1203.0567
Understanding and reducing statistical uncertainties in nebular abundance determinations
Wesson, Stock, Scicluna
Many determinations of temperatures, densities and abundances in photo ionized nebulae do not quote associated uncertainty. Develop NEAT (Nebular Empirical Analysis Tool) to calculate chemical abundances in photo ionized nebulae. Analysis of emission lines to estimate the amount of interstellar extinction, calculate temperatures and densities, compute ionic abundances from collision ally excited lines and recombination lines, and to estimate total elemental abundances using an ionization correction scheme. Uses MC to robustly propagate uncertainties from line flux measurements through to the derived abundances. Accounts for upward biasing on measurements of lines with low S/N. Investigate the effect of possible uncertainties in R, the ratio of selective to total extinction, on abundance determinations. Find: uncertainty due to this parameter is negligible compared to statistical uncertainties.
1203.0568
Infrared colors of the gamma-ray detected blazers
D'Abrusco, Massaro, Ajello, Grindlay, Smith, Tosti
* synchrotron self-Compton: inverse Compton scattering of synchrotron radiation by the same relativistic electrons that produced the synchrotron radiation.
* Compton scattering: type of scattering that x-rays and gamma rays undergo in matter. Inelastic scattering (usually) results in decrease in energy. Part of the energy is transferred to a scattering electron, which recoils and is ejected from the atom; the rest of the energy is taken by the scattered, "degraded" photon.
Blasars: observational features ascribed to a relativistic jet closely aligned to the line of sight. BL Lac objects and flat spectrum radio quasars (FSRQs): BL Lacs: double bumped SED is generally described by the synchrotron self Compton emission (SSC), while FSRWs it is interpreted as due to External Compton (EC) emission. [what is EC?] Correlation between IR colors and Blazar types found.
1203.0570
A common solution to the CR anisotropy and gradient problems
Evoli, Gaggero, Grasso, Maccione
CM spectra and large scale anisotropy can hardly be made compatible; std model also has problems explaining the longitude distribution and the radial emissivity gradient of the gamma-ray galactic interstellar emission. Accounting for correlation between CR escape time and the spatially dependent magnetic turbulence power can naturally solve both problems.
1203.0571
Fast shape estimation for WL analysis
Li, Xin, Cui
Model fitting frequently used in WL studies to determine the shape of galaxies and the point spread function, but the number of parameters are too large. Propose a set of algorithms to speed up the fitting process, in 3 steps: centroiding, ellipticity measurement, and fitting. Demonstrate that centroiding and ellipticity of an object leaves small number of parameters for model fitting.
1203.0590
NOAO 4-m telescopes for future surveys
Schlegel, Scholl
The 4-m telescopes (CTIO and KPNO) can have 3 deg sq FOV, and are suitable for surveys. DES and BigBOSS are planned on them. Continue investings in these telescopes!
1203.0591
LSST is not "Big Data"
Schlegel
LSST: largest optical imaging survey of the sky. Data storage, transfer and analysis would be challenging with available computer resources, if LSST were available today. Fortunately, Moore's law progression will make LSST a "small" data set (i.e., tractable). Only 22 hard drives!
1203.0601
Comparing single-epoch virial black hole mass estimators for luminous quasars
Shen, Liu
Investigate the consistency between different line estimators for high-z BH masses in quasars (Halpha, Hbeta, MgII, CIV), using 60 SDSS quasar spectra (z~1.5-2.2). MgII line FWHM correlates well with Balmer line FWHM; MgII line estimator can be calibrated to yield consistent virial mass estimates with those based on Halpha/Hbeta. CIV FWHM poorly correlated with Balmer line FWHM, some irreducible scatter between CIV and Hbeta FWHM, and a part that correlates with the blueshift of CIV centroid relative to Hbeta. CIII FWHM correlate with CIV, hence also poorly correlated with Hbeta FWHM. CIV/CIII can be used for virial mass estimates consistent with that from Hbeta (on average), but the scatter is larger than MgII.
1203.0627
A new model for the IR emission of IRAS F10214+4724
Efstathiou, Christopher, Verma, Siebenmorgen
A new model for IR emission in the high-z, hyper luminous IR galaxy. Combination of AGN tapered disk and starburst models fails to match the SED, mainly due to the fact that nuSnu distribution of the galaxy falls very steeply with increasing frequency (a characteristic of heavy absorption by dust) but shows a silicate feature in emission. New model: two components of emission. Clouds that are ssociated wit hthe narrow-line region and a highly obscured starburst. Emission from the clouds must suffer significantly stronger gravitational lensing compared to the emission from the torus to explain the observed SED.
1203.0629
Dynamical friction in an isentropic gas
Khajenabi, Dib
As the title says.
1203.0684
Hydroxyl as a tracer of H2 in the envelope of MBM40
Cotten et al
OH 1667 Mhz line is an excellent tracers of gas in very low extinction regions and high-sensitivity mapping of the envelopes of molecular clouds may reveal the presence of significant quantities of molecular mass.
1203.0693
Inflation or Curvaton? Constraints on bimodal primordial spectra from mixed perturbations
Kinney, Dizgah, Ppowell, Riotto
If isocurvature modes or large non-Gaussianity not detected in CMB, it will not be possible to directly distinguish inflation and curvaton contributions.
1203.0810
On the effect of cosmological inflow on turbulence and instability in galactic discs
Genel, Deckel, Cacciato
Could unstable disks with Toomre parameter Q~1 be due to cosmic in-streaming gas? Strongly couple cosmological inflow tends to stabilize the disc at low z, with Q ~ a few. ...
1203.0814
Assembly of massive galaxies in a high-z protocluster
Uchimoto, ... et al
JHK imaging of SSA22 field using MOIRCS on Subaru; covers the z=3.1 protolcuster characterized by the LAE and LABlob overdensities. 5 sigma limiting magnitude is 24.3. Extract protocluster members from K-sample using photo-z selection, as well as simple color cuts for distant red galaxies (DRGs: J-K>1.4). Found over densities appropriately located near LAE density peak. K-band counterpart detected for 75% of the LABs, and 50% of LABs have multiple components. Stellar mass of LABs correlates with their luminosity, isophotal area, and the LyA velocity widths, impinge that the physical sale and the dynamical motion of LyA emission are closely related to their previous SF activities. Highly dust-obscured galaxies (J-K>2.1) and plausible K-band counterpart of sub millimeter sources are also populated in the high density region.
1203.0820
Low-mass SF triggered by early SNe explosions
Chiaki, Yoshida, Kitayama
Study the formation of low-mass and extremely metal-poor stars in the early universe. Propose a model that early SN explosions trigger the formation of low mass stars via shell fragmentation. Shocked shell undergoes efficient radiative cooling and then becomes gravitationally unstable to fragment and collapse in about 1e7 years. Early SNe can trigger the formation of low-mass stars in the extremely metal-poor environment, as seen in observation.
1203.0869
Voids in redshift space
Shoji, Lee (Jounghun)
Study ellipticity probability distribution of voids in redshift space with galaxies as traces of the shapes of voids. Find z-space distortion on the shape of voids statistically increases the ellipticities of voids, and leaves a prominent feature on the ellipticity PDF as a substantial reduction in the probability of having voids with small ellipticity. Location of this characteristic cutoff of the ellipticity PDF is an explicit function of the logarithmic growth rate, and it can be used as a probe of cosmology once the radial density profile of voids is better understood. The biggest limiting factor for using ellipticity PDF as a probe of cosmology lies in the Poisson noise from the small number of galaxies to define the shape of the void, creating significant contamination of the resulting ellipticity PDF; but use Alcock-Paczynski test on the shape of stacked voids to overcome this problem. Stacked void has non-zero ellipticity (void is elongated along the LoS), a sign of logarithmic growth rate.
1203.0978
A 5.5-year robotic optical monitoring of Q0957+561: substructure in a non-local cD galaxy
Shalyapin, Goicoechea, Gil-Merino
New light curves of lensed double quasar in the gr bands during 2008-2010 include densely sampled, shape intrinsic fluctuations with unprecedentedly high S/N; violent flux variations measure time delay accurately; r-band delay exceeding the 417-day delay in the g band by about 3 days. Also studied the log-term evolution of the delay-corrected flux ratio B/A from the homogeneous two-band monitoring between 2005 and 2010: the B/A ratio slightly increases in periods of violent activity, which seems to be correlated with the flux level in these periods. The presence of the previously reported dense cloud within the cD lensing galaxy, along the line of sight to the A image, could account for the observed time delay and flux ratio anomalies.
1203.1002
Cosmology with clustering anisotropies: disentangling dynamic and geometric distortions in galaxy redshift surveys
Marulli, Bianchi, Branchini, Guzzo, Moscardini, Angulo
Investigate observational effects affecting a precise and accurate measurement of growth rate of fluctuations from the anisotropy of clustering in galaxy redshift surveys. Focus on redshift measurement errors, reconstruction of underlying real-space clustering, and on the apparent degeneracy existing with the geometrical distortions induced by the cosmology-dependent conversion of redshifts into distances. Use a suite of mock catalogues extracted from large N-body simulations, focusing on the analysis of intermediate, mildly non-linear scales and apply the standard linear dispersion model to fit the anisotropy of the observed correlation function. Mildly non-linear scales, fit the anisotropy of the observed correlation function. Verify that redshift errors up to ~0.2% have negligible impact on the precision with which the specific growth rate beta can be measured. Larger redshift errors introduce a positive systematic error, which can be alleviated by adopting a Gaussian distribution function of pairwise velocities. This is smaller than the systematic error up to 10% due to the limitations of the linear dispersion model, which is studied in a separate paper. Then show that 50% of the statistical error budget on beta depends on the deprojection procedure through which the real-space correlation function is obtained. Finally, demonstrate that the degeneracy with geometric distortions can in fact be circumvented. This is obtained through a modified version of the Alcock-Paczynski test in redshift space, which successfully recovers the correct cosmology by searching for the solution that optimizes the description of dynamical redshift distortions. For a flat cosmology, obtain largely independent, robust constraints on beta and OmegaM. In a volume of 2.4 (Gpc/h)^3, the correct OmegaM is obtained with ~12% error and negligible bias, once the real-space correlation function is properly reconstructed.
1202.5193
The similarity of broad iron lines in x-ray binaries and AGN
Walton, Reis, Cackett, Fabian, Miller
Optically thick accretion disks and optically thin coronae, which in combination naturally give rise to relativistically broadened iron lines when the disk extends close to the BH, are commonly observed in both class of object. The simplest solution is that the broad emission features present arise from a common process: must be a reflection from the inner regions of an accretion disc around a rapidly rotating black hole. Other interpretations proposed for AGN is too complicated.
1202.5206
The velocity field of 2MRS Ks=11.75 galaxies: constraints on beta and bulk flow from the luminosity function
Branchini, Davis, Nusser
Use 45k galaxies from 2MRS to construct the underlying peculiar velocity field and constrain the cosmological bulk flow within ~100 Mpc/h. Results are obtained by maximizing the probability to estimate the absolute magnitude of a galaxy given its observed apparent magnitude and redshift. At a depth of 60 Mpc/h, find a bulk flow in agreement with LCDM predictions. The reconstructed peculiar velocity field v that maximizes the likelihood is characterized by the parameter beta=0.32. Agrees with previous results from 23k galaxies in the shallower (Ks<11.25) 2MRS survey. Luminosity function of 2MRS galaxies are poorly fitted by the Schechter form; luminosity evolves such that objects become fainter with increasing redshift according to L(z) propto (1+z)^2.7.
1202.5212
A warm mode of gas accretion on forming galaxies
Murante et al
High-res hydro cosmo simulations of MW-sized halo to study the effect of feedback on the nature of gas accretion. Simulations include a model of ISM and SF; SNe provide effective thermal feedback. Distinguish between gas accretion onto the halo, which occurs when gas particles cross the halo virial radius, and accretion onto the galaxy (0.1 virial radius). Three different gas accretion channels: cold (T_max<2.5e5 K), hot (T_max>1e6 K), and intermediate. Find the the warm channel is at least as important as the cold one for gas accretion onto the central galaxy. Result is at variance with previous findings that the cold mode dominates gas accretion at high redshift. Ascribe this difference to the different SNe feedback scheme in the simulation. Simulations here include only effective thermal feedback (others include ineffective thermal feedback or kinetic feedback). Argue that observational detections of a warm accretion mode in the high-z circum-galactic medium provide useful constraints on the nature of the feedback that regulates star formation in galaxies.
1202.5232
The cosmological 7Li problem from a nuclear physics perspective
Broggini, Canton, Fiorentini, Villante
The primordial abundance of 7Li predicted by BBN is >2x larger than observed in metal-poor stars. Possibility: discrepancies originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. Introduce efficient method to calculate the changes in the 7Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. 7Li mainly produced from 7Be + e- capture, assess the impact of the various channels of 7Be destruction. New: consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration, that does not rely on the use of the narrow resonance approximation; parameter space to nuclear physics solution considerably reduced. Exclude that resonant destruction in the channels 7Be+T and 7Be+3He can explain 7Li puzzle. 7Be+D and 7Be+alpha could potentially produce relevant effects but very favorable conditions are required. For the 7Be+alpha channel, the possibility of a (partially) suitable resonant level in 11C studied in the framework of a coupled-channel model.
1202.5238
Robust constraints on DE and gravity from galaxy clustering data
Wang
Scaled expansion history of the universe and the scaled angular diameter distance depend on the methods used to analyze the galaxy clustering data. Using galaxy power spectrum gives more accurate measurements that are significantly less correlated with each other, compared to BAO. DETF FoM ~2x larger than using BAO only. Adding linear growth rate boosts FoM.
1202.5242
Analytical properties of Einasto DM haloes
Retana-Montenegro, Van Hese, Gentile, Baes, Frutos-Alfaro
Einasto profile perform better than NFW in N-body sims. Analytical formula for the surface density from Mellin integral transform to derive a closed expression for the EInasto surface density and related properties in named functions, which can be written as series expansions. Enables arbitrary-precision calculations of surface density and lensing properties of realistic DM halo models. Compare Sersic and Einasto surface mass densities and found differences.
1202.5248
Physical structure and nature of SNe remnants in M101
Franchetti, et al
55 SNR candidates in the giant spiral M101, HST Halpha and broad-band images; examine physical structure, interstellar environment, and underlying stellar population. Spectra to search for shocked high-velocity gas in 18 SNR candidates, and identified X-ray counterparts to SNR candidates using data from archival observations from Chandra. 21/55 candidates have x-ray counter parts. Nature of SNR from photometry/spectra. 16% SNIa, 45% core collapse, 36% super bubbles or OB/HII complexes. Radio cannot detect non-thermal emission from SNR candidates; any detection are probably from HII regions or BG galaxies. Need SII images to complete SNR cesus for distribution, population, and rates of SNe in this galaxy.
1202.5254
Image analysis for cosmology: results from the GREAT10 galaxy challenge
Kitching et al
Results for GREAT10: 10 evaluation metrics, 24 simulation branches. First shape measurement challenge to include variable fields; both the shear field and the PSF vary across the images in a realistic manner. Present a general pseudo-Cl formalism, propagates spatially varying systematics in cosmic shear through to power spectrum estimates. Also show how one-point estimators of bias can be extracted from variable shear simulations. Factor of 3 improvement in accuracy in shape-measurement methods. Strong dependence in accuracy as function of S/N, weak dependence on galaxy type and size. Some meet requirements when S/N>20, but PSF here is ground-based.
1202.5267
Constraints on the low-mass end of the mass-metallicity relation at z=1-2 from lensed galaxies
Wuyts, Rigby, Sharon, Gladders
Lensed galaxies at 0.9<z<2.5 from SDSS DR7 SL sample. Derive stellar mass from SED, SFR from Ha flux (dust corrected) and metallicities from N II/Ha flux ratio. Combine with 60 SF galaxies from literature in the same redshift range for which measurements have been published. Due to magnification, probe intrinsic stellar masses that are on average a factor of 11 lower than previous studies at this z. Measure an evolution of 0.16 dec in mass-metallicity relation, smaller at lower stellar masses. No correlation between SFR and metallicity at fixed stellar mass, and thus no evidence for the existence of fundamental relation for the high sSFR rates at z=1-2 probed by this sample. Infer gas fraction from Kennicutt-Schmidt law; gas inflow and outflow on the shape of mass-metallicity relation using simple analytical models. Conclude: both an absolute metallicity calibration and direct measurements of the gas mass are needed to use the observed mass-metllicity relation to gain insight into the impact of gas flows on the chemical evolution of galaxies.
1202.5268
SGAS143845.1+145407: a big, cool starburst at redshift 0.816
Gladders et al
Strongly lensed luminous IR galaxy at high-z detected and studied in detail. This source is red (unlike other lensed galaxies), due to ongoing dusty SF. Overall lensing magnification (17x) helps observation from blue to 500um, capturing both photospheric emission as well as re-processed thermal dust emission. Optical-IR spectra also presented. This galaxy in may ways typical of IR-detected sources at z~1 from Spitzer. Far IR SED is well-fit by local templates that are an order of magnitude less luminous than the lensed galaxy; local templates of comparable luminosity are too hot to fit. Size (D~7kpc) much larger than local luminous IR galaxies, but in line with sizes observed for galaxies at z~1. SF appears uniform across this spatial scale. This lensed galaxy, which appears representative of vigorously SF z~1 galaxies, is forming stars in a fundamentally different mode than seen at z~0.
1202.5283
Quasometry, its use and purpose
Makarov
A precision measurement of celestial positions and apparent motion of very distant extragalactic objects, such as quasars, galactic nuclei, and QSOs; methodology differs from that of general astrometry. Main purpose: link the sub-milliarcsecond radio frame (ICRF) wit the existing and merging optical reference frames of similar accuracy, constructed by astrometric satellites. Main difficulties: e.g., extended structures of quasar hosts, apparent motion on the sky, optical variability, galactic companions, faintness. Useful for (aside from "strategic purpose"): global astrometric surveys, verify or correct the resulting reference frames. Two options of using measurements of distant quasars in a global astrometric solution: 1) hard constraints embedded in the fabric of observational equations, 2) a posteriori fitting of zonal errors. 200 carefully selected reference quasars can go a long way in improving the astrometric value of a space mission (needs to be bright, stable, uniformly distributed on the sky). Ongoing program at USNO to construct a quality set of optical quasars with required properties.
1202.5301
The first maximum-light UV through NIR spectrum of SNIa
Foley et al
UV region of a SNIa spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. This SNe is normal, but has a relatively fast decline. Tentatively find: SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shape have very different UV spectra. (ejecta correlated with UV?) Find: both a solar metallicity W7 and zero-metallicity delayed-detonation model provide a seasonal fit to the spectrum.
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