scholarly journals AGN Feedback Driven Molecular Outflow in NGC 1266

2012 ◽  
Vol 8 (S290) ◽  
pp. 175-176
Author(s):  
K. Alatalo ◽  
K. E. Nyland ◽  
G. Graves ◽  
S. Deustua ◽  
J. Wrobel ◽  
...  
Keyword(s):  
Star Formation ◽  
Brightness Temperature ◽  
Significant Role ◽  
Molecular Gas ◽  
High Brightness ◽  
Continuum Source ◽  
Low Level ◽  
Molecular Outflow ◽  
Field Galaxy ◽  
Red Sequence

AbstractNGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high brightness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies.

scholarly journals Major impact from a minor merger

2018 ◽  
Vol 615 ◽  
pp. A122 ◽  
Author(s):  
S. König ◽  
S. Aalto ◽  
S. Muller ◽  
J. S. Gallagher III ◽  
R. J. Beswick ◽  
...  
Keyword(s):  
Star Formation ◽  
Brightness Temperature ◽  
Central Region ◽  
Molecular Clouds ◽  
Molecular Gas ◽  
Transfer Model ◽  
Dense Gas ◽  
Giant Molecular Clouds ◽  
Minor Mergers ◽  
Co Emission

Context. Minor mergers are important processes contributing significantly to how galaxies evolve across the age of the Universe. Their impact on the growth of supermassive black holes and star formation is profound – about half of the star formation activity in the local Universe is the result of minor mergers. Aims. The detailed study of dense molecular gas in galaxies provides an important test of the validity of the relation between star formation rate and HCN luminosity on different galactic scales – from whole galaxies to giant molecular clouds in their molecular gas-rich centers. Methods. We use observations of HCN and HCO+ 1−0 with NOEMA and of CO3−2 with the SMA to study the properties of the dense molecular gas in the Medusa merger (NGC 4194) at 1′′ resolution. In particular, we compare the distribution of these dense gas tracers with CO2−1 high-resolution maps in the Medusa merger. To characterize gas properties, we calculate the brightness temperature ratios between the three tracers and use them in conjunction with a non-local thermodynamic equilibrium (non-LTE) radiative line transfer model. Results. The gas represented by HCN and HCO+ 1−0, and CO3−2 does not occupy the same structures as the less dense gas associated with the lower-J CO emission. Interestingly, the only emission from dense gas is detected in a 200 pc region within the “Eye of the Medusa”, an asymmetric 500 pc off-nuclear concentration of molecular gas. Surprisingly, no HCN or HCO+ is detected for the extended starburst of the Medusa merger. Additionally, there are only small amounts of HCN or HCO+ associated with the active galactic nucleus. The CO3−2/2−1 brightness temperature ratio inside “the Eye” is ~2.5 – the highest ratio found so far – implying optically thin CO emission. The CO2−1/HCN 1−0 (~9.8) and CO2−1/HCO+ 1−0 (~7.9) ratios show that the dense gas filling factor must be relatively high in the central region, consistent with the elevated CO3−1/2−1 ratio. Conclusions. The line ratios reveal an extreme, fragmented molecular cloud population inside the Eye with large bulk temperatures (T > 300 K) and high gas densities (n(H2) > 104 cm-3). This is very different from the cool, self-gravitating structures of giant molecular clouds normally found in the disks of galaxies. The Eye of the Medusa is found at an interface between a large-scale minor axis inflow and the central region of the Medusa. Hence, the extreme conditions inside the Eye may be the result of the radiative and mechanical feedback from a deeply embedded, young and massive super star cluster formed due to the gas pile-up at the intersection. Alternatively, shocks from the inflowing gas entering the central region of the Medusa may be strong enough to shock and fragment the gas. For both scenarios, however, it appears that the HCN and HCO+ dense gas tracers are not probing star formation, but instead a post-starburst and/or shocked ISM that is too hot and fragmented to form newstars. Thus, caution is advised in taking the detection of emission from dense gas tracers as evidence of ongoing or imminent star formation.

scholarly journals DETECTION OF A HIGH BRIGHTNESS TEMPERATURE RADIO CORE IN THE ACTIVE-GALACTIC-NUCLEUS-DRIVEN MOLECULAR OUTFLOW CANDIDATE NGC 1266

2013 ◽  
Vol 779 (2) ◽  
pp. 173 ◽  
Author(s):  
Kristina Nyland ◽  
Katherine Alatalo ◽  
J. M. Wrobel ◽  
Lisa M. Young ◽  
Raffaella Morganti ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Active Galactic Nucleus ◽  
High Brightness ◽  
Molecular Outflow

scholarly journals Detection of a high brightness temperature radio core in the AGN-driven molecular outflow candidate NGC 1266

2013 ◽  
Vol 9 (S303) ◽  
pp. 388-389
Author(s):  
K. Nyland ◽  
K. Alatalo ◽  
J. M. Wrobel ◽  
L. M. Young ◽  
R. Morganti ◽  
...  
Keyword(s):  
Star Formation ◽  
Brightness Temperature ◽  
Spatial Resolution ◽  
Spectral Component ◽  
Formation Rate ◽  
Radio Continuum ◽  
Absorption Data ◽  
Additional Energy ◽  
Molecular Outflow ◽  
Sgr A

AbstractWe present new Karl G. Jansky Very Large Array (VLA) Hi absorption and Very Long Baseline Array (VLBA) continuum observations of the active galactic nucleus (AGN)-driven molecular outflow candidate NGC 1266. Although other well-known systems with molecular outflows may be driven by star formation in a central molecular disk, the molecular mass outflow rate reported in Alatalo et al. (2011) in NGC 1266 of 13 M⊙ year−1 exceeds star formation rate estimates from a variety of tracers. This suggests that an additional energy source, such as an AGN, may play a significant role in powering the outflow. Our high spatial resolution Hi absorption data reveal compact absorption against the radio continuum core co-located with the putative AGN, and the presence of a blueshifted spectral component re-affirms that gas is indeed flowing out of the system. Our VLBA observations at 1.65 GHz reveal one continuum source within the densest portion of the molecular gas, with a diameter d < 8 mas (1.2 pc), a radio power Prad = 1.48 × 1020 W Hz−1, and a brightness temperature Tb > 1.5 × 107 K that is most consistent with an AGN origin. The radio continuum energetics implied by the compact VLBA source, as well as archival VLA continuum observations at lower spatial resolution, further support the possibility that the AGN in NGC 1266 could be driving the molecular outflow. These findings suggest that even low-level AGNs, with supermassive black hole masses similar to Sgr A*, may be able to launch massive outflows in their host galaxies.

scholarly journals A Study of Dense Molecular Gas and Star Formation toward the Vela Molecular Ridge with NANTEN

1999 ◽  
Vol 51 (6) ◽  
pp. 775-790 ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Norikazu Mizuno ◽  
Hiro Saito ◽  
Ken'ichi Matsunaga ◽  
Akira Mizuno ◽  
...  
Keyword(s):  
Star Formation ◽  
Total Mass ◽  
Massive Stars ◽  
Emission Lines ◽  
Molecular Gas ◽  
H Ii Regions ◽  
Molecular Outflow ◽  
Total Luminosity ◽  
Preceding Work ◽  
Order Of Magnitude

Abstract New observations of the J=1−0 12CO, 13CO, and C18O emission lines have been extensively made toward the Vela Molecular Ridge (VMR) with NANTEN. The most prominent cloud is the giant molecular cloud, corresponding to the VMR-C region (Vela C). The present C18O distribution has been identified as 29 clouds. Among them, the most massive one is included in Vela C, having a total mass of ∼ 4.4 × 104M⊙. The rest of them are smaller C18O clouds of 102-103M⊙. Star formation in the region is almost exclusively occurring in the C18O clouds. The luminosities of the associated protostellar IRAS sources range from 5 L⊙ to 1.1 × 104L⊙, and the luminosity distribution is found to be well represented by the relation dNstar/dLIR ∞ L-1.65±0.14IR. We find that the ratios of the total luminosity of the sources associated with given C18O clouds to the cloud masses are significantly enhanced for those clouds associated with H II regions by an order of magnitude. This is interpreted as meaning that the formation of massive stars is enhanced due to the effects of H II regions, as is consistent with the preceding work. We have also newly found molecular outflow toward IRAS 08588–4347 as well as five possible candidates for outflows.

An H I Mosaic of the Small Magellanic Cloud

1995 ◽  
Vol 12 (1) ◽  
pp. 13-19 ◽  
Author(s):  
L. Staveley-Smith ◽  
R. J. Sault ◽  
D. McConnell ◽  
M. J. Kesteven ◽  
D. Hatzidimitriou ◽  
...  
Keyword(s):  
Star Formation ◽  
Neutral Hydrogen ◽  
Optical Emission ◽  
Magellanic Cloud ◽  
Molecular Gas ◽  
Small Magellanic Cloud ◽  
High Brightness ◽  
First Results ◽  
Low Metallicity ◽  
High Column

AbstractThis paper describes the first results from a 20 deg2 mosaic of the Small Magellanic Cloud (SMC) in the λ21-cm line of neutral hydrogen. The mosaic consists of 320 separate pointings with the 375-m array of the Australia Telescope Compact Array. The angular resolution is 1′· 5 (26 pc, for a distance of 60 kpc) and the velocity resolution is l·6kms−1. The images reveal a structure of remarkable complexity, with much of the spatial power contained in high-brightness temperature compact knots and filaments. Numerous wind-blown ‘bubbles’ and ‘supershells’ are evident in the data, both inside and outside the stellar confines of the SMC. Some high-density H I regions are seen to correlate with Hα regions, indicating sites of current star formation. However, many high-column-density H I regions are devoid of optical emission and may represent regions of future star formation. These regions may be under-abundant in diffuse molecular gas due to the high radiation field and low metallicity of the SMC.

scholarly journals Quenching of Star Formation in Molecular Outflow Host NGC 1266

2012 ◽  
Vol 8 (S292) ◽  
pp. 371-371
Author(s):  
K. Alatalo ◽  
K. E. Nyland ◽  
G. Graves ◽  
S. Deustua ◽  
L. M. Young ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Population Analysis ◽  
Young Stars ◽  
Molecular Gas ◽  
Molecular Outflow ◽  
Deep Imaging ◽  
The Galaxy ◽  
The Rich ◽  
Stellar Kinematic

AbstractWe detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a role in instigating outflows in other systems, deep imaging of NGC 1266 as well as stellar kinematic observations from SAURON, have failed to provide evidence that NGC 1266 has recently been involved in a major interaction. The molecular gas and the instantaneous SF tracers indicate that the current sites of star formation are located in a hypercompact disk within 200 pc of the nucleus (Fig. 1; SF rate ≈ 2 M⊙ yr−1). On the other hand, tracers of recent star formation, such as the Hβ absorption map from SAURON and stellar population analysis show that the young stars are distributed throughout a larger area of the galaxy than current star formation. As the AGN at the center of NGC 1266 continues to drive cold gas out of the galaxy, we expect star formation rates to decline as the star formation is ultimately quenched. Thus, NGC 1266 is in the midst of a key portion of its evolution and continued studies of this unique galaxy may help improve our understanding of how galaxies transition from the blue to the red sequence (Alatalo et al. 2011).

scholarly journals Molecular gas and star formation in the red-sequence counter-rotating disc galaxy NGC 4550

2009 ◽  
Vol 393 (4) ◽  
pp. 1255-1264 ◽  
Author(s):  
Alison F. Crocker ◽  
Hyunjin Jeong ◽  
Shinya Komugi ◽  
Francoise Combes ◽  
Martin Bureau ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Gas ◽  
Rotating Disc ◽  
Disc Galaxy ◽  
Sequence Counter ◽  
Red Sequence

scholarly journals Molecular Gas and Star-formation in Selected H-ATLAS SDP Lensed SMGs

2012 ◽  
Vol 8 (S292) ◽  
pp. 192-192
Author(s):  
Lerothodi L. Leeuw ◽  
Dominik A. Riechers ◽  
John M. Carpenter ◽  
Mattia Negrello ◽  
Rob J. Ivison ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Brightness Temperature ◽  
Millimeter Wave ◽  
Molecular Gas ◽  
Large Area ◽  
Spatially Resolved ◽  
Area Survey ◽  
Science Demonstration

AbstractWe present detections of spatially resolved CO(J = 2→1) and CO(J = 3→2) emission, respectively, from the lensed submillimeter (submm) galaxies (SMGs), ID 9 (z = 1.577) and ID 17b (z = 2.308), found in the Science Demonstration Phase (SDP) of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS, www.h-atlas.org). The detections were obtained using the Combined Array for Research in Millimeter-wave Astronomy (CARMA, www.mmarray.org) and confirm redshifts of the lensed galaxies. We exploit the CARMA data together with existing high-J observations, to determine, among other physical properties of the lensed SMGs, the CO line luminosities, brightness temperature ratios, gas masses, and spatial sizes.

scholarly journals Interaction between molecular outflows and dense gas in the cluster-forming region OMC-2/FIR4

2006 ◽  
Vol 2 (S237) ◽  
pp. 475-475
Author(s):  
Yoshito Shimajiri ◽  
S. Takahashi ◽  
S. Takakuwa ◽  
M. Saito ◽  
R. Kawabe
Keyword(s):  
Cluster Formation ◽  
Major Axis ◽  
List Type ◽  
Dense Gas ◽  
Continuum Source ◽  
Molecular Outflows ◽  
Molecular Outflow ◽  
Dense Cores ◽  
Potential Source ◽  
Molecular Lines

AbstractSince most stars are born as members of clusters (Lada & Lada 2003), it is important to clarified the detailed mechanism of cluster formation for comprehensive understanding of star formation. However, our current understanding of cluster formation is limited due to the followings; (a)Cluster forming regions are located at the far distance.(b)There are complex mixtures of outflows and dense gas in cluster forming regions. So, we focused on the Orion Molecular Cloud 2 region (OMC-2), a famous cluster-forming region (Lada & Lada 2003) and the most nearest GMC. We observed the FIR 4 region with the Nobeyama Millimeter Array(NMA), Atacama Submillimeter Telescope Experiment (ASTE). In this region, there are 3 protostars (FIR3, FIR4, FIR5) which were identified as 1.3 mm dust continuum sources (Chini et al. 1997) and driving sources of mixed outflows, and FIR 4 is the most strongest source of 1.3 mm dust continuum in OMC-2. Molecular lines we adopted are a high density (105cm−3) gas tracer of H13CO+ (J=1-0), a molecular outflow tracer of 12CO(J=1-0) and 12CO(J=3-2), and SiO(J=2-1 v=0) as a tracer of shocks associated with an interaction between outflows and dense gas.From results of the 12CO(J=1-0) outflow, H13CO+ dense gas, and the SiO shock, the outflow from FIR 3 interacts with dense gas in the FIR 4 region. Moreover the Position-Velocity diagram along the major axis of the 12CO(J=3-2) outflow shows that the 12CO(J=1-0) and SiO emission exhibits a L shape (the line widths increase in the interacting region in morphology). This is an evidence of interaction between the outflows and dense gas (Takakuwa et al. 2003). From result of the 3 mm dust continuum, the interacted region by the molecular outflow of FIR 3 is an assemble of seven dense cores. The mass of each core is 0.1-0.8 M. This clumpy structure is evident only at FIR 4 in the entire OMC-2/3 region. There are possible that two cores are in the proto-stellar phase, because 3 mm dust continuum source correspond to NIR source or 3.6 cm f-f jet source. From these results, cores in the FIR 4 region may be potential source of the next-generation stars. In the other words, there is a possibility that the molecular outflow ejected from FIR 3 is triggering the cluster formation in the FIR 4 region.

From global to local scales in galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 391-395
Author(s):  
Sebastian F. Sánchez ◽  
Carlos Lopez Cobá
Keyword(s):  
Star Formation ◽  
Spatial Scales ◽  
Bimodal Distribution ◽  
Spectroscopic Properties ◽  
Molecular Gas ◽  
Ionized Gas ◽  
Galaxy Surveys ◽  
Quenching Process ◽  
Formation Efficiency ◽  
Integral Field

AbstractWe summarize here some of the results reviewed recently by Sanchez (2020) comprising the advances in the comprehension of galaxies in the nearby universe based on integral field spectroscopic galaxy surveys. In particular we explore the bimodal distribution of galaxies in terms of the properties of their ionized gas, showing the connection between the star-formation (quenching) process with the presence (absence) of molecular gas and the star-formation efficiency. We show two galaxy examples that illustrates the well known fact that ionization in galaxies (and the processes that produce it), does not happen monolitically at galactic scales. This highlight the importance to explore the spectroscopic properties of galaxies and the evolutionary processes unveiled by them at different spatial scales, from sub-kpc to galaxy wide.

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