858 research outputs found

    The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow

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    We present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO observations obtained with IRAM/PdBI, and we analyze archival Chandra and NuSTAR observations. We constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular outflow has a size of ~1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to ~1 kpc, thus implying that the density of the outflowing material decreases from the nucleus outwards as r2r^{-2}. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to ~1 kpc, thus implying a limit on its age of ~1 Myr. We find M˙OF=[5001000] M yr1\dot M_{OF}=[ 500-1000]~ M_{\odot}~yr^{-1} and E˙kin,OF=[710]×1043\dot E_{kin,OF}=[7-10]\times 10^{43} erg s1^{-1}. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity -20000 km s1^{-1}, M˙UFO=[0.32.1] Myr1\dot M_{UFO}=[0.3- 2.1] ~M_\odot yr^{-1}, and momentum load P˙UFO/P˙rad=[0.21.6]\dot P_{UFO}/\dot P_{rad}=[0.2-1.6].We find E˙kin,UFOE˙kin,OF\dot E_{kin,UFO}\sim \dot E_{kin,OF} as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO kinetic energy is transferred to mechanical energy of the kpc-scale outflow, strongly supporting that the energy released during accretion of matter onto super-massive black holes is the ultimate driver of giant massive outflows. We estimate a momentum boost P˙OF/P˙UFO[3060]\dot P_{OF}/\dot P_{UFO}\approx [30-60]. The ratios E˙kin,UFO/Lbol,AGN=[15]%\dot E_{kin, UFO}/L_{bol,AGN} =[ 1-5]\% and E˙kin,OF/Lbol,AGN=[13]%\dot E_{kin,OF}/L_{bol,AGN} = [1-3]\% agree with the requirements of the most popular models of AGN feedback.Comment: 16 pages, 17 figures. Accepted for publication in A&

    The WISSH quasars Project: II. Giant star nurseries in hyper-luminous quasars

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    Studying the coupling between the energy output produced by the central quasar and the host galaxy is fundamental to fully understand galaxy evolution. Quasar feedback is indeed supposed to dramatically affect the galaxy properties by depositing large amounts of energy and momentum into the ISM. In order to gain further insights on this process, we study the SEDs of sources at the brightest end of the quasar luminosity function, for which the feedback mechanism is supposed to be at its maximum. We model the rest-frame UV-to-FIR SEDs of 16 WISE-SDSS Selected Hyper-luminous (WISSH) quasars at 1.8 < z < 4.6 disentangling the different emission components and deriving physical parameters of both the nuclear component and the host galaxy. We also use a radiative transfer code to account for the contribution of the quasar-related emission to the FIR fluxes. Most SEDs are well described by a standard combination of accretion disk+torus and cold dust emission. However, about 30% of them require an additional emission component in the NIR, with temperatures peaking at 750K, which indicates the presence of a hotter dust component in these powerful quasars. We measure extreme values of both AGN bolometric luminosity (LBOL > 10^47 erg/s) and SFR (up to 2000 Msun/yr). A new relation between quasar and star-formation luminosity is derived (LSF propto LQSO^(0.73)) by combining several Herschel-detected quasar samples from z=0 to 4. Future observations will be crucial to measure the molecular gas content in these systems, probe the impact between quasar-driven outflows and on-going star-formation, and reveal the presence of merger signatures in their host galaxies.Comment: 19 pages, 12 figures; Accepted for publication in Astronomy & Astrophysics on June 13, 201

    Alterações do teor de nitrogênio na folha e pecíolo, na produção e composição da uva pela adubação nitrogenada em videiras no Planalto do Rio Grande do Sul.

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    O trabalho objetivou avaliar como a aplicação de N afeta o seu teor na folha inteira e pecíolo, usados para a recomendação de N à videira no RS e SC, e sobre a produção e composição da uva.bitstream/CNPUV/10104/1/cot087.pd

    The dense molecular gas in the z6\rm z\sim6 QSO SDSS J231038.88+185519.7 resolved by ALMA

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    We present ALMA observations of the CO(6-5) and [CII] emission lines and the sub-millimeter continuum of the z6z\sim6 quasi-stellar object (QSO) SDSS J231038.88+185519.7. Compared to previous studies, we have analyzed a synthetic beam that is ten times smaller in angular size, we have achieved ten times better sensitivity in the CO(6-5) line, and two and half times better sensitivity in the [CII] line, enabling us to resolve the molecular gas emission. We obtain a size of the dense molecular gas of 2.9±0.52.9\pm0.5 kpc, and of 1.4±0.21.4\pm0.2 kpc for the 91.5 GHz dust continuum. By assuming that CO(6-5) is thermalized, and by adopting a CO--to--H2H_2 conversion factor αCO=0.8 M K1 (km/s)1 pc2\rm \alpha_{CO} = 0.8~ M_{\odot}~K^{-1}~ (km/s)^{-1} ~pc^{2}, we infer a molecular gas mass of M(H2)=(3.2±0.2)×1010M\rm M(H_2)=(3.2 \pm0.2) \times 10^{10}\rm M_{\odot}. Assuming that the observed CO velocity gradient is due to an inclined rotating disk, we derive a dynamical mass of Mdyn sin2(i)=(2.4±0.5)×1010 M\rm M_{dyn}~sin^2(i) = (2.4\pm0.5) \times 10^{10}~ M_{\odot}, which is a factor of approximately two smaller than the previously reported estimate based on [CII]. Regarding the central black hole, we provide a new estimate of the black hole mass based on the C~IV emission line detected in the X-SHOOTER/VLT spectrum: MBH=(1.8±0.5)×109 M\rm M_{BH}=(1.8\pm 0.5) \times 10^{9}~ M_{\odot}. We find a molecular gas fraction of μ=M(H2)/M4.4\rm \mu=M(H_2)/M^*\sim4.4, where MMdynM(H2)M(BH)\rm M^*\approx M_{dyn} - M(H_2)-M(BH). We derive a ratio vrot/σ12v_{rot}/\sigma \approx 1-2 suggesting high gas turbulence, outflows/inflows and/or complex kinematics due to a merger event. We estimate a global Toomre parameter Q0.20.5Q\sim 0.2-0.5, indicating likely cloud fragmentation. We compare, at the same angular resolution, the CO(6-5) and [CII] distributions, finding that dense molecular gas is more centrally concentrated with respect to [CII]. We find that the current BH growth rate is similar to that of its host galaxy.Comment: A&A in pres

    Shallow BF2 implants in Xe-bombardment-preamorphized Si: the interaction between Xe and F

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    Si(100) samples, preamorphized to a depth of ~30 nm using 20 keV Xe ions to a nominal fluence of 2×1014 cm-2 were implanted with 1 and 3 keV BF2 ions to fluences of 7×1014 cm-2. Following annealing over a range of temperatures (from 600 to 1130 °C) and times the implant redistribution was investigated using medium-energy ion scattering (MEIS), secondary ion mass spectrometry (SIMS), and energy filtered transmission electron microscopy (EFTEM). MEIS studies showed that for all annealing conditions leading to solid phase epitaxial regrowth, approximately half of the Xe had accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF2 implant. These depths correspond to the end of range of the B and F within the amorphous Si. SIMS showed that in the preamorphized samples, approximately 10% of the F migrates into the bulk and is trapped at the same depths in a ~1:1 ratio to Xe. These observations indicate an interaction between the Xe and F implants and a damage structure that becomes a trapping site. A small fraction of the implanted B is also trapped at this depth. EXTEM micrographs suggest the development of Xe agglomerates at the depths determined by MEIS. The effect is interpreted in terms of the formation of a volume defect structure within the amorphized Si, leading to F stabilized Xe agglomerates or XeF precipitates

    The WISSH Quasars Project III. X-ray properties of hyper-luminous quasars

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    We perform a survey of the X-ray properties of 41 objects from the WISE/SDSS selected Hyper-luminous (WISSH) quasars sample, composed by 86 broad-line quasars (QSOs) with bolometric luminosity LBol2×1047ergs1L_{Bol}\geq 2\times 10^{47}\,erg\, s^{-1}, at z~2-4. All but 3 QSOs show unabsorbed 2-10 keV luminosities L2101045ergs1L_{2-10}\geq10^{45} \,erg \,s^{-1}. Thanks to their extreme radiative output across the Mid-IR-to-X-ray range, WISSH QSOs offer the opportunity to significantly extend and validate the existing relations involving L210L_{2-10}. We study L210L_{2-10} as a function of (i) X-ray-to-Optical (X/O) flux ratio, (ii) mid-IR luminosity (LMIRL_{MIR}), (iii) LBolL_{Bol} as well as (iv) αOX\alpha_{OX} vs. the 2500A˚\mathring{A} luminosity. We find that WISSH QSOs show very low X/O(<0.1) compared to typical AGN values; L210/LMIRL_{2-10}/L_{MIR} ratios significantly smaller than those derived for AGN with lower luminosity; large X-ray bolometric corrections kBol,Xk_{\rm Bol,X}\sim 100-1000; and steep 2<αOX<1.7-2<\alpha_{OX}<-1.7. These results lead to a scenario where the X-ray emission of hyper-luminous quasars is relatively weaker compared to lower-luminosity AGN. Models predict that such an X-ray weakness can be relevant for the acceleration of powerful high-ionization emission line-driven winds, commonly detected in the UV spectra of WISSH QSOs, which can in turn perturb the X-ray corona and weaken its emission. Accordingly, hyper-luminous QSOs represent the ideal laboratory to study the link between the AGN energy output and wind acceleration. Additionally, WISSH QSOs show very large BH masses (log[MBH/M]\log[M_{\rm BH}/M_{\odot}]>9.5). This enables a more robust modeling of the ΓMBH\Gamma-M_{BH} relation by increasing the statistics at high masses. We derive a flatter Γ\Gamma dependence than previously found over the broad range 5 <log(MBH/M)\log(M_{\rm BH}/M_{\odot}) < 11.Comment: 20 pages, 14 Figures. Accepted for publication on A&

    The hidden quasar nucleus of a WISE-selected, hyperluminous, dust-obscured galaxy at z ~ 2.3

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    We present the first X-ray spectrum of a Hot dust-obscured galaxy (DOG), namely W1835+4355 at z ~ 2.3. Hot DOGs represent a very rare population of hyperluminous (>= 10^47 erg/s), dust-enshrouded objects at z > 2 recently discovered in the WISE All Sky Survey. The 40 ks XMM-Newton spectrum reveals a continuum as flat (Gamma ~ 0.8) as typically seen in heavily obscured AGN. This, along with the presence of strong Fe Kalpha emission, clearly suggests a reflection-dominated spectrum due to Compton-thick absorption. In this scenario, the observed luminosity of L(2-10 keV) ~ 2 x 10^44 erg/s is a fraction (~ 5 x 10^45 erg/s by using several proxies. The Herschel data allow us to constrain the SED up to the sub-mm band, providing a reliable estimate of the quasar contribution (~ 75%) to the IR luminosity as well as the amount of star formation (~ 2100 Msun/yr). Our results thus provide additional pieces of evidence that associate Hot DOGs with an exceptionally dusty phase during which luminous quasars and massive galaxies co-evolve and a very efficient and powerful AGN-driven feedback mechanism is predicted by models.Comment: Accepted for publication in A&A Letter

    Targeting Phosphatases and Kinases: How to Checkmate Cancer

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    Metastatic disease represents the major cause of death in oncologic patients worldwide. Accumulating evidence have highlighted the relevance of a small population of cancer cells, named cancer stem cells (CSCs), in the resistance to therapies, as well as cancer recurrence and metastasis. Standard anti-cancer treatments are not always conclusively curative, posing an urgent need to discover new targets for an effective therapy. Kinases and phosphatases are implicated in many cellular processes, such as proliferation, differentiation and oncogenic transformation. These proteins are crucial regulators of intracellular signaling pathways mediating multiple cellular activities. Therefore, alterations in kinases and phosphatases functionality is a hallmark of cancer. Notwithstanding the role of kinases and phosphatases in cancer has been widely investigated, their aberrant activation in the compartment of CSCs is nowadays being explored as new potential Achille’s heel to strike. Here, we provide a comprehensive overview of the major protein kinases and phosphatases pathways by which CSCs can evade normal physiological constraints on survival, growth, and invasion. Moreover, we discuss the potential of inhibitors of these proteins in counteracting CSCs expansion during cancer development and progression
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