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‣ Influence of Parasympathetic Modulation in Doppler Mitral Inflow Velocity in Individuals without Heart Disease

ANTELMI, Ivana; YAMADA, Alice Tatsuko; HSIN, Chang Nan; TSUTSUI, Jeane M.; GRUPI, Cesar Jose; MANSUR, Alfredo Jose
Fonte: MOSBY-ELSEVIER Publicador: MOSBY-ELSEVIER
Tipo: Artigo de Revista Científica
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Background: The relation between left ventricular filing velocities determined by Doppler echocardiography and autonomic nervous system function assessed by heart rate variability (HRV) is unclear. The aim of this study was to evaluate the influence of the autonomic nervous system assessed by the time and frequency domain indices of HRV in the Doppler indices of left ventricular diastolic filling velocities in patients without heart disease. Methods: We studied 451 healthy individuals (255 female [56.4%]) with normal blood pressure, electrocardiogram, chest x-ray, and treadmill electrocardiographic exercise stress test results, with a mean age of 43 +/- 12 (range 15-82) years, who underwent transthoracic Doppler echocardiography and 24-hour electrocardiographic ambulatory monitoring. We studied indices of HRV on time (standard deviation [SD] of all normal sinus RR intervals during 24 hours, SD of averaged normal sinus RR intervals for all 5-minute segments, mean of the SD of all normal sinus RR intervals for all 5-minute segments, root-mean-square of the successive normal sinus RR interval difference, and percentage of successive normal sinus RR intervals > 50 ms) and frequency (low frequency, high frequency, very low frequency, low frequency/high frequency ratio) domains relative to peak flow velocity during rapid passive filling phase (E)...

‣ Gas streaming motions towards the nucleus of M81

MUELLER, Allan Schnorr; STORCHI-BERGMANN, Thaisa; RIFFEL, Rogemar A.; FERRARI, Fabricio; STEINER, J. E.; AXON, David J.; ROBINSON, Andrew
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
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We present two-dimensional stellar and gaseous kinematics of the inner 120 x 250 pc2 of the LINER/Seyfert 1 galaxy M81, from optical spectra obtained with the Gemini Multi-Object Spectrograph (GMOS) integral field spectrograph on the Gemini-North telescope at a spatial resolution of approximate to 10 pc. The stellar velocity field shows circular rotation and, overall, is very similar to the published large-scale velocity field, but deviations are observed close to the minor axis which can be attributed to stellar motions possibly associated with a nuclear bar. The stellar velocity dispersion of the bulge is 162 +/- 15 km s-1, in good agreement with previous measurements and leading to a black hole mass of M(BH) = 5.5+3.6(-2.0) x 107 M(circle dot) based on the M(BH)-Sigma relationship. The gas kinematics is dominated by non-circular motions and the subtraction of the stellar velocity field reveals blueshifts of approximate to-100 km s-1 on the far side of the galaxy and a few redshifts on the near side. These characteristics can be interpreted in terms of streaming towards the centre if the gas is in the plane. On the basis of the observed velocities and geometry of the flow, we estimate a mass inflow rate in ionized gas of approximate to 4.0 x 10-3 M(circle dot) yr-1...

‣ Desemprego de jovens: um estudo sobre a dinâmica do mercado de trabalho juvenil brasileiro. ; "Youth unemployment: a study about the dynamics of the Brazilian youth job market"

Flori, Priscilla Matias
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/11/2003 Português
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Este trabalho tem como objetivo analisar a estrutura do desemprego dos jovens no Brasil, procurando identificar os motivos da taxa de desemprego dos jovens ser muito superior à dos adultos. Apesar de sua importância, este tema tem recebido pouca atenção na literatura sobre o mercado de trabalho brasileiro. Na primeira análise deste estudo, decompõe-se a taxa de desemprego em dois determinantes, duração média e taxa de entrada no desemprego de jovens, adultos e idosos; percebe-se que a duração do desemprego é praticamente a mesma para as três categorias, enquanto a taxa de entrada dos jovens é maior que a das outras duas, sendo, portanto, o determinante que faz com que o desemprego juvenil seja mais elevado que o de trabalhadores mais velhos; assim, com uma nova decomposição da taxa de entrada de jovens, verifica-se que cerca de 80% dessa taxa é composta de jovens que já trabalharam. Outro método será o cálculo, para jovens e adultos, das matrizes de transição entre os estados do mercado de trabalho. Para avaliar a questão do desemprego dos jovens no Brasil, recalcula-se as taxas de desemprego de cada categoria, substituindo uma de cada vez nas matrizes, as probabilidades de transição da outra categoria; os resultados mostram a alta rotatividade dos jovens no mercado de trabalho. Com esses resultados...

‣ Mapping of molecular gas inflow towards the Seyfert nucleus of NGC 4051 using Gemini NIFS

Riffel, Rogemar André; Storchi-Bergmann, Thaisa; Winge, Claudia; McGregor, Peter J.; Beck, Tracy; Schmitt, Henrique Roberto
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
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We present 2D stellar and gaseous kinematics of the inner ~ 130×180 pc² of the Narrow-Line Seyfert 1 galaxy NGC4051 at a sampling of 4.5 pc, from near-infrared K-band spectroscopic observations obtained with the Gemini’s Near-infrared Integral Field Spectrograph (NIFS) operating with the ALTAIR adaptive optics module. We have used the CO absorption band heads around 2.3 μm to obtain the stellar kinematics which show the turnover of the rotation curve at only ≈ 55 pc from the nucleus, revealing a highly concentrated gravitational potential. The stellar velocity dispersion of the bulge is ≈ 60 km s-ˡ – implying on a nuclear black hole mass of ≈ 10 6 Mʘ – within which patches of lower velocity dispersion suggest the presence of regions of more recent star formation. From measurements of the emission-line profiles we have constructed 2D maps for the flux distributions, line ratios, radial velocities and gas velocity dispersions for the H2, HII and [Ca VIII] emitting gas. Each emission-line samples a distinct kinematics. The Brγ emission-line shows no rotation as well as no blueshifts or redshifts in excess of 30 km s-ˡ, and is thus not restricted to the galaxy plane. The [Ca VIII] coronal region is compact but resolved...

‣ MRI estimation of global brain oxygen consumption rate

Jain, Varsha; Langham, Michael C; Wehrli, Felix W
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
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Measuring the global cerebral metabolic rate of oxygen (CMRO2) is a valuable tool for assessing brain vitality and function. Measurement of blood oxygen saturation (HbO2) and flow in the major cerebral outflow and inflow vessels can provide a global estimate of CMRO2. We demonstrate a rapid noninvasive method for quantifying CMRO2 by simultaneously measuring venous oxygen saturation in the superior sagittal sinus with magnetic resonance susceptometry-based oximetry, a technique that exploits the intrinsic susceptibility of deoxygenated hemoglobin, and the average blood inflow rate with phase-contrast magnetic resonance imaging. The average venous HbO2, cerebral blood flow, and global CMRO2 values in eight healthy, normal study subjects were 64%±4%, 45.2±3.2 mL per 100 g per minute, and 127±7 μmol per 100 g per minute, respectively. These values are in good agreement with those reported in literature. The technique described is noninvasive, robust, and reproducible for in vivo applications, making it ideal for use in clinical settings for assessing the pathologies associated with dysregulation of cerebral metabolism. In addition, the short acquisition time (∼30 seconds) makes the technique suitable for studying the temporal variations in CMRO2 in response to physiologic challenges.

‣ Relationship between Arterial Inflow Rate and Venous Filling Index of the Lower Extremities Assessed by Air Plethysmography in Subjects with or without Axial Reflux in the Great Saphenous Vein

Shiraishi, Yasushi
Fonte: The Editorial Committee of Annals of Vascular Diseases Publicador: The Editorial Committee of Annals of Vascular Diseases
Tipo: Artigo de Revista Científica
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Objective: To evaluate the relationship between arterial inflow rate (AIR) and venous filling index (VFI) in limbs with or without varicose veins, assessed by air plethysmography (APG).

‣ Capital inflows and the real exchange rate: a comparative study of Asia and Latin America

Athukorala, Prema-Chandra; Rajapatirana, Sarath
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Working/Technical Paper Formato: 166873 bytes; 360 bytes; application/pdf; application/octet-stream
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The nexus of real exchange rate (RER) and capital inflows is examined through a comparative analysis of the experiences of emerging market economies in Asian and Latin America during the period 1985-2000. It is found that the degree of appreciation in RER associated with capital inflow is uniformly much higher in Latin American countries compared to their Asian counterparts, despite the fact that the latter experienced far greater foreign capital inflows relative to the size of the economy. The econometric evidence suggests that both the composition of capital flows and differences in the degree of response of RER to capital flows matter in explaining these contrasting experiences. While RER appreciation is a phenomenon predominantly associated with other (non-FDI) forms of capital inflows (OCFW), a given level of OCFW brings about a far greater degree of appreciation of the real exchange rate in Latin America where the importance of these flows in total capital inflow is also far greater. On the policy front, Asian countries seem to have used fiscal contraction and nominal exchange rate adjustment more effectively to cushion the RER against the appreciation pressure of capital inflows. There is, however, no evidence to suggest that sterilized intervention can generate a lasting impact on the real exchange rate.; no

‣ Does "Good Government" Draw Foreign Capital? Explaining China's Exceptional Foreign Direct Investment Inflow

Fan, Joseph P. H.; Morck, Randall; Xu, Lixin Colin; Yeung, Bernard
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
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China is now the world's largest destination of foreign direct investment (FDI), despite assessments highlighting its institutional deficiencies. But this FDI inflow corresponds closely to predicted FDI flows into China from a model that predicts FDI inflow based on government quality indicators and controls and is estimated across a sample of other weak-institution countries. The only real discrepancy is that, if government quality is measured by constraints on executive power, China receives somewhat more FDI than the model predicts. This might reflect an underestimation of the strength of these constraints in China, a unique institutional setting for FDI operations, FDI based on expected future institutional improvements, or a unique Chinese model of development. The authors conclude that Ockham's razor disfavors the last. They also note that FDI may be elevated because Chinese institutions protect foreign firms better than domestic ones.

‣ From capital inflow to inflation: the role of exchange rate and government debt

Muinhos,Marcelo Kfoury
Fonte: Fundação Getúlio Vargas Publicador: Fundação Getúlio Vargas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 Português
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As an extension of Muinhos (1998), which found a negative relationship between capital inflows and inflation in Brazil, this paper attempts to obtain the intermediate variables that connect this relationship. Based on a three-good model of Agenor and Montiel (1996) it tests the real exchange rate and government debt as the intermediate using time series' tools, such as error correction VAR, impulse response function, and Granger causality, for the period that covers from 1975 to 1994. It concludes that in a context of capital inflows, there is an appreciation of the real exchange rate that causes a decrease in wages and inflation. Another possibility is that capital inflows decrease the government debt and that reduction affects negatively inflation.

‣ Inflow rate, a time-symmetric observable obeying fluctuation relations

Baiesi, Marco; Falasco, Gianmaria
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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While entropy changes are the usual subject of fluctuation theorems, we seek fluctuation relations involving time-symmetric quantities, namely observables that do not change sign if the trajectories are observed backward in time. We find detailed and integral fluctuation relations for the (time integrated) difference between "entrance rate" and escape rate in mesoscopic jump systems. Such "inflow rate", which is even under time reversal, represents the discrete-state equivalent of the phase space contraction rate. Indeed, it becomes minus the divergence of forces in the continuum limit to overdamped diffusion. This establishes a formal connection between reversible deterministic systems and irreversible stochastic ones, confirming that fluctuation theorems are largely independent of the details of the underling dynamics.; Comment: v3: published version, slightly shorter title and abstract

‣ An Estimate of the Gas Inflow Rate Along the Bar in NGC 7479

Quillen, A. C.; Frogel, Jay. A.; Kenney, Jeffrey D. P.; Pogge, R. W.; DePoy, D. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/09/1994 Português
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We present images of the barred galaxy NGC 7479 in the optical and near infrared broad--bands $B,V,R,J,H,K$, and images in H$\alpha$+[N II] and CO(J=1$\rightarrow$0) emission. The H$\alpha$ and CO emission in the bar are coincident and confined to narrow linear features that are offset from the center of the bar as observed in the near infrared. We estimate the gravitational potential from the $K$ image, which provides an estimate of the torque on the gas at the position of the CO emission in the bar. We find that the implied gas inflow velocity derived from the torque is $10-20$ km s$^{-1}$. Our inflow velocity is independent of the large streaming motions which can be observed in CO and HI.; Comment: 16pages, postscript, ~accepted to ApJ, Paper is available with compressed postscript figures via anonymous ftp from payne.mps.ohio-state.edu in the directory pub/quillen/n7479, AYOSU-9-94-002

‣ Mass Outflow Rate From Accretion Discs around Compact Objects

Das, Tapas K.; Chakrabarti, Sandip K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 23/12/1999 Português
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We compute mass outflow rates from accretion disks around compact objects, such as neutron stars and black holes. These computations are done using combinations of exact transonic inflow and outflow solutions which may or may not form standing shock waves. Assuming that the bulk of the outflow is from the effective boundary layers of these objects, we find that the ratio of the outflow rate and inflow rate varies anywhere from a few percent to even close to a hundred percent (i.e., close to disk evacuation case) depending on the initial parameters of the disk, the degree of compression of matter near the centrifugal barrier, and the polytropic index of the flow. Our result, in general, matches with the outflow rates obtained through a fully time-dependent numerical simulation. In some region of the parameter space when the standing shock does not form, our results indicate that the disk may be evacuated and may produce quiescence states.; Comment: 30 Latex pages and 13 figures. crckapb.sty; Published in Class. Quantum Grav. Vol. 16. No. 12. Pg. 3879

‣ The Mass Inflow Rate in the Barred Galaxy NGC 1530

Regan, Michael W.; Vogel, Stuart N.; Teuben, Peter J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/04/1997 Português
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Mass inflow in barred galaxies has been invoked to account for a wide variety of phenomena, but until now direct evidence for inflow has been lacking. We present Fabry-Perot H-alpha observations of the barred spiral galaxy NGC 1530 from which we determine velocities of the ionized gas for the entire region swept by the bar. We compare the velocity field to models of gas flow in barred spirals and show that it is well reproduced by ideal gas hydrodynamic models. Inspection of the models and observations reveals that gas entering the bar dust lanes streams directly down the dust lanes toward the 2 kpc radius nuclear ring. The models predict that approximately 20% of the gas flowing down the dust lane enters the nuclear ring; the remaining gas sprays around the ring to the other bar dust lane. The fraction of the gas entering the ring is relatively insensitive to the shape or size of the bar. Our observations of the velocity field and dust optical depth yield a mass inflow rate into the nuclear ring of 1 solar mass per year.; Comment: 13 pages, 3 figures, aastex 4.0, accepted for publication in Ap J Letters

‣ The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way

Fox, Andrew J.; Wakker, Bart P.; Barger, Kathleen A.; Hernandez, Audra K.; Richter, Philipp; Lehner, Nicolas; Bland-Hawthorn, Joss; Charlton, Jane C.; Westmeier, Tobias; Thom, Christopher; Tumlinson, Jason; Misawa, Toru; Howk, J. Christopher; Haffner, L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/04/2014 Português
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Dynamic interactions between the two Magellanic Clouds have flung large quantities of gas into the halo of the Milky Way, creating the Magellanic Stream, the Magellanic Bridge, and the Leading Arm (collectively referred to as the Magellanic System). In this third paper of a series studying the Magellanic gas in absorption, we analyze the gas ionization level using a sample of 69 Hubble Space Telescope/Cosmic Origins Spectrograph sightlines that pass through or within 30 degrees of the 21 cm-emitting regions. We find that 81% (56/69) of the sightlines show UV absorption at Magellanic velocities, indicating that the total cross section of the Magellanic System is ~11 000 square degrees, or around a quarter of the entire sky. Using observations of the Si III/Si II ratio together with Cloudy photoionization modeling, we calculate that the total mass (atomic plus ionized) of the Magellanic System is ~2.0 billion solar masses, with the ionized gas contributing over twice as much mass as the atomic gas. This is larger than the current-day interstellar H I mass of both Magellanic Clouds combined, indicating that they have lost most of their initial gas mass. If the gas in the Magellanic System survives to reach the Galactic disk over its inflow time of ~0.5-1.5 Gyr...

‣ Mass Outflow Rate From Advective Accretion Disks around Compact Objects

Das, Tapas K.; Chakrabarti, Sandip K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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We compute mass outflow rates from advective accretion disks around compact objects, such as neutron stars and black holes. These computations, for the first time, are done using combinations of exact transonic inflow and outflow solutions which may or may not form standing shock waves. Assuming that the bulk of the outflow is from the effective boundary layers of these objects, we find that the ratio of the outflow rate and inflow rate varies anywhere from a few percent to even close to a hundred percent (i.e., close to disk evacuation case) depending on the initial parameters of the disk, the degree of compression of matter near the centrifugal barrier, and the polytropic index of the flow. Our result, in general, matches with the outflow rates obtained through a fully time-dependent numerical simulation. In some region of the parameter space when the standing shock does not form, our results indicate that the disk may be evacuated and may produce quiescence states.; Comment: 24 Latex pages and nine figures. Latest version explaining Centrifugal barrier! Submitted to ApJ

‣ Stellar and Molecular Gas Kinematics of NGC1097: Inflow Driven by a Nuclear Spiral

Davies, R.; Maciejewski, W.; Hicks, E.; Tacconi, L.; Genzel, R.; Engel, H.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
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We present spatially resolved distributions and kinematics of the stars and molecular gas in the central 320pc of NGC1097. The stellar continuum confirms the previously reported 3-arm spiral pattern extending into the central 100pc. The stellar kinematics and the gas distribution imply this is a shadowing effect due to extinction by gas and dust in the molecular spiral arms. The molecular gas kinematics show a strong residual (i.e. non-circular) velocity, which is manifested as a 2-arm kinematic spiral. Linear models indicate that this is the line-of-sight velocity pattern expected for a density wave in gas that generates a 3-arm spiral morphology. We estimate the inflow rate along the arms. Using hydrodynamical models of nuclear spirals, we show that when deriving the accretion rate into the central region, outflow in the disk plane between the arms has to be taken into account. For NGC1097, despite the inflow rate along the arms being ~1.2Msun/yr, the net gas accretion rate to the central few tens of parsecs is much smaller. The numerical models indicate that the inflow rate could be as little as ~0.06Msun/yr. This is sufficient to generate recurring starbursts, similar in scale to that observed, every 20-150Myr. The nuclear spiral represents a mechanism that can feed gas into the central parsecs of the galaxy...

‣ Gas Inflow and Outflow Histories in Disk Galaxies as Revealed from Observations of Distant Star-Forming Galaxies

Toyouchi, Daisuke; Chiba, Masashi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 20/07/2015 Português
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We investigate gas inflow and outflow histories in Milky Way-like disk galaxies, to get new insights into the baryonic processes in galaxy formation and evolution. For this purpose, we solve the equations for the evolutions of the surface mass densities of gas and metals at each radius in a galactic disk, based on the observed structural properties of distant star-forming galaxies, including the redshift evolution of their stellar mass distribution, their scaling relation between the mass of baryonic components, star formation rate (SFR) and chemical abundance, as well as the supposed evolution of their radial metallicity gradients (RMGs). We find that the efficiency of gas inflow for a given SFR decreases with time and that the inflow rate is always nearly proportional to the SFR. For gas outflow, although its efficiency for a given SFR is a decreasing function of time, similarly to gas inflow, the outflow rate is not necessarily proportional to the SFR and the relation between the outflow rate and SFR strongly depends on the evolution of the adopted RMG. We also find that the results on the outflow rate can be reproduced in the framework of momentum-driven (energy-driven) wind mechanism if the RMG is steepening (flattening) with time. Therefore if the well measured RMGs and their evolution for Milky Way-like galaxies are obtained from future observations...

‣ The gas inflow and outflow rate in star-forming galaxies at $z\sim1.4$

Yabe, Kiyoto; Ohta, Kouji; Akiyama, Masayuki; Iwamuro, Fumihide; Tamura, Naoyuki; Yuma, Suraphong; Dalton, Gavin; Lewis, Ian
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/10/2014 Português
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We try to constrain the gas inflow and outflow rate of star-forming galaxies at $z\sim1.4$ by employing a simple analytic model for the chemical evolution of galaxies. The sample is constructed based on a large near-infrared (NIR) spectroscopic sample observed with Subaru/FMOS. The gas-phase metallicity is measured from the [\ion{N}{2}]$\lambda$6584/H$\alpha$ emission line ratio and the gas mass is derived from the extinction corrected H$\alpha$ luminosity by assuming the Kennicutt-Schmidt law. We constrain the inflow and outflow rate from the least-$\chi^{2}$ fittings of the observed gas mass fraction, stellar mass, and metallicity with the analytic model. The joint $\chi^{2}$ fitting shows the best-fit inflow rate is $\sim1.8$ and the outflow rate is $\sim0.6$ in unit of star-formation rate (SFR). By applying the same analysis to the previous studies at $z\sim0$ and $z\sim2.2$, it is shown that the both inflow rate and outflow rate decrease with decreasing redshift, which implies the higher activity of gas flow process at higher redshift. The decreasing trend of the inflow rate from $z\sim2.2$ to $z\sim0$ agrees with that seen in the previous observational works with different methods, though the absolute value is generally larger than the previous works. The outflow rate and its evolution from $z\sim2.2$ to $z\sim0$ obtained in this work agree well with the independent estimations in the previous observational works.; Comment: 11 pages...

‣ Overlapping Inflow Events as Catalysts for Supermassive Black Hole Growth

Carmona-Loaiza, Juan Manuel; Colpi, Monica; Dotti, Massimo; Valdarnini, Riccardo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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One of the greatest issues in modelling black hole fuelling is our lack of understanding of the processes by which gas loses angular momentum and falls from galactic scales down to the nuclear region where an accretion disc forms, subsequently guiding the inflow of gas down to the black hole horizon. It is feared that gas at larger scales might still retain enough angular momentum and settle into a larger scale disc with very low or no inflow to form or replenish the inner accretion disc (on ~0.01 pc scales). In this paper we report on hydrodynamical simulations of rotating infalling gas shells impacting at different angles onto a pre-existing, primitive large scale (~10 pc) disc around a super-massive black hole. The aim is to explore how the interaction between the shell and the disc redistributes the angular momentum on scales close to the black hole's sphere of influence. Angular momentum redistribution via hydrodynamical shocks leads to inflows of gas across the inner boundary, enhancing the inflow rate by more than 2-3 orders of magnitude. In all cases, the gas inflow rate across the inner parsec is higher than in the absence of the interaction, and the orientation of the angular momentum of the flow in the region changes with time due to gas mixing. Warped discs or nested misaligned rings form depending on the angular momentum content of the infalling shell relative to the disc. In the cases in which the shell falls in near counter-rotation...

‣ Molecular Gas and the Nuclear Star Cluster in IC342: Sufficient Inflow for Recurring Star Formation Events?

Schinnerer, E.; Boeker, T.; Meier, D. S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 28/05/2003 Português
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We present high spatial resolution (1.2") mm-interferometric observations of the CO(2-1) line emission in the central 300pc of the late-type spiral galaxy IC342. The data, obtained with the Owens Valley Radio Observatory, allow first-time detection of a molecular gas disk that coincides with the luminous young stellar cluster in the nucleus of IC342. The nuclear CO disk has a diameter of ~30pc and a molecular gas mass of M(H2) ~ 2x10^5 M_sun. It connects via two faint CO bridges to the well-known, 100pc diameter circumnuclear gas ring. Analysis of the gas kinematics shows that the line-of-nodes in the inner 15pc is offset by about 45degree from the major kinematic axis, indicating non-circular motion of the gas within a few parsec of the dynamical center of IC342. Both the morphology and the kinematics of the CO gas indicate ongoing inflow of molecular gas into the central few parsec of IC342. We infer a gas inflow rate between 0.003 and 0.14 M_sun/yr, based on the observed surface density of the nuclear gas disk and estimates of the radial velocities of the surrounding gas. Inflow rates of this order can support repetitive star formation events in the nucleus of IC342 on timescales much smaller than a Hubble time.; Comment: 11 pages...