1205.1507
The dynamics, appearance and demographics of relativistic jets triggered by tidal disruption of stars in quiescent supermassive black holes
De Colle, Guillochon, Naiman, Ramirez-Ruiz
Consequences of a model in which relativistic jets can be triggered in quiescent massive black holes when a geometrically thick and hot accretion disk forms as a result of the tidal disruption of a star. Estimate power, thrust, and lifetime of the jet, use mass accretion history onto the BH as calculated by detailed hydrodynamic simulations of the tidal disruption of stars. Determine the states of the ISM in various types of quiescent galactic nuclei, and describe how this can affect jets propagating through it. Study the dynamics of the jet, propagation of which is regulated by the density stratification of the environment and by its inception history. The breaking of symmetry involved in transitioning from one to 2d is crucial, and leads to qualitatively new phenomena. Many of the observed properties of a Swift GRB event can be understood as resulting from accretion onto and jets driven by a 1e6 Msun central mass BH following the disruption of sun-like star. Model can explain the X-ray light curve without invoking a rarely-occuring deep encounter. .... [basically, what they saw was not unusual]
1205.1511
A survey of molecular gas in luminous sub-millimetere galaxies
Bothwell, Smail, Chapman, Genzel, ... et al
Survey for 12CO emission in 40 luminous SMGs with 850um fluxes of S850 = 4-20 mJy, conducted with the Plateau de Bure Interferometer. Detect 12CO emission in 32 SMGs at z~1.2-4.1. Devie median spectral line energy distribution for luminous SMGs and estimate median bass mass of 4e10 Msun. Discovery of fundamental relationship between 12CO FWHM and 12CO line luminosity in high-z starbursts, which is interpreted as a natural consequence of the baryon-dominated dynamics within the regions probed by observations. Use FIR luminosities to assess the star-formation efficiency in SMGs, finding a steepening of the L'CO-LFIR relation as a function of increasing 12CO J_up transition. Derive dynamical masses and molecular gas masses, and use them for z-evolution of gas content of SMGs; find that they are not more gas rich than less vigorously SF galaxies at high-z. Use X-ray to study correlation of AGN activity and SMBH mass with gas and dynamical properties of SMGs: find SMGs lie significantly below the local M_B-sigma relation. Conclude that SMGs represent a class of massive, gas-rich ULG with somewhat heterogeneous properties, ranging from star bursting disk-like systems with L~1e12 Lsun, to the most highly star-forming mergers in the universe.
1205.1512
Large-scale structure with gravitational waves I: galaxy clustering
Jeong, Schmidt
A gravitational wave background can in principle be probed through clustering statistics of large-scale structure. Calculate observed angular clustering of galaxies in the presence of GW BG at linear order, including all relativistic effects. For a scale-invariant spectrum of gravitational waves, the effects are most significant at the smallest multipoles (2 <= l <= 5), but typically suppressed by six or more orders of magnitude with respect to scalar contributions for currently allowed amplitudes of the inflationary gravitational wave background. [why suppressed?] Discuss the most relevant second-order terms, corresponding to the distortion of tracer correlation functions by gravitational waves.
1205.1514
Large-scale structure with gravitational waves II: shear
Schmidt, Jeong
The B-mode of correlation of galaxy ellipiticties (shear) can be used to detect a stochastic gravitational wave background, such as that predicted by inflation. Derive the tensor mode contributions to shear from both gravitational lensing and intrinsic alignments, using the gauge-invariant, full-sky results of 1204.3625. Find that the intrinsic alignment contribution, calculated using the in ear alignment model, is larger than the lensing contribution by an order of magnitude or mre, if the alignment strength for tensor modes is of the same orders for scalar modes. This contribution also extends to higher multipoles. [IA stronger than GW signal.] These results make the prospects for probing tensor modes using galaxy surveys less pessimistic than previously thought, though still very challenging.
1205.1537
Self-gravitating equilibrium models of dwarf galaxies and the minimum mass for star formation
Vorobyov, Recchi, Hensler
Construct a series of model galaxies in rotational equilibrium consisting of gas, stars, ad nixed DM halo: study how these equilibrium systems depend on the mass and form of the DM halo, gas temperature, non-thermal and rotation support against gravity, and also on the redshift of galaxy formation. Find a minimum gas mass for SF to happen. Aim: construct realistic initial models of dwarf galaxies (take into account gas self-gravity; basis for dynamical and chemical evolution of DGs). Find: for a given M_DM the value of M_g^min depends crucially on the gas temperature T_g, gas spin parameter \alpha, degree of non-thermal support \sigma_eff, and somewhat on the redshift for galaxy formation z_gf. Depending on the actual values of these parameters, model galaxies may have M_g^min that are either greater or smaller than M_b. Galaxies with M_DM >~ 1e9 Msun are usually characterized by M_g^min <~M_b, implying that SF in such objects is a natural outcome as the required bass mass is consistent with what is available according to the LCDM theory. On the other hand, models with M_DM <~ 1e9 Msun are often characterized by M_g^min >> M_b, implying that they need more gas than available to achieve a state in which SF is allowed.
1205.1543
Observing the first galaxies
Dunlop
Overview of current knowledge of high-z galaxies (z>5). Techniques for discovery; two that has high yields (Lyman-break and Lyman-alpha selection). Sample selection for 5<z<8 objects, completeness and contamination; erroneous reports. Overview of current knowledge of evolving UV continuum and Lya galaxy luminosity functions at z~5-8; discuss what can be learned from exploring the relationship between the Ly-break and ly-a selected populations. Summparize physical properties of these galaxies in the young universe, cosmic history of star formation, reionization of the universe. Conclude with a brief summary of the exciting prospects for further progress in this field. This chapter can be used as an introduction to the observational study of high-z galaxies, and some review of latest results.
1205.1547
Extending the galaxy intrinsic alignment self-calibration to the GII cross-correlation
Troxel, Ishak
Extend the 3-pt intrinsic alignment self-calibration technique to the GII bispectrum. Allow measurement and removal of GII IA contamination from the X-corr of WL signal. GII persists in adjacent photo-z bins and must be accounted for and removed from the lensing signal. Relate the GII and gII bispectra through the use of galaxy bias, and develop the estimator necessary to isolate the gII bispectrum from observations. Find that the GII self-calibration technique performs at a level comparable to that of the GGI self-calibration technique, with measurement error introduced through the gII estimator generally negligible when compared to minimum survey error. The accuracy of the relationship between the GII and gII bispectra typically allows the GII self-calibratiin to reduce the GII contamination by a factor of10 or more for all adjacent photo-z bin combinations at l>300. For larger scales, find that the GII contamination can be reduced by a factor of 3-5 or more. The GII self-calibration technique is complementary to the existing GGI self-caoibration technique, which together will allow the total intrinsic alignment X-corr signal in 3-pt WL to be measured and removed.
1205.1588
Environmental dependence of galaxy merger rate in {\Lambda}CDM universe
Jian, Lin, Chiueh
Use 4 different SAMs to create 4 galaxy catalogs from Millennium, to study the environmental effects and model dependence of galaxy merger rate. Find galaxy merger rate Fmg shows strong dependence on the local overdensiiy and the dependence is similar at all redshifts. Difference in merger rates can be 4 to 20 between low and high density regions.
1205.1785
Early-type galaxies at z=1.3. I. The Lynx supercluster: cluster and groups at z=1.3. Morphology ad color-magnitude relation
Mei, Stanford, .... Finoguenov, ... et al
Finding early-type galaxies in groups.
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