Day 1126

Monday.



1607.06472
Quasar-driven outflows account for the missing extragalactic gamma-ray background
Wang, Loeb

The origin of the extragalactic gamma-ray BG permeating throughout the Universe remains a mystery 40 years after its discovery.  The extrapolated population of blazers can account for only half of the background radiation at the energy range of ~0.1-10 GeV.  Show that quasar-driven outflows generate relativistic protons that produce the missing component of the extragalactic gamma-ray background and naturally match its spectral fingerprint, with a generic break above ~1 GeV.  The associated gamma-ray sources are too faint to be detected individually, explaining why they had not been identified so far.  However, future radio observations may image their shock fronts directly.  The best fit to the Fermi-LAT observations of extragalactic gamma-ray background spectrum provides constraints on the outflow parameters that agree with observations of these outflows and theoretical predictions.


1607.06476
Cumulative neutrino background from quasar-driven outflows
Wang, Loeb

Quasar-driven outflows naturally account for the missing component of the extragalactic gamma-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons.  Study the simultaneous neutrino emission by the same protons.  Adopt outflow parameters that best fit the extragalactic gamma-ray background data and derive a cumulative neutrino background of ~1e-7 GeV/cm^2/s/sr at neutrino energies E_nu>~ 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters.  The link between the gamma-ray and neutrino emission from quasar outflows can be used to constrain the high-energy physics of wrong shocks at cosmo distances.

1607.06479
The cold dark matter content of Galactic dwarf spheroidal: no cores, no failures, no problem
Fattahi, Navarro, et al

Examine the DM content of satellite galaxies in LCDM cosmo hydro sims of the Local Group from the APOSTLE project.  Find excellent agreement between simulation results and estimates for the 9 brightest Galactic dwarf spheroidal (dSphs) derived from their stellar velocity dispersions and half-light radii.  Tidal stripping plays an important role by gradually removing DM from the outside in, affecting in particular fainter satellites and systems of larger-than-average size for their luminosity.  The models suggest that tides have significantly reduced the DM content of Can Ven I, Sextans, Carina, and Fornax, a prediction that may be tested by comparing them with field galaxies of matching luminosity and size.  Uncertainties in observational estimates of the DM content of individual dwarfs have been underestimated in the past, at times substantially.  Use the improved estimates to revisit the 'too-big-to-fail' problem highlighted in earlier N-body work.  Reinforce and extend the previous conclusion that the APOSTLE sims show no sign of this problem.  The resolution does not require 'cores' in the DM profiles, but rather,  relies on revising assumptions and uncertainties in the interpretation of observational data and accounting for 'baryon effects' in the theoretical modeling.


1607.06768
ALMA spectroscopic survey in the Hubble Ultra Deep Field: Survey Description
Walter, ... Bertoldi, et al

Present the rational for the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available.  The overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-z (z>0.5) galaxies.  The ~1' region covered within the UDF was chosen to overlap with the deepest available imaging from HST.  The ALMA observations consist of full frequency scans in band 3 (84-115 GHz) and band 6 (12-272 GHz) at approximately uniform line sensitivity (L'_CO~2e9 K km/s pc^2), and continuum noise levels of 3.8 uJy beam^-1 and 12.7 uJy beam^-1, respectively.  The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [CII] emission line is also covered at redshifts 6.0<z<8.0.  Present a customized algorithm to identify line candidates in the molecular line scenes, and quantify the ability to recover artificial sources from the data.  Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, constrain the most likely line identification.  Report 10 (11) CO line candidates in the 3mm (1mm) band, and the statistical analysis shows that <4 of these (in each band) are likely spurious.  Less than 1/3 of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart.  Also present continuum maps of both the band 3 and band 6 observations.  The data presented here from the basis of a number of dedicated studies that are presented in subsequent papers.


1607.06769: 
ASPECS: Continuum number counts, resolved 1.2-mm extragalactic background, and properties of the faintest dusty star forming galaxies


1607.06770:
ASPECS:  CO luminosity functions and the evolution of the cocmis density of molecular gas


1606.06771:
ASPECS: Molecular gas reservoirs in high-redshift galaxies


1607.06772:
ASPECS: Search for [CII] line and dust emission in $6<z<8$ galaxies


1607.06773:
ASPECS: implications for spectral line intensity mapping at millimeter wavelengths and CMB spectral distortions


1607.07140
Impact of baryonic physics on intrinsic alignmentsTenet, Gnedin, Feng

Explore the effects of specific assumptions in the sub grid models of star formation and stellar and AGN feedback on intrinsic alignments of galaxies in cosmo simulations of "MassiveBlack-II" family.  Using smaller volume sims, explore the parameter space of the sub grid star formation and feedback model and find remarkable robustness of the observable statistical measures to the details of sub grid physics.  The one observational probe most sensitive to modeling details is the distribution of misalignment angles.  Hypothesize that the amount of angular momentum carried away by the galactic wind is the primary physical quantity that controls the orientation of the stellar distribution.  The results are also consistent with a similar study by the EAGLE simulation team.