Search

We investigate the coalescence of massive black hole ($M_{\rm BH}\gtrsim 10^{6}~\rm {\rm M}_{\odot }$) binaries (MBHBs) at 6 < z < 10 by adopting a suite of cosmological hydrodynamical simulations of galaxy formation, zoomed-in on biased (>3σ) overdense regions (Mh ∼ 1012 M⊙ dark matter haloes at z = 6) of the Universe. We first analyse the impact of different resolutions and AGN feedback prescriptions on the merger rate, assuming instantaneous mergers. Then, we compute the halo bias correction factor due to the overdense simulated region. Our simulations predict merger rates that range between 3 and 15 $\rm yr^{-1}$ at z ∼6, depending on the run considered, and after correcting for a bias factor of ∼20−30. For our fiducial model, we further consider the effect of delay in the MBHB coalescence due to dynamical friction. We find that 83 per cent of MBHBs will merge within the Hubble time, and 21 per cent within 1 Gyr, namely the age of the Universe at z > 6. We finally compute the expected properties of the gravitational wave (GW) signals and find the fraction of LISA detectable events with high signal-to-noise ratio (SNR > 5) to range between 66 per cent and 69 per cent. However, identifying the electro-magnetic counterpart of these events remains challenging due to the poor LISA sky localization that, for the loudest signals ($\mathcal {M}_c\sim 10^6~{{\rm M}_{\odot }}$ at z = 6), is around 10 $\rm deg^2$.

In my presentation, I review the expected performances of the Athena-WFI survey, with a particular focus on the high redshift Universe and the first SMBH science topic. I put these performances in the broader context of present and future missions and facilities in other wavelengths, from optical/IR large-area surveys to mm/sub-mm and radio observations. The unique capability of Athena-WFIto identify obscured sources up to very high redshift, where they are expected to be the vast majority of the AGN population and derive their intrinsic accretion properties,makes it competitive even with the rich landscape of the late '30s.

W-CDF-S, ELAIS-S1, and XMM-LSS will be three Deep-Drilling Fields (DDFs) of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), but their extensive multi-wavelength data have not been fully utilized as done in the COSMOS field, another LSST DDF. To prepare for future science, we fit source spectral energy distributions (SEDs) from X-ray to far-infrared in these three fields mainly to derive galaxy stellar masses and star-formation rates. We use CIGALE v2022.0, a code that has been regularly developed and evaluated, for the SED fitting. Our catalog includes 0.8 million sources covering $4.9~\mathrm{deg^2}$ in W-CDF-S, 0.8 million sources covering $3.4~\mathrm{deg^2}$ in ELAIS-S1, and 1.2 million sources covering $4.9~\mathrm{deg^2}$ in XMM-LSS. Besides fitting normal galaxies, we also select candidates that may host active galactic nuclei (AGNs) or are experiencing recent star-formation variations and use models specifically designed for these sources to fit their SEDs; this increases the utility of our catalog for various projects in the future. We calibrate our measurements by comparison with those in well-studied smaller regions and briefly discuss the implications of our results. We also perform detailed tests of the completeness and purity of SED-selected AGNs. Our data can be retrieved from a public website., Comment: 49 pages, 39 figures, 9 tables, accepted for publication in ApJS

Background: In Western society, discussions about death have shifted from the domain of the everyday to the domain of medicine. Such censorship does not reduce the fear of death; rather, it deprives people of the means to elaborate their experiences of death, generating negative effects such as difficult mourning and stigmatisation of palliative care environments. The objective of this follow-up study was to detect whether and how death education can help to improve individuals’ relationship with death. Methods: This was a qualitative research study based on grounded theory. We conducted semi-structured interviews with both palliative care professionals and teachers who had taken part in a death education intervention three years earlier. The interviews were interpreted through thematic analysis. Results: The results confirmed death education’s positive effect for both palliative care professionals and teachers. These individuals reported that the education initiative helped them to positively modify their perspectives on death and dying, as well as their attitudes towards life. It also helped to improve community attitudes towards the hospice and its workers. Conclusions: This study confirmed that school education initiatives can create continuity between hospices and local communities. The death education project provided an educational space in which it was possible to elaborate experiences linked to death and to re-evaluate and appreciate hospices and their staff.

We present the X-ray source catalog for the ∼479 ks Chandra exposure of the SDSS J1030+0524 field, which is centered on a region that shows the best evidence to date of an overdensity around a z > 6 quasar, and also includes a galaxy overdensity around a Compton-thick Fanaroff-Riley type II (FRII) radio galaxy at z = 1.7. Using wavdetect for initial source detection and ACIS Extract for source photometry and significance assessment, we create preliminary catalogs of sources that are detected in the full (0.5-7.0 keV), soft (0.5-2.0 keV), and hard (2-7 keV) bands, respectively. We produce X-ray simulations that mirror our Chandra observation to filter our preliminary catalogs and achieve a completeness level of > 91% and a reliability level of ∼95% in each band. The catalogs in the three bands are then matched into a final main catalog of 256 unique sources. Among them, 244, 193, and 208 are detected in the full, soft, and hard bands, respectively. The Chandra observation covers a total area of 335 arcmin2 and reaches flux limits over the central few square arcmins of ∼3 × 10-16, 6 × 10-17, and 2 × 10-16 erg cm-2 s-1 in the full, soft, and hard bands, respectively This makes J1030 field the fifth deepest extragalactic X-ray survey to date. The field is part of the Multiwavelength Survey by Yale-Chile (MUSYC), and is also covered by optical imaging data from the Large Binocular Camera (LBC) at the Large Binocular Telescope (LBT), near-infrared imaging data from the Canada France Hawaii Telescope WIRCam (CFHT/WIRCam), and Spitzer IRAC. Thanks to its dense multi-wavelength coverage, J1030 represents a legacy field for the study of large-scale structures around distant accreting supermassive black holes. Using a likelihood ratio analysis, we associate multi-band (r, z, J, and 4.5 μm) counterparts for 252 (98.4%) of the 256 Chandra sources, with an estimated reliability of 95%. Finally, we compute the cumulative number of sources in each X-ray band, finding that they are in general agreement with the results from the Chandra Deep Fields., We acknowledge the referee for a prompt and constructive report. We acknowledge financial contribution from the agreement ASI-INAF n. 2017-14-H.O. We thank P. Broos for providing great support for the analysis of our simulations with AE, and H. M. Günther for the support provided for using MARX. We also thank B. Luo for providing us the log(N)–log(S) of the 7Ms CDF-S. FV acknowledges financial support from CONICYT and CASSACA through the Fourth call for tenders of the CAS-CONICYT Fund, and CONICYT grants Basal-CATA AFB-170002. DM and MA acknowledge support by grant number NNX16AN49G issued through the NASA Astrophysics Data Analysis Program (ADAP). Further support was provided by the Faculty Research Fund (FRF) of Tufts University.

We present a series of new, publicly available mock catalogs of X-ray selected active galactic nuclei (AGNs), non-active galaxies, and clusters of galaxies. They are based on up-to-date observational results on the demographic of extragalactic X-ray sources and their extrapolations.These mocks reach fluxes below 1E-20 erg s-1 cm-2 in the 0.5-2 keV band, i.e., more than an order of magnitude below the predicted limits of future deep fields, and therefore represent an important tool for simulating extragalactic X-ray surveys with both current and future telescopes. We use our mocks to perform a set of end-to-end simulations of X-ray surveys with the forthcoming Athena mission and with the AXIS probe, a sub-arcsecond resolution X-ray mission concept proposed to the Astro 2020 Decadal Survey. We find that these proposed, next generation surveys may transform our knowledge of the deep X-ray Universe. As an example, in a total observing time of 15\,Ms, AXIS would detect ~225,000 AGNs and ~$50,000 non-active galaxies, reaching a flux limit f_0.5-2~5E-19 erg/s/cm2 in the 0.5-2 keV band, with an improvement of over an order of magnitude with respect to surveys with current X-ray facilities. Consequently, 90% of these sources would be detected for the first time in the X-rays. Furthermore, we show that deep and wide X-ray surveys with instruments like AXIS and Athena are expected to detect ~20,000 z>3 AGNs and ~250 sources at redshift z>6, thus opening a new window of knowledge on the evolution of AGNs over cosmic time and putting strong constraints on the predictions of theoretical models of black hole seed accretion in the early universe., 19 pages, 13 figures. Accepted for publication in A&A. Mock catalogs available online at http://cxb.oas.inaf.it/mock.html

We present a procedure to constrain the redshifts of obscured ($N_H > 10^{22}$ cm$^{-2}$) Active Galactic Nuclei (AGN) based on low-count statistics X-ray spectra, which can be adopted when photometric and/or spectroscopic redshifts are unavailable or difficult to obtain. We selected a sample of 54 obscured AGN candidates on the basis of their X-ray hardness ratio, $HR>-0.1$, in the Chandra deep field ($\sim$479 ks, 335 arcmin$^2$) around the $z=6.3$ QSO SDSS J1030+0524. The sample has a median value of $\approx80$ net counts in the 0.5-7 keV energy band. We estimate reliable X-ray redshift solutions taking advantage of the main features in obscured AGN spectra, like the Fe 6.4 keV K$\mathrm{\alpha}$ emission line, the 7.1 keV Fe absorption edge and the photoelectric absorption cut-off. The significance of such features is investigated through spectral simulations, and the derived X-ray redshift solutions are then compared with photometric redshifts. Both photometric and X-ray redshifts are derived for 33 sources. When multiple solutions are derived by any method, we find that combining the redshift solutions of the two techniques improves the rms by a factor of two. Using our redshift estimates ($0.1\lesssim z \lesssim 4$), we derived absorbing column densities in the range $\sim 10^{22}-10^{24}$ cm$^{-2}$ and absorption-corrected, 2-10 keV rest-frame luminosities between $\sim 10^{42}$ and $10^{45}$ erg s$^{-1}$, with median values of $N_H = 1.7 \times 10^{23}$ cm$^{-2}$ and $L_{\mathrm{2-10\, keV}} = 8.3\times10^{43}$ erg s$^{-1}$, respectively. Our results suggest that the adopted procedure can be applied to current and future X-ray surveys, for sources detected only in the X-rays or that have uncertain photometric or single-line spectroscopic redshifts., Comment: 22 pages, 18 figures

For over 60 years, the scientific community has studied actively growing central super-massive black holes (active galactic nuclei -- AGN) but fundamental questions on their genesis remain unanswered. Numerical simulations and theoretical arguments show that black hole growth occurs during short-lived periods ($\sim$ 10$^{7}$ -10$^{8}$ yr) of powerful accretion. Major mergers are commonly invoked as the most likely dissipative process to trigger the rapid fueling of AGN. If the AGN-merger paradigm is true, we expect galaxy mergers to coincide with black hole accretion during a heavily obscured AGN phase (N$_H$ $ > 10^{23}$ cm$^{-2}$). Starting from one of the largest samples of obscured AGN at 0.5 $, Comment: 19 pages, 11 figures, accepted in ApJ

We investigate the population of high-redshift ($3\leq z < 6$) AGN selected in the two deepest X-ray surveys, the 7 Ms \textit{Chandra} Deep Field-South and 2 Ms \textit{Chandra} Deep Field-North. Their outstanding sensitivity and spectral characterization of faint sources allow us to focus on the sub-$L_*$ regime (log$L_{\mathrm{X}}\lesssim44$), poorly sampled by previous works using shallower data, and the obscured population. Taking fully into account the individual photometric-redshift probability distribution functions, the final sample consists of $\approx102$ X-ray selected AGN at $3\leq z < 6$. The fraction of AGN obscured by column densities log$N_{\mathrm{H}}>23$ is $\sim0.6-0.8$, once incompleteness effects are taken into account, with no strong dependence on redshift or luminosity. We derived the high-redshift AGN number counts down to $F_{\mathrm{0.5-2\,keV}}=7\times10^{-18}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$, extending previous results to fainter fluxes, especially at $z>4$. We put the tightest constraints to date on the low-luminosity end of AGN luminosity function at high redshift. The space-density, in particular, declines at $z>3$ at all luminosities, with only a marginally steeper slope for low-luminosity AGN. By comparing the evolution of the AGN and galaxy densities, we suggest that such a decline at high luminosities is mainly driven by the underlying galaxy population, while at low luminosities there are hints of an intrinsic evolution of the parameters driving nuclear activity. Also, the black-hole accretion rate density and star-formation rate density, which are usually found to evolve similarly at $z\lesssim3$, appear to diverge at higher redshifts., Accepted 2017 September 15 (MNRAS). 31 Pages, 25 figures

We study the X-ray variability properties of distant AGNs in the Chandra Deep Field-South region over 17 years, up to $z\sim 4$, and compare them with those predicted by models based on local samples. We use the results of Monte Carlo simulations to account for the biases introduced by the discontinuous sampling and the low-count regime. We confirm that variability is an ubiquitous property of AGNs, with no clear dependence on the density of the environment. The variability properties of high-z AGNs, over different temporal timescales, are most consistent with a Power Spectral Density (PSD) described by a broken (or bending) power-law, similar to nearby AGNs. We confirm the presence of an anti-correlation between luminosity and variability, resulting from the dependence of variability on BH mass and accretion rate. We explore different models, finding that our acceptable solutions predict that BH mass influences the value of the PSD break frequency, while the Eddington ratio $\lambda_{Edd}$ affects the PSD break frequency and, possibly, the PSD amplitude as well. We derive the evolution of the average $\lambda_{Edd}$ as a function of redshift, finding results in agreement with measurements based on different estimators. The large statistical uncertainties make our results consistent with a constant Eddington ratio, although one of our models suggest a possible increase of $\lambda_{Edd}$ with lookback time up to $z\sim 2-3$. We conclude that variability is a viable mean to trace the accretion history of supermassive BHs, whose usefulness will increase with future, wide-field/large effective area X-ray missions., Comment: 15 pages, 9 Figures, 2 Tables, in press on MNRAS

Background The theme of death in Western society has been removed from everyday life and replaced with specialized medical language. Such censorship does not reduce the fear of death, especially among young people, and it limits the possibility to elaborate on experiences linked to death, generating negative effects, especially in cases of traumatic grief. The objective of this follow-up study was to detect how and if experiences of death education changed the relationship between the community and a local hospice. Furthermore, it was stressed the theme of representation of death, in order to see whether participants were able to remind any possible attitude change following the project. Finally, it was analysed how they considered how they remembered the effect of the elaboration of the trauma caused by the suicide of a student. Methods This was a qualitative research study based on semi-structured interviews with palliative care professionals and teachers of students who had taken part in a death education intervention 3 years earlier. The interviews were examined through thematic analysis. Results The results confirmed the efficacy of the death education intervention initiated 3 years earlier. The education initiative contributed to modifying the students’ and teachers’ perspectives of end-of-life professionals and their understanding of the structures within which palliative care is implemented. It also modified the participants’ perspectives on the representation of death and promoted a new outlook on life. The hospice staff also perceived a change in the attitudes of the community, and this change had a positive impact on their everyday work. Conclusions This study confirmed the usefulness of creating continuity between a hospice and the community through a school education initiative. The death education project provided an educational space in which it was possible to elaborate on experiences linked to death and to re-evaluate and appreciate the structures of end-of-life care and the professionals who work in the area. Keywords: Hospice, Palliative care, Death education, Adolescents, Suicide.

Population synthesis models of actively accreting super-massive black holes (or active galactic nuclei -- AGN) predict a large fraction that must grow behind dense, obscuring screens of gas and dust. Deep X-ray surveys are thought to have provided the most complete and unbiased samples of AGN, but there is strong observational evidence that a portion of the population of obscured AGN is being missed. In this paper we use a sample of AGN derived from the deepest X-ray survey to date, the Chandra 7Ms GOODS-South Survey, to investigate the nature of low flux X-ray sources. We make full use of the extensive multi-wavelength coverage of the GOODS-South field, and cross-match our objects with wavelengths from the Radio to the IR. We find the low X-ray flux AGN in our sample have X-ray luminosities that indicate low-luminosity AGN classification, while their radio, infrared and optical counterparts indicate moderate to powerful AGN classification. We find the predicted column densities is on average an order of magnitude higher than the calculated column densities via X-ray detections for X-ray faint sources. We interpret our results as evidence of obscured AGN disguising as low-luminosity AGN via their X-ray luminosities. When we compare the estimation of the obscured AGN space density with and without these objects, we find a difference of 40% in the lowest X-ray luminosity regime probed by our sample., Comment: 23 pages, 16 figures, Accepted to the Astrophysical Journal

We present an X-ray point-source catalog from the XMM-Large Scale Structure survey region (XMM-LSS), one of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields. We target the XMM-LSS region with $1.3$ Ms of new XMM-Newton AO-15 observations, transforming the archival X-ray coverage in this region into a 5.3 deg$^2$ contiguous field with uniform X-ray coverage totaling $2.7$ Ms of flare-filtered exposure, with a $46$ ks median PN exposure time. We provide an X-ray catalog of 5242 sources detected in the soft (0.5-2 keV), hard (2-10 keV), and/or full (0.5-10 keV) bands with a 1% expected spurious fraction determined from simulations. A total of 2381 new X-ray sources are detected compared to previous source catalogs in the same area. Our survey has flux limits of $1.7\times10^{-15}$, $1.3\times10^{-14}$, and $6.5\times10^{-15}$ erg cm$^{-2}$ s$^{-1}$ over 90% of its area in the soft, hard, and full bands, respectively, which is comparable to those of the XMM-COSMOS survey. We identify multiwavelength counterpart candidates for 99.9% of the X-ray sources, of which 93% are considered as reliable based on their matching likelihood ratios. The reliabilities of these high-likelihood-ratio counterparts are further confirmed to be $\approx 97$% reliable based on deep Chandra coverage over $\approx 5$% of the XMM-LSS region. Results of multiwavelength identifications are also included in the source catalog, along with basic optical-to-infrared photometry and spectroscopic redshifts from publicly available surveys. We compute photometric redshifts for X-ray sources in 4.5 deg$^2$ of our field where forced-aperture multi-band photometry is available; $>70$% of the X-ray sources in this subfield have either spectroscopic or high-quality photometric redshifts., MNRAS, accepted. 34 pages, 25 figures, and 8 tables. The data products are available at this http url: http://personal.psu.edu/wnb3/xmmservs/xmmservs.html

This paper introduces fl\"uela driverless: the first autonomous racecar to win a Formula Student Driverless competition. In this competition, among other challenges, an autonomous racecar is tasked to complete 10 laps of a previously unknown racetrack as fast as possible and using only onboard sensing and computing. The key components of fl\"uela's design are its modular redundant sub-systems that allow robust performance despite challenging perceptual conditions or partial system failures. The paper presents the integration of key components of our autonomous racecar, i.e., system design, EKF-based state estimation, LiDAR-based perception, and particle filter-based SLAM. We perform an extensive experimental evaluation on real-world data, demonstrating the system's effectiveness by outperforming the next-best ranking team by almost half the time required to finish a lap. The autonomous racecar reaches lateral and longitudinal accelerations comparable to those achieved by experienced human drivers., Comment: 8 pages, 10 figures, accepted to International Conference on Robotics and Automation | 21-25 May 2018 | Brisbane

In deep X-ray surveys, active galactic nuclei (AGNs) with a broad range of luminosities have been identified. However, cosmologically distant low-luminosity AGN (LLAGN, $L_{\mathrm{X}} \lesssim 10^{42}$ erg s$^{-1}$) identification still poses a challenge due to significant contamination from host galaxies. Based on the 7 Ms Chandra Deep Field-South (CDF-S) survey, the longest timescale ($\sim 17$ years) deep X-ray survey to date, we utilize an X-ray variability selection technique to search for LLAGNs that remain unidentified among the CDF-S X-ray sources. We find 13 variable sources from 110 unclassified CDF-S X-ray sources. Except for one source which could be an ultraluminous X-ray source, the variability of the remaining 12 sources is most likely due to accreting supermassive black holes. These 12 AGN candidates have low intrinsic X-ray luminosities, with a median value of $7 \times10^{40}$ erg s$^{-1}$. They are generally not heavily obscured, with an average effective power-law photon index of 1.8. The fraction of variable AGNs in the CDF-S is independent of X-ray luminosity and is only restricted by the total number of observed net counts, confirming previous findings that X-ray variability is a near-ubiquitous property of AGNs over a wide range of luminosities. There is an anti-correlation between X-ray luminosity and variability amplitude for high-luminosity AGNs, but as the luminosity drops to $\lesssim 10^{42}$ erg s$^{-1}$, the variability amplitude no longer appears dependent on the luminosity. The entire observed luminosity-variability trend can be roughly reproduced by an empirical AGN variability model based on a broken power-law power spectral density function., Comment: 18 pages, 11 figures, accepted for publication in ApJ

We present X-ray source catalogs for the $\approx7$ Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2 arcmin$^2$. Utilizing WAVDETECT for initial source detection and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5-7.0 keV, 0.5-2.0 keV, and 2-7 keV. A supplementary source catalog is also provided including 47 lower-significance sources that have bright ($K_s\le23$) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous $\approx4$ Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central $\approx1$ arcmin$^2$ region of $\approx1.9\times10^{-17}$, $6.4\times10^{-18}$, and $2.7\times10^{-17}$ erg cm$^{-2}$ s$^{-1}$ in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5-2.0 keV flux levels. The highest X-ray source density reaches $\approx50\,500$ deg$^{-2}$, and $47\%\pm4\%$ of these sources are AGNs ($\approx23\,900$ deg$^{-2}$)., Comment: 31 pages, 31 figures, 8 tables, ApJS in press, minor text updates; full-resolution PDF version and data products available at http://www.astro.psu.edu/users/niel/cdfs/cdfs-chandra.html

We present the hard-band ($2-10\,\mathrm{keV}$) X-ray luminosity function (HXLF) of $0.5-2\,\mathrm{keV}$ band selected AGN at high redshift. We have assembled a sample of 141 AGN at $310^{44}\mathrm{erg\,s^{-1}}}$) obscured AGN fraction from $z=0$ to $z>3$., Comment: MNRAS, Accepted 2014 September 23. Received 2014 September 10; in original form 2014 August 5; 19 pages, 11 figures, 5 tables

The generation of the NW-verging Ribeira belt that fringes the Sao Francisco craton to the south resulted from collisional episodes dated at 620–605, 605–565, and 535–510 Ma. During these collisional events, micro-continents and magmatic arcs converged and accreted to a continental margin system formed along the previously amalgamated Sao Francisco-Paranapanema landmass. The Sao Francisco-Paranapanema collision at around 640–620 Ma led to the development of the Southern Brasilia belt. The Ribeira orogenic front overprinted the pre-existent southern end of east-verging Brasilia belt, thereby creating a tectonically very complex interference zone. The Ribeira belt as whole comprises four tectono-stratigraphic terranes: the Occidental, Paraiba do Sul, Oriental, and Cabo Frio terranes. The Occidental terrane, representing the external sector of the belt, involves the reworked cratonic basement (Archean and Paleoproterozoic orthogneisses and orthogranulites), Mesoproterozoic intra-cratonic basins and a Neoproterozoic passive margin unit (Andrelândia Group). The uppermost unit of the Andrelândia Group is regarded to be deposited in an active margin setting and sourced by a magmatic arc installed in the Paranapanema plate. The Paraiba do Sul terrane, composed of an Archean-Paleoproterozoic basement, Neoproterozoic metasedimentary units, and a continental magmatic arc (the 640–595 Ma Serra da Bolivia complex), accreted to southeastern sector of the craton margin between 620 and 605 Ma. Afterwards, the juvenile to immature magmatic arc of the Oriental terrane (860–620 Ma Rio Negro and Serra da Prata complexes) collided to proto-Ribeira belt. The crustal thickening resulting from these collisions gave rise to widespread generation of I, S and hybrid granites that intrudes both basement and cover units in the most deformed sectors of the belt. The Cambrian (535–510 Ma) docking of the Cabo Frio terrane (an Angola craton fragment) reworked the previous accreted terranes, generating large scale folds and dextral transpresional shear zones that reached the SFC margin. Finally, a vigorous bimodal magmatic event associated with transtensional deformation episodes characterizes the orogenic collapse of the belt and marks its stabilization in the interior of the Gondwana supercontinent.

We present results from the deep XMM-Newton observations of the two brightest X-ray sources in the Chandra Deep Field South (CDFS), PID 203 (z = 0.544) and PID 319 (z = 0.742). The long exposure of 2.5 Ms over a 10 year period (net 4 yr with a 6 yr gap) makes it possible to obtain high quality X-ray spectra of these two Type I AGN with X-ray luminosity of 1044 erg s-1, which is the typical luminosity for low-redshift PG quasars, and track their X-ray variability both in flux and spectral shape. Both sources showed X-ray flux variability of ~10−20% in rms, which is similar in the soft (0.5−2 keV) and hard (2−7 keV) bands. PID 203, which has evidence for optical extinction, shows modest amount of absorption (NH≤ 1 × 1021 cm-2) in the X-ray spectrum. Fe K emission is strongly detected in both objects with EW ~ 0.2 keV. The lines in both objects are moderately broad and exhibit marginal evidence for variability in shape and flux, indicating that the bulk of the line emission comes from their accretion disks rather than distant tori., K.I. acknowledges support by DGI of the Spanish Ministerio de Economía y Competitividad (MINECO) under grant AYA2013-47447-C3-2-P. W.N.B. thanks the NASA ADP grant NNX10AC99G. We acknowledge financial contribution from the agreement ASI-INAF I/009/10/0.

The Triassic Hope Bay Formation (Trinity Peninsula Group) includes a diverse ichnocoenosis in the Puerto Moro succession (Hope Bay, Antarctic Peninsula). The Hope Bay Formation is a thick turbidite succession with a minimum vertical exposure of 533 meters along the Hope Bay coast. The rocks are locally affected by contact metamorphism related to later arc magmatism. The ichnofossils are found mainly in thick- and thin-bedded sandstone-mudstone facies composed of a monotonous repetition of sandstone-mudstone cycles. The sandstones are usually medium grained, massive or parallel laminated; the mudstones are massive and rarely laminated. In the fine-grained rocks, mainly the mudstones, there are distinct densities of bioturbation, and at least six patterns were observed. The following ichnogenera were recognized: Arenicolites Salter 1857, Lophoctenium Richter 1850, Taenidium Heer 1877, Palaeophycus Hall 1847, Phycosiphon von Fischer-Ooster 1858 and Rhizocorallium Zenker 1836. All appear to be feeding-traces....

The tectonic evolution at the junction of the Panafrican Kaoko and Damara belts is well recorded in the siliciclastic and carbonate successions of the Neoproterozoic Zerrissene turbidite system, metamorphosed to the biotite zone of the greenschist facies. The structures in the turbidites are attributed to two main deformational events. The older one generated two continuous folding phases, D1 and D2, and the younger one resulted in D3 deformation. D1, of dominant E–W shortening, caused upright kilometre-scale folds with well-developed axial planar cleavage, N–S trending axial planes and subhorizontal axes. This phase graded into D2 that refolded the first folds coaxialy and developed a crenulation cleavage at a high angle to the first cleavage. D2 is interpreted as a phase associated with shear movement to the north and minor continuing E–W shortening. The third phase, D3, of apparently sinistral transpression caused localised fold trains on a metre to kilometre scale with NE to NNE trending subvertical axial planes. The first two phases predate intrusion of a 530 Ma syenite and probably correlate with the main deformation in both the Kaoko and Damara belts. D2 is likely coeval with motion of the sinistral strike-slip Purros lineament in the central part of the Kaoko belt. D3 postdates the syenite intrusion and is restricted in occurrence to the Damara and southern Kaoko belts. Deformation in the Damara belt therefore outlasted that in the central and northern parts of the Kaoko belt.

New structural data from Elephant Island and adjacent islands are presented with the objective to improve the understanding of subduction kinematics in the area northeast of the Antarctic Peninsula. On the island, a first deformation phase, D 1 , produced a strong SL fabric with steep stretching and mineral lineations, partly defined by relatively high pressure minerals, such as crossite and glaucophane. D 1 is interpreted to record southward subduction along an E–W trench with respect to the present position of the island. A second phase, D 2 , led to intense folding with steep E–W-trending axial surfaces. The local presence of sinistral C′-type shear bands related to this phase and the oblique inclination of the L 2 stretching lineations are the main arguments to interpret this phase as representing oblique sinistral transpressive shear along steep, approximately E–W-trending shear zones, with the northern (Pacific) block going down with respect to the southern (Antarctic Peninsula) block. The sinistral strike-slip component may represent a trench-linked strike-slip movement as a consequence of oblique subduction. Lithostatic pressure decreased and temperature increased to peak values during D 2 , interpreted to represent the collision of thickened oceanic crust with the active continental margin. The last deformation phase, D 3 , is characterised by post-metamorphic kink bands, partially forming conjugate sets consistent with E–W shortening and N–S extension. The rock units that underlie the island probably rotated during D 3 , in Cenozoic times, together with the trench, from an NE–SW to the present ENE–WSW position, during the progressive opening of the Scotia Sea. The similarity between the strain orientation of D 3 and that of the sinistral NE–SW Shackleton Fracture Zone is consistent with this interpretation.

We present results from a spectral analysis of a sample of high-redshift (z > 3) X-ray-selected active galactic nucleus (AGN) in the 4-Ms Chandra Deep Field-South (CDF-S), the deepest X-ray survey to date. The sample is selected using the most recent spectroscopic and photometric information available in this field. It consists of 34 sources with median redshift z = 3.7, 80 median net counts in the 0.5-7 keV band and median rest-frame absorption-corrected luminosity L2-10 keV ≈ 1.5 × 1044 erg s-1. Spectral analysis for the full sample is presented and the intrinsic column density distribution, corrected for observational biases using spectral simulations, is compared with the expectations of X-ray background (XRB) synthesis models. We find that ≈57 per cent of the sources are highly obscured (NH > 1023 cm-2). Source number counts in the 0.5-2 keV band down to flux F0.5-2 keV ≈ 4 × 10-17 erg s-1 cm-2 are also presented. Our results are consistent with a decline of the AGN space density at z > 3 and suggest that, at those redshifts, the AGN obscured fraction is in agreement with the expectations of XRB synthesis models.

Neste trabalho apresentamos o resultado de varios anos de trabalho em mapeamento geológico realizado no sul de Minas Gerais pela equipe do Núcleo de Estudos Pré-Cambrianos. Um estudo detalhado foi realizado objetivando uma melhor caracterização das litologias aflorantes, visando elaborar reconstruções paleoambientais, paleogeografías e geotectónicas. Foram editadas seis folhas na escala 1:50.000 através do processo de digitalização pelo programa SAGA/UFRJ.

Improving the capabilities of detecting faint X-ray sources is fundamental to increase the statistics on faint high-z AGN and star-forming galaxies. We performed a simultaneous Maximum Likelihood PSF fit in the [0.5-2] keV and [2-7] keV energy bands of the 4 Ms{\em Chandra} Deep Field South (CDFS) data at the position of the 34930 CANDELS H-band selected galaxies. For each detected source we provide X-ray photometry and optical counterpart validation. We validated this technique by means of a raytracing simulation. We detected a total of 698 X-ray point-sources with a likelihood $\mathcal{L}$$>$4.98 (i.e. $>$2.7$��$). We show that the prior knowledge of a deep sample of Optical-NIR galaxies leads to a significant increase of the detection of faint (i.e. $\sim$10$^{-17}$ cgs in the [0.5-2] keV band) sources with respect to "blind" X-ray detections. By including previous X-ray catalogs, this work increases the total number of X-ray sources detected in the 4 Ms CDFS, CANDELS area to 793, which represents the largest sample of extremely faint X-ray sources assembled to date. Our results suggest that a large fraction of the optical counterparts of our X-ray sources determined by likelihood ratio actually coincides with the priors used for the source detection. Most of the new detected sources are likely star-forming galaxies or faint absorbed AGN. We identified a few sources sources with putative photometric redshift z$>$4. Despite the low number statistics and the uncertainties on the photo-z, this sample significantly increases the number of X--ray selected candidate high-z AGN., 15 Pages, 10 Figures, Accepted by ApJ, version before editing, Catalog available at: http://www.astrodeep.eu/chandra-counterparts/ , CDS and www.astrodeep.edu

Resumo

We perform long-term ($\approx 15$ yr, observed-frame) X-ray variability analyses of the 68 brightest radio-quiet active galactic nuclei (AGNs) in the 6 Ms $Chandra$ Deep Field-South (CDF-S) survey; the majority are in the redshift range of $0.6-3.1$, providing access to penetrating rest-frame X-rays up to $\approx 10-30$ keV. Twenty-four of the 68 sources are optical spectral type I AGNs, and the rest (44) are type II AGNs. The time scales probed in this work are among the longest for X-ray variability studies of distant AGNs. Photometric analyses reveal widespread photon-flux variability: $90\%$ of AGNs are variable above a 95% confidence level, including many X-ray obscured AGNs and several optically classified type II quasars. We characterize the intrinsic X-ray luminosity ($L_{\rm{X}}$) and absorption ($N_{\rm{H}}$) variability via spectral fitting. Most (74%) sources show $L_{\rm{X}}$ variability; the variability amplitudes are generally smaller for quasars. A Compton-thick candidate AGN shows variability of its high-energy X-ray flux, indicating the size of reflecting material to be $\lesssim 0.3$ pc. $L_{\rm{X}}$ variability is also detected in a broad absorption line (BAL) quasar. The $N_{\rm{H}}$ variability amplitude for our sample appears to rise as time separation increases. About 16% of sources show $N_{\rm{H}}$ variability. One source transitions from an X-ray unobscured to obscured state while its optical classification remains type I; this behavior indicates the X-ray eclipsing material is not large enough to obscure the whole broad-line region., 21 pages, 17 figures, accepted for publication in ApJ

A bacia da Formação Camarinha, no centro-leste do Estado do Paraná, representa uma unidade da transição Neoproterozóico-Eocambriano na região. Assenta-se discordantemente sobre os metassedimentos proterozóicos do Cinturão Ribeira, constituídos pelas formações Água Clara, Votuverava e Capiru e próximos ao Complexo Atuba, Núcleo Betara e Complexo Granítico Três Córregos, e é recoberta também discordantemente, a oeste, pelos sedimentos basais devonianos da Bacia do Paraná. A Formação Camarinha consiste em conglomerados, brechas, arenitos, siltitos, lamitos e ritmitos imaturos, medianamente a mal selecionados, distribuídos em quatro unidades intercaladas e com contatos transicionais entre si, das quais duas apresentam natureza mais conglomerática, e duas natureza mais síltico-arenosa. Estas unidades foram depositadas por processos como fluxos gravitacionais subaéreos a subaquosos, correntes de turbidez, sheet-floods e processos atuantes em frentes deltaicas, comuns em leques progradantes e retrogradantes de ambientes costeiros (fandeltas). As áreas-fontes dos sedimentos são representadas pelas formações Água Clara, Votuverava e Capiru e pelos complexos Atuba e Três Córregos. Posteriormente, a bacia foi deformada pela atuação da Zona de Cisalhamento Transcorrente da Lancinha, com deslocamento lateral direito que gerou diversas estruturas rúpteis a rúpteis-dúcteis previstas no Modelo de Riedel. Reativações deste sistema proporcionaram intensa alteração hidrotermal, refletida em isócronas Rb-Sr obtidas. A Formação Camarinha encontra-se atualmente preservada em duas faixas dobradas na forma de sinclinais relacionados à Falha da Lancinha, constituindo remanescentes da bacia original. Os limites originais da bacia não se encontram preservados, tendo a mesma sido formada em ambiente tardi a pós-orogênico com relação ao Ciclo Brasiliano, bem como outras bacias similares do sul e sudeste do Brasil. Camarinha Formation (central-eastern part of the State of Paraná, southern Brazil) is a transitional unit between Neoproterozoic and Cambrian in that region. It lies unconformably on proterozoic sediments of the Ribeira Belt (Água Clara, Votuverava and Capiru formations), near the Atuba, Betara and Três Córregos complexes. On its western part, it is also unconformably covered by the devonian basal sediments of the Paraná Basin. Camarinha Formation consits of medium-to-poorly sorted, immature rocks, such as conglomerates, breccias, sandstones, siltstones, mudstones and rythmites, grouped into four altenating units with transitional contacts. Two of these units have a conglomeratic nature, and two have a sandy and muddy nature. These units were deposited by processes such as subaerial to subaqueous gravity-flows, turbidity currents, sheet-floods and other processes that occur in delta fronts. These processes are common in prograding and retrograding fans at coastal environments (fandeltas). The sediments source areas are represented by the Água Clara, Votuverava and Capiru formations, and Atuba and Três Córregos complexes. The basin was later deformed by the Lancinha shear Zone, whose right-lateral movement generated several ruptile to ruptile-ductile structures of the Riedel Model. Later reactivations of the shear zone caused intense hydrothermal alteration, whose age was measured with Rb-Sr data. Camarinha Formation is now preserved as remains of the original basin, in two folded zones forming synclinals related to the Lancinha Shear Zone. The basin original borders are not preserved. The basin was formed in a late-to-post orogenic environment related to the Brasiliano Cycle, just like other similar basins in southern and southeastern Brazil.