Characterizing the radial oxygen abundance distribution in disk galaxies

We examine the possible dependence of the radial oxygen abundance distribution on non-axisymmetrical structures (bar/spirals) and other macroscopic parameters such as the mass, the optical radius R25, the color g-r, and the surface brightness of the galaxy. A sample of disk galaxies from the CALIFA DR3 is considered. We adopted the Fourier amplitude A2 of the surface brightness as a quantitative characteristic of the strength of non-axisymmetric structures in a galactic disk, in addition to the commonly used morphologic division for A, AB, and B types based on the Hubble classification. To distinguish changes in local oxygen abundance caused by the non-axisymmetrical structures, the multiparametric mass--metallicity relation was constructed as a function of parameters such as the bar/spiral pattern strength, the disk size, color index g-r in the SDSS bands, and central surface brightness of the disk. The gas-phase oxygen abundance gradient is determined by using the R calibration. We find that there is no significant impact of the non-axisymmetric structures such as a bar and/or spiral patterns on the local oxygen abundance and radial oxygen abundance gradient of disk galaxies. Galaxies with higher mass, however, exhibit flatter oxygen abundance gradients in units of dex/kpc, but this effect is significantly less prominent for the oxygen abundance gradients in units of dex/R25 and almost disappears when the inner parts are avoided. We show that the oxygen abundance in the central part of the galaxy depends neither on the optical radius R25 nor on the color g-r or the surface brightness of the galaxy. Instead, outside the central part of the galaxy, the oxygen abundance increases with g-r value and central surface brightness of the disk.Comment: 11 pages, 6 figures; accepted for publication in A&

Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&

Searching for Milky Way twins: Radial abundance distribution as a strict criterion

We search for Milky Way-like galaxies among a sample of approximately 500 galaxies. The characteristics we considered of the candidate galaxies are the following: stellar mass M_star, optical radius R_25, rotation velocity V_rot, central oxygen abundance (O/H)_0, and abundance at the optical radius (O/H)_R25. If the values of R_25 and M_star of the galaxy were close to that of the Milky Way, then the galaxy was referred to as a structural Milky Way analogue (sMWA). The oxygen abundance at a given radius of a galaxy is defined by the evolution of that region, and we then assumed that the similarity of (O/H)_0 and (O/H)_R25 in two galaxies suggests a similarity in their evolution. If the values of (O/H)_0 and (O/H)_R25 in the galaxy were close to that of the Milky Way, then the galaxy was referred to as an evolutionary Milky Way analogue (eMWA). If the galaxy was simultaneously an eMWA and sMWA, then the galaxy was considered a Milky Way twin. We find that the position of the Milky Way on the (O/H)_0 - (O/H)_R25 diagram shows a large deviation from the general trend in the sense that the (O/H)_R25 in the Milky Way is appreciably lower than in other galaxies of similar (O/H)_0. This feature of the Milky Way evidences that its (chemical) evolution is not typical. We identify four galaxies (NGC~3521, NGC~4651, NGC~2903, and MaNGA galaxy M-8341-09101) that are simultaneously sMWA and eMWA and can therefore be considered as Milky Way twins. In previous studies, Milky Way-like galaxies were selected using structural and morphological characteristics, that is, sMWAs were selected. We find that the abundances at the centre and at the optical radius (evolutionary characteristics) provide a stricter criterion for selecting real Milky Way twinsComment: Accepted to Astronomy and Astrophysics, 28 pages, 13 figure

A study of central galaxy rotation with stellar mass and environment

© 2017. The American Astronomical Society. All rights reserved. We present a pilot analysis of the influence of galaxy stellar mass and cluster environment on the probability of slow rotation in 22 central galaxies at mean redshift z = 0.07. This includes new integral-field observations of five central galaxies selected from the Sloan Digital Sky Survey, observed with the SPIRAL integral-field spectrograph on the Anglo-Australian Telescope. The composite sample presented here spans a wide range of stellar masses, 10.9 < log(M∗/M⊙)lt; 12.0, and are embedded in halos ranging from groups to clusters, 12.9 < log(M 200 Ṁ) < 15.6. We find a mean probability of slow rotation in our sample of P(SR) = 54 ± 7%. Our results show an increasing probability of slow rotation in central galaxies with increasing stellar mass. However, when we examine the dependence of slow rotation on host cluster halo mass, we do not see a significant relationship. We also explore the influence of cluster dominance on slow rotation in central galaxies. Clusters with low dominance are associated with dynamically younger systems. We find that cluster dominance has no significant effect on the probability of slow rotation in central galaxies. These results conflict with a paradigm in which halo mass alone predetermines central galaxy properties

Two types of distribution of the gas velocity dispersion of MaNGA galaxies

The distribution of the gas velocity dispersion sigma across the images of 1146 MaNGA galaxies is analyzed. We find that there are two types of distribution of the gas velocity dispersion across the images of galaxies: (i) the distributions of 909 galaxies show a radial symmetry with or without the sigma enhancement at the center (R distribution) and (ii) distributions with a band of enhanced sigma along the minor axis in the images of 159 galaxies with or without the sigma enhancement at the center (B distribution) The sigma distribution across the images of 78 galaxies cannot be reliable classified. We select 806 galaxies with the best defined characteristics (this sample includes 687 galaxies with R distribution and 119 galaxies with B distribution) and compare the properties of galaxies with R and B distributions. We find that the median value of the gas velocity dispersion sigma_m in galaxies with B distribution is higher by around 5 km/s, on average, than that of galaxies with R distribution. The optical radius R_25 of galaxies with B distribution is lower by around 0.1 dex, on average, than that of galaxies with similar masses with R distribution. Thus the properties of a galaxy are related to the type of distribution of the gas velocity dispersion across its image. This suggests that the presence of the band of the enhanced gas velocity dispersion can be an indicator of a specific evolution (or a specific stage in the evolution) of a galaxy.Comment: 5 pages, 4 figures, accepted to Astron.Astrophys. arXiv admin note: text overlap with arXiv:2005.1274

Viral Coinfections in Kawasaki Disease: A Meta-analysis.

CONTEXT: Viral infections are suspected triggers in Kawasaki disease (KD); however, a specific viral trigger has not been identified. OBJECTIVES: In children with KD, to identify (1) overall prevalence of viral infections; (2) prevalence of specific viruses; and (3) whether viral positivity was associated with coronary artery aneurysms (CAAs) or refractoriness to intravenous immunoglobin (IVIG). DATA SOURCES: We searched Embase, Medline, and Cochrane databases and gray literature. STUDY SELECTION: Eligible studies were conducted between 1999 and 2019, and included children diagnosed with KD who underwent viral testing. DATA EXTRACTION: Two investigators independently reviewed full-text articles to confirm eligibility, extract data, appraise for bias, and assess evidence quality for outcomes using the Grading of Recommendations Assessment Development and Evaluation criteria. We defined viral positivity as number of children with a positive viral test divided by total tested. Secondary outcomes were CAA (z score ≥2.5) and IVIG refractoriness (fever ≥36 hours after IVIG). RESULTS: Of 3189 unique articles identified, 54 full-text articles were reviewed, and 18 observational studies were included. Viral positivity weighted mean prevalence was 30% (95% confidence interval [CI], 14-51) and varied from 5% to 66%, with significant between-study heterogeneity. Individual virus positivity was highest for rhinovirus (19%), adenovirus (10%), and coronavirus (7%). Odds of CAA (odds ratio, 1.08; 95% CI, 0.75-1.56) or IVIG refractoriness (odds ratio, 0.88; 95% CI, 0.58-1.35) did not differ on the basis of viral status. LIMITATIONS: Low or very low evidence quality. CONCLUSIONS: Viral infection was common with KD but without a predominant virus. Viral positivity was not associated with CAAs or IVIG refractoriness

The metallicity - redshift relations for emission-line SDSS galaxies: examination of the dependence on the star formation rate

We analyse the oxygen abundance and specific star formation rates (sSFR) variations with redshift in star-forming SDSS galaxies of different masses. We find that the maximum value of the sSFR, sSFRmax, decreases when the stellar mass, Ms, of a galaxy increases, and decreases with decreasing of redshift. The sSFRmax can exceed the time-averaged sSFR by about an order of magnitude for massive galaxies. The metallicity - redshift relations for subsamples of galaxies with sSFR = sSFRmax and with sSFR = 0.1sSFRmax coincide for massive (log(Ms/Mo) > 10.5, with stellar mass Ms in solar units) galaxies and differ for low-mass galaxies. This suggests that there is no correlation between oxygen abundance and sSFR in massive galaxies and that the oxygen abundance correlates with the sSFR in low-mass galaxies. We find evidence in favour of that the irregular galaxies show, on average, higher sSFR and lower oxygen abundances than the spiral galaxies of similar masses and that the mass - metallicity relation for spiral galaxies differs slightly from that for irregular galaxies. The fact that our sample of low-mass galaxies is the mixture of spiral and irregular galaxies can be responsible for the dependence of the metallicity - redshift relation on the sSFR observed for the low-mass SDSS galaxies. The mass - metallicity and luminosity - metallicity relations obtained for irregular SDSS galaxies agree with corresponding relations for nearby irregular galaxies with direct abundance determinations. We find that the aperture effect does not make a significant contribution to the redshift variation of oxygen abundances in SDSS galaxies.Comment: 14 pages, 7 figures, accepted for publication in the MNRA

Radical radiotherapy in epidermoid cancer in the orbitary region: ideal scheme of hypo-fractionation in times of COVID-19: a case report

There are adverse events in the patient's environment that impact on therapeutic decisions and become a medical challenge, as is currently the management of cancer patients with radiotherapy, particularly the elderly in times of a COVID-19 pandemic, due the high risk of infection and fatal complications from non-cancer causes. Here we present the case of an 84-year-old woman with voluminous squamous cell cancer in the left orbital region, which caused intense pain, stench, and persistent bleeding. And due to persistence and time, it impacted with deterioration in the patient’s quality of life. In the end, of hypo fractionated radiotherapy management as the only modality, it evolves with a complete clinical response and total palliation of initial symptoms. The reasons for the decision to manage radiotherapy and the excellent clinical results that reinforce the idea of personalized medicine and the importance of evaluating the biopsychosocial environment of the cancer patient will be discussed