Day 422

Sunday and Monday.


1306.0818
A new method for gravitational wave detection with atomic sensors
Graham, Hogan, Kasevich, Rajendran

Dominant noise background for detection of gravitational waves using long-baseline optical interferometry is "laser frequency noise"; amelioration of this noise requires near simultaneous strain measurements on more than one interferometer baseline, necessitating more than two satellites for a space-based detector, or two interferometer arms for a ground-based detector.  Describe a new detection strategy based on recent advances in optical atomic clocks and atom interferometry which can operate at long-baselines and which is immune to laser frequency noise; suppressed because the signal arises strictly from the light propagation time between two ensembles of atoms.  This new class of sensor allows sensitive gravitational wave detection with only a single baseline.  This approach also has practical applications in the development of ultra-sensitive gravimeters and gravity gradiometers.

1304.7003
Molecular hydrogen in the damped Lyman-alpha system towards GRB 120815A at z=2.36
Krühler et al

As the title says.  Molecular H2 hard to detect beyond z~0, but found one in the GRB host DLA system at z=2.36.

1304.7005
Ultraviolet extinction at high galactic latitudes
Peek, Schiminovich

Study GALEX WISE all-sky data of 373k galaxies; examine the variation in aggregate UV colors and number density of these galaxies, and measure the extinction curve at high latitude.  Additionally consider SDSS spectra in optical.  Find: dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws.  Extinction in the FUV and NUV is ~10% and 35% higher than expected, with significant variation across the sky.  Find that no single R_V parameter fits both the optical and UV extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related.  Propose that the overall trends detected likely stem from an increase in very small silicate grains in the ISM.

1304.7015
Keck spectroscopy of gravitationally lensed z=4 galaxies: improved constraints on the escape fraction of ionizing photons
Jones, Ellis, Schenker, Stark

The fraction of photons that escape from young SF galaxies is one of the largest uncertainties in determining the role of galaxies in cosmic reionization.  Yet traditional techniques for measuring this fraction are inapplicable at the redshifts of interest due to FG screening by Lya forest.  Earlier, demonstrated a reduction in the EW of low-ioinization absorption lines in composite spectra of LBG at z=4 compared to similar measures at z=3.  This might imply a lower covering fraction of neutral gas and hence an increase with redshift in the escape fraction of ionizing photons.  However, spectral resolution was inadequate to differentiate between several alternative explanations, including changes with redshift int the outflow kinematics.  Present higher quality spectra of 3 gravitationally lensed LBGs at z=4 with a spectral resolution sufficient to break this degeneracy of interpretation.  Present a method for deriving the covering fraction lf low-ioinization gas as a function of outflow velocity and compare the results with similar quality data taken for galaxies at lower redshift.  Find a significant trend of lower covering fractions of low-ioinization gas for galaxies with strong Lya emission.  Present a method for deriving the covering fraction of low-ionization gas as a function of outflow velocity and compare the results with similar quality data taken for galaxies at lower redshift.  Find a significant trend of lower covering fractions of low-ioinization gas for galaxies with strong Lya emission.  In combination with the demographic trends of Lya emission with redshift from earlier work, results provide new evidence for a reduction in the average HI covering fraction, and hence an increase in the escape fraction of ionizing radiation from LBG, with redshift.

1304.7156
The M_BH - sigma relation for intermediate-mass black holes in globular clusters
Lützgendorf, et al

The total mass of the globular cluster correlates with the mass of the IMBH.  While the slope of the M_BH - sigma correlation differs strongly from the one observed for SMBHs, the other scaling relations M_BH - M_TOT, and M_BH - L are similar to the correlations in galaxies.  Significant correlations of BH mass with other cluster properties were not found in the present sample of 14.

1304.7175
The nature of obscuration in AGN: I. Insights from host galaxies
Shao, Kauffmann, et al

30k nearby obscured AGNs with SDSS spectra and MIR photometry from WISE.  Investigate the host galaxy properties in AGNs where the nuclear activity level is indicated by L_MIR, and to compare the results to previous studies, which have used the [OIII] emission line as the main BH activity indicator.  First carry out a systematic study of how the MIR colors of AGN hosts vary as a function of age-sensitive 4000A break strength and optical "Eddington parameter" (L[OIII]/M_BH).  The MIR color has weak dependence on break strength, but strong dependence on L[OIII]/M_BH.  Then use a "pari-matching" technique to subtract the 4.6 um stellar emission contributed by the host galaxy.  Intrinsic 4.6 um AGN luminosities can be recovered for most Seyferts, but only statistically for LINERs.  Combine sample of Seyferts with type 1 AGN and quasars at z<0.7 from SDSS; show that the [OIII] and 4.6 um luminosities correlate roughly linearly over 4 orders of magnitude, but with substantial scatter.   ...  supports the hypothesis that an abundant supply of gas is a prerequisite for the formation of an obscuring "torus".