16400877
VECTOR MAGNETIC FIELDS OF SOLAR GRANULATION
Observations of the quiet Sun from the Solar Optical Telescope/Spectro-Polarimeter aboard the Hinode spacecraft reveal the magnetic characteristics of the solar photosphere. By making use of the deep-mode observations of three quiet regions, we have statistically studied the vector magnetic fields of solar granulation. More than 2000 normal granules are manually selected to form a sample. It is recognized that some granules are even darker than the mean photosphere in intensity, and there is a linear correlation between intensity and Doppler velocity in the granules. The distributions of longitudinal and transverse apparent magnetic flux densities, Doppler velocity, and continuum intensity of granules are obtained, and their unsigned magnetic flux measured. Two approaches are used in this study. First, we obtained the magnetic properties of granulation by averaging the measurements for all the sampling granules. Second, we reconstructed an average granular cell based on a subsample, and obtained the detailed distribution of apparent magnetic flux density within the model granular cell. All the results have been compared with those for intergranular lanes and a few typical abnormal granules. Our statistical analysis reveals the following results. (1) The unsigned magnetic flux of individual granules spans the range from 1.1 × 1015 Mx to 3.3 × 1018 Mx with a peak distribution at 1.6 × 1016 Mx. (2) The unsigned longitudinal apparent flux density of granules ranges from almost 0 to 212 Mx cm–2 with a mean longitudinal apparent flux density of 12 Mx cm–2, while the transverse apparent flux density of granules ranges from 4 to 218 Mx cm–2 with a mean transverse apparent flux density of 79 Mx cm–2. The longitudinal and transverse apparent magnetic flux densities of granules are positively correlated, and the longitudinal apparent flux density of granules is weaker than the corresponding transverse apparent flux density. (3) The magnetic inclination of granules with respect to the surface that is perpendicular to the line of sight falls in the range of 4.8-76.7 degrees with a peak distribution at 25 degrees. On average, the magnetic vectors in granules are more vertical than those in the intergranular lanes. (4) There is a strong preference that both the vertical and horizontal fields on the quiet Sun reside in the intergranular lanes. (5) The detailed distributions of apparent flux density, Doppler velocity, and continuum intensity within an average granular cell are presented. These distributions can be empirically formulated well.
17485528
Periodicities in Solar Coronal Mass Ejections
ABSTRACT Mid-term quasi-periodicities in solar coronal mass ejections (CMEs) during the mostrecent solar maximum cycle 23 are reported here for the ﬁrst time using the four-year data (February 5, 1999 to February 10, 2003) of the Large Angle SpectrometricCoronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Inparallel, mid-term quasi-periodicities in solar X-ray ﬂares (class >M5.0) from theGeosynchronous Operational Environment Satellites (GOES) and in daily averages ofAp index for geomagnetic disturbances from the World Data Center (WDC) at theInternationalAssociation for Geomagnetism andAeronomy (IAGA)are alsoexaminedfor the same four-year time span. By Fourier power spectral analyses, the CME dataappears to contain signiﬁcant power peaks at periods of ∼ 358 ± 38, ∼ 272 ± 26,∼ 196±13 days and so forth, while except for the ∼ 259±24-day period, X-ray solarﬂares of class >∼ M5.0 show the familiar Rieger-type quasi-periods at ∼ 157 ± 11,∼ 122± 5, ∼ 98±3 days and shorter ones until ∼ 34±0.5 days. In the data of dailyaverages of Ap index, the two signiﬁcant peaks at periods ∼ 273±26 and ∼ 187±12days (the latter is most prominent) could imply that CMEs (periods at ∼ 272±26and∼ 196 ± 13 days) may be proportionally correlated with quasi-periodic geomagneticstorm disturbances; at the speculative level, the ∼ 138 ± 6-day period might implythat X-ray ﬂares of class >∼ M5.0 (period at ∼ 157±11 days) may drive certain typesof geomagnetic disturbances; and the ∼ 28±0.2-day periodicity is most likely causedby recurrent high-speed solar winds at the Earth’s magnetosphere. For the same threedata sets, we further perform Morlet wavelet analysis to derive period-time contoursand identify wavelet power peaks and timescales at the 99 percent conﬁdence level forcomparisons. Several conceptual aspects of possible equatorially trapped Rossby-typewaves at and beneath the solar photosphere are discussed.Key words: oscillations — space weather — Sun: activities — corona — coronalmass ejections — magnetic ﬁelds
119115722
CHANDRA HIGH-ENERGY GRATING OBSERVATIONS OF THE Fe Kα LINE CORE IN TYPE II SEYFERT GALAXIES: A COMPARISON WITH TYPE I NUCLEI
We present a study of the core of the Fe K{alpha} emission line at {approx}6.4 keV in a sample of type II Seyfert galaxies observed by the Chandra high-energy grating. The sample consists of 29 observations of 10 unique sources. We present measurements of the Fe K{alpha} line parameters with the highest spectral resolution currently available. In particular, we derive the most robust intrinsic line widths for some of the sources in the sample to date. We obtained a weighted mean full width at half-maximum (FWHM) of 2000 {+-} 160 km s{sup -1} for 8 out of 10 sources (the remaining sources had insufficient signal to noise). From a comparison with the optical emission-line widths obtained from spectropolarimetric observations, we found that the location of Fe K{alpha} line-emitting material is a factor of {approx}0.7-11 times the size of the optical broad-line region. Furthermore, compared to 13 type I active galactic nuclei (AGNs) for which the best Fe K{alpha} line FWHM constraints were obtained, we found no difference in the FWHM distribution or the mean FWHM, and this conclusion is independent of the central black hole mass. This result suggests that the bulk of the Fe K{alpha} line emission may originatemore » from a universal region at the same radius with respect to the gravitational radius, {approx}3 x 10{sup 4} r{sub g} on average. By examining the correlation between the Fe K{alpha} luminosity and the [O IV] line luminosity, we found a marginal difference in the Fe K{alpha} line flux between type I and type II AGNs, but the spread in the ratio of L{sub Fe} to L{sub [OIV]} is about two orders of magnitude. Our results confirm the theoretical expectation that the Fe K{alpha} emission-line luminosity cannot trivially be used as a proxy of the intrinsic AGN luminosity, unless a detailed comparison of the data with proper models is applied.« less
59441736
Kinematics of the compact symmetric object OQ 208 revisited
Aims. A long-timeline kinematic study of the archetypal compact symmetric object (CSO) OQ 208 sheds light on the physical properties of the most compact radio sources.
118454726
Search for light resonances decaying into pairs of muons as a signal of new physics
A search for groups of collimated muons is performed using a data sample collected by the CMS experiment at the LHC, at a centre-of-mass energy of 7TeV, and corresponding to an integrated luminosity of 35 pb−1. The analysis searches for production of new low-mass states decaying into pairs of muons and is designed to achieve high sensitivity to a broad range of models predicting leptonic jet signatures. With no excess observed over the background expectation, upper limits on the production cross section times branching fraction times acceptance areset, ranging from 0.1 to 0.5 pb at the 95% CL depending on event topology. In addition, the results are interpreted in several benchmark models in the context of supersymmetry with a new light dark sector exploring previously inaccessible parameter space.
118352407
THE SUN'S SMALL-SCALE MAGNETIC ELEMENTS IN SOLAR CYCLE 23
With the unique database from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million small-scale magnetic elements are selected, and the following results are found. (1) The quiet regions dominated the Sun's magnetic flux for about 8 years in the 12.25 year duration of cycle 23. They contributed (0.94-1.44) x10{sup 23} Mx flux to the Sun from the solar minimum to maximum. The monthly average magnetic flux of the quiet regions is 1.12 times that of the active regions in the cycle. (2) The ratio of quiet region flux to that of the total Sun equally characterizes the course of a solar cycle. The 6 month running average flux ratio of the quiet regions was larger than 90.0% for 28 continuous months from July 2007 to October 2009, which very well characterizes the grand solar minima of cycles 23-24. (3) From the small to the large end of the flux spectrum, the variations of numbers and total flux of the network elements show no correlation, anti-correlation, and correlation with sunspots, respectively. The anti-correlated elements, covering the fluxmore » of (2.9-32.0)x10{sup 18} Mx, occupy 77.2% of the total element number and 37.4% of the quiet-Sun flux. These results provide insight into the reason for anti-correlations of small-scale magnetic activity during the solar cycle.« less
117397172
Search for $B \to h^{(*)} \nu \bar{\nu}$ with the full Belle $\Upsilon(4S)$ data sample
We report a search for the rare decays B -> h(*) nu nubar, where h(*) stands for K+, Ks0, K*+, K*0, pi+, pi0, rho+, rho0 and phi. The results are obtained from a 711 fb-1 data sample that contains 772 million BB pairs collected at the Y(4S) resonance with the Belle detector at the KEKB e+e- collider. We search for signal candidates by fully reconstructing a hadronic decay of the accompanying B meson and requiring a single h(*) meson left on the signal side. No significant signal is observed and we set upper limits on the branching fractions at 90% confidence level. The measurements of B+ -> K*+ nu nubar, B+ -> pi+ nu nubar, B0 -> pi0 nu nubar and B0 -> rho^0 nu nubar provide the world's currently most restrictive limits.