Persistent and Transient Blank Field Sources

Blank field sources (BFS) are good candidates for hosting dim isolated neutron stars (DINS). The results of a search of BFS in the ROSAT HRI images are revised. We then focus on transient BFS, arguing that they belong to a rather large population. The perspectives of future research on DINS are then discussed.Comment: 3 pages, 0 figures. Paper presented at the Conference "Isolated Neutron Stars: from the interior to the surface", London, April 2006. Astrophysics and Space Science, in pres

The Ultraluminous X-ray Sources NGC 1313 X-1 and X-2

We present a detailed analysis of XMM archival data of two Ultraluminous X-ray Sources (ULXs) in the nearby spiral galaxy NGC 1313: NGC 1313 X-1 and X-2. The spectral continuum of these sources was modeled with a soft thermal component plus a power-law. If the soft component originates from an accretion disk, the inferred mass of the compact remnant is > 100 M_sun, making it an Intermediate Mass Black Hole (IMBH). A detailed analysis of the residuals of the XMM EPIC-pn spectrum shows some evidence for the presence of an Oxygen emission line in NGC 1313 X-1. The simultaneous presence of an excess in emission, although at a much reduced significance level, at different energies in the X-ray spectra of NGC 1313 X-1 and X-2 is suggestive of typical emission lines from young supernova remnants. An optical counterpart for NGC 1313 X-2 was also identified. On an ESO 3.6 m image, the Chandra error box embraces a R \~ 23 mag stellar-like object and excludes a previously proposed optical counterpart.Comment: 7 pages, 2 figures, to be published in Advances in Space Researc

Detection of pulsations and a spectral feature in the X-ray emission of the isolated neutron star 1RXS J214303.7+065419/RBS 1774

We report on the results of a deep XMM-Newton observation of RBS 1774, the most recent dim isolated neutron star candidate found in the ROSAT archive data. Spectral and timing analysis of the high-quality PN and MOS data confirm the association of this source with an isolated neutron star. The spectrum is thermal and blackbody-like, and there is evidence at a significance level > 4sigma that the source is an X-ray pulsar, with spin period of 9.437 s. Spectral fitting reveils the presence of an absorption feature at ~0.7 keV, but at this level data do not have enough resolution to allow us to discriminate between an absorption line or an edge. We compare the newly measured properties of RBS 1774 with those of other known dim isolated neutron stars, and discuss possible interpretations for the absorption feature.Comment: 21 pages, 5 figures, ApJ accepte

1RXS J214303.7+065419/RBS 1774: A New Isolated Neutron Star Candidate

We report on the identification of a new possible Isolated Neutron Star candidate in archival ROSAT observations. The source 1RXS J214303.7+065419, listed in the ROSAT Bright Survey as RBS 1774, is very soft, exhibits a thermal spectrum well fitted by a blackbody at ${T}\sim 90$ eV and has a low column density, ${N_H}\sim 5\times 10^{20}$ ${cm}^{-2}$. Catalogue searches revealed no known sources in other energy bands close to the X-ray position of RBS 1774. Follow-up optical observations with NTT showed no peculiar object within the X-ray error circle. The absence of any plausible optical counterpart down to ${m_R}\sim 23$ results in an X-ray to optical flux ratio in excess of 1000.Comment: LaTeX (A&A style files), 5 pages, 3 figures. Accepted for publication in Astronomy and Astrophysics Letters. Minor correction

Autonomic responses to emotional linguistic stimuli and amplitude of low-frequency fluctuations predict outcome after severe brain injury

An accurate prognosis on the outcome of brain-injured patients with disorders of consciousness (DOC) remains a significant challenge, especially in the acute stage. In this study, we applied a multiple-technique approach to provide accurate predictions on functional outcome after 6 months in 15 acute DOC patients. Electrophysiological correlates of implicit cognitive processing of verbal stimuli and data-driven voxel-wise resting-state fMRI signals, such as the fractional amplitude of low-frequency fluctuations (fALFF), were employed. Event-related electrodermal activity, an index of autonomic activation, was recorded in response to emotional words and pseudo-words at baseline (T0). On the same day, patients also underwent a resting-state fMRI scan. Six months later (T1), patients were classified as outcome-negative and outcome-positive using a standard functional outcome scale. We then revisited the baseline measures to test their predictive power for the functional outcome measured at T1. We found that only outcome-positive patients had an earlier, higher autonomic response for words compared to pseudo-words, a pattern similar to that of healthy awake controls. Furthermore, DOC patients showed reduced fALFF in the posterior cingulate cortex (PCC), a brain region that contributes to autonomic regulation and awareness. The event-related electrodermal marker of residual cognitive functioning was found to have a significant correlation with residual local neuronal activity in the PCC. We propose that a residual autonomic response to cognitively salient stimuli, together with a preserved resting-state activity in the PCC, can provide a useful prognostic index in acute DOC

Al2O3-Supported W-V-O bronzes catalysts for oxidative dehydrogenation of ethane

[EN] Supported vanadium-containing hexagonal tungsten bronzes (HTBs) were prepared for the first time using a combination of a new soft synthetic procedure and fine-tuned heat treatments. The characterization of heat-treated samples indicates that both unsupported and Al2O3-supported materials present mainly vanadium-containing crystals with HTB structure smaller in the supported materials. Raman, diffuse reflectance UV-visible and EPR spectroscopic results suggest the presence of different V species depending on the V loading and catalyst composition. When used as catalysts for ethane oxidative dehydrogenation (ODH), selected supported vanadium-HTBs show selectivity to ethylene as high as 80% at ethane conversion of around 18%. These values position these new materials among the most active and selective catalysts so far reported in the literature for ethane ODH over supported vanadium oxide catalysts.The authors acknowledge the DGICYT in Spain (projects RTI2018-099668-B-C21 and SEV-2016-0683) for financial support. The research group of Prof. Fabrizio Cavani (University of Bologna, Italy) and Consorzio INSTM (Firenze) are gratefully acknowledged for a PhD grant to A. C. The authors also thank the Electron Microscopy Service of Universitat Politecnica de Valencia for its support.Benomar, S.; Chieregato, A.; Masso, A.; Soriano Rodríguez, MD.; Vidal Moya, JA.; Blasco Lanzuela, T.; Issaadi, R.... (2020). Al2O3-Supported W-V-O bronzes catalysts for oxidative dehydrogenation of ethane. Catalysis Science & Technology. 10(23):8064-8076. https://doi.org/10.1039/d0cy01220cS806480761023GUO, J.-D., & WHITTINGHAM, M. S. (1993). TUNGSTEN OXIDES AND BRONZES: SYNTHESIS, DIFFUSION AND REACTIVITY. International Journal of Modern Physics B, 07(23n24), 4145-4164. doi:10.1142/s0217979293003607Whittingham, M. S., Guo, J.-D., Chen, R., Chirayil, T., Janauer, G., & Zavalij, P. (1995). The hydrothermal synthesis of new oxide materials. Solid State Ionics, 75, 257-268. doi:10.1016/0167-2738(94)00220-mChen, J., Wang, H., Deng, J., Xu, C., & Wang, Y. (2018). Low-crystalline tungsten trioxide anode with superior electrochemical performance for flexible solid-state asymmetry supercapacitor. Journal of Materials Chemistry A, 6(19), 8986-8991. doi:10.1039/c8ta01323cBartha, L., Kiss, A. B., & Szalay, T. (1995). Chemistry of tungsten oxide bronzes. International Journal of Refractory Metals and Hard Materials, 13(1-3), 77-91. doi:10.1016/0263-4368(94)00031-xTilley, R. J. D. (1995). The crystal chemistry of the higher tungsten oxides. International Journal of Refractory Metals and Hard Materials, 13(1-3), 93-109. doi:10.1016/0263-4368(95)00004-6Michailovski, A., Krumeich, F., & Patzke, G. R. (2004). Hierarchical Growth of Mixed Ammonium Molybdenum/Tungsten Bronze Nanorods. Chemistry of Materials, 16(8), 1433-1440. doi:10.1021/cm0311731Quan, H., Gao, Y., & Wang, W. (2020). Tungsten oxide-based visible light-driven photocatalysts: crystal and electronic structures and strategies for photocatalytic efficiency enhancement. Inorganic Chemistry Frontiers, 7(4), 817-838. doi:10.1039/c9qi01516gMichailovski, A., & Patzke, G. R. (2006). Hydrothermal Synthesis of Molybdenum Oxide Based Materials: Strategy and Structural Chemistry. Chemistry - A European Journal, 12(36), 9122-9134. doi:10.1002/chem.200600977Michailovski, A., Kiebach, R., Bensch, W., Grunwaldt, J.-D., Baiker, A., Komarneni, S., & Patzke, G. R. (2006). Morphological and Kinetic Studies on Hexagonal Tungstates. Chemistry of Materials, 19(2), 185-197. doi:10.1021/cm061020oKiebach, R., Pienack, N., Bensch, W., Grunwaldt, J.-D., Michailovski, A., Baiker, A., … Patzke, G. R. (2008). Hydrothermal Formation of W/Mo-Oxides: A Multidisciplinary Study of Growth and Shape. Chemistry of Materials, 20(9), 3022-3033. doi:10.1021/cm7028036Magnéli, A., Blomberg, B., Reio, L., Saluste, E., Stjernholm, R., & Ehrensvärd, G. (1951). Contribution to the Knowledge of the Alkali Tungsten Bronzes. Acta Chemica Scandinavica, 5, 372-378. doi:10.3891/acta.chem.scand.05-0372C. N. R. Rao and K.Biswas , Soft Chemistry Routes, in Essentials of Inorganic Materials Synthesis , ed. C. N. R. Rao and K. Biswas , John Wiley & Sons, Inc. , New Jersey , 2015 , ch. 10Li, F., Qian, Y., & Stein, A. (2010). Template-Directed Synthesis and Organization of Shaped Oxide/Phosphate Nanoparticles. Chemistry of Materials, 22(10), 3226-3235. doi:10.1021/cm100478zGopalakrishnan, J. (1995). Chimie Douce Approaches to the Synthesis of Metastable Oxide Materials. Chemistry of Materials, 7(7), 1265-1275. doi:10.1021/cm00055a001Stevenson, S., & Sermon, P. A. (1987). Promotion of nitrogen and hydrogen chemisorption and ammonia synthesis on alumina-supported hexagonal tungsten bronze, Kx WO3. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 83(7), 2175. doi:10.1039/f19878302175Szilágyi, I. M., Hange, F., Madarász, J., & Pokol, G. (2006). In situ HT-XRD Study on the Formation of Hexagonal Ammonium Tungsten Bronze by Partial Reduction of Ammonium Paratungstate Tetrahydrate. European Journal of Inorganic Chemistry, 2006(17), 3413-3418. doi:10.1002/ejic.200500875Soriano, M. D., Concepción, P., Nieto, J. M. L., Cavani, F., Guidetti, S., & Trevisanut, C. (2011). Tungsten-Vanadium mixed oxides for the oxidehydration of glycerol into acrylic acid. Green Chemistry, 13(10), 2954. doi:10.1039/c1gc15622eGarcía-González, E., Soriano, M. D., Urones-Garrote, E., & López Nieto, J. M. (2014). On the origin of the spontaneous formation of nanocavities in hexagonal bronzes (W,V)O3. Dalton Trans., 43(39), 14644-14652. doi:10.1039/c4dt01465kChieregato, A., López Nieto, J. M., & Cavani, F. (2015). Mixed-oxide catalysts with vanadium as the key element for gas-phase reactions. Coordination Chemistry Reviews, 301-302, 3-23. doi:10.1016/j.ccr.2014.12.003Cavani, F., Ballarini, N., & Cericola, A. (2007). Oxidative dehydrogenation of ethane and propane: How far from commercial implementation? Catalysis Today, 127(1-4), 113-131. doi:10.1016/j.cattod.2007.05.009Gärtner, C. A., van Veen, A. C., & Lercher, J. A. (2013). Oxidative Dehydrogenation of Ethane: Common Principles and Mechanistic Aspects. ChemCatChem, 5(11), 3196-3217. doi:10.1002/cctc.201200966Kube, P., Frank, B., Wrabetz, S., Kröhnert, J., Hävecker, M., Velasco-Vélez, J., … Trunschke, A. (2017). Functional Analysis of Catalysts for Lower Alkane Oxidation. ChemCatChem, 9(4), 573-585. doi:10.1002/cctc.201601194Rozanska, X., Fortrie, R., & Sauer, J. (2014). Size-Dependent Catalytic Activity of Supported Vanadium Oxide Species: Oxidative Dehydrogenation of Propane. Journal of the American Chemical Society, 136(21), 7751-7761. doi:10.1021/ja503130zDinse, A., Schomäcker, R., & Bell, A. T. (2009). The role of lattice oxygen in the oxidative dehydrogenation of ethane on alumina-supported vanadium oxide. Physical Chemistry Chemical Physics, 11(29), 6119. doi:10.1039/b821131kBlasco, T., Galli, A., López Nieto, J. M., & Trifiró, F. (1997). Oxidative Dehydrogenation of Ethane andn-Butane on VOx/Al2O3Catalysts. Journal of Catalysis, 169(1), 203-211. doi:10.1006/jcat.1997.1673Argyle, M. D., Chen, K., Bell, A. T., & Iglesia, E. (2002). Effect of Catalyst Structure on Oxidative Dehydrogenation of Ethane and Propane on Alumina-Supported Vanadia. Journal of Catalysis, 208(1), 139-149. doi:10.1006/jcat.2002.3570Al-Ghamdi, S., Volpe, M., Hossain, M. M., & de Lasa, H. (2013). VOx/c-Al2O3 catalyst for oxidative dehydrogenation of ethane to ethylene: Desorption kinetics and catalytic activity. Applied Catalysis A: General, 450, 120-130. doi:10.1016/j.apcata.2012.10.007SOLSONA, B., VAZQUEZ, M., IVARS, F., DEJOZ, A., CONCEPCION, P., & LOPEZNIETO, J. (2007). Selective oxidation of propane and ethane on diluted Mo–V–Nb–Te mixed-oxide catalysts. Journal of Catalysis, 252(2), 271-280. doi:10.1016/j.jcat.2007.09.019Botella, P., Dejoz, A., Abello, M. C., Vázquez, M. I., Arrúa, L., & López Nieto, J. M. (2009). Selective oxidation of ethane: Developing an orthorhombic phase in Mo–V–X (X=Nb, Sb, Te) mixed oxides. Catalysis Today, 142(3-4), 272-277. doi:10.1016/j.cattod.2008.09.016Gaffney, A. M., & Mason, O. M. (2017). Ethylene production via Oxidative Dehydrogenation of Ethane using M1 catalyst. Catalysis Today, 285, 159-165. doi:10.1016/j.cattod.2017.01.020HERACLEOUS, E., & LEMONIDOU, A. (2006). Ni–Nb–O mixed oxides as highly active and selective catalysts for ethene production via ethane oxidative dehydrogenation. Part I: Characterization and catalytic performance. Journal of Catalysis, 237(1), 162-174. doi:10.1016/j.jcat.2005.11.002Ipsakis, D., Heracleous, E., Silvester, L., Bukur, D. B., & Lemonidou, A. A. (2017). Reduction and oxidation kinetic modeling of NiO-based oxygen transfer materials. Chemical Engineering Journal, 308, 840-852. doi:10.1016/j.cej.2016.09.114Solsona, B., Concepción, P., López Nieto, J. M., Dejoz, A., Cecilia, J. A., Agouram, S., … Rodríguez Castellón, E. (2016). Nickel oxide supported on porous clay heterostructures as selective catalysts for the oxidative dehydrogenation of ethane. Catalysis Science & Technology, 6(10), 3419-3429. doi:10.1039/c5cy01811kZhu, H., Rosenfeld, D. C., Harb, M., Anjum, D. H., Hedhili, M. N., Ould-Chikh, S., & Basset, J.-M. (2016). Ni–M–O (M = Sn, Ti, W) Catalysts Prepared by a Dry Mixing Method for Oxidative Dehydrogenation of Ethane. ACS Catalysis, 6(5), 2852-2866. doi:10.1021/acscatal.6b00044Carrero, C. A., Burt, S. P., Huang, F., Venegas, J. M., Love, A. M., Mueller, P., … Hermans, I. (2017). Supported two- and three-dimensional vanadium oxide species on the surface of β-SiC. Catalysis Science & Technology, 7(17), 3707-3714. doi:10.1039/c7cy01036bLove, A. M., Carrero, C. A., Chieregato, A., Grant, J. T., Conrad, S., Verel, R., & Hermans, I. (2016). Elucidation of Anchoring and Restructuring Steps during Synthesis of Silica-Supported Vanadium Oxide Catalysts. Chemistry of Materials, 28(15), 5495-5504. doi:10.1021/acs.chemmater.6b02118Grant, J. T., Carrero, C. A., Love, A. M., Verel, R., & Hermans, I. (2015). Enhanced Two-Dimensional Dispersion of Group V Metal Oxides on Silica. ACS Catalysis, 5(10), 5787-5793. doi:10.1021/acscatal.5b01679Barman, S., Maity, N., Bhatte, K., Ould-Chikh, S., Dachwald, O., Haeßner, C., … Basset, J.-M. (2016). Single-Site VOx Moieties Generated on Silica by Surface Organometallic Chemistry: A Way To Enhance the Catalytic Activity in the Oxidative Dehydrogenation of Propane. ACS Catalysis, 6(9), 5908-5921. doi:10.1021/acscatal.6b01263Maffia, G. J., Gaffney, A. M., & Mason, O. M. (2016). Techno-Economic Analysis of Oxidative Dehydrogenation Options. Topics in Catalysis, 59(17-18), 1573-1579. doi:10.1007/s11244-016-0677-9Sanati, M., & Andersson, A. (1990). Ammoxtoation of toluene over TiO2(B)-supported vanadium oxide catalysts. Journal of Molecular Catalysis, 59(2), 233-255. doi:10.1016/0304-5102(90)85055-mSoriano, M. D., Chieregato, A., Zamora, S., Basile, F., Cavani, F., & López Nieto, J. M. (2015). Promoted Hexagonal Tungsten Bronzes as Selective Catalysts in the Aerobic Transformation of Alcohols: Glycerol and Methanol. Topics in Catalysis, 59(2-4), 178-185. doi:10.1007/s11244-015-0440-7SOLSONA, B., DEJOZ, A., GARCIA, T., CONCEPCION, P., NIETO, J., VAZQUEZ, M., & NAVARRO, M. (2006). Molybdenum–vanadium supported on mesoporous alumina catalysts for the oxidative dehydrogenation of ethane. Catalysis Today, 117(1-3), 228-233. doi:10.1016/j.cattod.2006.05.025Spałek, T., Pietrzyk, P., & Sojka, Z. (2004). Application of the Genetic Algorithm Joint with the Powell Method to Nonlinear Least-Squares Fitting of Powder EPR Spectra. Journal of Chemical Information and Modeling, 45(1), 18-29. doi:10.1021/ci049863sPietrzyk, P., & Góra-Marek, K. (2016). Paramagnetic dioxovanadium(iv) molecules inside the channels of zeolite BEA – EPR screening of VO2 reactivity toward small gas-phase molecules. Physical Chemistry Chemical Physics, 18(14), 9490-9496. doi:10.1039/c6cp01046fShaikh, S. F., Kalanur, S. S., Mane, R. S., & Joo, O.-S. (2013). Monoclinic WO3 nanorods–rutile TiO2 nanoparticles core–shell interface for efficient DSSCs. Dalton Transactions, 42(28), 10085. doi:10.1039/c3dt50728aSzilágyi, I. M., Madarász, J., Pokol, G., Király, P., Tárkányi, G., Saukko, S., … Varga-Josepovits, K. (2008). Stability and Controlled Composition of Hexagonal WO3. Chemistry of Materials, 20(12), 4116-4125. doi:10.1021/cm800668xCHAN, S. (1985). Laser Raman characterization of tungsten oxide supported on alumina: Influence of calcination temperatures. Journal of Catalysis, 92(1), 1-10. doi:10.1016/0021-9517(85)90231-3G. Deo , F. D.Hardcastle , M.Richards , A. M.Hirt and I. E.Wachs , ACS Symposium Series, in Novel Materials in Heterogeneous Catalysis , ed. R. Baker , et al. , American Chemical Society , Washington, DC , 1990 , p. 317França, M. C. K., da Silva San Gil, R. A., & Eon, J.-G. (2003). Alumina-supported catalysts for propane oxidative dehydrogenation from mixed VXM(6−X)O19n− (M=W, Mo) hexametalate precursors. Catalysis Today, 78(1-4), 105-115. doi:10.1016/s0920-5861(02)00302-4Catana, G., Rao, R. R., Weckhuysen, B. M., Van Der Voort, P., Vansant, E., & Schoonheydt, R. A. (1998). Supported Vanadium Oxide Catalysts: Quantitative Spectroscopy, Preferential Adsorption of V4+/5+, and Al2O3 Coating of Zeolite Y. The Journal of Physical Chemistry B, 102(41), 8005-8012. doi:10.1021/jp981482sBrückner, A. (2010). In situ electron paramagnetic resonance: a unique tool for analyzing structure–reactivity relationships in heterogeneous catalysis. Chemical Society Reviews, 39(12), 4673. doi:10.1039/b919541fBrückner, A. (2006). Spin–spin exchange in vanadium-containing catalysts studied by in situ-EPR: a sensitive monitor for disorder-related activity. Topics in Catalysis, 38(1-3), 133-139. doi:10.1007/s11244-006-0078-6Strassberger, Z., Ramos-Fernandez, E. V., Boonstra, A., Jorna, R., Tanase, S., & Rothenberg, G. (2013). Synthesis, characterization and testing of a new V2O5/Al2O3–MgO catalyst for butane dehydrogenation and limonene oxidation. Dalton Transactions, 42(15), 5546. doi:10.1039/c3dt32954bKompio, P. G. W. A., Brückner, A., Hipler, F., Auer, G., Löffler, E., & Grünert, W. (2012). A new view on the relations between tungsten and vanadium in V2O5WO3/TiO2 catalysts for the selective reduction of NO with NH3. Journal of Catalysis, 286, 237-247. doi:10.1016/j.jcat.2011.11.008Concepción, P., Knözinger, H., López Nieto, J. M., & Martínez-Arias, A. (2002). Characterization of Supported Vanadium Oxide Catalysts. Nature of the Vanadium Species in Reduced Catalysts. The Journal of Physical Chemistry B, 106(10), 2574-2582. doi:10.1021/jp010918sSilversmit, G., Depla, D., Poelman, H., Marin, G. B., & De Gryse, R. (2004). Determination of the V2p XPS binding energies for different vanadium oxidation states (V5+ to V0+). 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Synthesis of Nanosize Tungsten Oxide and Its Evaluation as an Electrocatalyst Support for Oxygen Reduction in Acid Media. ACS Catalysis, 2(3), 456-463. doi:10.1021/cs200657wNieto, J. M. L. (2006). The selective oxidative activation of light alkanes. From supported vanadia to multicomponent bulk V-containing catalysts. Topics in Catalysis, 41(1-4), 3-15. doi:10.1007/s11244-006-0088-

A quasar companion to the puzzling quasar SDSS J0927+2943

We report the discovery of a quasar close to SDSS J0927+2943 (z = 0.713), which is a massive binary / recoiling black hole candidate. The companion quasar is at a projected distance of 125 h_70^{-1} kpc and exhibits a radial velocity difference of ~1400 km/s with respect to the known quasar. We discuss the nature of this peculiar quasar pair and the properties of its environment. We propose that the overall system is caught in the process of ongoing structure formation.Comment: 4 pages, 3 figures. Accepted for publication in A&

The Ultraluminous X-ray Source NGC 1313 X-2 (MS 0317.7-6647) and its Environment

We present new optical and {\it Chandra} observations of the field containing the ultraluminous X-ray source NGC 1313 X-2. On an ESO 3.6 m image, the {\it Chandra} error box embraces a $R=21.6$ point-like object and excludes a previously proposed optical counterpart. The resulting X-ray/optical flux ratio of NGC 1313 X-2 is $\sim 500$. The value of $f_X/f_{opt}$, the X-ray variability history and the spectral distribution derived from a re-analysis of the {\it ROSAT}, {\it ASCA} and {\it XMM} data indicate a luminous X-ray binary in NGC 1313 as a likely explanation for NGC 1313 X-2. If the X-ray soft component observed in the {\it XMM} EPIC spectrum originates from an accretion disk, the inferred mass of the compact remnant is $\approx 100 M_\odot$, making it an intermediate mass black hole. The derived optical luminosity ($L\approx 10^5 L_\odot$) is consistent with that of a $\approx 15-20 M_\odot$ companion. The properties of the environment of NGC 1313 X-2 are briefly discussed.Comment: 12 pages, 6 figures; submitted to The Astrophysical Journa

The Brera Multi-scale Wavelet Chandra Survey. I. Serendipitous source catalogue

We present the BMW-Chandra source catalogue drawn from essentially all Chandra ACIS-I pointed observations with an exposure time in excess of 10ks public as of March 2003 (136 observations). Using the wavelet detection algorithm developed by Lazzati et al. (1999) and Campana et al. (1999), which can characterise both point-like and extended sources, we identified 21325 sources. Among them, 16758 are serendipitous, i.e. not associated with the targets of the pointings, and do not require a non-automated analysis. This makes our catalogue the largest compilation of Chandra sources to date. The 0.5--10 keV absorption corrected fluxes of these sources range from ~3E-16 to 9E-12 erg cm^-2 s^-1 with a median of 7E-15 erg cm^-2 s^-1. The catalogue consists of count rates and relative errors in three energy bands (total, 0.5-7keV; soft, 0.5-2keV; and hard, 2-7keV), and source positions relative to the highest signal-to-noise detection among the three bands. The wavelet algorithm also provides an estimate of the extension of the source. We include information drawn from the headers of the original files, as well, and extracted source counts in four additional energy bands, SB1 (0.5-1keV), SB2 (1-2keV), HB1 (2-4keV), and HB2 (4-7keV). We computed the sky coverage for the full catalogue and for a subset at high Galactic latitude (|b|> 20deg). The complete catalogue provides a sky coverage in the soft band (0.5-2keV, S/N =3) of ~8 deg^2 at a limiting flux of 1E-13 erg cm^-2 s^-1, and ~2 deg^2 at a limiting flux of ~1E-15 erg cm^-2 s^-1.Comment: Accepted by A&A, Higher res. Figs 4 and 5 at http://www.ifc.inaf.it/~romano/BMC/Docs/aapaper/9601f4.eps http://www.ifc.inaf.it/~romano/BMC/Docs/aapaper/9601f5.eps, Catalog Web pages: http://www.brera.inaf.it/BMC/bmc_home.html http://www.ifc.inaf.it/~romano/BMC/bmc_home.html (Mirror