We analyze publicly available void catalogs of the Baryon Oscillation Spectroscopic Survey Data Release 10 at redshifts $0.4<z<0.7$. The first goal of this paper is to extend the Cosmic Microwave Background stacking analysis of previous spectroscopic
void samples at $z<0.4$. In addition, the DR10 void catalog provides the first chance to spectroscopically probe the volume of the Granett et al. (2008) supervoid catalog that constitutes the only set of voids which has shown a significant detection of a cross-correlation signal between void locations and average CMB chill. We found that the positions of voids identified in the spectroscopic DR10 galaxy catalog typically do not coincide with the locations of the Granett et al. supervoids in the overlapping volume, in spite of the presence of large underdense regions of high void-density in DR10. This failure to locate the same structures with spectroscopic redshifts may arise due to systematic differences in the properties of voids detected in photometric and spectroscopic samples. In the stacking measurement, we first find a $Delta T = - 11.5 pm 3.7~mu K$ imprint for 35 of the 50 Granett et al. supervoids available in the DR10 volume. For the DR10 void catalog, lacking a prior on the number of voids to be considered in the stacking analysis, we find that the correlation measurement is fully consistent with no correlation. However, the measurement peaks with amplitude $Delta T = - 9.8 pm 4.8~mu K$ for the a posteriori-selected 44 largest voids of size $R>65~Mpc/h$ that does match in terms of amplitude and number of structures the Granett et al. observation, although at different void positions.
We use a WISE-2MASS-Pan-STARRS1 galaxy catalog to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. We obtain photometric redshifts using our multicolor data set to create a tomographic map of the galaxy distributi
on. The radial density profile centred on the Cold Spot shows a large low density region, extending over 10s of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, $5^circ$, and $15^circ$. Our data, combined with an earlier measurement by Granett et al 2010, are consistent with a large $R_{rm void}=(192 pm 15)h^{-1} Mpc $ $(2sigma)$ supervoid with $delta simeq -0.13 pm 0.03$ centered at $z=0.22pm0.01$. Such a supervoid, constituting a $sim3.5 sigma$ fluctuation in the $Lambda CDM$ model, is a plausible cause for the Cold Spot.
Standard inflationary hot big bang cosmology predicts small fluctuations in the Cosmic Microwave Background (CMB) with isotropic Gaussian statistics. All measurements support the standard theory, except for a few anomalies discovered in the Wilkinson
Microwave Anisotropy Probe maps and confirmed recently by the Planck satellite. The Cold Spot is one of the most significant of such anomalies, and the leading explanation of it posits a large void that imprints this extremely cold area via the linear Integrated Sachs-Wolfe (ISW) effect due to the decay of gravitational potentials over cosmic time, or via the Rees-Sciama (RS) effect due to late-time non-linear evolution. Despite several observational campaigns targeting the Cold Spot region, to date no suitably large void was found at higher redshifts $z > 0.3$. Here we report the detection of an $R =(192 pm 15) h^{-1}Mpc$ size supervoid of depth $delta = -0.13 pm 0.03$, and centred at redshift $z = 0.22$. This supervoid, possibly the largest ever found, is large enough to significantly affect the CMB via the non-linear RS effect, as shown in our Lemaitre-Tolman-Bondi framework. This discovery presents the first plausible explanation for any of the physical CMB anomalies, and raises the possibility that local large-scale structure could be responsible for other anomalies as well.
We use the WISE-2MASS infrared galaxy catalog matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. Our imaging catalog has median redshift $zsimeq 0.14$, and we obtain photom
etric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial profile centred on the Cold Spot shows a large low density region, extending over 10s of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, $5^circ$, and $15^circ$. The counts in photometric redshift bins show significantly low densities at high detection significance, $gtrsim 5 sigma$ and $gtrsim 6 sigma$, respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is $zsimeq 0.15-0.25$. Our data, combined with an earlier measurement by Granett et al. 2010, are consistent with a large $R_{rm void}=(220 pm 50) h^{-1}Mpc $ supervoid with $delta_{m} simeq -0.14 pm 0.04$ centered at $z=0.22pm0.03$. Such a supervoid, constituting at least a $simeq 3.3sigma$ fluctuation in a Gaussian distribution of the $Lambda CDM$ model, is a plausible cause for the Cold Spot.
Nanometric inclusions filled with nitrogen, located adjacent to FenN (n = 3 or 4) nanocrystals within (Ga,Fe)N layers, are identified and characterized using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS
). High-resolution STEM images reveal a truncation of the Fe-N nanocrystals at their boundaries with the nitrogen-containing inclusion. A controlled electron beam hole drilling experiment is used to release nitrogen gas from an inclusion in situ in the electron microscope. The density of nitrogen in an individual inclusion is measured to be 1.4 +- 0.3 g/cm3. These observations provide an explanation for the location of surplus nitrogen in the (Ga,Fe)N layers, which is liberated by the nucleation of FenN (n> 1) nanocrystals during growth.
