scholarly journals SMA observations of Haro 2: molecular gas around a hot superbubble

2020 ◽  
Vol 494 (1) ◽  
pp. 1-9
Author(s):  
Sara C Beck ◽  
Pei-Ying Hsieh ◽  
Jean Turner
Keyword(s):  
Dwarf Galaxy ◽  
Star Clusters ◽  
Molecular Gas ◽  
Apparent Velocity ◽  
Velocity Range ◽  
X Ray ◽  
Ideal Candidate ◽  
The Galaxy ◽  
Extended Emission

ABSTRACT Haro 2, a nearby dwarf starburst dwarf galaxy with strong Ly α emission, hosts a starburst that has created outflows and filaments. The clear evidence for galactic outflow makes it an ideal candidate for studying the role of molecular gas in feedback processes in a dwarf galaxy. We observed CO(2–1) in Haro 2 at the Submillimeter Array in the compact and extended configurations, and have mapped the molecular emission with velocity resolution 4.1 km s−1 and spatial resolution 2.0 × 1.6 arcsec2. With this significant increase of resolution over previous measurements, we see that the molecular gas comprises two components: bright clumps associated with the embedded star clusters of the starburst, and fainter extended emission east of the starburst region. The extended emission coincides with an X-ray bubble and has the kinematic signatures of an outflowing cone or of an expanding shell or bubble; the velocity range is ∼35 km s−1. We suggest that the starburst winds that created the X-ray bubble have entrained the molecular gas, and that the apparent velocity gradient at an angle to the photometric axis is an artefact caused by the outflow. The molecular and X-ray activity is on the east of the galaxy and the ionized outflow and optical filaments are west; their relationship is not clear.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

scholarly journals The accreted nuclear clusters of the Milky Way

2020 ◽  
Vol 500 (2) ◽  
pp. 2514-2524
Author(s):  
Joel Pfeffer ◽  
Carmela Lardo ◽  
Nate Bastian ◽  
Sara Saracino ◽  
Sebastian Kamann
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Dwarf Galaxy ◽  
Star Clusters ◽  
Host Galaxy ◽  
The Galaxy ◽  
Nuclear Clusters ◽  
The Common ◽  
Massive Clusters ◽  
Peculiar Case

ABSTRACT A number of the massive clusters in the halo, bulge, and disc of the Galaxy are not genuine globular clusters (GCs) but instead are different beasts altogether. They are the remnant nuclear star clusters (NSCs) of ancient galaxies since accreted by the Milky Way. While some clusters are readily identifiable as NSCs and can be readily traced back to their host galaxy (e.g. M54 and the Sagittarius Dwarf galaxy), others have proven more elusive. Here, we combine a number of independent constraints, focusing on their internal abundances and overall kinematics, to find NSCs accreted by the Galaxy and trace them to their accretion event. We find that the true NSCs accreted by the Galaxy are: M54 from the Sagittarius Dwarf, ω Centari from Gaia-Enceladus/Sausage, NGC 6273 from Kraken, and (potentially) NGC 6934 from the Helmi Streams. These NSCs are prime candidates for searches of intermediate-mass black holes (BHs) within star clusters, given the common occurrence of galaxies hosting both NSCs and central massive BHs. No NSC appears to be associated with Sequoia or other minor accretion events. Other claimed NSCs are shown not to be such. We also discuss the peculiar case of Terzan 5, which may represent a unique case of a cluster–cluster merger.

Dwarf Galaxies and Cluster Environments

2018 ◽  
Vol 14 (S344) ◽  
pp. 373-376
Author(s):  
Yasuhiro Hashimoto ◽  
J. Patrick Henry ◽  
Hans Böhringer
Keyword(s):  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Detection Algorithm ◽  
Diffuse Light ◽  
X Ray ◽  
Optical Images ◽  
Highly Sensitive ◽  
The Galaxy ◽  
Galaxy Populations ◽  
Selection Of

AbstractWe report an investigation of the properties of dwarf galaxies (Mr < -15) inside 26 clusters at z = 0.15 – 0.25, using the X-ray data from the Chandra archive, and optical images taken with Subaru Suprime-Cam. Our results include: 1. Investigation of the dwarf galaxy density distribution is sensitive to the background galaxies and the choice of colour selection of galaxies. 2. Cluster-centric dwarf-to-giant ratio is highly sensitive to the level of subtracted background galaxies. 3. A certain fraction of faint galaxies always remain undetected by the detection algorithm near the center of clusters, even after carefully treating the halo or extra diffuse light created by bright galaxies. The number of ‘undetected’ faint galaxies varies significantly from cluster to cluster, and even from pointing to pointing. 4. Dwarf galaxies extend up to 2 Mpc from the center in most clusters. Meanwhile, the distribution of blue dwarf galaxies extends more to the outside. 5. For a given colour, the spatial distributions of dwarf galaxies and giant galaxies become similar. Namely, the most of the radial distribution comes from the colour, rather than the size, of galaxies. 6. Relative to the NFW profile, all of the galaxy populations are showing a deficit near the cluster core (r < 0.3 Mpc). 7. The dwarf-to-giant ratio shows no variation against cluster measures such as the richness and X-ray luminosity, as well as various cluster X-ray characteristics related to possible dynamical status of clusters.

scholarly journals 5.2. Molecular gas and nuclear outflows

1998 ◽  
Vol 184 ◽  
pp. 213-214
Author(s):  
Judith A. Irwin
Keyword(s):  
Spiral Galaxies ◽  
Molecular Gas ◽  
X Ray ◽  
Overwhelming Evidence ◽  
The Galaxy

There is now overwhelming evidence that spiral galaxies can experience nuclear outflows, from radio lobes perpendicular to the disks of edge-on galaxies (Hummel et al. 1983), to optical ionization cones (see list in Wilson and Tsvetanov 1994), to spectacular X-ray emission extending many kpc beyond the disk (e.g. Dahlem et al. 1996). These observations indicate that hot and/or energetic components of the ISM can escape away from the plane of the galaxy from their origin in the nuclear vicinity.

scholarly journals Star Formation and Molecular Gas in Extremely Metal-poor Galaxies: Insights from the Thermal Balance in the Neutral Gas

2018 ◽  
Vol 14 (S344) ◽  
pp. 259-262 ◽  
Author(s):  
Vianney Lebouteiller
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Large Fraction ◽  
Formation Rate ◽  
Conversion Function ◽  
Molecular Gas ◽  
Apparent Lack ◽  
X Ray ◽  
Heating Mechanism ◽  
Neutral Gas

AbstractThe apparent lack of cold molecular gas in blue compact dwarf (BCD) galaxies is at variance with their intense star-formation episode. The CO molecule, often used a tracer of H2 through a conversion function, is selectively photodissociated in dust-poor environments and, as a result, a potentially large fraction of H2 is expected to reside in the so-called CO-dark gas, where it could be traced instead by infrared cooling lines [CI], [CII], and [OI]. Although the fraction of CO-dark gas to total molecular gas is in theory expected to be relatively large in metal-poor galaxies, many uncertainties remain due to the difficulty in identifying the main heating mechanism associated to the cooling lines observed in such galaxies.Investigations of the Herschel Dwarf Galaxy Survey (DGS; Madden et al.2013) show that the heating mechanism in the neutral gas of BCDs cannot be dominated by the photoelectric effect on dust grains below some threshold metallicity due to the low abundance of dust and polycyclic aromatic hydrocarbons, implying that other heating mechanisms need to be invoked, along with a new interpretation of the corresponding infrared line diagnostics. In the study presented here and in Lebouteiller et al. (2017), we use optical and infrared lines to constrain the physical conditions in the HII region + HI region of the BCD I Zw 18 (18 Mpc; ≍2% solar metallicity) within a consistent photoionization and photodissociation model. We show that the HI region is entirely heated by a single ultraluminous X-ray source with important consequences on the applicability of [CII] to trace the star-formation rate and to trace the CO-dark gas. We derive stringent upper limits on the size of H2 clumps that may be detected in the future with JWST and IRAM/NOEMA. We also show that the nature of the X-ray source can be inferred from the corresponding signatures in the ISM. Finally we speculate that star formation may be quenched in extremely metal-poor dwarf galaxies due to X-ray photoionization.

scholarly journals The AGNIFS survey: distribution and excitation of the hot molecular and ionised gas in the inner kpc of nearby AGN hosts

2021 ◽  
Author(s):  
R A Riffel ◽  
T Storchi-Bergmann ◽  
R Riffel ◽  
M Bianchin ◽  
N L Zakamska ◽  
...  
Keyword(s):  
Major Axis ◽  
Thermal Processes ◽  
X Ray ◽  
Accretion Rates ◽  
The Galaxy ◽  
Dusty Torus ◽  
Extended Emission ◽  
The Continuum

Abstract We use the Gemini NIFS instrument to map the H2 2.1218 μm and Brγ flux distributions in the inner 0.04–2 kpc of a sample of 36 nearby active galaxies (0.001 ≲ z ≲ 0.056) at spatial resolutions from 4 to 250 pc. We find extended emission in 34 galaxies. In ∼55 per cent of them, the emission in both lines is most extended along the galaxy major axis, while in the other 45 per cent the extent follows a distinct orientation. The emission of H2 is less concentrated than that of Brγ, presenting a radius that contains half of the flux 60 per cent greater, on average. The H2 emission is driven by thermal processes – X-ray heating and shocks – at most locations for all galaxies, where $0.4&lt;\rm H_2/Br\gamma &lt;6$. For regions where H2/Brγ &gt; 6 (seen in 40 per cent of the galaxies), shocks are the main H2 excitation mechanism, while in regions with H2/Brγ &lt; 0.4 (25 per cent of the sample) the H2 emission is produced by fluorescence. The only difference we found between type 1 and type 2 AGN was in the nuclear emission-line equivalent widths, that are smaller in type 1 than in type 2 due to a larger contribution to the continuum from the hot dusty torus in the former. The gas masses in the inner 125 pc radius are in the range 101 − 104 M⊙ for the hot H2 and 103 − 106 M⊙ for the ionised gas and would be enough to power the AGN in our sample for 105 − 108 yr at their current accretion rates.

scholarly journals Molecular gas in the central region of NGC 7213

2020 ◽  
Vol 641 ◽  
pp. A151
Author(s):  
F. Salvestrini ◽  
C. Gruppioni ◽  
F. Pozzi ◽  
C. Vignali ◽  
A. Giannetti ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Large Scale ◽  
Host Galaxy ◽  
Molecular Gas ◽  
X Ray ◽  
Gas Kinematics ◽  
Star Formation Activity ◽  
Multi Wavelength

We present a multi-wavelength study (from X-ray to mm) of the nearby low-luminosity active galactic nucleus NGC 7213. We combine the information from the different bands to characterise the source in terms of contribution from the AGN and the host-galaxy interstellar medium. This approach allows us to provide a coherent picture of the role of the AGN and its impact, if any, on the star formation and molecular gas properties of the host galaxy. We focused our study on archival ALMA Cycle 1 observations, where the CO(2–1) emission line has been used as a tracer of the molecular gas. Using the 3DBAROLO code on ALMA data, we performed the modelling of the molecular gas kinematics traced by the CO(2–1) emission, finding a rotationally dominated pattern. The molecular gas mass of the host galaxy was estimated from the integrated CO(2–1) emission line obtained with APEX data, assuming an αCO conversion factor. Had we used the ALMA data, we would have underestimated the gas masses by a factor ∼3, given the filtering out of the large-scale emission in interferometric observations. We also performed a complete X-ray spectral analysis on archival observations, revealing a relatively faint and unobscured AGN. The AGN proved to be too faint to significantly affect the properties of the host galaxy, such as star formation activity and molecular gas kinematics and distribution.

scholarly journals Properties of Dust in Giant Elliptical Galaxies: The rôle of the Environment

2000 ◽  
Vol 174 ◽  
pp. 74-80
Author(s):  
Paul Goudfrooij
Keyword(s):  
Large Scale ◽  
Elliptical Galaxies ◽  
Short Time Scale ◽  
X Ray ◽  
Hot Gas ◽  
The Galaxy ◽  
The Masses ◽  
Short Time ◽  
Galaxy Nucleus

AbstractThe properties of dust in giant elliptical galaxies are reviewed, with particular emphasis on the influence of the environment.After normalizing by the optical luminosities, a strong anticorrelation between the masses of dust and hot gas in X-ray bright ellipticals is found. Furthermore, large-scale, regularly-shaped dust lanes (which are symmetric with respect to the galaxy nucleus) are only found to be present in ellipticals with the lowest ratios of the mass of hot gas to the blue luminosity (Mhot/LB ≲ 0.04 in solar units). This can be explained by the short time scale for the destruction of dust grains within the hot, X-ray- emitting gas compared to the formation timescale of such dust lanes in early-type galaxies.Dust within ellipticals in “loose” environments (i.e. in the field or in loose groups) is typically characterized by small values of RV ≡ AV/EB−V (i-e. small characteristic grain sizes), and distributed in dust lanes with a smooth, relaxed morphology. On the other hand, dust in ellipticals that are in or near the center of dense groups or clusters is typically much more irregularly distributed, and characterized by RV values that are close to the Galactic one.I predict that ellipticals containing “relaxed” dust lanes with typical dust masses of 106 − 107M⊙ do not contain hot, X-ray-emitting gas.

scholarly journals The Role of Quasars in Galaxy Formation

2009 ◽  
Vol 5 (S267) ◽  
pp. 17-25 ◽  
Author(s):  
D. Elbaz
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Positive Feedback ◽  
Local Environment ◽  
Active Role ◽  
Molecular Gas ◽  
Massive Galaxies ◽  
Radio Jets ◽  
The Galaxy

AbstractWe discuss evidence that quasars, and more generally radio jets, may have played an active role in the formation stage of galaxies by inducing star formation, i.e., through positive feedback. This mechanism first proposed in the 1970s has been considered as anecdotal until now, contrary to the opposite effect that is generally put forward, i.e., the quenching of star formation in massive galaxies to explain the galaxy bimodality, downsizing, and the universal black hole mass over bulge stellar mass ratio. This suggestion is based on the recent discovery of an ultra-luminous infrared galaxy, i.e., an extreme starburst, that appears to be triggered by a radio jet from the QSO HE 0450-2958 at z = 0.2863, together with the finding in several systems of a positional offset between molecular gas and quasars, which may be explained by the positive feedback effect of radio jets on their local environment.

The birth of an AGN: NGC 4111

2020 ◽  
Vol 15 (S359) ◽  
pp. 362-363
Author(s):  
Gabriel R. H. Roier ◽  
Thaisa Storchi-Bergmann
Keyword(s):  
Near Infrared ◽  
Dwarf Galaxy ◽  
Molecular Gas ◽  
Stellar Kinematics ◽  
Gas Kinematics ◽  
Integral Field Spectroscopy ◽  
Optical Images ◽  
Counter Rotation ◽  
The Galaxy ◽  
Nearby Galaxies

AbstractWe have used near-infrared and optical Integral Field Spectroscopy along with optical images to study the inner 100 pc of NGC 4111 in a project to investigate the stellar and gas kinematics in the surroundings of Supermassive Black Holes in nearby galaxies. We have compared the inner stellar and gas kinematics with data of the outer regions of the galaxy. We found larger scale hot ionized gas and warm molecular gas within the inner 100 pc that is in counter-rotation relative to the stellar kinematics, a sign of inflowing material that is probably triggering an Active Galactic Nucleus. This is supported by the nuclear X-ray emission which is heating the molecular gas and causing it to emit. The presence of large amounts of dust in a polar ring suggests that this is a fairly recent event probably due to the capture of a dwarf galaxy.

Sign in / Sign up

Export Citation Format

Share Document