Strong lens search in the ESO public Survey KiDS

We have started a systematic search of strong lens candidates in the ESO public survey KiDS based on the visual inspection of massive galaxies in the redshift range $0.1<z<0.5$. As a pilot program we have inspected 100 sq. deg., which overlap with SDSS and where there are known lenses to use as a control sample. Taking advantage of the superb image quality of VST/OmegaCAM, the colour information and accurate model subtracted images, we have found 18 new lens candidates, for which spectroscopic confirmation will be needed to confirm their lensing nature and study the mass profile of the lensing galaxies.Comment: 4 pages, 1 figure, to appear on the refereed Proceeding of the "The Universe of Digital Sky Surveys" conference held at the INAF--OAC, Naples, on 25th-28th november 2014, to be published on Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodic

Systematic variation of central mass density slope in early-type galaxies

We study the total density distribution in the central regions ($<\, 1$ effective radius, $R_{\rm e}$) of early-type galaxies (ETGs), using data from the SPIDER survey. We model each galaxy with two components (dark matter halo + stars), exploring different assumptions for the dark matter (DM) halo profile, and leaving stellar mass-to-light ($M_{\rm \star}/L$) ratios as free fitting parameters to the data. For a Navarro et al. (1996) profile, the slope of the total mass profile is non-universal. For the most massive and largest ETGs, the profile is isothermal in the central regions ($\sim R_{\rm e}/2$), while for the low-mass and smallest systems, the profile is steeper than isothermal, with slopes similar to those for a constant-M/L profile. For a concentration-mass relation steeper than that expected from simulations, the correlation of density slope with mass tends to flatten. Our results clearly point to a "non-homology" in the total mass distribution of ETGs, which simulations of galaxy formation suggest may be related to a varying role of dissipation with galaxy mass.Comment: 3 pages, 1 figure, to appear on the refereed Proceeding of the "The Universe of Digital Sky Surveys" conference held at the INAF--OAC, Naples, on 25th-28th november 2014, to be published on Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodic

Inflation, quantum fields, and CMB anisotropies

Inflationary cosmology has proved to be the most successful at predicting the properties of the anisotropies observed in the cosmic microwave background (CMB). In this essay we show that quantum field renormalization significantly influences the generation of primordial perturbations and hence the expected measurable imprint of cosmological inflation on the CMB. However, the new predictions remain in agreement with observation, and in fact favor the simplest forms of inflation. In the near future, observations of the influence of gravitational waves from the early universe on the CMB will test our new predictions.Comment: 11 pages, 1 figure, Awarded with the fourth prize in the Gravity Research Foundation 2009 Essay Competitio

VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager

In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative transfer equation (VFISV: Very Fast inversion of the Stokes vector). VFISV will routinely analyze pipeline data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096$\times$4096 pixels) of the magnetic field vector on the Solar Photosphere every 10 minutes. For this reason VFISV is optimized to achieve an inversion speed that will allow it to invert 16 million pixels every 10 minutes with a modest number (approx. 50) of CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of the Hinode spacecraft.Comment: 23 pages, 9 figures (2 color). Submitted for publication to Solar Physic

Resultados oncológicos en enfermedad N1 posterior a la prostatectomía radical

ResumenAntecedentesLa prostatectomía radical+linfadenectomía pélvica puede mejorar la supervivencia libre de progresión y supervivencia cáncer-específica en la enfermedad ganglionar.ObjetivoAnalizar las características de los pacientes con enfermedad ganglionar en el análisis histopatológico de la prostatectomía radical.Material y métodosEstudio retrospectivo de pacientes sometidos a prostatectomía radical con enfermedad ganglionar metastásica de 1988 a 2015.ResultadosSe incluyeron 25 pacientes, de 66.5 años (DE±6.5); antígeno prostático específico medio de 20.17ng/dL (RIC: 18); con una mediana de seguimiento en 63 meses (RIC: 86). Clasificación de riesgo por D’Amico, 15 (60%) pacientes de alto, 8 (32%) intermedio y 2 (8%) de riesgo bajo. Se encontraron márgenes positivos en 15 casos (60%); estadio tumoral T2 en 4 (16%), T3A en 3 (12%), T3B en 17 (68%) y T4 en 1 (4%); cantidad de ganglios positivos, uno en 14 (56%), 2 en 3 (12%) y más de 2 en 8 (32%) casos. Recibieron radioterapia 3 pacientes (16%) y bloqueo hormonal 24 (96%). La supervivencia libre de progresión fue de 105 meses y la supervivencia cáncer-específica fue del 86 y 45% a 5 y 10 años respectivamente. El HR para progresión bioquímica fue significativo en márgenes positivos (HR: 9.5, IC95%: 0.99-91.5, p=0.50) y ≥2 ganglios positivos (HR: 8.5, IC95%: 1.1-61.9, p=0.34). La afectación≥2 ganglios predijo progresión con una OR de 7.2 (IC95% 1.06-48.6, p=0.043).ConclusionesLa supervivencia media a 5 años es superior al 80%. El número de ganglios positivos podría ser un factor predictor de progresión bioquímica.AbstractBackgroundRadical prostatectomy+pelvic lymph node dissection can improve progression-free survival and cancer-specific survival in lymph node disease.AimTo analyze the characteristics of patients with lymph node disease in the histopathologic findings of the radical prostatectomy and lymph node dissection.Material and methodsA retrospective study was carried out on patients that underwent radical prostatectomy with metastatic lymph node disease within the time frame of 1988 to 2015.ResultsThe study included 25 patients with a mean 66.5 years of age (SD±6.5), a mean prostate-specific antigen of 20.17ng/dl (IQR: 18), and a median follow-up period of 63 months (IQR: 86). According to the D’Amico classification, 15 (60%) patients were high-risk, 8 (32%) were intermediate-risk, and 2 (8%) were low-risk. Positive margins were found in 15 cases (60%); 4 (16%) patients had T2 tumor stage, 3 (12%) had T3A, 17 (68%) had T3B, and one patient (4%) had T4. Fourteen (56%) patients had one positive lymph node, 3 (12%) patients had 2 positive lymph nodes, and 8 (32%) patients had more than 2 positive lymph nodes. Three (16%) patients received radiotherapy and 24 (96%) underwent hormone blockade. Progression-free survival was 105 months and cancer-specific survival was 86% at 5 years and 45% at ten years. The HR for biochemical progression was significant in positive margins (HR: 9.5, 95% CI: 0.99-91.5, P=.50) and when there were≥2 positive lymph nodes (HR: 8.5, 95% CI: 1.1-61.9, P=0.34). Involvement of≥2 lymph nodes predicted progression with an odds ratio of 7.2 (95% CI: 1.06-48.6, P=.043).ConclusionsThe average 5-year survival was above 80%. The number of positive lymph nodes could be a predictive factor for biochemical progression

Dark Matter from a gas of wormholes

The simplistic model of the classical spacetime foam is considered, which consists of static wormholes embedded in Minkowski spacetime. We explicitly demonstrate that such a foam structure leads to a topological bias of point-like sources which can equally be interpreted as the presence of a dark halo around any point source. It is shown that a non-trivial halo appears on scales where the topological structure possesses a local inhomogeneity, while the homogeneous structure reduces to a constant renormalization of the intensity of sources. We also show that in general dark halos possess both (positive and negative) signs depending on scales and specific properties of topological structure of space.Comment: minor corrections (eq. 18

Structural Invariance of Sunspot Umbrae Over the Solar Cycle: 1993-2004

Measurements of maximum magnetic flux, minimum intensity, and size are presented for 12 967 sunspot umbrae detected on the NASA/NSO spectromagnetograms between 1993 and 2004 to study umbral structure and strength during the solar cycle. The umbrae are selected using an automated thresholding technique. Measured umbral intensities are first corrected for a confirming observation of umbral limb-darkening. Log-normal fits to the observed size distribution confirm that the size spectrum shape does not vary with time. The intensity-magnetic flux relationship is found to be steady over the solar cycle. The dependence of umbral size on the magnetic flux and minimum intensity are also independent of cycle phase and give linear and quadratic relations, respectively. While the large sample size does show a low amplitude oscillation in the mean minimum intensity and maximum magnetic flux correlated with the solar cycle, this can be explained in terms of variations in the mean umbral size. These size variations, however, are small and do not substantiate a meaningful change in the size spectrum of the umbrae generated by the Sun. Thus, in contrast to previous reports, the observations suggest the equilibrium structure, as testified by the invariant size-magnetic field relationship, as well as the mean size (i.e. strength) of sunspot umbrae do not significantly depend on solar cycle phase.Comment: 17 pages, 6 figures. Published in Solar Physic

The Galactic Halo in Mixed Dark Matter Cosmologies

A possible solution to the small scale problems of the cold dark matter (CDM) scenario is that the dark matter consists of two components, a cold and a warm one. We perform a set of high resolution simulations of the Milky Way halo varying the mass of the WDM particle ($m_{\rm WDM}$) and the cosmic dark matter mass fraction in the WDM component ($\bar{f}_{\rm W}$). The scaling ansatz introduced in combined analysis of LHC and astroparticle searches postulates that the relative contribution of each dark matter component is the same locally as on average in the Universe (e.g. $f_{\rm W,\odot} = \bar{f}_{\rm W}$). Here we find however, that the normalised local WDM fraction ($f_{\rm W,\odot}$ / $\bar{f}_{\rm W}$) depends strongly on $m_{\rm WDM}$ for $m_{\rm WDM} <$ 1 keV. Using the scaling ansatz can therefore introduce significant errors into the interpretation of dark matter searches. To correct this issue a simple formula that fits the local dark matter densities of each component is provided.Comment: 19 pages, 10 figures, accepted for publication in JCA

Conservative Constraints on Dark Matter from the Fermi-LAT Isotropic Diffuse Gamma-Ray Background Spectrum

We examine the constraints on final state radiation from Weakly Interacting Massive Particle (WIMP) dark matter candidates annihilating into various standard model final states, as imposed by the measurement of the isotropic diffuse gamma-ray background by the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope. The expected isotropic diffuse signal from dark matter annihilation has contributions from the local Milky Way (MW) as well as from extragalactic dark matter. The signal from the MW is very insensitive to the adopted dark matter profile of the halos, and dominates the signal from extragalactic halos, which is sensitive to the low mass cut-off of the halo mass function. We adopt a conservative model for both the low halo mass survival cut-off and the substructure boost factor of the Galactic and extragalactic components, and only consider the primary final state radiation. This provides robust constraints which reach the thermal production cross-section for low mass WIMPs annihilating into hadronic modes. We also reanalyze limits from HESS observations of the Galactic Ridge region using a conservative model for the dark matter halo profile. When combined with the HESS constraint, the isotropic diffuse spectrum rules out all interpretations of the PAMELA positron excess based on dark matter annihilation into two lepton final states. Annihilation into four leptons through new intermediate states, although constrained by the data, is not excluded.Comment: 11 pages, 5 figures. v3: minor revisions, matches version to appear in JCA

Constraining scalar fields with stellar kinematics and collisional dark matter

The existence and detection of scalar fields could provide solutions to long-standing puzzles about the nature of dark matter, the dark compact objects at the centre of most galaxies, and other phenomena. Yet, self-interacting scalar fields are very poorly constrained by astronomical observations, leading to great uncertainties in estimates of the mass $m_\phi$ and the self-interacting coupling constant $\lambda$ of these fields. To counter this, we have systematically employed available astronomical observations to develop new constraints, considerably restricting this parameter space. In particular, by exploiting precise observations of stellar dynamics at the centre of our Galaxy and assuming that these dynamics can be explained by a single boson star, we determine an upper limit for the boson star compactness and impose significant limits on the values of the properties of possible scalar fields. Requiring the scalar field particle to follow a collisional dark matter model further narrows these constraints. Most importantly, we find that if a scalar dark matter particle does exist, then it cannot account for both the dark-matter halos and the existence of dark compact objects in galactic nucleiComment: 23 pages, 8 figures; accepted for publication by JCAP after minor change