1,743 research outputs found

    Hydrogen Column Density Variability in a Sample of Local Compton-Thin AGN II

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    We present the multi-epoch analysis of 13 variable, nearby (z<0.1), Compton-thin (22<logN_H<24) active galactic nuclei (AGN) selected from the 105-month BAT catalog. Analyzing all available archival soft and hard X-ray observations, we investigate the line-of-sight hydrogen column density (N_H) variability on timescales ranging from a few days to approximately 20 years. Each source is analyzed by simultaneously modeling the data with three physical torus models, providing tight constraints on torus properties, including the covering factor, the cloud dispersion, and the torus average hydrogen column density (N_H,av). For each epoch, we measure the N_H and categorize the source as `N_H Variable', `Non-variable in N_H', or `Undetermined' based on the degree of variability. Our final sample includes 27 variable, Compton-thin AGN after implementing another 14 AGN analyzed in our previous work. We find that all sources require either flux or N_H variability. We classify 37% of them as `N_H Variable', 44% as `Non-variable in N_H', and 19% as `Undetermined'. Noticeably, there is no discernible difference between geometrical and intrinsic properties among the three variability classes, suggesting no intrinsic differences between the N_H-variable and non-variable sources. We measure the median variation in N_H between any observation pair of the same source to be 25% with respect to the lowest N_H measure in the pair. Furthermore, 48% of the analyzed sources require the inclusion of a Compton-thick reflector in the spectral fitting. Among these, the 30% exhibits recorded 22 GHz water megamaser emission, suggesting a potential shared nature between the two structures.Comment: Submitted to Ap

    Revealing high-z Fermi-LAT BL Lacs using Swift and SARA data with photometric analysis

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    BL Lacertae (BL Lac) objects are one type of blazar, distinguished by their featureless optical spectrum. This presents a challenge in measuring the redshift of the BL Lacs. This paper uses the photometric dropout technique to measure the redshifts of BL Lac objects. Space-based telescope \emph{Swift} and ground-based SARA telescopes are employed to provide magnitudes in the $uvw2,\ uvm2,\ uvw1,\ u,\ b,\ v,\ g',\ r',\ i',\ z'filters.Weobserve60BLLacsandreportreliableredshiftupperlimitsfor41sources.Wediscoverfourhigh filters. We observe 60 BL Lacs and report reliable redshift upper limits for 41 sources. We discover four high-zBLLacs( BL Lacs (z>1.3),bringingthenumberofhigh), bringing the number of high-z BL Lacs found by this method up to 20. We also discuss the blazar sequence, the \emph{Fermi} blazar divide, and the gamma-ray horizon using the 4LAC catalog and all high-z$ BL Lacs discovered with the photo-z technique.Comment: 16pages, 7 figure

    Compton-thick AGN in the NuSTAR Era VI: The Observed Compton-thick Fraction in the Local Universe

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    We present the analysis of simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton data of eight Compton-thick active galactic nuclei (CT-AGN) candidates selected in the Swift-BAT 100 month catalog. This work is part of an ongoing effort to find and characterize all CT-AGN in the Local (z = 0.05) Universe. We used two physically motivated models, MYTorus and borus02, to characterize the sources in the sample, finding five of them to be confirmed CT-AGN. These results represent an increase of ~19% over the previous NuSTAR-confirmed, BAT-selected CT-AGN at z = 0.05, bringing the total number to 32. This corresponds to an observed fraction of ~8% of all AGN within this volume-limited sample, although it increases to 20% 5% when limiting the sample to z = 0.01. Out of a sample of 48 CT-AGN candidates, selected using BAT and soft (0.3-10 keV) X-ray data, only 24 are confirmed as CT-AGN with the addition of the NuSTAR data. This highlights the importance of NuSTAR when classifying local obscured AGN. We also note that most of the sources in our full sample of 48 Seyfert 2 galaxies with NuSTAR data have significantly different lines of sight and average torus column densities, favoring a patchy torus scenario

    Compton-Thick AGN in the NuSTAR Era X: Analysing seven local CT-AGN candidates

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    Context. We present the broad-band X-ray spectral analysis (0.6a-50 keV) of seven Compton-Thick active galactic nuclei (CT-AGN; line-of-sight (LOS) column density &gt; 1024 cma-2) candidates selected from the Swift-BAT 100 month catalogue using archival NuSTAR data. Aims. We aim to obtain a complete census of the heavily obscured AGN in the local Universe (za-0.05). Methods. This work is in continuation of the ongoing research of the Clemson-INAF group to classify CT-AGN candidates at redshift za-0.05 using physically motivated torus models. Results. Our results confirm that three out of seven targets are bona fide CT-AGN. Adding our results to the previously analysed sources using NuSTAR data, we increase the population of bona fide CT-AGN by a9%, bringing the total number to 35 out of 414 AGN. We also performed a comparative study using MYTorus and borus02 on the spectra in our sample, finding that both physical models are strongly consistent in the parameter space of LOS column density and photon index. Furthermore, we also investigate the clumpiness of the torus clouds by separately computing the LOS and average torus column densities in each of the seven sources. Adding our results to all the previous 48 CT-AGN candidates analysed by the Clemson-INAF research team for which NuSTAR observations are available, we find that 78% of the sources are likely to have a clumpy distribution of the obscuring material surrounding the accreting supermassive black hole

    Carga del cuidador en familiares de personas con enfermedad mental vinculadas al programa de Hospital Día de una institución de tercer nivel de la ciudad de Cali.

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    Los familiares de una persona con enfermedad mental que asumen el rol de cuidadores, cumplen un papel determinante en la adherencia a procesos de rehabilitación psicosocial puesto que contribuyen a la toma de decisiones al establecer mecanismos de participación de la persona con enfermedad mental. Sin embargo, permanentemente se enfrentan a situaciones de estrés, ansiedad y desesperanza, síntomas que repercuten directamente sobre su capacidad productiva y adaptativa ante situaciones vitales. La manifestación de dicha sintomatología constituye el Síndrome de Carga del Cuidador

    Compton-thick AGN in the NuSTAR Era. VIII. A joint NuSTAR-XMM-Newton Monitoring of the Changing-look Compton-thick AGN NGC 1358

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    We present the multi-epoch monitoring with NuSTAR and XMM-Newton of NGC 1358, a nearby Seyfert 2 galaxy whose properties made it a promising candidate X-ray changing-look active galactic nucleus (AGN), i.e., a source whose column density could transition from its 2017 Compton-thick (having LOS hydrogen column density NH,LOS&gt; 1024cm−2) state to a Compton-thin (NH,LOS&lt; 1024cm−2) one. The multi-epoch X-ray monitoring confirmed the presence of significant NH,LOSvariability over timescales of weeks to years, and allowed us to confirm the changing-look nature of NGC 1358, which has most recently been observed in a Compton-thin status. Multi-epoch monitoring with NuSTAR and XMM-Newton is demonstrated to be highly effective in simultaneously constraining three otherwise highly degenerate parameters: the torus average column density and covering factor, and the inclination angle between the torus axis and the observer. We find a tentative anticorrelation between column density and luminosity, which can be understood under the framework of chaotic cold accretion clouds driving recursive AGN feedback. The monitoring campaign of NGC 1358 has proven the efficiency of our newly developed method to select candidate NH,LOS-variable, heavily obscured AGN, which we plan to soon extend to a larger sample to better characterize the properties of the obscuring material surrounding accreting supermassive black holes, as well as to constrain AGN feeding models

    Hospital-acquired influenza infections detected by a surveillance system over six seasons, from 2010/2011 to 2015/2016

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    In addition to outbreaks of nosocomial influenza, sporadic nosocomial influenza infections also occur but are generally not reported in the literature. This study aimed to determine the epidemiologic characteristics of cases of nosocomial influenza compared with the remaining severe cases of severe influenza in acute hospitals in Catalonia (Spain) which were identified by surveillance. An observational case-case epidemiological study was carried out in patients aged ≥18 years from Catalan 12 hospitals between 2010 and 2016. For each laboratory-confirmed influenza case (nosocomial or not) we collected demographic, virological and clinical characteristics. We defined patients with nosocomial influenza as those admitted to a hospital for a reason other than acute respiratory infection in whom ILI symptoms developed ≥48 h after admission and influenza virus infection was confirmed using RT-PCR. Mixed-effects regression was used to estimate the crude and adjusted OR. One thousand seven hundred twenty-two hospitalized patients with severe laboratory-confirmed influenza virus infection were included: 96 (5.6%) were classified as nosocomial influenza and more frequently had > 14 days of hospital stay (42.7% vs. 27.7%, P <.001) and higher mortality (18.8% vs. 12.6%, P <.02). The variables associated with nosocomial influenza cases in acute-care hospital settings were chronic renal disease (aOR 2.44 95% CI 1.44-4.15) and immunodeficiency (aOR 1.79 95% CI 1.04-3.06). Nosocomial infections are a recurring problem associated with high rates of chronic diseases and death. These findings underline the need for adherence to infection control guidelines

    Effects of luteectomy in early pregnancy on the maintenance of gestation and plasma progesterone concentrations in the viviparous temperate lizard Barisia imbricata imbricata

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    <p>Abstract</p> <p>Background</p> <p>Several studies have shown that the corpus luteum is the principal source of progesterone during the gravidity period in reptiles; however, its participation in the maintenance of gestation in the viviparous squamata is in dispute. The effects of ovariectomy or luteectomy vary according to the species and the time at which the procedure is performed. In this paper, we describe the effects of luteectomy during early pregnancy on the maintenance of gestation and progesterone concentrations in the temperate Mexican viviparous lizard <it>Barisia imbricata imbricata.</it></p> <p>Methods</p> <p>Twenty-four lizards were subjected to three different treatments: luteectomy, sham luteectomy or non-surgical treatment, and blood samples were obtained before and after surgical treatment at different stages of gestation to determine the effects of luteectomy on the maintenance of gestation and progesterone concentrations.</p> <p>Results</p> <p>Spontaneous abortion was not observed in any of the females. However, luteectomy provoked abnormal parturition and a significant reduction in the number of young born alive. Parturition was normal in untreated females as well as those submitted to sham luteectomy. The surgical treatment also caused a significant reduction in progesterone concentrations in luteectomised females during early and middle gestation. However, no significant differences in hormone concentrations were observed among the three groups during late gestation or immediately post-parturition.</p> <p>Conclusions</p> <p>Our observations indicate that the presence of the corpus luteum is not necesary for the maintenance of gestation, but that it does participate in parturition control. Moreover, the corpus luteum of the viviparous lizard <it>B. i. imbricata</it> produces progesterone, at least during the first half of pregnancy, and that an extra-ovarian source of progesterone must maintain gestation in the absence of luteal tissue.</p

    A hard X-ray view of luminous and ultra-luminous infrared galaxies in GOALS - I. AGN obscuration along the merger sequence

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    The merger of two or more galaxies can enhance the inflow of material from galactic scales into the close environments of active galactic nuclei (AGNs), obscuring and feeding the supermassive black hole (SMBH). Both recent simulations and observations of AGN in mergers have confirmed that mergers are related to strong nuclear obscuration. However, it is still unclear how AGN obscuration evolves in the last phases of the merger process. We study a sample of 60 luminous and ultra-luminous IR galaxies (U/LIRGs) from the GOALS sample observed by NuSTAR. We find that the fraction of AGNs that are Compton thick (CT;N-H &gt;= 10(24)cm(-2) ) peaks at at a late merger stage, prior to coalescence, when the nuclei have projected separations (d(sep)) of 0.4-6 kpc. A similar peak is also observed in the median N-H [[(1.6 +/- 0.5) x 10(24) cm(-2)].]. The vast majority (85(-9)(+7) per cent)) of the AGNs in the final merger stages (d(sep) less than or similar to 10 kpc) are heavily obscured (N-H = 10(23) cm(-2)), and the median N-H of the accreting SMBHs in our sample is systematically higher than that of local hard X-ray-selected AGN, regardless of the merger stage. This implies that these objects have very obscured nuclear environments, with the gas almost completely covering the AGN in late mergers. CT AGNs tend to have systematically higher absorption-corrected X-ray luminosities than less obscured sources. This could either be due to an evolutionary effect, with more obscured sources accreting more rapidly because they have more gas available in their surroundings, or to a selection bias. The latter scenario would imply that we are still missing a large fraction of heavily obscured, lower luminosity (L2-10 less than or similar to 10(43) erg s(-1)) AGNs in U/LIRGs

    Assessment of ecosystem services of an urbanized tropical estuary with a focus on habitats and scenarios

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    Tropical estuaries are one of the most valuable ecosystems on the planet because of the number of ecosystem services they provide. The increasing anthropogenic pressure to which these estuaries are subject has caused a reduction in their natural capital stock. Therefore, the application of a pragmatic and rational ecosystem-based management approach to sustainably manage the multiple ecosystem services provided by this ecosystem is necessary. The aim of our study is to present an approach that combines prospective scenarios with habitat-based perspective to assess the supply capacity of ecosystem services, plus determine the impact of protected areas in an urbanized tropical estuary. The current situation and two scenarios were generated to evaluate the capacity of habitats to supply ecosystem services. This type of assessment will allow the decision makers to visualize the effect of their choices or the occurrence of events which might produce significant changes in the estuary. Thus, over time, measures can be taken to sustain the supply of ecosystem services. We determined that the establishment of protected areas have a positive impact; however, the effect is not the same for all of them. Consequently, indicating that actions such as community participation, research, education, management planning and infrastructure development must accompany the development of a protected area
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