Wednesday. Hope to get some good work done today.
1112.2698
Spectrosphotometric libraries, revised photonic passbands and zero-points for UBVRI, Hipparcos and Tycho photometry
Bessell, Murphy
Improved photonic passbands for UBVRI, compare with zero-points of SAAO UBVRI, homogenized UBV system and Walraven VB system. Adjusted flux levels of stars in the spectrophotmetric libraries for the synthetic Hp magnitudes matched the precise Hipparcos catalog value.
1112.2701
Simulating the cooling flow of cool-core clusters
Li, Bryan
AMR simulations of a cool core cluster, resolving the flow from Mpc scales down to pc scales. No AGN heating yet, but look at flow to understand how gas gets to the SMBH at the center of the cluster. Cooling catastrophe only in the central 10-100 pc of the cluster. Outside, the temperature is flat, flow is smooth, no local cooling instabilities, as with observations. Cooling produces a thin accretion disk. Cooled gas grows rapidly until the presumed AGN turn-on happens--like a thermostat. Outcome is sensitive to resolution.
1112.2706
The baryon cencus in ta multiphase intergaalctic medium: one-third of the baryons are still missing
Shull, Smith, Danforth
Although galaxies and clusters contain 10% of the baryons, many more reside in the photoionized Lyman-alpha forest and shocked-heated warm-hot intergalactic medium (WHIM) at T=1e5K to 1e7K. Low T WIM traced by O VI absorption lines, broad Ly-a absorbers (BLAs) and EUV/X-ray absorption lines from Ne VIII, O VII, and O VIII. Improve the O VI baryon and metal transport in a density-temperature structured medium. Statistically, their product correlates with column density. Try lots of things. Find substantial baryon fractions in the photoionized Lya formest at 28%, WHIM at 25%, and collapsed phase 18% in galaxies, groups, clusters, and circumgalactic gas. Baryon shortfall is 29%, which may be detected in X-ray absorbers from hotter WHIM or weaker Lya and O VI absorbers.
1112. 2710
Pair-instability SNe at the epoch of reionization
Pan, Kasen, Loeb
Model the light curves and spectra of pair-instability SNe over a range of masses and envelope structures. At redshifts of reionization z>=6, calculate the rates and detectability of pair-instability and core collapse SNe, and show that with the JWST, it is possible to determine the contribution of Pop III and Pop II stars toward reionization by constraining the stellar initial mass function at that epoch using these SNe. Also find rates of Types Ia SNe, and show that they are not rare during reionization, and can be used to probe the mass function at 4-8 Msun. If budget of ionizing photos was dominated by contributions from top-heavy Pop III stars, predict that the bright end of the galaxy luminosity function will be contaminated by pair-instability SNe.
1112.2712
What shapes the galaxy mass function? Exploring the roles of SN-driven winds and AGN
Bower, Benson, Crain
Observed stellar mass function (SMF) is very different to the halo mass function predicted by LCDM, and is widely accepted that this is due to energy feedback from SNe and BHs; but the strength and form of this feedback is not understood. Use GALFORM to study how strength and the halo mass dependence of feedback affects the SF. Focus on "expulsion" models in which the wind mass loading, beta, is proportional to 1/vdisk^n, n={0,1,2}, and contrast these models wit hthe successful Bower+ 2008 model. Code explicitly accounts for the recapture of expelled gas as the system's halo mass increases. Find: model with modest wind speed but high mass loading matches the flat portion of the SMF. With AGN feedback, model provides a good description of the observed SMF above 1e9 Msun/h. In the expulsion models, the brightest galaxies are assembled more recently than in Bower+2008, and sSFR of galaxies decrease strongly. The Expulsion models also tend to have a comic SF density that is dominated by lower mass galaxies at z=1~3, and dominated high mass galaxies at low z.
1112.2726
The growth of the stellar seeds of SMBH
Johnson, Whalen, Fryer, Li
Maximum masses the first stars can attain by accreting primordial gas is M*~1e3 Msun * (some function), however, at higher central infall rates, the lifetime of the star instead limits its final mass to >1e6 Msun. Furthermore, the spherical accretion rates at which the star can grow, its ionizing radiation is confined deep within the protogalaxy, so the evolution of the star is decoupled from that of its host galaxy. Lya emission from the surrounding H II region is trapped in these heavy accretion flows and likely reprocessed into strong Balmer series emission, which may be observable by JWST. This, along with the He II 1640 A and continuum emission, are likely to be the key observational signatures of the progenitors of SMBH at high z.
1112.2740
Do nuclear star clusters and BHs follow the same host-galaxy correlations?
Erwin, Gadotti
Strong correlation between nuclear star clusters (NSCs) and their host galaxies--not to the SMBH mass, but rather the stellar mass of the total stellar mass of the galaxies. The M_nsc/Mstar,tot ratio is an order of magnitude smaller than M_bh/Mstar,bulge of SMBHs. Galaxies with Hubble types earlier than Sbc appear to host systematically more massive NSCs than do types Sc and later.
1112.2752
The effects of baryon physics, BHs and AGN feedback on the mass distribution in clusters of galaixes
Martizzi, Teyssier, Moor, Wentz
Simulations find usual effects of overcooling and adiabatic contraction, but find very different results when implementing SMBHs and AGN feedback. Star formation is strongly quenched, and much less cold gas is available for SF at low redshifts. At redshift z=0 find a flat density core of radius 10 kpc in both the dark and stellar matter density profiles. Speculate core formation mechanisms: can be produced through the coupling of different processes: (i) dynamical friction from the decay of BH orbits during galaxy mergers, (ii) AGN driven gas outflows producing fluctuations of the gravitational potential causing the removal of collisionless matter from the central region of the cluster, (iii) adiabatic expansion in response to the slow expulsion of gas from the central region of the cluster during the quiescent mode of AGN activity.
1112.2764
The compositions of KBOs
Brown
A review of KBO surface composition.
1112.2772
The stagnation of contemporary stellar astronomy
Skoda
Nuclear fusion in stellar cores, exchange of mass in interacting binaries, models of stellar evolution towards WDs or NSs. Despite its importance, it seems to be losing attention from the astronomical community. Extra-galactic research and cosmology has taken over. Analyse main obstacles lowering the efficiency of research in contemporary stellar astronomy.
1112.2944
A comporehensive GALEX UV catalog of star clusters in M31 and a study of the young clusters
Kang, Rey, Bianchi, Lee, Kim, Sohn
Catalog of 700 confirmed star clusters in the M31 field compiled from 3 major catalogs. Photometry in 16 passbands ranging from FUV to NIR as well as ancillary information such as reddening, metallicity, and radial velocities. Ages and masses of star clusters derived from multi-band photometry SED; UV photometry enables more accurate age estimation of young clusters. 182 of them < 1Gyr old. Good agreement with previous literature. Mean age and mass of young clusters are 300 Myr old and weigh 1e4 Msun. The compiled [Fe/H] values of young clusters included in the catalog are systematically lower than those from recent high-quality spectroscopic data and the SED fitting result. Confirm that most of the young cluster kinematics show systematic rotation around the minor axis and association with the thin disk of M31. The young clusters distribution exhibits a distinct peak in the M31 disk around 10-12 kpc from the center and follow a spatial distribution similar to other tracers of disk structure such as OB stars, UV SF regions, and dust. Some young clusters also show concentration around the ring splitting regions found in the southern part of the M31 disk and most of them have systematically younger (<100 Myr) ages.
1112.3004
Time in the 10,000-year clock
Hillis, Seaman, Allen, Giorgini
Long Now Foundation: building a mechanical clock that is designed to keep time for the next 10,000 years; maintains the long-term accuracy by synchronizing to the Sun. Keeps track of 5 different types of time: (i) Pendulum Time: generated from the mechanical pendulum and adjusted according to the equation of time to produce: (ii) Uncorrected Solar Time: which in turn mechanically corrected by the Sun to create (iii) Corrected Solar Time. (iv) Displayed Solar Time: used to compute various time indicators to be displayed, including the positions of the Sun, and Gregorian calendar date. (v) Orrery Time: better approximation of dynamical time, used to compute positions of the Moon, planets and stars and the phase of the Moon. Describe in particular how it reconciles the approximate Dynamical Time generated by its mechanical pendulum with the unpredictable rotation of the Earth.
1112.3006
The impact of assuming flatness in the determination of neutrino properties from cosmological data
Smith, Archidiacono, Cooray, De Bernardis, Melchiorri, Smidt
Find negative correlation between curvature and N_eff. Even if Omega_k is allowed to vary, N_eff=3 is disfavored at 95% confidence. Correlation between neutrino mass and curvature is much stronger, shifts upper limit from Sum m_nu < 0.446 eV to <0.948 eV. The impact of assuming flatness in neutrino cosmology is significant and an essential consideration in future experiments.
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