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Relevant bibliographies by topics / NGC 4945

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Academic literature on the topic 'NGC 4945'

Author: Grafiati

Published: 10 March 2023

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Journal articles on the topic "NGC 4945"

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Tang, X. D., C. Henkel, K. M. Menten, Y. Gong, S. Martín, S. Mühle, S. Aalto, et al. "ALMA view of the 12C/13C isotopic ratio in starburst galaxies." Astronomy & Astrophysics 629 (August 22, 2019): A6. http://dx.doi.org/10.1051/0004-6361/201935603.

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We derive molecular-gas-phase 12C/13C isotope ratios for the central few hundred parsecs of the three nearby starburst galaxies NGC 253, NGC 1068, and NGC 4945 making use of the λ ∼ 3 mm 12CN and 13CN N = 1–0 lines in the ALMA Band 3. The 12C/13C isotopic ratios derived from the ratios of these lines range from 30 to 67 with an average of 41.6 ± 0.2 in NGC 253, from 24 to 62 with an average of 38.3 ± 0.4 in NGC 1068, and from 6 to 44 with an average of 16.9 ± 0.3 in NGC 4945. The highest 12C/13C isotopic ratios are determined in some of the outskirts of the nuclear regions of the three starburst galaxies. The lowest ratios are associated with the northeastern and southwestern molecular peaks of NGC 253, the northeastern and southwestern edge of the mapped region in NGC 1068, and the very center of NGC 4945. In the case of NGC 1068, the measured ratios suggest inflow from the outer part of NGC 1068 into the circum-nuclear disk through both the halo and the bar. Low 12C/13C isotopic ratios in the central regions of these starburst galaxies indicate the presence of highly processed material.

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Harnett, Julienne I. "The magnetic fields of NGC 6946 and NGC 4945." Geophysical & Astrophysical Fluid Dynamics 50, no. 1-3 (January 1990): 35–37. http://dx.doi.org/10.1080/03091929008219866.

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Koornneef, Jan. "NGC 4945 - A postburst infrared galaxy." Astrophysical Journal 403 (February 1993): 581. http://dx.doi.org/10.1086/172229.

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Wang, M., C. Henkel, Y. N. Chin, J. B. Whiteoak, M. Hunt Cunningham, and R. Mauersberger. "The Nuclear Starburst in NGC 4945." Highlights of Astronomy 13 (2005): 871. http://dx.doi.org/10.1017/s1539299600017366.

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AbstractNGC 4945 is with D ~3-4 Mpc one of the nearest starburst galaxies known and a goldmine for molecular cloud research. A multi-line mm-wave study has been carried out towards its nuclear region with the Swedish-ESO Sub-millimetre Telescope (SEST). The study covers the frequency range from 82 GHz to 354 GHz and includes 80 transitions of 19 molecules, including rare isotope-bearing species. Applying a Large Velocity Gradient (LVG) code to the data, H2 densities and column densities of 22 molecular species are calculated. Many of these species indicate the presence of a prominent high density interstellar gas component characterized by nH2 ~105cm-3. Abundances of molecular species are calculated and compared with abundances observed toward the starburst galaxies NGC 253 and M 82 and galactic sources. Apparent is an ‘overabundance’ of HNC and CN in the nuclear environment of NGC 4945. NGC 4945 is the second known starburst galaxy with an HNC/HCN abundance ratio ≥1. Carbon, nitrogen, oxygen and sulfur isotope ratios are also determined. The data indicate that high 18O/17O, low 16O/18O and 14N/15N and perhaps also low 32S/34S ratios (6.4±0.3, 195±45, 105±25 and 13.5±2.5, respectively) are characteristic properties of a starburst environment in an advanced evolutionary stage.

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Ag�ero, E. L., and G. J. Carranza. "The ionized gas in NGC 4945." Astrophysics and Space Science 121, no. 2 (1986): 403–11. http://dx.doi.org/10.1007/bf00653711.

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McCarthy, Tiege P., Simon P. Ellingsen, Xi Chen, Shari L. Breen, Maxim A. Voronkov, and Hai-hua Qiao. "Class I Methanol Maser Emission in NGC 4945." Proceedings of the International Astronomical Union 13, S336 (September 2017): 105–8. http://dx.doi.org/10.1017/s1743921317010687.

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AbstractWe have detected maser emission from the 36.2 GHz (4−1 → 30E) methanol transition towards NGC 4945. This emission has been observed in two separate epochs and is approximately five orders of magnitude more luminous than typical emission from this transition within our Galaxy. NGC 4945 is only the fourth extragalactic source observed hosting class I methanol maser emission. Extragalactic class I methanol masers do not appear to be simply highly-luminous variants of their galactic counterparts and instead appear to trace large-scale regions where low-velocity shocks are present in molecular gas.

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Pérez-Beaupuits, J. P., H. W. W. Spoon, M. Spaans, and J. D. Smith. "The deeply obscured AGN of NGC 4945." Astronomy & Astrophysics 533 (August 26, 2011): A56. http://dx.doi.org/10.1051/0004-6361/201117153.

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Cunningham, M. R., and J. B. Whiteoak. "The nuclear molecular clouds of NGC 4945." Monthly Notices of the Royal Astronomical Society 364, no. 1 (November 21, 2005): 37–46. http://dx.doi.org/10.1111/j.1365-2966.2005.09502.x.

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Monje, R. R., S. Lord, E. Falgarone, D. C. Lis, D. A. Neufeld, T. G. Phillips, and R. Güsten. "HYDROGEN FLUORIDE TOWARD LUMINOUS NEARBY GALAXIES: NGC 253 AND NGC 4945." Astrophysical Journal 785, no. 1 (March 21, 2014): 22. http://dx.doi.org/10.1088/0004-637x/785/1/22.

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Roy, A. L., T. Oosterloo, W. M. Goss, and K. R. Anantharamaiah. "Detection of the H92αrecombination line from NGC 4945." Astronomy and Astrophysics 517 (July 2010): A82. http://dx.doi.org/10.1051/0004-6361/200913926.

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Dissertations / Theses on the topic "NGC 4945"

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Walther, Tobias. "The role of Peripheral Nuclear Pore Complex (NPC) structures in nuclear transport and NPC architecture." Diss., lmu, 2002. http://nbn-resolving.de/urn:nbn:de:bvb:19-4945.

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Venturi, Giacomo. "The impact of galactic outflows on their host galaxies through spatially resolved spectroscopy." Doctoral thesis, 2019. http://hdl.handle.net/2158/1160629.

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The observed properties of galaxies and supermassive black holes (BH) at their centers suggest that there must be a non-gravitational feedback mechanism regulating their evolution. These are the discrepancy at low and high masses between the observed stellar mass function of galaxies and that predicted by ΛCDM models, the scaling relations between the mass of BHs and the velocity dispersion, mass and luminosity of the host galaxy spheroid and the similarity between BH growth and star formation cosmic histories. Models of galaxy formation and evolution in fact routinely include feedback from active galactic nuclei (AGN) and supernovae (SNe), which can successfully reproduce the observed properties cited above. Models consider the following two types of AGN feedback: the radiative mode (or quasar mode), that operates during a luminous AGN phase through winds powered by radiation pressure, and the kinetic (or radio) mode, in which kinetic energy is released by the AGN on longer timescales through relativistic jets, which heat the surrounding halo in galaxy clusters, thus preventing cooling and further accretion on the central galaxy, and consequently further star formation. So far, the clearest observational evidence of AGN feedback comes from the kinetic mode in massive central cluster galaxies. Radiative feedback is instead more elusive, and has been recently revealed in action only in a few luminous quasars around the peak of AGN activity history (z~2), where most powerful outflows are observed. However, it is not possible to study high-z quasar outflows on small spatial scales (<100 pc), being poorly-resolved or even unresolved in observations, due to their large distances. This can lead to systematics and uncertainties in the determination of outflow properties and forces to make some assumptions on them, which further increases the uncertainties on the outflow energetics and complicates the evaluation of the impact of outflows on host galaxies and the comparison with models. On the contrary, due to their vicinity, nearby active galaxies are ideal laboratories to explore in detail outflow properties, their formation and acceleration mechanisms, as well as the effects of AGN activity on host galaxies. This work focuses on investigating the properties of outflows in nearby Seyfert galaxies, the physical conditions of the ionized gas and the interplay between nuclear activity and star formation in the galaxy, thanks to the unprecedented combination of spatial and spectral coverage provided by the integral field spectrograph MUSE at the Very Large Telescope (VLT). We introduce our optically- and X-ray selected sample of nearby Seyferts, called MAGNUM survey. We present our MUSE emission-line flux and kinematic maps of the 10 objects we have analyzed so far, including a star-forming galaxy, NGC 6810, to study the properties of a starburst outflow for comparison as well. We map the ionized gas down to spatial scales as low as ~10 pc. We find ubiquitous ionization cones and outflows with various morphologies and extensions, from a few hundred pc to several kpc. We detect peculiar kinematic features suggestive of outflows with hollow-conical structures. We also identify enhanced linewidths perpendicular to radio jets, which point to a correlation between the presence of jets and perpendicular turbulent or outflowing gas motions. We then focus on a detailed multi-wavelength study of the ionized gas and outflow, in terms of physical properties, kinematics, and ionization mechanisms, in one specific galaxy of our sample, NGC 1365, from MUSE in optical band and Chandra satellite in X-rays. Here we map a kpc-scale biconical outflow ionized by the AGN prominent in [O III], while Hα emission traces star formation in a circumnuclear ring and along the bar of the galaxy. Soft X-rays are mostly due to thermal emission from the star-forming regions, but we manage to isolate the AGN photoionized component which matches the [O III] emission from MUSE. We map the mass outflow rate of the galactic ionized outflow, which matches that of the nuclear X-ray wind and then decreases with radius. The integrated mass outflow rate, kinetic energy rate, and outflow velocity are broadly consistent with the typical relations observed in more luminous AGN. We extend our analysis to the nearby star-forming galaxy NGC 6810, whose bipolar galactic ionized outflow we map with MUSE. We determine the dominant ionization mechanism in the outflow, its density and ionization parameter, discovering the first case of star formation occurring within an outflow in an unambiguously star-forming galaxy. We finally investigate with MUSE also the kinetic AGN feedback, by studying the ionized gas enshrouding the X-ray cavity inflated by radio jets around the massive radio-galaxy 3C 317 at the center of the local cluster Abell 2052. Thanks to MUSE capabilities, by mapping the warm gas filaments enshrouding the bubble we are able to directly measure the expansion velocity of the cavity, which usually is instead assumed or derived from indirect and model-dependent methods.

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Books on the topic "NGC 4945"

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Kemp, Michael, and Martin Maiers, eds. Application of Next Generation Sequencing (NGS) in Infection Prevention. Frontiers Media SA, 2022. http://dx.doi.org/10.3389/978-2-88976-495-2.

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Book chapters on the topic "NGC 4945"

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Kramer, Carsten, Marc Hitschfeld, Manuel Aravena, Frank Bertoldi, Jürgen Stutzki, and Yasuo Fukui. "CO 4–3 and [CI] 1–0 in Circinus and NGC 4945." In Astrophysics and Space Science Proceedings, 291–92. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6933-8_70.

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Hunt, Maria R., and John B. Whiteoak. "High-Resolution Acta Observations of the Circumnuclear Molecular Clouds of NGC 4945." In Dense Molecular Gas Around Protostars and in Galactic Nuclei, 257–62. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-3831-3_30.

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Mathur, Smita, Martin Elvis, and Belinda Wilkes. "Testing Unified X-ray — UV Absorber Models with NGC 5548." In QSO Absorption Lines, 245–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-540-49458-4_50.

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Conference papers on the topic "NGC 4945"

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MATTANA, Fabio, Marie-Luise Menzel, and Volker Beckmann. "Emission processes in NGC 4945." In The Extreme and Variable High Energy Sky. Trieste, Italy: Sissa Medialab, 2012. http://dx.doi.org/10.22323/1.147.0075.

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Roy, A. L. "Radio Recombination Lines from Starbursts: NGC 3256, NGC 4945 and the Circinus Galaxy." In THE EVOLUTION OF STARBURSTS: The 331st Wilhelm and Else Heraeus Seminar. AIP, 2005. http://dx.doi.org/10.1063/1.2034998.

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Wojaczyński, Rafał, and Andrzej Niedźwiecki. "X-ray/γ-ray correlation in Seyfert 2 galaxy NGC 4945." In HIGH ENERGY GAMMA-RAY ASTRONOMY: 6th International Meeting on High Energy Gamma-Ray Astronomy. Author(s), 2017. http://dx.doi.org/10.1063/1.4968978.

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Marinucci, A., G. Risaliti, E. Nardini, S. Bianchi, G. Matt, and M. Elvis. "The unique Suzaku discovery of variability in the Compton-thick absorber in NGC 4945." In SUZAKU 2011: Exploring the X-ray Universe: Suzaku and Beyond. AIP, 2012. http://dx.doi.org/10.1063/1.3696167.

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Mueller, Martin. "The X-ray Variability of NGC 4945: Characterizing the Power Spectrum through Light Curve Simulations." In X-RAY TIMING 2003: Rossie and Beyond. AIP, 2004. http://dx.doi.org/10.1063/1.1781025.

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Wojaczynski, Rafal, and Andrzej Niedzwiecki. "The X/$\gamma$-ray correlation in NGC 4945 and the nature of its $\gamma$-ray source." In 7th International Fermi Symposium. Trieste, Italy: Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.312.0051.

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Życki, P. "Structure of the circumnuclear region of Seyfert 2 galaxies—clues from RXTE observations of NGC 4945." In X-RAY ASTRONOMY: Stellar Endpoints,AGN, and the Diffuse X-ray Background. AIP, 2001. http://dx.doi.org/10.1063/1.1434800.

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Al-Sadooni, Ameerah Ab, and Jacco Th van Loon. "The kinematics and physical properties for some H II regions to the North-East of NGC 4945**." In 3RD INTERNATIONAL SCIENTIFIC CONFERENCE OF ALKAFEEL UNIVERSITY (ISCKU 2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0067075.

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Spinelli, Maurizio, Stefano Campanari, Matteo C. Romano, Stefano Consonni, Thomas G. Kreutz, Hossein Ghezel-Ayagh, Stephen Jolly, and Matthew Di Nitto. "Molten Carbonate Fuel Cells as Means for Post-Combustion CO2 Capture: Retrofitting Coal-Fired Steam Plants and Natural Gas-Fired Combined Cycles." In ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2015 Power Conference, the ASME 2015 9th International Conference on Energy Sustainability, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fuelcell2015-49454.

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The state-of-the-art conventional technology for post combustion capture of CO2 from fossil-fuelled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. Apromising alternative, available in the near future, is the application of Molten Carbonate Fuel Cells (MCFC) for CO2 separation from post-combustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC based CO2 separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a ‘retrofit’ to the original power plant. Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behaviour simulated using a 0D model calibrated against manufacturers’ specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO2 separation efficiency as well as an economic comparison of the cost of CO2 avoided under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO2 capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO2 emission and a competitive cost for CO2 avoided (25–40 €/ton).

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Desiderio, Mayane Freitas, Marcela Bonalumi Santos, André Mattar, Jorge Yoshinori Shida, and Luiz Henrique Gebrim. "PATHOLOGICAL COMPLETE RESPONSE IN 2,141 PATIENTS SUBMITTED TO NEOADJUVANT CHEMOTHERAPY IN A BREAST CANCER REFERENCE CENTER." In Scientifc papers of XXIII Brazilian Breast Congress - 2021. Mastology, 2021. http://dx.doi.org/10.29289/259453942021v31s1087.

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Introduction: The pathologic complete response (pCR) definition after neoadjuvant chemotherapy (NAC) for breast cancer is better defined as the absence of residual invasive cancer, although it allows the presence of ductal carcinoma in situ (DCIS). In the past, the presence of positive axillary lymph node was allowed; nowadays studies have shown that any positive lymph node should be not considered as pCR. In Brazil, the proportion of advanced cases varies between 30% to 55% of patients treated by the public health system (SUS). NAC has been recommended more frequently, especially for triple negative tumors and overexpressed Her 2 tumors because you can possibly change the adjuvant treatment, and it is an excellent predictor of prognosis. There is little data on pCR in the therapeutic regimens used in SUS. Objectives: Evaluate data on pathologic complete response in patients subjected to neoadjuvant chemotherapy in SUS schemes. Methods: We performed a retrospective study in Pérola Byington Hospital official database from January 2011 to December 2018 and 2,141 patients that underwent neoadjuvant chemotherapy (NAC) were included. Chemotherapy regimens varied during this period according to institutional protocols and availability of new drugs. The pCR was considered after a histopathological study of the surgical specimen in four molecular subtypes (luminal A and B, triple negative and HER -2 enriched). Results: We included 494 patients in Stage IIB and 1,645 patients in Stage III, most of them were luminal (1,077/50.3%), followed by triple negative (766/35,8%) and Her2 (298/13,9%). The pCR rate varied across the subtypes: luminal 78 (7.2%), triple negative 163 (21.3%) and Her2 69 (23.1%). Conclusions: NAC is an important treatment for breast cancer and is gradually obtainingmore indications. Most of the indications for NAC are: To allow surgical approaches (advanced cases); To allow / increase rate of conservative surgery; To allow conservative approach to the axila and recently select some cases for specific treatment (adjuvant TDM1 and capecitabine). The pCR rate varies through the studies: Cortazar et al. found 16% in Luminal; 33% in triple negative; 50% in Her2 when trastuzumab was used and 30,2% when it was not used. When platin is used for triple negative it is possible to achieve up to 50% of pCR. When double blockage for Her2 is used we can expect between 50%-70% in pCR. In our data most of our patients were stage III and we only had access to neoadjuvant trastuzumab after 2016; this directly impacted our results. The NAC protocols varied during this period and nowadays we have included platin compounds for triple negative.

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Reports on the topic "NGC 4945"

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Miller, Amara. Long-term X-ray Variability of NGC 4945. Office of Scientific and Technical Information (OSTI), August 2007. http://dx.doi.org/10.2172/915381.

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Harrison, Sarah M. Analysis of Off-Nuclear X-Ray Sources in Galaxy NGC 4945. Office of Scientific and Technical Information (OSTI), September 2006. http://dx.doi.org/10.2172/908225.

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Madejski, Grzegorz. Simultaneous Chandra and RXTE Observations of the nearby bright Seyfert 2 galaxy NGC 4945. Office of Scientific and Technical Information (OSTI), January 2003. http://dx.doi.org/10.2172/812617.

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Mueller, M. The X-ray Variability of NGC 4945: Characterizing the Power Spectrum through Light Curve Simulations. Office of Scientific and Technical Information (OSTI), December 2003. http://dx.doi.org/10.2172/826601.

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Mueller, Martin. The X-ray Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: Analysis and Application of the Method of Light Curve Simulations. Office of Scientific and Technical Information (OSTI), December 2010. http://dx.doi.org/10.2172/1000376.

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