Day 869

Friday.



1504.04011
Constraints on the missing baryons from the kinetic Sunyaev-Zeldovich effect in Planck data
Hernández-Monteagudo, et al

Estimate the amount of the missing barons detected by Planck of kSZ effect around members of the Central Galaxy Catalogue (CGC) from SDSS DR7.  Use 2 statistics yielding evidence for kSZ signal, namely the pairwise peculiar momentum and the correlation function of the kSZ temperature estimates and predicted line-of-sight peculiar velocities.  Find that both statistics yields consistent measurements of the Thomson optical depth tau_T in the range of 0.5-1.4e-4 for angular apertures that, on average, correspond to a range of distances of >1 to almost 3 viral radii from the centers of the CG host halos.  Find that, for the larger apertures for which we still have significant (2-2.5 sigma) kSZ detection, the regions probed around CGs contain roughly half the total amount of baryons present in the cosmological volume sampled by the Sloan footprint at z~0.12.  Furthermore, under the assumption that baryons trace the DM distribution, the tau_T measurements are compatible with having detected all the missing baryons around the CGs.  Finally, the kSZ measurements yields no evidence for a kSZ dipole on the positions of the CGs, providing the strongest constraints on the local bulk flow at a distance of 350 Mpc/h (below 290 km/s at 95% CL), and adding further evidence for the Copernican principle of homogeneity.


1504.04015
Beacons in the dark: using novae and supernovae to detect dwarf galaxies in the local universe
Conroy, Bullock

As the title says.  Dwarf galaxies with M*<1e6 Msun beyond a few Mpc will likely be too faint and/or too low in surface brightness to be directly detected in upcoming large area ground-based photometric surveys, but novae can be detected.  Depending on the form of the stellar mass-halo mass relation and the underlying SFHs of low mass dwarfs, the expected nova rates will be a few to ~100/yr and the expected NS rates will be ~1e2-4 within the observable volume.  The transient rate associated with intrahalo stars will be comparably large, but these transients will be located close to bright galaxies, in contrast to the dwarfs, which should trace the underlying LSS of the cosmic web.  Aggressive follow-up of hostess transients has the potential to uncover the predicted enormous population of low mass field dwarf galaxies.


1504.04025
The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations
Velliscig, Cacciato, et al

Report the alignment and shape of DM, stellar, and hot gas distributions in the EAGLE and cosmos-OWLS sims: 0<z<1, 11<log10(M200)<15.  The shape parameters of the DM, stellar, and hot gas distributions follow qualitatively similar trends: they become more aspherical (and triaxial) with increasing halo mass, radius and redshift.  Measure the misalignment of the baryonic components (hot gas and stars) of galaxies with their host halo as a function of halo mass, radius, z, and galaxy type (centrals vs satellites and early vs late-type).  Overall, galaxies align well with local distribution of the total (most dark) matter.  However, the stellar distributions on galactic scales exhibit a median misalignment of about 45-50 deg with respect to their host halos.  This misalignment is reduced to 25-30 deg in the most massive haloes (13-15 log10(M200)).  Halo of the disc galaxies in EAGL have a misalignment angle wrt their host halos larger than 40 deg.  Present fitting functions and tabulated values for the probability distribution of galaxy-halo misalignment to enable a straightforward inclusion of the results into models of galaxy formations based on purely collisionless N-body sims.


1504.04088
Large-scale clustering of Lyman-alpha emission intensity from SDSS/BOSS
Croft et al

Consistent with LCDM with Omega_M=0.30+0.10-0.07. [...] 97% of the Lya emission in the universe at z<0.8 is therefore undetected in previous surveys of Lya emitters.  [...]  Also detect z-space anisotropy of the quasar-lay emission cross-correlation, finding evidence at the 3 sigma level that it is radially elongated, consistent with distortions caused by radiative-transfer effects.  These measurements represent the first application of the intensity mapping technique to optical observations.


1504.04366
Equivalence principle and the Baryon Acoustic Peak
Baldauf et al

Study the dominant effect of a long wavelength density perturbation delta(lambda_L) on short distance physics.  In the non-relativistic limit, the result is a uniform acceleration, fixed by the EP, and typically has no effect on statistical averages due to translational invariance.  This same reasoning has been formalized to obtain a "consistency condition" on the cosmo correlation functions.  In the presence of a feature, such as the acoustic peak at l_BAO, this naive expectations breaks down for lambda_L<l_BAO.  Calculate a universal piece of the 3pt correlation function in this regime.  The same effect is shown to underlie the spread of the acoustic peak, and is calculable to all orders in the long modes.  This can be used to improve the result of perturbative calculations - a technique known as "IR resummation"  - and is explicitly applied to the one-loop calculation of PS.  Finally, the success of BAO reconstruction schemes is argued to be another empirical evidence for the validity of the results.