Monday. Nice to have been caught up with astro-ph. Violet, upon my having tried to recalibrate its battery indicator, went dead (battery not charging properly; turned off, even with the battery in and power cable connected). Should not have emptied the battery. But, Violet's power cable showed that it was charging this morning. We'll see how it goes. I'll have to pick up MacBook Air on the morning of the 16th at Adam's place. Went to Düsseldorf this morning, came back and submitted the translation of the driver's license to Führerschein office. Went to computer store and bought casing and external HD for my new MacBook Air. A little e-mail exchange about Hallo Vietnam definitely lifted my spirits.
1202.2116
The universal initial mass function in the XUV Disk of M83
Koda, Yagi, Boissier, Gil de Paz, Imanishi, Meyer, Madore, Thilker
Subaru Ha observations of the XUV disk of M83; observe very young stellar clusters. SPS + Subaru + GALEX, find: (1) The standard (but stochastically-sampled) IMF is preferred over the truncated IMF. Low mass stellar clusters (1e2-3 Msun) that host massive O-type stars; (2) the standard Salpeter IMF and a simple aging effect explain the counts of FUV-bright and Ha-bright clusters with masses >1e3 Msun; (3) the Ha to FUV flux ratio over the XUV disk supports the standard IMF. New data, model and previous spectroscopic studies provide overall consistent results with respect to the internal dust extinction (Av~0.1 mag) and low metallicity (~0.2 Zsun) using the dust extinction curve of SMC.
1202.2118
A new ULX source in the nearby edge-on spiral NGC 891
Hodges-Kluck, Bregman, Miller, Pellegrini
New candidate ultraluminous x-ray source (ULX) in NGC 891. Outburst probably began in the past 5 years (undetected between 1986 and 2006). No definite fits to: hot disk, cool irradiated disk, or blurred reflection from innermost region of disk.
1202.2119
Dust and ionized gas association in E/S0 galaxies with dust lanes: clues to their origin
Finkelman, Brosch, Funes, Barway, Kniazev, Vaisanen
Dust and ionized bas in E/S0 galaxies with dust lanes: two components haave a tight relationship. Discussed in light of origin of ISM, and in particular in the context of the interplay between the different multi-temperature components. Show that dust obscured regions as tracers of the ISM and their properties, serves as independent evidence for the external origin of the dust and ionized gas.
* not enough info in the abstract!
1202.2120
RAMSES-CH: a new chemodynamics code
Few, Courty, Gibson
New chemodynaimcal code based on AMR code RAMSES. Uses Eulerian hydrodynamics and N-body dynamics in a cosmological framework to trace the production and advection of several chemical species. First such code to follow the self-consistent evolution of chemical elements in cosmological volumes while maintaining sub-kiloparsec resolution. Use for simulating disk galaxies and explore the influence of chemical evolution models and SF on galactic abundance ratios.
(*) 1202.2122
Why do stars form in clusters? An analytic model for stellar correlation functions
Hopkins
If ISM is governed by super-sonic turbulent flows, the excursion-set formalism can be used to calculate the statistics of self-gravitating objects over a wide range of scales. On the largest self-gravitating scales ('first crossing'), these correspond to GMCs, and on the smallest non-fragmenting self-gravitating scales ('last crossing'), to protostellar cores. Extend this formalism to rigorously calculate the auto and cross-correlation of halo clustering. Show that this generically predicts that SF is very strongly clustered on small scales: stars form in clusters, themselves inside GMCs. Outside the binary-star regime, the projected correlation function declines as a weak power-law, until a characteristic scale which corresponds to the characteristic mass scale of GMCs. On much larger scales the clustering declines such that SF is not strongly biased on galactic scales, relative to the actual dense gas distribution. The precise correlation function shape depends on properties of the turbulent spectrum, but its qualitative behavior is quite general. The predictions agree well with observations of young star and core autocorrelation functions over ~4dex in radius. Clustered SF is a generic consequence of supersonic turbulence if most of the power in the velocity field, hence the contribution to density fluctuations, comes from large scales. The distribution of self-gravitating masses near the sonic length is then imprinted by fluctuations on large scales. Similarly show that the fraction of stars formed in 'isolated' modes should be small (<10%).
1202.2124
Mergers of unequal mass galaxies: supermassive BH binary evolution and structure of merger remnants
Khan, Preto, Berczik, Berentzen, Just, Spurzem
"Final parsec problem" (FPP): SMBH binaries stall at a separation of approximately one parsec in a spherical galaxy model. If triaxiality is induced in equal-mass SMBH binary, then FPP avoided with a constant supply of stars on centrophilic orbits that interact with the SMBH. Use N-body sims to drive unequal-mass SMBH binaries into coalescence through merger-induced triaxiality. Binary hardening rates [?] are high and depend only weakly on the mass ratios of SMBHs for a wide range of mass ratios q; significantly higher for galaxies having steep cusps in comparison to those having shallow cusps at center. Evolution of the binary SMBH leads to relatively shallower inner slopes at the centers of the merger remnants. The stellar mass displaced by the SMBH binary on its way to coalescence is ~1-5 times the combined mass of binary SMBHs. The coalescence times for SMBH binary with mass ~ 1e6 Msun are less than 1 Gyr for highly eccentric binaries. SMBH binaries are thus expected to be promising sources of gravitational waves at low and high redshifts.
(**) 1202.2125
Luminous satellites II: spatial distribution, luminosity function and cosmic evolution
Nierenberg, Auger, Treu, Marshall, Fassnacht, Bucha
Infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (M*h/Msun>1e10.5) between 0.1<z<0.8 as a function of host stellar mass, redshift, morphology and satellite luminosity. Exploiting the depth and resolution of the COSMOS HST images, detect satellites up to eight magnitudes fainter than the host galaxies and as close as 0.3 (1.4) arcseconds (kpc). (*) Describing the number density profile of satellite galaxies to be a projected power law such that P(R) propto R^rpow where rpow=-1.1pm0.3. Find no dependency of rpow on host stellar mass, z, morphology or satellite luminosity. (*) Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. (*) High-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, likely a result of environmental differences [isn't the number of satellite "environment"?] No significant evolution in the number of satellites per host is detected. THe cumulative luminosity function of satellites is qualitative in good agreement with that predicted using subhalo abundance matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.
1202.2128
Berkeley SNIa Program I: Observations, data reduction, and spectroscopic sample of 582 low-redshift type Ia SNe
Silverman, ... Filippenko, ... et al
Present 1298 z<0.2 optical spectra of 582 SNIa observed from 1989 through 2008 as part of BSNIP. 3300-10400A range. Observing and reduction procedures, and a public, searchable online database (SNDB) with fully reduced spectra and companion photometry. In addition, discuss the spectral classification scheme. Construct spectral templates. 90 spectroscopically peculiar SNIa found in dataset. Consistent observation and reduction methods makes this a unique sample and complementary to other datasets.
1202.2129
Berkeley SNIa Program II: initial analysis of spectra obtained near maximum brightness
Silverman, Kong, Filippenko
Present measurements of spectral features of 432 low-z optical spectra of 261 SNIa within 20d of maximum brightness. Measure expansion velocities, pseudo-equivalent widths (pEW), spectral feature depths, and fluxes at the centre and endpoints of each of nine major spectral complexes. Investigate how velocity and pEW evolve with time, and how they correlate with each other. Various spectral classification schemes are employed and quantitative spectral differences among the subclasses are investigated. Several ratios of pEW calculated; Si II ratio, often used a s luminosity indicator, is found to be well correlated to the "SiFe" ratio and anticorrelated with the analogous "SSi" ratio. SNIa that show strong evidence for interaction with circumstellar material or and aspherical explosion are found to have the largest near-maximum expansion velocities and pWEs, possibly linking extreme values of spectral observables with specific progenitor or explosion scenarios.
1202.2130
BSNIP III: Spectra near maximum brightness improve the accuracy of derived distances to type Ia SNe
Silverman, Ganeshalingam, Li, Filippenko
Find no significant relationship between expansion velocity at or near maximum brightness and SN colour. The pEW of the Si II 4000 line is found to be a good indicator of light-curve width, and the pEWs of the Mg II and Fe II complexes are relatively good proxies for SN colour. Also employ a combination of light-curve parameters (SALT2 stretch and colour parameters x1 and c, respectively) and spectral measurements to calculate distance moduli. The residuals from these models are then comared to the standard model which uses only ilght-curve stretch and colour. Show that distance model that uses x1, c, and velocity of the Si II 6455 feature does not lead to a decrease in the Hubble residuals. Also find that distance models with flux ratios alone or in conjunction with light-curve information rarely perform better than (x1,c) model. However, combining ratio of fluxes near 3750 and 4550 A with both x1 and c decreases Hubble residual by 10%, significant at around 2 sigma level. The weighted root-mean-square of the residuals using this model is 0.130 pm 0.017 mag (cf 0.144 pm 0.019 from std model). Discuss how it can improve the cosmological accuracy of the future SNIa surveys.
1202.2150
The Ysz-Yx scaling relation as determined from Planck and Chandra
Rozo, Vikhlinin, More
SZ cluster surveys will soon reach several hundred SZ-selected clusters. Ingredient required to transport the mass calibration from current X-ray selected cluster samples to those SZ systems is the Ysz-Yx scaling relation. Constrain the amplitude, slope and scatter of the Ysz-Yx scaling relation using SZ data from Planck, and X-ray data from Chandra. Find a best fit amplitude at a pivot point 8e-1 Mpc^2. Corresponds to Ysz/Yx ratio of 0.82 pm 0.024, in good agreement wit X-ray expenctations after including the effects of gas clumping. The slope of the relation is alpha=0.916 pm 0.032, consistent with unity at ~2.3 sigma. Unable to detect intrinsic scatter, and find no evidence that the scaling relation depends on cluster dynamical state.
1202.2151
The hypothesis of the dust origin of the broad line region in AGN
Czerny, Hryniewicz
Strong broad emission lines: signature of AGN, but reason for formation still unknown. In the case of low ionization lines (LIL), there must be a mechanism which leads to an efficient rise of material from the surface of the accretion disk surrounding a BH but at the same time should not give a strong signature of the systematic outflow, as the Balmer lines are not significantly shifted wrt the narrow line region. Determine the effective temperature of the accretion disk underlying the Hbeta line at the basis of the time delay measured from reverberation and the simple Shakura-Sunyaev theory of accretion disks. Obtain that the temperature is universally 995 pm 74 K, independent from the BH mass and accretion rate of the source. Results suggest that the dust formation in the disk atmosphere is responsible fro the strong rise of the material. As material gains heigh above the disk it becomes irradiated, dust evaporates, the radiation pressure force suddenly drops, and the material fall back to the disk (a failed wind). The simple version of the model -- neglect irradiation, but discuss this irradiation and use observed variation of the broad line region in NGC 5548 to constrain the character of the non-local non-stationary phenomenon. The current instruments cannot resolve the BLR but future instrumentations may allow.
1202.2233
Spiral galaxies rotation curves in the H-L gravity theory
Cardone, Capone, Radicella, Ruggiero
* Horava-Lifshitz gravity: quantum gravity theory that solves the problem of different concepts of time in QFT and GR by treating the quantum concept as the more fundamental so that space and time are not equivalent (anisotropic). The relativistic concept of time with its Lorentz invariance emerges at large distances. The theory relies on the theory of foliations to produce its causal structure. It is related to topologically massive gravity and the Cotton tensor. It is a possible UV completion of GR. Compared to Loop quantum gravty, it uses concepts from condensed matter physics suuch as quantum critical phenomena. Horava's initial formulation was found to have side-effects such as predicting very different results for a spherical Sun compared to a slightlly non-spherical Sun, so others have modified the theory. Inconsistencies remain.
* foliations: a geometric devise used to study manifolds, consisting of an integrable subbundle of the tangent bundle. A foliation looks locally like a decomposition of the manifold as a union of parallel submanifolds of smaller dimension.
Test case: consider a sample of spiral galaxies with smooth baryon matter distribution and well measured circular velocity profiles. Agreement can only be found if the DM halo has an unrealistically small virial mass and incredibly large concentration.
1202.2254
Spatially resolved [FeII] 1.64 mu m Emission in NGC 5135. Cluse for understanding the origin of the hard x-rays in LIRGs
Colina, Pereira-Santaella, Alaonso-Herrero, Bedregal, Arribas
Kinematical signatures of strong outflows detected in FeII emission line in a compact region at 0.9 kpc from the nucleus, from spatially resolved NIR and x-ray imaging of NGC 5135. Derived mechanical energy release equivalent to SNe rate of 0.05-0.1 /yr. Apex of outflowing gas spatially coincides with the strongest [FeII] emission peak and with the dominant component of the extranuclear hard X-ray emission. Outflow likely linked to SNe outflow. Result consistent with model predictions of starursts concentrated in small volumes and with high thermalization efficiencies. A single high-mass x-ray binary as the major source of the hard X-ray emission appears to be dominated by the hot ISM from SNe explosions in a compact SF region, and not by the emission due to HMXB. If this scenario is common to U/LIRGs, the hard X-rays would only trace the most compact (<100 pc) regions with high SNe and SF densities, therefore a lower limit to their integrated SF. The SFR derived in NGC 5135 based on its hard X-ray luminosity is a factor of two and four lower than the values obtained from the 24 mu m and soft X-ray luminosities, respectively.
1202.2272
Radio relics in cosmological simulations
Hoeft, et al
Radio relics in galaxy clusters: believed to trace shock fronts induced b cluster mergers. Cosmological simulations allow study of merger shocks in detail, since the ICM is heated by shock dissipation. Using high-res cosmo siulations, identifying shock fronts and applying a parametric model for the radio emission allows simulation formation of radio relics. Analyze a simulated shock front in detail. Find a rather broad Mach number distribution. Mach number strongly affects the number density of relativistic electrson in the donwstream rea, hence, the radio luminosity varies significantly across the shock surface. The abundance of radio relics can be modeled with the help of the radio power probability distribution which aims at predicting radio relic number counts. Since the aactual electron acceleration efficiency is not known, predictions for the number counts need to be normalized by the observed number of radio relics. For the characteristics of upcoming low frequency surveys find that about thousand relics are awaiting discovery.
1202.2332
Gravitational lensing simulations I : covariance matrices and halo catalogues
Harnois-Deraps, Vafaei, Van Waerbeke
WL is in NL regime, need numerical simulations to reproduce the various effects of (theoretical) limitations and (systematic) biases. Use realistic mock catalogues in which GL corrections known is implemented. This paper: present TCS simulation suite and compare basic statistic such as the second and the third order convergence and shear correlation functions to predictions for a large range of scales and redshifts. These simple tests set the range of validity of the simulatons. Also copute the non-Gaussian covarance matricies of several statistical estimators, some of them are used in the CFHTLenS survey. From the same realizations, construct halo catalogues and present a series of halo properties that are required by most galaxy population algorithms.
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