1203.3539
The Morphology of Hadronic emission models for the gamma-ray source at the galactic center
Linden, Lovegrove, Profumo
TeV emission at Galactic center consistent with point source at HESS resolution (3pc), but GeV emission may be spatially extended. If emission if hadronic and in a steady state, then expected gamma-ray morphology is dominated by distribution of target gas, rather than by details of CR injection and propagation; expect significant portion of hadronic emission to coincide with position of circum-nuclear ring (1-3 pc from center). Cherenkov telescope array (CTA) will be able to observe the morphology of TeV gamma-ray source and observed gas density; this will then confirm or rule out a hadronic origin of the gamma-ray emission.
A tale of dwarfs and giants: using a z=1.62 cluster to understand how the red sequence grew over the last 9.5 billion years
Rudnick, Tran, Papovich, Momcheva, Willmer
Construct rest-frame i-band LF of z=1.62 luster, compare with z=0.7, and z<0.7 cluster LF (correct for passive evolution of luminosity). LF initially has deficit of faint red galaxies at high z which does not evolve till z=0.7, then at z<0.7 builds up rapidly. The inferred total light on the red sequence grows by a factor of ~3 and the bright end of the LF becomes more populated over z=1.62 to 0.7. Construct a model for red sequence evolution that matches LF shape at z>0.7: Cluster accretes quenched blue galaxies from the field, and subsequently allows them to merge. An average of 3 mergers between 0.7<z<1.62 match the observed luminosity functions at the two redshifts. The inferred merger rate consistent with other studies of this cluster. Galaxy merging during the major growth phase of massive clusters in an important process in shaping the red sequence population at all luminosities.
1203.3543
MMT Hypervelocity star survey. II. Five new unbound stars
Brown, Geller, Kenyon
Use conservative estimate of Galactic escape velocity, use spectroscopy to identify HVSs. A Galactic center origin for the HVSs is supported by their unbound velocities, the observed number of unbent stars, their stellar nature, their ejection time distribution, and their Galactic latitude and longitude distribution. There is a spatial anisotropy of HVSs on the sky. Need southern sky HVSs spatial distribution.
1203.3547
The isotropic radio background and annihilating Dark Matter
Hooper, Belikov, Jeltema, Linden, Profumo, Slatyer
Presence of isotropic radio background with a hard spectral index found: intensity exceed the flux predicted from astrophysical sources by factor of 5-6. Consider possibility that annihilating DM particles provide the primary contribution; if this is the case, a significant fraction of the isotropic gamma ray background observed by Fermi must result from DM as well.
A tale of dwarfs and giants: using a z=1.62 cluster to understand how the red sequence grew over the last 9.5 billion years
Rudnick, Tran, Papovich, Momcheva, Willmer
Construct rest-frame i-band LF of z=1.62 luster, compare with z=0.7, and z<0.7 cluster LF (correct for passive evolution of luminosity). LF initially has deficit of faint red galaxies at high z which does not evolve till z=0.7, then at z<0.7 builds up rapidly. The inferred total light on the red sequence grows by a factor of ~3 and the bright end of the LF becomes more populated over z=1.62 to 0.7. Construct a model for red sequence evolution that matches LF shape at z>0.7: Cluster accretes quenched blue galaxies from the field, and subsequently allows them to merge. An average of 3 mergers between 0.7<z<1.62 match the observed luminosity functions at the two redshifts. The inferred merger rate consistent with other studies of this cluster. Galaxy merging during the major growth phase of massive clusters in an important process in shaping the red sequence population at all luminosities.
1203.3543
MMT Hypervelocity star survey. II. Five new unbound stars
Brown, Geller, Kenyon
Use conservative estimate of Galactic escape velocity, use spectroscopy to identify HVSs. A Galactic center origin for the HVSs is supported by their unbound velocities, the observed number of unbent stars, their stellar nature, their ejection time distribution, and their Galactic latitude and longitude distribution. There is a spatial anisotropy of HVSs on the sky. Need southern sky HVSs spatial distribution.
1203.3547
The isotropic radio background and annihilating Dark Matter
Hooper, Belikov, Jeltema, Linden, Profumo, Slatyer
Presence of isotropic radio background with a hard spectral index found: intensity exceed the flux predicted from astrophysical sources by factor of 5-6. Consider possibility that annihilating DM particles provide the primary contribution; if this is the case, a significant fraction of the isotropic gamma ray background observed by Fermi must result from DM as well.
1203.3548
Recovering galaxy stellar population properties from broad-band spectral energy distribution fitting
Pforr, Maraston, Tonini
For SF galaxies, age, mass and reddening can be well determined by broad-band SED fitting only if the correct SFH is identified; which for stellar mass can be good to 0.04 dex. SFH is usually not known; this uncertainty brings 0.1 dex, although with a large scatter.
1203.3551
The primordial Lithium problem
Fields
7Li observations lie a factor 3-4 below the BBN+WMAP prediction (4-5 sigma). Solutions: (1) Astrophysical systematics (but are increasingly constrained); (2) nuclear physics experiments have well-measured cross-section data, but 7Li could be enhanced by unknown or poorly-measured resonances; (3) Physics behind the SM can alter 7Li abundance, though D and 4He must remain unperturbed. Discuss (3).
1203.3558
Separable and non-separable multi-field inflation and large non-Gaussianity
Mazumdar, Wang
Large f_NL ~80 and tau_NL ~2e5 can be obtained for the case of separable and non-separable inflationary potentials.
1203.3598
The power spectrum of redshifted 21cm fluctuations in hierarchical galaxy formation models I: the imprint of supernova feedback
Kim, Wyithe, Raskutti, Lacey
Measurement of redshifted 21cm fluctuation power spectra from neutral H during Epoch of Reionization--goal is toe measure the epoch and duration of reionization, and to learn about the properties of the first galaxies. Structure of reioinzation sensitive to the astrophysical properties of the galaxies that drove reionization. Connect details of 21cm power spectrum with realistic models for galaxy formation. Combine SAM (GALFORM) model for high-z sources within Millennium DM simulation, with semi-numerical scheme to describe the resulting ionization structure. Semi-analytic models based on MS are limited to halo masses greater than 1e10 Msun at z>6; as a result the modeling is sensitive to astrophysics that is relevant for relatively large galaxies. Show that the details of SNe feedback affect the slope and amplitude of the 21cm power spectrum; measurements of these quantities would be sufficient to determine the level at which SNe feedback operated in high-z galaxies.
1203.3608
LEDA 074886: A remarkable rectangular-looking galaxy
Graham, Spitler, Forbes, Lisker, Moore, Janz
Rectangular dwarf galaxy at 21Mpc away, with M_R=-17.3mag; has embedded, edge-on stellar disk of 1.2 kpc diameter, V_rot/sigma ~ 1.4. Result of a combined dry and wet merger (inner stellar disk from wet merging, outer box from dry merging).
1203.3633
Profiles of Lyman\alpha\ emission lines
Yamada, Matsuda, Kousai, Hayashino, Morimoto, Umemura
Lya profiles of 91 emission-line galaxies at z=3.1 with 180km/s resolution (R~1700). ~50% of observed objects show double peak, with red peak being much stronger than blue. Red peak show asymmetry, widths correlated with velocity separation of the red and blue peaks. Must be a single line modified by the absorption and/or scattering by associated neutral H gas. Natrual explanation: scattering in the expanding shell of neutral H surrounding the Lya emitting region, while the attenuation by the IGM should also be considered. Results suggest SF in Lya emitters are dominated by the young burst-like events which produce the intrinsic Lya emission as well as the gas flow.
1203.3639
Bayesian physical reconstruction of initial conditions from large scale structure surveys
Jasche, Wandelt
Present fully probabilistic physical model of the NL evolved density field, as probed by realistic galaxy surveys. Valid in the linear and mildly NL regimes, uses second order Lagrangian perturbation theory to connect initial condition with final density field. byproduct: optimal non-linear reconstruction of the present density and velocity fields, including a full propagation of the observational uncertainties. This method on simulated data gives accurate reconstruction of scales larger than 6Mpc/h. Reconstructs NL features corresponding to 3-pt and higher order correlation functions such as walls and filaments. Demonstrates statistical approaches based on physical models of the LSS distribution are now becoming feasible for realistic current and future surveys.
1203.3647
Direct imaging constraints on planet populations detected by microlensing
Quanz, Lafreniere, Meyer, Reggiani, Buenzli
Results from gravitational microlensing suggests the existence of a large population of free-floating planetary mass objects. Current observational data consistent with a rising planetary surface density for giant exoplanets around M-dwarfs out to ~30 AU.
1203.3649
An upper limit to the variation in the fundamental constants at redshift z=5.2
Levshakov, Combes, Boone, Agafonova, Reimers, Kozlov
Constrain a hypothetical variation in the fundamental physical constants over a course of cosmic time. Use CO(7-8) rotational and [CI] fine-structure line towards a lensed galaxy at redshift z=5.2 to constrain temporal variation in the constant F=alpha^2/mu, where mu is the electron-to-proton mass ratio and alpha is the fine structure constant. Estimate difference from radial velocity offset between the rotational transitions in CO and the fine-structure transition in atomic carbon. dF/F < 2e-5. Other independent methods restrict dmu/mu<1e-7 at z=0.7 (6.4 Gyr). If variation is linear, then dmu/mu<2e-7 at z=5.2 (12.9 Gyr). From both constraints on dF/F and dmu/mu, one obtains for the relative change in alpha da/a<8e-6.
1203.3677
Interstellar polarization and grain alignment: the role of iron and silicon
Voshchinnikov, Henning, Prokopjeva, Das
Polarimetric data of LoS with known Mg, Si and Fe abundances. Correlate polarization and its efficiency with dust phase abundances. Find: anticorrelation between P and the dust phase abundance of iron in non-silicate-containing grains; a correlation between P and the abundance of Si, and no correlation between P/E(B-V) or P/A_V and dust phase abundances. Explanation: if mainly the silicate grains aligned by the radiative mechanism are responsible for the observed interstellar linear polarization.
1203.3681
Origin of Cosmic Rays
Drury
3 origins of particles: particle, energy, site of acceleration. Evidence for each origin is discussed; plausible synthesis outline for the particles of Galactic origin where the energy comes mainly from SNe explosions, the site of the acceleration is at strong collisionless shock waves, and the accelerated particles come from the interstellar and circumstellar material swept over by these shocks. If these shocks are capable of significantly amplifying magnetic fields, this picture appears capable of explaining the CR particles at all energies below the ankle at 3e18 eV. The particles above this energy are generally taken to be of extra-galactic origin and possible acceleration sites for these UHE particles are briefly discussed.
1203.3695
SubHaloes going Notts: The SubHalo-Finder Comparison Project
Onions, Knebe, ... Behroozi, ... Neyrinck, .. Springel, et al
Detailed comparison of the substructure properties of a single MW sized DM halo from the Aquarius suite at five different resolutions, as identified by a variety of different (sub-)halo finders for simulations of cosmic structure formation. Techniques: real-space, phase-space, velocity-space and time-space based finders; Voronoi tesselation, FoF, refined meshes as the starting point for locating substructure. Extract quantitative and comparable measures for the subhaloes, primarily focusing on mass and the peak of the rotation curve. Find: all agree extremely well on the presence and location of substructure and even for properties relating to the inner part of the subhalo (maximum value of the rotation curve). For properties that rely on particles near the outer edge of the subhalo, the agreement is at around 20% level. Find that basic properties (mass, circular velocities) of a subhalo can be reliably recovered if the subhalo contains more than 100 particles; position reliable for 20 particles. Logarithmic slope of the subhalo cumulative number count is consistent and <1 for all finders that reached high resolution. If correct, indicate that the larger and more massive substructures are the most dynamically interesting and that higher levels of the (sub-)subhalo hierarchy become progressively less important.
* It doesn't state why differences in subhalo finder algorithms are important.
1203.3787
Time structure of gamma-ray signals generated in line-of-sight interactions of cosmic rays from distant blazars
Prosekin, Essey, Kusenko, Aharonian
Blazars expected to produce both gamma rays and cosmic rays. Observed high-energy gamma rays from distant blazars may contain significant contribution from secondary gamma rays produced along the LoS by the interactions of CR protons with background photons. If CR contribution included, predicts that even ~10TeV photons hsould be detectable from distant objects with z>0.1. Secondary photons contribute to signals of point sources only if the intergalactic B-fields are very small (<10 fG), and their detection can be used to set upper bounds on magnetic fields along the LoS. Secondary gamma rays have distinct spectral and temporal features (including magnetic deflections); elucidate the interplay of time delays coming from the proton deflections and from the EM cascade; find, at TeV, secondayr gamma-rays can show variability on timescales of years for fG B-fields.
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