Climate dynamics experiments using a GCM simulations

The study of surface-atmosphere interactions has begun with studies of the effect of altering the ocean and land boundaries. A ten year simulation of global climate using observed sea surface temperature anomalies has begun using the NCAR Community Climate Model (CCM1). The results for low resolution (R15) were computed for the first 8 years of the simulation and compared with the observed surface temperatures and the MSU (Microwave Sounding Unit) observations of tropospheric temperature. A simulation at higher resolution (T42) was done to ascertain the effect of interactive soil hydrology on the system response to an El Nino sea surface temperature perturbation. Initial analysis of this simulations was completed

The F-GAMMA program: Multi-frequency study of Active Galactic Nuclei in the Fermi era. Program description and the first 2.5 years of monitoring

To fully exploit the scientific potential of the Fermi mission, we initiated the F-GAMMA program. Between 2007 and 2015 it was the prime provider of complementary multi-frequency monitoring in the radio regime. We quantify the radio variability of gamma-ray blazars. We investigate its dependence on source class and examine whether the radio variability is related to the gamma-ray loudness. Finally, we assess the validity of a putative correlation between the two bands. The F-GAMMA monitored monthly a sample of about 60 sources at up to twelve radio frequencies between 2.64 and 228.39 GHz. We perform a time series analysis on the first 2.5-year dataset to obtain variability parameters. A maximum likelihood analysis is used to assess the significance of a correlation between radio and gamma-ray fluxes. We present light curves and spectra (coherent within ten days) obtained with the Effelsberg 100-m and IRAM 30-m telescopes. All sources are variable across all frequency bands with amplitudes increasing with frequency up to rest frame frequencies of around 60 - 80 GHz as expected by shock-in-jet models. Compared to FSRQs, BL Lacs show systematically lower variability amplitudes, brightness temperatures and Doppler factors at lower frequencies, while the difference vanishes towards higher ones. The time scales appear similar for the two classes. The distribution of spectral indices appears flatter or more inverted at higher frequencies for BL Lacs. Evolving synchrotron self-absorbed components can naturally account for the observed spectral variability. We find that the Fermi-detected sources show larger variability amplitudes as well as brightness temperatures and Doppler factors, than non-detected ones. Flux densities at 86.2 and 142.3 GHz correlate with 1 GeV fluxes at a significance level better than 3sigma, implying that gamma rays are produced very close to the mm-band emission region.Comment: Accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics (18 pages, 9 figures

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016-2017

CONTEXT: Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to understanding the crucial physical processes giving rise to jet formation, as well as to their extraordinary radiation output up to γ-ray energies. AIMS: We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm VLBI polarimetric observations, reaching an unprecedented resolution (∼50 μas). We also investigate the variability and physical processes occurring in the source during the observing period, which coincides with a very active state of the source over the entire electromagnetic spectrum. METHODS: We perform the Faraday rotation analysis using 3 and 7 mm data and we compare the obtained rotation measure (RM) map with the polarization evolution in 7 mm VLBA images. We study the kinematics and variability at 7 mm and infer the physical parameters associated with variability. From the analysis of γ-ray and X-ray data, we compute a minimum Doppler factor value required to explain the observed high-energy emission. RESULTS: Faraday rotation analysis shows a gradient in RM with a maximum value of ∼6 × 104⁴ rad m⁻² and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7 mm EVPA orientation is different when the component is exiting the core or crossing a stationary feature at ∼0.1 mas. The interaction between the superluminal component and a recollimation shock at ∼0.1 mas could have triggered the multi-wavelength flares. The variability Doppler factor associated with such an interaction is large enough to explain the high-energy emission and the remarkable optical flare occurred very close in time.Accepted manuscrip

Ballistic dynamics of a convex smooth-wall billiard with finite escape rate along the boundary

We focus on the problem of an impurity-free billiard with a random position-dependent boundary coupling to the environment. The response functions of such an open system can be obtained non-perturbatively from a supersymmetric generating functional. The derivation of this functional is based on averaging over the escape rates and results in a non-linear ballistic $\sigma$-model, characterized by system-specific parameters. Particular emphasis is placed on the {}``whispering gallery modes'' as the origin of surface diffusion modes in the limit of large dimensionless conductance.Comment: 12 pages, no figure

HST astrometry in the 30 Doradus region: II. Runaway stars from new proper motions in the Large Magellanic Cloud

We present a catalog of relative proper motions for 368,787 stars in the 30 Doradus region of the Large Magellanic Cloud (LMC), based on a dedicated two-epoch survey with the Hubble Space Telescope (HST) and supplemented with proper motions from our pilot archival study. We demonstrate that a relatively short epoch difference of 3 years is sufficient to reach a $\sim$0.1 mas yr$^{-1}$ level of precision or better. A number of stars have relative proper motions exceeding a 3-sigma error threshold, representing a mixture of Milky Way denizens and 17 potential LMC runaway stars. Based upon 183 VFTS OB-stars with the best proper motions, we conclude that none of them move faster than $\sim$0.3 mas yr$^{-1}$ in each coordinate -- equivalent to $\sim$70 km s$^{-1}$. Among the remaining 351 VFTS stars with less accurate proper motions, only one candidate OB runaway can be identified. We rule out any OB star in our sample moving at a tangential velocity exceeding $\sim$120 km s$^{-1}$. The most significant result of this study is finding 10 stars over wide range of masses, which appear to be ejected from the massive star cluster R136 in the tangential plane to angular distances from $35^{\prime\prime}$ out to $407^{\prime\prime}$, equivalent to 8-98 pc. The tangential velocities of these runaways appear to be correlated with apparent magnitude, indicating a possible dependence on the stellar mass.Comment: 45 pages (in referee format), 12 figures, 3 tables. Submitted to AJ. Comments are welcom

The relationship between labour unions’ bargaining power and firms’ operating flexibility: New evidence from emerging markets

This study analyses the relevance between the bargaining power of labour unions and the operating flexibility on firms’ capital costs by using non-financial firms listed on the Korean stock exchange from 1999 to 2013. Under the assumption that constraints in business activities attributed to the collective bargaining power of labour unions lead to reduced operating flexibility and increased capital costs, we test this notion empirically; the main test results are as follows: First, we find from portfolio analysis that the cost of capital is higher for firms in more unionized industries. Second, we find that union coverage positively affects the cost of capital at a significant level. Third, we confirm through robustness tests that the industry adjusted union coverage (IAUC) also has a positive effect on the cost of capital at a significant level. As a result, the effect holds after controlling for a host of industry- and firm-level characteristics, and is stronger when unions have more favourable bargaining power. Thus, our findings are consistent with the hypothesis that the increase of labour unions’ bargaining power leads to raise firms’ capital costs by decreasing operating flexibility in the Korean firms

86 GHz polarimetry of OVV1633+382 after a major mm flare

The 18 mag QSO 1633+382 (4C38.41, z=1.807) showed a very pronounced outburst in 2001/2002. With a peak amplitude of more than 9 Jy at 90GHz, this flare was brighter than any known previous flare in this source (data available since 1980).During onset, the mm-flare was particulary fast, with an increase of more than 2 Jy at 230 GHz in less than 8 days. Since January 2002, the mm-flux of 1633+382 is decaying. During this decline, however, local flux variations with amplitudes of 1-3 Jy were seen, indicative of underlying and more rapid source activity on time scales of 1-2 months. After the main peak occurring in 2001.99, the 90 GHz flux showed secondary maxima at approximately half year intervals in 2002.3, 2002.7 and 2003.13. This kind of periodicity might be explained via the lighthouse model (Camenzind and Krockenberger 1992), which is based on the magnetic accelerator of Blanford and Payne (1982). At present the millimeter flux is nearly back to its quiescent level of 2-2.5 Jy, which the source had before the flare began. Our VLBA Polarimetry monitoring started June 2002 during the onset of the flare. At cm wavelength, the flare is only marginally detected which implies very high opacity of the source.Comment: 4 pages. 5 figures. Proceedings of the 7th European VLBI Network Symposium held in Toledo, Spain on October 12-15, 2004. Editors: R. Bachiller, F. Colomer, J.-F. Desmurs, P. de Vicente (Observatorio Astronomico Nacional), p. 85-88. Needs evn2004.cl

Notes on Supersymmetry Enhancement of ABJM Theory

We study the supersymmetry enhancement of ABJM theory. Starting from a ${\cal N}=2$ supersymmetric Chern-Simons matter theory with gauge group U(2)$\times$U(2) which is a truncated version of the ABJM theory, we find by using the monopole operator that there is additional ${\cal N}=2$ supersymmetry related to the gauge group. We show this additional supersymmetry can combine with ${\cal N}=6$ supersymmetry of the original ABJM theory to an enhanced ${\cal N}=8$ SUSY with gauge group U(2)$\times$U(2) in the case $k=1,2$. We also discuss the supersymmetry enhancement of the ABJM theory with U($N$)$\times$U($N$) gauge group and find a condition which should be satisfied by the monopole operator.Comment: 23 pages, no figure, minor corrections, version to appear in JHE