurements of coherence between orthogonal polarization states.
1203.2179
Modeling high-energy light curves of the PSF B1259-63/LS 2883 binary based on 3-D SPH simulation
Takata et al
Model light curves of VHE gamma-ray emissions from the pulsar-Be star binary based on 3d SPH simulations of pulsar wind interaction with Be-disk and wind. Focus on periastron passage of the binary and calculate the variation of the synchrotron and inverse-Compton emissions using the simulated shock geometry and pressure distribution of the pulsar wind: characteristic double-peaked X-ray light curve reproduced. Interpret pre-and post periastron peaks as being due to significant increase in the conversion efficiency from pulsar spin down power to the shock-accelerated particle energy at orbital phases when the pulsar crosses the Be disk before periastron passage, and when the pulsar wind creates a cavity in the disk gas after periastron passage, respectively. Some discrepancy of model with observation.
1203.2180
Bias on w from large-scale structure
Marra, Pääkkönen, Wessel Valkenburg
Observational constraints on w depend strongly on the local matter density around the observer. Find: if we live at the center of an inhomogeneity with density contrast of roughly 0.1, DE is not a cosmological constant at 95% confidence level. Model spherical DM over density and DE fluid with constant w and no sound speed that reaches a homogeneous solution at finite radius. Fit this model to observations of the local expansion rate, distant SNe and CMB. Possible bias from LSS has to be taken into account if one wants to progress towards not just precision but also accurate cosmology.
* what radius are they talking about?
1203.2181
Molecules in bipolar outflows
Tafalla, Bachiller
Study shock chemistry in ISM. Enhanced abundance by several orders of magnitude in the outflow gas, likely as a combined result of dust mantle disruption and high temperature gas chemistry; sensitive indicators of the physical changes taking place in the shock. Tracers of shock chemistry important; a number of limitations include a very limited statistical approach in the observations and a dependence of the models on plane-parallel shocks, which cannot reproduce the observed wing morphology of the lines. Discuss chemistry of the extremely high velocity component, which seems to different form the rest of the outflow, originate in the wind from the very vicinity of the protostar.
1203.2186
Auto-consistent metallicity and star formation history of the nearest blue compact dwarf galaxy NGC 6789
Garcia-Benito, Perez-Montero
Present detailed auto-consistent study of the nearest blue compact dwarf galaxy NGC 6789 by means of optical and UV archive photometry data and optical long-slit ISIS-WHT spectroscopy observations of the five brightest star-forming knots; derivation of ionic chemical abundances of O, N, S, Ar and Ne possible, using measures of both the high- and lo-excitation electron temperatures, leading to the conclusion that 6789 is chemically homogeneous with low values of he abundance of O in the range 12+log(O/H)=7.9, but higher values of N/O ratio than expected. Color-magnitude diagram from HST of the resolved stellar populations, derive SFH. Compatible with the presence of different young and old stellar populations whose metallicities do not necessarily increase with age. Fit optical spectrum in all 5 knots with single stellar population following the SFH obtained from CMD. Compare resulting stellar mass and relative fractions of the ionizing populations with a non-constrained SFH case. Properties of the younger populations were obtained using CLOUDY, similar ages in all knots of the range 3-6 Myr and estimation of the dust factor (correlates with GALEX FUV-NUV color). Total photometric extinction and dust-absorption corrected Halpha fluxes used to derive the SFR.
1203.2188
An inverse Compton scattering origin of X-ray flares from Sgr A*
Yusef-Zadeh, ..Genzel, et al
The X-ray and NIR emission from Sgr A* is dominated by flaring, while a quiescent component dominates the emission at radio and sub-mm wavelengths. This SED of the quiescent emission peaks at sub-mm wavelengths and is modeled as synchrotron radiation from a thermal population of electron in the accretion flow, with electron temperatures ranging to 5-20MeV. Investigate the mechanism by which X-ray flare emission is produced through the interaction of the quiescent and flaring components of Sgr A*. The X-ray flare emission has been interpreted as inverse Compton, self-synchrotron-Compton, or synchrotron emission. Results of simultaneous X-ray and NIR observations show evidence that X-ray peak flare emission lags behind NIR flare emission with a delay of few to tens of minutes; inverse Compton scattering modeling places constraints on the electron density and temperature distributions of the accretion flow and on the locations where flares are produced. In the context of this model, the strong X-ray counterparts to NIR flares arising from the inner disk should show no significant time delay, where NIR flares in the outer disk should show a broadened and delayed X-ray flare.
1203.2196
A z~3 radio galaxy and its protocluster: evidence for a superstructure?
Kuiper, Venemans, Hatch, Miley, Rottering
Present spectroscopic follow-up observations of Lyman break galaxies (LBGs) selected in the field surrounding the radio galaxy MRC0316-257 at z~3.13 (0316). 20/24 objects with redshifts determined, 3 of the confirmed galaxies have 3.12<z<3.13, indicating part of a larger structure. Additional 5 objects are found 1600 km/s blue wards, in addition to 3 [OIII] emitters found at this redshift; an evidence for a foreground structure; probably responsible for half the surface overdensity of LBGs found in the field as a whole. Ongoing merger possible scenario, if two structures have 5e14 Msun each, and have separation of 2.5-3 Mpc. Also possible that the foreground structure unrelated to the protocluster.
1203.2312
MHD simulations of AGN jets in a dynamic galaxy cluster medium
Mendygral, Jones, Dolag
Pair of 3d MHD simulations of intermittent jets from a central AGN in a galaxy cluster, extracted from a high resolution cosmological simulation. Even for these relaxed clusters, the large-scale, bulk ICM motions can significantly distort the jets and lobes. Synthetic X-ray observations of the simulations show that the jets produce complex cavity systems, while synthetic radio observations reveal bending of the jets and lobes similar to WAT radio sources. While the jet and ICM B-fields are generally too weak in the simulations to play a major role in the dynamics, Maxwell stresses can sill become locally significant.
1203.2329
Evolution of luminosity function and obscuration of AGN: connecting X-ray and Infrared
Han, Dai, Wang, Zhang, Han
Present detailed comparison between the 2-10 keV hard x-ray and IR luminosity function of AGN. The composite X-ray to IR SEDs of AGN for connecting HXLF and IRLF, are models with a simple but well tested torus model based on the radiative transfer and photoionization code CLOUDY. Several evolution models and observational determinations considered. The 8.0 and 15 um LF for the type 1 and 2 AGN are predicted from HXLFs, then compared with measurements. IRLFs predicted from HXLFs tend to underestimate the number of the most IR-luminous AGN. This is independent of the choices of HXLF and AGN fraction, and for observations. Show discrepancy between HXLF and IRLFs can be largely resolved when the anti correlation of the uv-xray slope and UV luminosity is considered. Other explanation: missing population of Compton-thick AGN and possible contribution of SF in the host. Find that HXLFs and IRLFs of AGN can be more consistent with each other if the obscuration mechanisms of quasars and Seyferts are assumed to be different, corresponding to their different triggering and fueling mechanisms. More accurate measurements of IRLF of AGN, especially that determined at smaller redshift bins and more accurately separated to that for type 1 and 2, are very helpful for clarifying these interesting issues.
1203.2486
Local tadpole galaxies
Elmegreen et al
Suggest: most local tadpoles are bulge-free galaxy disks with lopsided star formation, perhaps from environmental effects such as ram pressure or disk impacts, or fraom a Jeans length comparable to half the disk size.
1203.2562
The Herschel Multi-tiered Extragalactic Survey: HerMES
HerMES Collaboration
A legacy program designed to map a set of nested fields totaling 380 deg sq. Fields range in size from 0.01 to 20 deg sq, using Herschel SPIRE (250, 350 and 500 um) and Herschel-PACS (100 and 160 um) with an additional wider component of 270 deg sq with SPIRE alone. Bands cover the peak of the redshifted thermal SED from interstellar dust and thus capture the re-processed optical and UV radiation from SF that has been absorbed by dust, and are critical for forming a complete multi-wavelength understanding of galaxy formation and evolution. Survey will detect an order of 100k galaxies at 5 sigma. Closely coordinated with the PACS evolutionary probe survey. Making maximum use of full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to:facilitate redshift determination, rapidly identify unusual objects, understand the relationships between thermal emission from dust and other processes. Total IR emission of galaxies, evolution of the luminosity function, the clustering properties of dusty galaxies, and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. Paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.
1203.2601
Creation of the CMB blackbody spectrum: precise analytic solutions
Khatri, Sunyaev
BB spectrum of CMB created behind the BB surface at z>2e6. At earlier times, the universe was dense and hot enough that complete thermal equilibrium between baryonic matter (electrons and ions) and photos could be established. Any perturbation away from the BB spectrum was suppressed exponentially. New physics, for example annihilation and decay of DM, can add energy and photos to CMB at redshift z>1e5 and result in a non-zero chemical potential of CMB. Precise evolution of the CMB spectrum around the critical redshift of z>2e6 is required in order to calculate the mu-type spectral distortion. Although numerical calculation of important processes involved (double Compton, componoization and bremsstrahlung) is not difficult, analytic solutions are much faster and easier to calculate and provide valuable physical insights. Provide better than 1% analytic solutions for the decay of mu, created at an earlier epoch, including all three processes, in the limit of small distortions. This is a significant improvement over the existing solutions with accuracy ~10 or worse. Also give a census of important sources of energy injection into CMB in standard cosmology; calculations of distortions from electron-positron annihilation and primordial nucleosynthesis illustrate in a dramatic way the strength of the equilibrium restoring processes in the early universe. Finally, point out the triple degeneracy in standard cosmology; i.e., the mu and y distortions from adiabatic cooling of baryons and electrons, Silk damping and annihilation of thermally produced WIMP dark matter are of similar order of magnitude.
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