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ALMA FOLLOWS STREAMING OF DENSE GAS DOWN TO 40 PC FROM THE SUPERMASSIVE BLACKHOLE IN NGC 1097
Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
Stockholm University, Faculty of Science, Department of Astronomy.
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2013 (English)In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 770, no 2, L27- p.Article in journal (Refereed) Published
Abstract [en]

We present a kinematic analysis of the dense gas in the central 200 parsecs of thenearby galaxy NGC1097, based on Cycle 0 observations with the Atacama LargeMillimeter/sub-millimeter Array (ALMA). We use the HCN(4-3) line to trace the densest interstellar molecular gas (nH2 ~ 10^8 cm-3), and quantify its kinematics by means of Fourier decomposition. We find a striking similarity between the ALMA kinematic data and the analytic spiral in ow model that we have previously constructed based onionized gas velocity fields on larger scales. We are able to follow dense gas streamingdown to 40 pc distance from the supermassive black hole in this Seyfert 1 galaxy. In order to fulll marginal stability, we deduce that the dense gas is conned to a very thin disc, with 6.0+2.2-2.7 10^6 Msun dynamical mass inside a radius of 40 pc. Finally, we derive a dense gas in ow rate of 0.09Msun yr-1 at 40 pc radius. Combined with previous valuesfrom the H and CO gas, we calculate a combined molecular and ionized gas in ow rateof 0.2Msun yr-1 at 40 pc distance from the central supermassive black hole of NGC1097.

Place, publisher, year, edition, pages
2013. Vol. 770, no 2, L27- p.
Keyword [en]
galaxies: active, galaxies: individual (NGC 1097), galaxies: kinematics and dynamics
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
URN: urn:nbn:se:su:diva-88635DOI: 10.1088/2041-8205/770/2/L27ISI: 000320709900011OAI: oai:DiVA.org:su-88635DiVA: diva2:612651
Available from: 2013-03-23 Created: 2013-03-23 Last updated: 2013-12-11Bibliographically approved
In thesis
1. Rearrangement of gas in disc galaxies
Open this publication in new window or tab >>Rearrangement of gas in disc galaxies
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Active galactic nuclei and bursts of star formation are two distinct phenomena that amply change their host environments. They are present in a significant number of galaxies at all redshifts. In this thesis, we aim toward a better understanding of the physical processes that allow for the formation and maintenance of these two phenomena. We focus on the study of the physical conditions of the interstellar gas in the central kiloparsec region of the barred active galaxy NGC 1097 (Paper I). In Paper I we present different CO transitions and the consequent analysis realized in order to derive the molecular gas content together with the molecular mass inflow toward the centre of the galactic gravitational potential well. To completely understand the physical processes that drive such gas rearrangement, a coherent picture for a dynamical system has to be considered. We have developed a code, Paper II, in order to model the dynamics of a predominantly rotating system with an arbitrary mass distribution. The formalism we have used is based on analytical solutions of the first order approximation of the equations of motion of a smooth medium that may be subject to dissipation. The most important free parameter to constrain the boundary conditions of the model is the angular frequency of the perturbing pattern, which may be assumed virtually invariant over significant ranges of galactocentric radii. We constrain the pattern velocity using the Tremaine-Weinberg method (Paper III). Hence, we have prepared all procedures needed to comprehend the physical processes that sustain the nuclear activity and bursts of star formation: the amount of gas in the region and the dynamics of the system. In Paper IV, we model the neutral and ionized gas kinematics in NGC 1097 and apply a combination of the methods described in Paper II and Paper III to comprehend the rearrangement of gas in the galaxy. In order to observationally discern the gas inflow in the nuclear region at a higher resolution, we apply the methods developed and used in this thesis to Cycle-0 ALMA observations of our target galaxy, and we confirm that we are able to follow the streaming of gas from 20 kiloparsec distances down to 40 parsecs from its central central supermassive black hole (Paper V).

Place, publisher, year, edition, pages
Stockholm: Department of Astronomy, Stockholm University, 2013. 54 p.
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Astronomy
Identifiers
urn:nbn:se:su:diva-88636 (URN)978-91-7447-673-6 (ISBN)
Public defence
2013-06-05, sal FB52, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Submitted.

Available from: 2013-05-14 Created: 2013-03-23 Last updated: 2013-04-25Bibliographically approved

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