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F Combes - One of the best experts on this subject based on the ideXlab platform.
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Molecular Gas in distant brightest cluster galaxies
Astron.Astrophys., 2020Co-Authors: G. Castignani, F Combes, P. Salomé, J. FreundlichAbstract:The mechanisms governing the stellar mass assembly and star formation history of brightest cluster galaxies (BCGs) are still being debated. By means of new and archival Molecular Gas observations we investigate the role of dense megaparsec-scale environments in regulating the fueling of star formation in distant BCGs, through cosmic time. We observed in CO with the IRAM 30 m telescope two star-forming BCGs belonging to SpARCS clusters, namely, 3C 244.1 (z = 0.4) and SDSS J161112.65+550823.5 (z = 0.9), and compared their Molecular Gas and star formation properties with those of a compilation of ∼100 distant cluster galaxies from the literature, including nine additional distant BCGs at z ∼ 0.4 − 3.5. We set robust upper limits of MH2 < 1.0 × 1010 M⊙ and < 2.8 × 1010 M⊙ to their Molecular Gas content, respectively, and to the ratio of Molecular Gas to stellar mass M(H2)/M⋆ ≲ 0.2 and depletion time τdep ≲ 40 Myr of the two targeted BCGs. They are thus among the distant cluster galaxies with the lowest Gas fractions and shortest depletion times. The majority (64%±15% and 73%±18%) of the 11 BCGs with observations in CO have lower M(H2)/M⋆ values and τdep, respectively, than those estimated for main sequence galaxies. Statistical analysis also tentatively suggests that the values of M(H2)/M⋆ and τdep for the 11 BCGs deviates, with a significance of ∼2σ, from those of the comparison sample of cluster galaxies. A morphological analysis for a subsample of seven BCGs with archival HST observations reveals that 71%±17% of the BCGs are compact or show star-forming components or substructures. Our results suggest a scenario where distant star-forming BCGs assemble a significant fraction ∼16% of their stellar mass on the relatively short timescale ∼τdep, while environmental mechanisms might prevent the replenishment of Gas feeding the star formation. We speculate that compact components also favor the rapid exhaustion of Molecular Gas and ultimately help to quench the BCGs. Distant star-forming BCGs are excellent targets for ALMA and for next-generation telescopes such as the James Webb Space Telescope.Key words: galaxies: clusters: general / galaxies: star formation / galaxies: evolution / galaxies: active / Molecular data
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Molecular Gas content of shell galaxies
Astronomy and Astrophysics - A&A, 2019Co-Authors: Brisa Mancillas, F Combes, Pierre-alain DucAbstract:Shells are fine stellar structures that are identified by their arc-like shapes around a galaxy. They are currently thought to be vestiges of galaxy interactions and/or mergers. The study of their number, geometry, stellar populations, and Gas content can help us to derive the interaction or merger history of a galaxy. Numerical simulations have proposed a mechanism of shell formation through phase wrapping during a radial minor merger. Alternatively, there could be merely a space wrapping, when particles have not yet radially oscillated, but are bound by their radial expansion, or produce an edge-brightened feature. These can be distinguished because they are expected to keep a high radial velocity. While shells are first a stellar phenomenon, HI and CO observations have revealed neutral Gas associated with shells. Some of the Gas, the most diffuse and dissipative, is expected to be quickly driven to the center if it is traveling on nearly radial orbits. Molecular Gas, which is distributed in dense clumps, is less dissipative, and may be associated with shells. It can then determine the shell velocity, which is too difficult to obtain from stars. We present here a search for Molecular Gas in nine shell galaxies with the IRAM-30 m telescope. Six of them are detected in their galaxy center, and in three galaxies, we clearly detect Molecular Gas in shells. The derived amount of Molecular Gas varies from 1.5 × 10 8 to 3.4 × 10 9 M in the shells. For two of them (Arp 10 and NGC 3656), the shells are characteristic of an oblate system. Their velocity is nearly systemic, and we conclude that these shells are phase wrapped. In the third galaxy (NGC 3934), the shells appear to participate in the rotation. Follow-up with higher spatial resolution is required to conclude.
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An Enormous Molecular Gas Flow in the RX J0821+0752 Galaxy Cluster
The Astrophysical journal letters, 2019Co-Authors: A. Vantyghem, F Combes, B. Mcnamara, H. Russell, A. Edge, P. Nulsen, A. Fabian, M. Mcdonald, P. SaloméAbstract:We present recent {\it Chandra} X-ray observations of the RXJ0821.0+0752 galaxy cluster in addition to ALMA observations of the CO(1-0) and CO(3-2) line emission tracing the Molecular Gas in its central galaxy. All of the CO line emission, originating from a 1010M⊙ Molecular Gas reservoir, is located several kpc away from the nucleus of the central galaxy. The cold Gas is concentrated into two main clumps surrounded by a diffuse envelope. They form a wide filament coincident with a plume of bright X-ray emission emanating from the cluster core. This plume encompasses a putative X-ray cavity that is only large enough to have uplifted a few percent of the Molecular Gas. Unlike other brightest cluster galaxies, stimulated cooling, where X-ray cavities lift low entropy cluster Gas until it becomes thermally unstable, cannot have produced the observed Gas reservoir. Instead, the Molecular Gas has likely formed as a result of sloshing motions in the intracluster medium induced by a nearby galaxy. Sloshing can emulate uplift by dislodging Gas from the galactic center. This Gas has the shortest cooling time, so will condense if disrupted for long enough.
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an enormous Molecular Gas flow in the rx j0821 0752 galaxy cluster
The Astrophysical Journal, 2019Co-Authors: F Combes, A. Vantyghem, P. Nulsen, B R Mcnamara, H R Russell, A C EdgeAbstract:We present recent Chandra X-ray observations of the RX J0821.0+0752 galaxy cluster, in addition to ALMA observations of the CO(1–0) and CO(3–2) line emission tracing the Molecular Gas in its central galaxy. All of the CO line emission, originating from a ${10}^{10}\,{M}_{\odot }$ Molecular Gas reservoir, is located several kiloparsecs away from the nucleus of the central galaxy. The cold Gas is concentrated into two main clumps surrounded by a diffuse envelope. They form a wide filament coincident with a plume of bright X-ray emission emanating from the cluster core. This plume encompasses a putative X-ray cavity that is only large enough to have uplifted a small percent of the Molecular Gas. Unlike other brightest cluster galaxies, stimulated cooling, where X-ray cavities lift low-entropy cluster Gas until it becomes thermally unstable, cannot have produced the observed Gas reservoir. Instead, the Molecular Gas has likely formed as a result of sloshing motions in the intracluster medium induced by a nearby galaxy. Sloshing can emulate uplift by dislodging Gas from the galactic center. This Gas has the shortest cooling time, so it will condense if disrupted for long enough.
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tango i interstellar medium in nearby radio galaxies Molecular Gas
Astronomy and Astrophysics, 2010Co-Authors: Ocana B Flaquer, F Combes, Stephane Leon, Jeremy LimAbstract:Context. Powerful radio-AGN are hosted by massive elliptical galaxies that are usually very poor in Molecular Gas. Nevertheless, Gas is needed at their very center to feed the nuclear activity. Aims. We study the Molecular Gas properties (i.e., mass, kinematics, distribution, origin) of these objects, and compare them with results for other known samples. Methods. At the IRAM-30m telescope, we performed a survey of the CO(1-0) and CO(2-1) emission from the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. Results. The main result of our survey is that the Molecular Gas content of these galaxies is very low compared to spiral or FIR-selected galaxies. The median value of the Molecular Gas mass, including detections and upper limits, is 2.2 × 10 8 M ⊙ . When separated into FR-I and FR-II types, a difference in their H 2 masses is found. The median value of FR-I galaxies is about 1.9 x 10 8 M ⊙ and higher for FR-II galaxies, at about 4.5 x 10 8 M ⊙ . Which is probably entirely because of a Malmquist bias. Our results contrast with those of previous surveys, whose targets were mainly selected by means of their FIR emission, implying that we measure higher observed masses of Molecular Gas. Moreover, the shape of CO spectra suggest that a central Molecular Gas disk exists in 30% of these radio galaxies, a lower rate than in other active galaxy samples. Conclusions. We find a low level of Molecular Gas in our sample of radio-selected AGNs, indicating that galaxies do not need much Molecular Gas to host an AGN. The presence of a Molecular Gas disk in some galaxies and the wide range of Molecular Gas masses may be indicative of different origins for the Gas, which we can not exclude at present (e.g., minor/major mergers, stellar mass loss, or accretion).
Jeremy Lim - One of the best experts on this subject based on the ideXlab platform.
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TANGO I: ISM in nearby radio galaxies. Molecular Gas
Astronomy and Astrophysics, 2010Co-Authors: Breezy Ocaña Flaquer, Stephane Leon, Francoise Combes, Jeremy LimAbstract:Powerful radio-AGN are hosted by massive elliptical galaxies which are usually very poor in Molecular Gas. Nevertheless Gas is needed in the very center to feed the nuclear activity. We aim to study the Molecular Gas properties (mass, kinematics, distribution, origin) in such objects, and to compare them with results of other known samples. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. The main result of our survey is the very low content in Molecular Gas of such galaxies compared to spiral or FIR-selected galaxies. The median value of the Molecular Gas mass, including detections and upper limits, is 2.2x10^8 Msun. If separated into FR-I and FR-II types, a difference in H_2 masses between them is found. The median value of FR-I galaxies is about 1.9x10^8 and higher for FR-II galaxies, about 4.5x10^8 Msun but this is very probably entirely due to a Malmquist bias. Our results contrast with previous surveys, mainly selected through the FIR emission, implying larger observed masses of Molecular Gas. Moreover, the shape of CO spectra suggest the presence of a central Molecular Gas disk in 30% of these radio galaxies, a lower rate than in other active galaxy samples.
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tango i interstellar medium in nearby radio galaxies Molecular Gas
Astronomy and Astrophysics, 2010Co-Authors: Ocana B Flaquer, F Combes, Stephane Leon, Jeremy LimAbstract:Context. Powerful radio-AGN are hosted by massive elliptical galaxies that are usually very poor in Molecular Gas. Nevertheless, Gas is needed at their very center to feed the nuclear activity. Aims. We study the Molecular Gas properties (i.e., mass, kinematics, distribution, origin) of these objects, and compare them with results for other known samples. Methods. At the IRAM-30m telescope, we performed a survey of the CO(1-0) and CO(2-1) emission from the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. Results. The main result of our survey is that the Molecular Gas content of these galaxies is very low compared to spiral or FIR-selected galaxies. The median value of the Molecular Gas mass, including detections and upper limits, is 2.2 × 10 8 M ⊙ . When separated into FR-I and FR-II types, a difference in their H 2 masses is found. The median value of FR-I galaxies is about 1.9 x 10 8 M ⊙ and higher for FR-II galaxies, at about 4.5 x 10 8 M ⊙ . Which is probably entirely because of a Malmquist bias. Our results contrast with those of previous surveys, whose targets were mainly selected by means of their FIR emission, implying that we measure higher observed masses of Molecular Gas. Moreover, the shape of CO spectra suggest that a central Molecular Gas disk exists in 30% of these radio galaxies, a lower rate than in other active galaxy samples. Conclusions. We find a low level of Molecular Gas in our sample of radio-selected AGNs, indicating that galaxies do not need much Molecular Gas to host an AGN. The presence of a Molecular Gas disk in some galaxies and the wide range of Molecular Gas masses may be indicative of different origins for the Gas, which we can not exclude at present (e.g., minor/major mergers, stellar mass loss, or accretion).
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Molecular Gas in nearby elliptical radio galaxies
AIP Conference Proceedings, 2008Co-Authors: B. Ocana-flaquer, Stephane Leon, Jeremy Lim, Francoise Combes, Dinh-v-trungAbstract:Powerful radio-AGN are hosted by massive elliptical galaxies which are usually very poor in Molecular Gas. Nevertheless the central Black Hole (BH) needs Molecular Gas for the nuclear activity. Thus it is important to study the origin, the distribution and the kinematics of the Molecular Gas in such objects. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. The main result of that survey is the low content in Molecular Gas of such galaxies compared to Seyfert galaxies. The median value of the Molecular Gas mass is 4x10^8 Msun. Moreover, the CO spectra indicate the presence of a central Molecular Gas disk in some of these radio galaxies. We complemented this survey with photometric data of SPITZER and IRAS fluxes with the purpose to study the dust and its relation with the Molecular Gas and AGN.
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Molecular Gas in Classical Elliptical Radio Galaxies
Astrophysics and Space Science Library, 2004Co-Authors: Jeremy Lim, Stephane Leon, Francoise Combes, Dinh-v-trungAbstract:We report the results of two comprehensive surveys for CO Molecular Gas in classical (i.e., extended double-lobed) radio galaxies, all of which are classified as elliptical (or perhaps S0) galaxies. Our first survey comprises all twenty-four elliptical galaxies in the revised 3C catalog at redshifts z ≤ 0.031; only one, 3C 84 (Perseus A), had previously been detected in Molecular Gas, with a mass of ~ 1010 M⊙. We detected four galaxies in this sample for the first time. Our second survey comprises all twenty-one classical elliptical (or SO) radio galaxies in the northern hemisphere at z ≤ 0.023 exceeding a selected radio flux density, including seven of the 3C galaxies (four detected) in our first survey. We deteced another four galaxies in this sample for the first time. Six of the eight galaxies detected have Molecular Gas masses in the narrow range 2–4 × 108 M⊙, which is comparable to that in Centaurus A, and in all span the range 1 × 107−1 × 109 M⊙. All have very broad double-horned line profiles characteristic of a central rotating disk or toms. The remaining galaxies have upper limits in Molecular Gas mass of a few 108 M⊙, and in one case a few 107 M⊙. By contrast, previous surveys of radio galaxies had found Molecular Gas masses of 109–1010 M⊙, but these surveys preferentially selected IR-bright (i.e., dusty) galaxies, and many of the detections are of systems with compact (nuclear) radio emission hosted by disk or merging galaxies. Our results suggest that the Molecular Gas in most classical elliptical radio galaxies probably originate from the cannibalism of a relatively low-mass but Gas-rich galaxy by the dominant host elliptical galaxy, as proposed by Lim et al. (2000) based on early results from the first survey.
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Molecular Gas Reservoir in low-z Powerful Radio Galaxies
arXiv: Astrophysics, 2002Co-Authors: Jeremy Lim, Stephane Leon, Francoise Combes, Dinh-v-trungAbstract:We report a survey for Molecular Gas in 3C radio galaxies at redshifts z < 0.031. Four of the twenty-three galaxies observed were detected with Molecular Gas masses in the range 10^7--10^9 Msun. The remainder had typical upper limits in Molecular Gas masses of ~10^8 Msun.
Min S. Yun - One of the best experts on this subject based on the ideXlab platform.
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COLD Molecular Gas IN MERGER REMNANTS. I. FORMATION OF Molecular Gas DISKS
The Astrophysical Journal Supplement Series, 2014Co-Authors: Junko Ueda, Daisuke Iono, Min S. Yun, Alison F. Crocker, Desika Narayanan, Shinya Komugi, Daniel Espada, Bunyo Hatsukade, Hiroyuki Kaneko, Yuichi MatsudaAbstract:We present the 1 kpc resolution 12CO imaging study of 37 optically selected local merger remnants using new and archival interferometric maps obtained with ALMA, CARMA, the Submillimeter Array, and the Plateau de Bure Interferometer. We supplement a sub-sample with single-dish measurements obtained at the Nobeyama Radio Observatory 45 m telescope for estimating the Molecular Gas mass (107 – 11 M ☉) and evaluating the missing flux of the interferometric measurements. Among the sources with robust CO detections, we find that 80% (24/30) of the sample show kinematical signatures of rotating Molecular Gas disks (including nuclear rings) in their velocity fields, and the sizes of these disks vary significantly from 1.1 kpc to 9.3 kpc. The size of the Molecular Gas disks in 54% of the sources is more compact than the K-band effective radius. These small Gas disks may have formed from a past Gas inflow that was triggered by a dynamical instability during a potential merging event. On the other hand, the rest (46%) of the sources have Gas disks that are extended relative to the stellar component, possibly forming a late-type galaxy with a central stellar bulge. Our new compilation of observational data suggests that nuclear and extended Molecular Gas disks are common in the final stages of mergers. This finding is consistent with recent major-merger simulations of Gas-rich progenitor disks. Finally, we suggest that some of the rotation-supported turbulent disks observed at high redshifts may result from galaxies that have experienced a recent major merger.
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Molecular Gas in Optically Selected Mergers
The Astrophysical Journal, 2001Co-Authors: Min S. Yun, John E. HibbardAbstract:We have mapped the 2.6 mm CO J \ 1 ] 0 emission in three optically selected ii Toomre sequence ˇˇ mergers (NGC 520, NGC 3921, NGC 4676). The Molecular Gas distribution is well resolved by the observations. For NGC 520 and NGC 4676A, the nuclear Gas concentrations form a disklike or a ringlike structure, and the Gas kinematics are regular and consistent with simple rotation. Discrete Molecular Gas complexes are found along the stellar bar in NGC 4676B, and the Gas kinematics is consistent with the disk rotation traced in Ha. The Molecular Gas distribution in NGC 3921 is asymmetric about the stellar remnant, and both the distribution and kinematics suggest that the Molecular Gas has not settled into the center of the remnant. Molecular Gas clouds are detected outside the central regions of NGC 3921 and NGC 4676, and they may be associated with the tidal tails and bridges mapped in H I. Departures from the canonical scenario for a merger involving two large spiral galaxies are found in all three Toomre sequence mergers studied. Our data suggest that one of the progenitor disks in NGC 520 and NGC 3921 was relatively Gas-poor. A detailed comparison of these optically selected mergers and more luminous IR-selected mergers is deferred to a separate paper. Subject headings: galaxies: individual (NGC 520, NGC 3921, NGC 4676) ¨ galaxies: interactions ¨ + + + +
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Molecular Gas in Optically Selected Mergers
arXiv: Astrophysics, 1999Co-Authors: Min S. Yun, John E. HibbardAbstract:We have mapped the 2.6 mm CO (1-0) emission in three optically selected "Toomre Sequence" mergers (NGC 520, NGC 3921, NGC 4676). The Molecular Gas distribution is well resolved by the observations. For NGC 520 and NGC 4676A, the nuclear Gas concentrations form a disk- or a ring-like structure, and the Gas kinematics are regular and are consistent with simple rotation. Discrete Molecular Gas complexes are found along the stellar bar in NGC 4676B, and the Gas kinematics is consistent with the disk rotation traced in H alpha. The Molecular Gas distribution in NGC 3921 is asymmetric about the stellar remnant, and both the distribution and kinematics suggest that the Molecular Gas has not settled into the center of the remnant. Molecular Gas clouds are detected outside the central regions of NGC 3921 and NGC 4676, and they may be associated with the tidal tails and bridges mapped in HI. Departures from the canonical scenario for a merger involving two large spiral galaxies are found in all three Toomre Sequence mergers studied. Our data suggest that one of the progentor disks in NGC 520 and NGC 3921 were relatively Gas-poor. A detailed comparison of these optically selected mergers and more luminous IR selected mergers is deferred to a companion paper (Paper II).
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Molecular Gas in the Inner 100 Parsecs of M51
The Astrophysical Journal, 1998Co-Authors: Nick Scoville, Min S. Yun, Lee Armus, Holland C. FordAbstract:We report imaging of CO (2-1) emission in the nucleus of M51 at 1'' (47 pc) resolution. Molecular Gas is found closely associated with the nuclear radio jet and the X-shaped dust absorption feature seen in the Hubble Space Telescope images. The CO emission lies along the side of the nuclear radio continuum "jet." The strongest Molecular emission is not symmetric in either position or velocity with respect to the nucleus—the dominant feature is at redshifted velocities and peaks 1'' to the west of the radio/optical nucleus. The CO (2-1) emission has an integrated flux implying a Molecular Gas mass of 107 M☉ for a standard Galactic giant Molecular cloud CO-to-H2 conversion ratio, which is consistent with the total virial mass of the individual complexes. The redshifted CO emission is elongated with a deconvolved semimajor axis of 65 pc (138). Assuming the Molecular Gas moves in circular orbit about the nucleus (defined by the point radio source), we find a dynamical mass of 2 × 108 M☉ at R≥47 pc with no correction for inclination. The Molecular Gas has sufficient density (≥105 cm-3) to collimate the radio jet and ionized outflow from the active galactic nucleus (AGN), and this Gas may in fact be the reservoir of matter that supplies the AGN.
Stephane Leon - One of the best experts on this subject based on the ideXlab platform.
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TANGO I: ISM in nearby radio galaxies. Molecular Gas
Astronomy and Astrophysics, 2010Co-Authors: Breezy Ocaña Flaquer, Stephane Leon, Francoise Combes, Jeremy LimAbstract:Powerful radio-AGN are hosted by massive elliptical galaxies which are usually very poor in Molecular Gas. Nevertheless Gas is needed in the very center to feed the nuclear activity. We aim to study the Molecular Gas properties (mass, kinematics, distribution, origin) in such objects, and to compare them with results of other known samples. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. The main result of our survey is the very low content in Molecular Gas of such galaxies compared to spiral or FIR-selected galaxies. The median value of the Molecular Gas mass, including detections and upper limits, is 2.2x10^8 Msun. If separated into FR-I and FR-II types, a difference in H_2 masses between them is found. The median value of FR-I galaxies is about 1.9x10^8 and higher for FR-II galaxies, about 4.5x10^8 Msun but this is very probably entirely due to a Malmquist bias. Our results contrast with previous surveys, mainly selected through the FIR emission, implying larger observed masses of Molecular Gas. Moreover, the shape of CO spectra suggest the presence of a central Molecular Gas disk in 30% of these radio galaxies, a lower rate than in other active galaxy samples.
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tango i interstellar medium in nearby radio galaxies Molecular Gas
Astronomy and Astrophysics, 2010Co-Authors: Ocana B Flaquer, F Combes, Stephane Leon, Jeremy LimAbstract:Context. Powerful radio-AGN are hosted by massive elliptical galaxies that are usually very poor in Molecular Gas. Nevertheless, Gas is needed at their very center to feed the nuclear activity. Aims. We study the Molecular Gas properties (i.e., mass, kinematics, distribution, origin) of these objects, and compare them with results for other known samples. Methods. At the IRAM-30m telescope, we performed a survey of the CO(1-0) and CO(2-1) emission from the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. Results. The main result of our survey is that the Molecular Gas content of these galaxies is very low compared to spiral or FIR-selected galaxies. The median value of the Molecular Gas mass, including detections and upper limits, is 2.2 × 10 8 M ⊙ . When separated into FR-I and FR-II types, a difference in their H 2 masses is found. The median value of FR-I galaxies is about 1.9 x 10 8 M ⊙ and higher for FR-II galaxies, at about 4.5 x 10 8 M ⊙ . Which is probably entirely because of a Malmquist bias. Our results contrast with those of previous surveys, whose targets were mainly selected by means of their FIR emission, implying that we measure higher observed masses of Molecular Gas. Moreover, the shape of CO spectra suggest that a central Molecular Gas disk exists in 30% of these radio galaxies, a lower rate than in other active galaxy samples. Conclusions. We find a low level of Molecular Gas in our sample of radio-selected AGNs, indicating that galaxies do not need much Molecular Gas to host an AGN. The presence of a Molecular Gas disk in some galaxies and the wide range of Molecular Gas masses may be indicative of different origins for the Gas, which we can not exclude at present (e.g., minor/major mergers, stellar mass loss, or accretion).
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Molecular Gas in nearby powerful radio galaxies
arXiv: Cosmology and Nongalactic Astrophysics, 2009Co-Authors: B. Ocana-flaquer, Stephane Leon, Dinh-v-trung, L. Lim, Francoise CombesAbstract:Powerful radio-AGN are normally hosted by massive elliptical galaxies which are usually very poor in Molecular Gas. Nevertheless the Gas is needed in the very center to feed the nuclear activity. Thus it is important to study the origin, the distribution and the kinematics of the Molecular Gas in such objects. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio-continuum fluxes. The main result of this survey is the very low content in Molecular Gas of such galaxies compared to FIR selected galaxies. The median value of the Molecular Gas mass, taking into account the upper limits, is 1x10^8 Msun; if we calculate it for all the galaxies together, and if we separate them into FR-I and FR-II type galaxies, an important difference is found between them. Moreover, the CO spectra indicates the presence of a central Molecular Gas disk in these radio galaxies. Our results contrast with previous surveys, mainly selected through the FIR emission, with a larger mass of Molecular Gas observed. The first results indicate that minor mergers are good candidates to fuel the central part of the radio galaxies of our sample.
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Molecular Gas in nearby elliptical radio galaxies
AIP Conference Proceedings, 2008Co-Authors: B. Ocana-flaquer, Stephane Leon, Jeremy Lim, Francoise Combes, Dinh-v-trungAbstract:Powerful radio-AGN are hosted by massive elliptical galaxies which are usually very poor in Molecular Gas. Nevertheless the central Black Hole (BH) needs Molecular Gas for the nuclear activity. Thus it is important to study the origin, the distribution and the kinematics of the Molecular Gas in such objects. We have performed at the IRAM-30m telescope a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radio continuum fluxes. The main result of that survey is the low content in Molecular Gas of such galaxies compared to Seyfert galaxies. The median value of the Molecular Gas mass is 4x10^8 Msun. Moreover, the CO spectra indicate the presence of a central Molecular Gas disk in some of these radio galaxies. We complemented this survey with photometric data of SPITZER and IRAS fluxes with the purpose to study the dust and its relation with the Molecular Gas and AGN.
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The Molecular Gas in the nuclear region of NGC 4569
AIP Conference Proceedings, 2005Co-Authors: Frédéric Boone, Stephane Leon, Francoise Combes, Eva Schinnerer, Andrew J. Baker, Santiago García-burillo, L. K. Hunt, R. Neri, Linda J. Tacconi, P. EnglmaierAbstract:Millimeter CO observations of the galaxy NGC 4569 made in the frame of the NUGA survey are presented. A large mass of Molecular Gas is found in the inner 1.6 kpc that can efficiently feed the strong nuclear starburst. The impact of the starburst on the ISM can be seen in the morphology and physical state of the Molecular Gas. Analysis of the dynamics is in progress.
John E. Hibbard - One of the best experts on this subject based on the ideXlab platform.
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Molecular Gas in Optically Selected Mergers
The Astrophysical Journal, 2001Co-Authors: Min S. Yun, John E. HibbardAbstract:We have mapped the 2.6 mm CO J \ 1 ] 0 emission in three optically selected ii Toomre sequence ˇˇ mergers (NGC 520, NGC 3921, NGC 4676). The Molecular Gas distribution is well resolved by the observations. For NGC 520 and NGC 4676A, the nuclear Gas concentrations form a disklike or a ringlike structure, and the Gas kinematics are regular and consistent with simple rotation. Discrete Molecular Gas complexes are found along the stellar bar in NGC 4676B, and the Gas kinematics is consistent with the disk rotation traced in Ha. The Molecular Gas distribution in NGC 3921 is asymmetric about the stellar remnant, and both the distribution and kinematics suggest that the Molecular Gas has not settled into the center of the remnant. Molecular Gas clouds are detected outside the central regions of NGC 3921 and NGC 4676, and they may be associated with the tidal tails and bridges mapped in H I. Departures from the canonical scenario for a merger involving two large spiral galaxies are found in all three Toomre sequence mergers studied. Our data suggest that one of the progenitor disks in NGC 520 and NGC 3921 was relatively Gas-poor. A detailed comparison of these optically selected mergers and more luminous IR-selected mergers is deferred to a separate paper. Subject headings: galaxies: individual (NGC 520, NGC 3921, NGC 4676) ¨ galaxies: interactions ¨ + + + +
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Molecular Gas in Optically Selected Mergers
arXiv: Astrophysics, 1999Co-Authors: Min S. Yun, John E. HibbardAbstract:We have mapped the 2.6 mm CO (1-0) emission in three optically selected "Toomre Sequence" mergers (NGC 520, NGC 3921, NGC 4676). The Molecular Gas distribution is well resolved by the observations. For NGC 520 and NGC 4676A, the nuclear Gas concentrations form a disk- or a ring-like structure, and the Gas kinematics are regular and are consistent with simple rotation. Discrete Molecular Gas complexes are found along the stellar bar in NGC 4676B, and the Gas kinematics is consistent with the disk rotation traced in H alpha. The Molecular Gas distribution in NGC 3921 is asymmetric about the stellar remnant, and both the distribution and kinematics suggest that the Molecular Gas has not settled into the center of the remnant. Molecular Gas clouds are detected outside the central regions of NGC 3921 and NGC 4676, and they may be associated with the tidal tails and bridges mapped in HI. Departures from the canonical scenario for a merger involving two large spiral galaxies are found in all three Toomre Sequence mergers studied. Our data suggest that one of the progentor disks in NGC 520 and NGC 3921 were relatively Gas-poor. A detailed comparison of these optically selected mergers and more luminous IR selected mergers is deferred to a companion paper (Paper II).