Monte Carlo simulations of dusty spiral galaxies: extinction and polarization properties

We present Monte Carlo simulations of dusty spiral galaxies, modelled as bulge + disk systems, aimed to study their extinction and polarization properties. The extinction parameters (absorption and scattering) of dust grains are calculated from Mie's theory for a full distribution of sizes and materials; the radiation transfer is carried on for the four Stokes parameters. Photometric and polarimetric maps of galaxies of different optical depths, inclinations and bulge-to-total ratios have been produced in the B and I bandpasses. As expected, the effect of scattering is to reduce substantially the extinction for a given optical depth, in particular for what concerns the obscuration of bright bulge cores. For the same reason, scattering reduces also the reddening, as evaluated from B-I maps. On the other hand the bluing directly due to forward scattering is hardly appreciable. Radial color gradients are often found. A comparison with ``sandwich'' models shows that they fail dramatically to reproduce the extinction - optical depth relation. The degree of linear polarization produced by scattering is usually of the order of a few percent; it increases with optical depth, and with inclination (less than 80 degrees). The polarization pattern is always perpendicular to the major axis, unless the dust distribution is drastically modified. There is little local correlation between extinction and polarization degree and there is a trend of increasing polarization from the B to the I band. We discuss implications and relevance of the results for studies of the structure and morphology of spiral galaxies and of their interstellar medium.Comment: 43 pages, 13 Postscript figures, Latex AAS manuscript substyle, Ap. J. Accepte

Near-infrared surface photometry of early-type spiral galaxies: I. Bulge and disk decomposition

We present near-infrared (NIR) surface photometry of a sample of 14 early-type spirals with observed rotation curves. In this first paper, we report the results of two-dimensional parametric and non-parametric decompositions to separate the bulge and disk components; the parametric bulge is modeled with a generalized exponential law of integer index n, and the disk with a simple exponential. We find that the derived bulge parameters, for a given galaxy, vary systematically with the bulge shape index n. The mean early-type bulge has a best-fit n = 2.6, and 80% of the sample has best n of 2 or 3. Bulges are rarely spherical; the median bulge intrinsic ellipticity is 0.33. The median early-type disk has (J-K)_d more than 0.1 mag bluer than the bulge, and a NIR disk surface brightness more than 1 mag arcsec^{-2} brighter than later-type disks. Our data are consistent with the well-established correlation of both bulge and disk surface brightness with physical scale length, and we note that the location of bulges within this projection of the fundamental plane depends on their shape index n. In agreement with previous work, the ratios of bulge and disk scale lengths are consistent with a constant value r_e/r_d = 0.3; however, such value again depends on the bulge index n, implying that claims for a scale-free Hubble sequence may be premature.Comment: 13 pages, 2 tables in postscript format, 6 figures. For the first figure only one page of 14 is shown; to retrieve the rest please contact the first author ([email protected]). Astronomy & Astrophysics Supplement, in pres

Embodied energy and operational energy evaluation in tall buildings according to different typologies of façade

Abstract Although recent studies demonstrate the importance of including the Embodied Energy (EE) in building analysis, only the Operational Energy (OE) is currently taken into account in building energy demand calculation method. In particular, the EE plays an important role in tall buildings evaluation, because the energy demand increases with building height. Aim of this study was to assess the Embodied Energy in evaluation of different types of tall building facade systems performances along with the Operational Energy, pointing out the importance of taking into account both these aspects. Within the research activity here presented, 8 glazed envelope typologies, in 5 different climate zones, have been evaluated

On the Dust Extinction in High-z Galaxies and the Case of Extremely Red Objects

We present the preliminary results of Monte Carlo simulations aimed to investigate the effects of realistic dust extinction (absorption + scattering) on the colours of high-z galaxies. In this paper, we concentrate on the case of spheroidal galaxies, and we obtain attenuation curves in the range 0.1-1.2$\mu$m for different dust spatial distributions, and for a range of values of the dust optical depth, geometrical thickness and inclination of the dust disk. We find that the resultant curves are strongly dependent on the dust geometrical distribution and optical depth. A serendipitous finding is that the strength of the 2200 \AA absorption feature depends not only on the optical depth, but also on the dust geometrical distribution. As a first application, we test our results on two high-z galaxies with extremely red colours (HR10 and HR14) in order to infer clues on their ages, dust content and dust spatial distribution. We confirm that HR10 must be a very dusty galaxy, and we suggest that its stellar component should be strongly embedded in the dust in order to reproduce the observed extremely red colours.Comment: 7 pages, MNRAS LaTeX, 3 figure

Acupuncture for migraine: a protocol for a meta-analysis and meta-regression of randomised controlled trials

INTRODUCTION Although the effectiveness of acupuncture for episodic migraine has been confirmed by multiple clinical trials and Cochrane systematic reviews, the mechanisms underlying the specific effect of acupuncture for migraine remain controversial. We aim to evaluate the effectiveness and safety of acupuncture for both episodic migraine and chronic migraine by meta-analysis and explore the possible factors influencing the specific effect of acupuncture for migraine by meta-regression. METHODS AND ANALYSIS We will search for randomised control trials of acupuncture for migraine in the following eight databases: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, AMED (via OVID) and four Chinese databases (Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Chinese Science and Technology Periodical Database and Wanfang Database) from inception to 31 December 2017. We will also search OpenSIGLE (opensigle.inist.fr) for conference abstracts. No language restriction will be applied. The selection of studies, data extraction and coding and assessment of risk of bias of the included studies will be conducted independently by two reviewers. Standard meta-analysis and, if appropriate, meta-regression will be performed using the R packages Meta and Metafor. ETHICS AND DISSEMINATION The results of this meta-analysis and meta-regression will be disseminated through publication in a peer-reviewed journal and presented at a relevant conference. The data used in this meta-analysis will not contain individual patient data; therefore, ethical approval is not required. PROSPERO REGISTRATION NUMBER CRD42018087270

The Herschel Virgo Cluster Survey - XIII. Dust in early-type galaxies

Aims. We study the dust content of a large optical input sample of 910 early-type galaxies (ETG) in the Virgo cluster, extending also to the dwarf ETG, and examine the results in relation with those on the other cold ISM components. Methods. We searched for far-infrared emission in all galaxies of the input sample using the 250 micron image of the Herschel Virgo Cluster Survey (HeViCS). This image covers a large fraction of the cluster. For the detected ETG we measured fluxes in 5 bands from 100 to 500 micron, and estimated the dust mass and temperature with modified black-body fits. Results. Dust is detected above the completeness limit of 25.4 mJy at 250 micron in 46 ETG, 43 of which are in the optically complete part of the input sample. In addition dust is present at fainter levels in another 6 ETG. We detect dust in the 4 ETG with synchrotron emission, including M 87. Dust appears to be much more concentrated than stars and more luminous ETG have higher dust temperatures. Dust detection rates down to the 25.4 mJy limit are 17% for ellipticals, about 40% for lenticulars (S0 + S0a) and around 3% for dwarf ETG. Dust mass does not correlate clearly with stellar mass and is often much more than that expected for a passive galaxy in a closed-box model. The dust-to-stars mass ratio anticorrelates with galaxy luminosity, and for some dwarf ETG reaches values as high as for dusty late-type galaxies. In the Virgo cluster slow rotators appear more likely to contain dust than fast ones. Comparing the dust results with those on HI from ALFALFA, there are only 8 ETG detected both in dust and in HI in the HeViCS area; 39 have dust but only an upper limit on HI, and 8 have HI but only an upper limit on dust. The locations of these galaxies in the cluster are different, with the dusty ETG concentrated in the densest regions, while the HI rich ETG are at the periphery.Comment: Accepted by Astronomy and Astrophysics; modified to reflect the on-line forthcoming version on the A&A web sit

An Atlas of Monte Carlo Models of Dust Extinction in Galaxies for Cosmological Applications

We present an extensive study of the radiative transfer in dusty galaxies based on Monte Carlo simulations. The main output of these simulations are the attenuation curves ${\cal A}_\lambda$ (i.e. the ratio between the observed, dust extinguished, total intensity to the intrinsic unextinguished one of the galaxy as a function of wavelength). We have explored the dependence of ${\cal A}_\lambda$ on a conspicuous set of quantities (Hubble type, inclination, dust optical thickness, dust distribution and extinction properties) for a large wavelength interval, ranging from 1250\AA to the K band, thus finally providing a comprehensive atlas of dust extinction in galaxies, which is electronically available. This study is particularly suitable for inclusion into galaxy formation evolution models and to directly interpret observational data on high redshift galaxies.Comment: 29 pages, aasms4.sty, LaTeX, 5 figures. ApJSS, accepte

The Effect of Light Scattering by Dust in Galactic Halos on Emission Line Ratios

We present results from Monte Carlo simulations describing the radiation transfer of $H\alpha$ line emission, produced both by HII regions in the disk and in the diffuse ionized gas (DIG), through the dust layer of the galaxy NGC891. This allows us to calculate the amount of light originating in the HII regions of the disk and scattered by dust at high $z$, and compare it with the emission produced by recombinations in the DIG. The cuts of photometric and polarimetric maps along the $z$-axis show that scattered light from HII regions is still 10\% of that of the DIG at $z\sim 600$~pc, whereas the the degree of linear polarization is small ($<1$\%). The importance of these results for the determination of intrinsic emission line ratios is emphasized, and the significance and possible implications of dust at high $z$ are discussed.Comment: 12 pages, LaTeX (aasms4.sty), 2 figures; ApJ Letters, accepted, June 5t