Day 539

Tuesday, in Munich.

1310.6402
Interpreting the ionization sequence in AGN emission-line spectra
Richardson et al

Investigate the physical cause of the great range n the ionization level seen in the spectra of narrow lined ACN.  Mean field independent component analysis: identifies examples of SDSS galaxies whose spectra are not dominated by emission due to SF, designate those as AGN.  Assemble high S/N ratio composite spectra of a sequence of these AGN defined by the ionization level of their narrow-line region (NLR), extending down to very low-ionization cases.  Used a local optimally emitting cloud (LOC) model to fit emission-line ratios in this AGN sequence.  These included the weak lines that can be measured only in the co-added spectra, providing consistency checks on strong line diagnostics.  After integrating over a wide range of radii and densities, models indicate that the radial extent of the NLR is the major parameter in determining the position of high to moderate ionization AGN along the sequence, providing a physical interpretation for their systematic variation.  Higher ionization AGN contain optimally emitting clouds that are more concentrated towards the central continuum source than in lower ionization AGN.  LOC models indicate that for the objects that lie on the AGN sequence, the ionizing luminosity is anti correlated with the NLR ionization level, and hence anti correlated with the radial concentration and physical extend of the NLR.  A possible interpretation that deserves further exploration is that the ionization sequence might be an age sequence where low ionization objects are older and have systematically cleared out their central regions by radiation pressure.  Consider that the AGN sequence instead represent a mixing curve of SF and AGN spectra, but argue that whie many galaxies do have this type of composite spectra, this AGN sequence appears to be a special set of objects with negligible SF excitation.

1310.6459
Neutrino clustering around spherical dark matter halos
LoVerde, Zaldarriaga

CDM haloes from within a smoothly distributed BG of relic neutrinos -- at least some of which are massive and non-relativistic at late times.  Calculate the accumulation of massive neutrinos around spherically collapsing CDM haloes in a cosmological background.  Identify the physical extent of the "neutrino halo" in the spherical collapse model, which is large in comparison with the virial radius of the DM, and conditions under which neutrinos reaching the CDM halo will remain bound to the halo at late times.  Calculate the total neutrino mass and bound neutrino mass associated with isolated spherical haloes for several neutrino mass hierarchies and provide fitting formulae for these quantities in terms of the CDM halo mass and the masses of the individual neutrino species.

1310.6495
Giant low surface brightness galaxies : evolution in isolation
Das

GLSB galaxies are amongst the most massive spiral galaxies known in the Universe.  Although they fall in the class of late type spiral galaxies, their properties are far more extreme.  They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in SF and hence low in surface brightness.  They often have bright bulges that are similar to those found in early type galaxies.  The bulges can host low luminosity AGN that have relatively low mass BHs.  GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies.  In fact many GLSB galaxies are found under dense regions close to the edges of voids.  These galaxies have very massive DM halos that also contribute to their stability and lack of evolution.  In this paper, briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive DM haloes have led to the low SFRs and the slower rate of evolution in these galaxies.

1310.6507
A Bcool spectropolarimetric survey of over 150 solar-type stars
Marsden, et al

Over 150 solar-type stars chosen mainly from planet search databases have been observed with spectropolarimeters at Bernard Lyot and at CFHT.  These single 'snapshot' observations have been used to detect the presence of B-fields on 40% of the sample, with the highest detection rates occurring for the youngest stars.  From the observations, determine the mean surface longitudinal field (or an upper limit for stars without detections) and the chromospheric surface fluxes, and find that the upper envelope of the absolute value of the mean surface longitudinal field is directly correlated to the chromospheric emission from the star and increases with rotation rate and decreases with age.

1310.6557
The occultation of Arcturus in the Vatican
Sigismondi

Dome of Saint Peter's Basilica occults Arcturus.  Youtube video available.

1310.6653
TADPOL: a 1.3 mm survey of dust polarization in star-forming cores and regions
Hull, … Bower, … et al

Present results of 1.3 mm dust polarization observations towards 29 SF cores and 8 hig-mass SF regions, mapped with 2.5" resolution at CARMA.  Find: (1) a subset of the sources have consistent B-field orientations between the large scales measured by single-dish sub millimeter telescopes (with ~20" resolution) and the small scales measured by CARMA.  Those same sources also tend to have higher fractional polarizations than the sources with inconsistent large-to-small-scale fields, possibly because there is less twisting of the B-fields to reduce the polarization fraction.  This suggests that in at least some sources, the B-fields play a role in regulating the infall of material over many orders of magnitude, all the way down to ~1000 AU protostellar envelope scales.  (2) Even in the sources with consistent large-to-small-scale field orientations, the magnetic fields in the cores are misaligned with outflows from the central protostars.  Furthermore, the sources with lower polarization fractions tend to have B-fields that are preferentially perpendicular to outflows, which suggests that in these sources the B-fields have been wrapped up by envelope rotation.  (3) Finally, find that all sources exhibit the so-called "polarization hole" effect, where the fractional polarization drops significantly near the total intensity peak.

1310.6688
DAMIC: a novel dark matter experiment
The DAMIC collaboration

DAMIC (Dark Matter in CCDs) is a DM experiment that has sensitivity to DM particles with m<10 GeV.  Due to low readout noise (rms ~3 e-), this instrument is able to reach a detection threshold below 0.5 keV nuclear recoil energy, making the search for DM particles with low mass possible.  Report on early results and experience gained from a detector that has been running at SNOLAB since Dec 2012.  Also discuss the measured and expected BGs and present the plan for future detectors to be installed in 2014.

1310.6716
Search for primordial non-Gaussianity in the quasars of SDSS-III BOSS DR9
Karagiannis, Shanks, Ross

Analyze 22k quasars of 2.2<z<2.9 on BOSS.  Fit the clustering results with a LCDM model to calculate the linear bias of the quasar sample, b=3.74pm0.12.  The measured value of bias is consistent with the findings of White+ (2012), where they analyze almost the same quasar sample, although only in the range s<40 Mpc/h.  Fitting the standard cosmological model at small and intermediate scales (3-120 Mpc/h) of the quasar clustering produces a rejection at the 2.2 sigma significance level.  At larger scales, observe and excess or plateau in the clustering correlation function.  Including this large-scale feature in the fit produces a rejection of LCDM at the 2.7 sigma level.  By fitting a model that incorporates a scale dependent additional term in the bias introduced by primordial non-Gaussianity of the local type, calculate the amplitude of the deviation from the Gaussian ICs at 70<f_NL<190 at the 95% CL.  Apply stricter cuts on Galactic extinction, where after keeping regions with A_r<0.14 mag, measure 81<f_NL<170 at 95% CL.  In this case the goodness-of-fit of LCDM shows a rejection of the model at a significance level of 1.7 sigma.  Investigating systematics further, make corrections according to the methods of Ross+2011, Ho+2012 and Ross+2011, 2012b, with the f_NL measurements after the application of the two methods being consistent with each other.  Consider as the final results on non-Gaussianity those originating after the correction of the sample with the weights methods of Ross+2011, 2012b, giving 46<f_NL<158 at 95% CL.  The rejection value of LCDM in this case is at the 2.3 sigma level.