scholarly journals The TANGO Project: Thorough ANalysis of radio-Galaxies Observations

2009 ◽  
Vol 5 (S267) ◽  
pp. 127-127
Author(s):  
Breezy Ocaña Flaquer ◽  
Stephane Leon Tanne ◽  
Francoise Combes ◽  
Jeremy Lim
Keyword(s):  
Selection Criteria ◽  
Radio Galaxies ◽  
Elliptical Galaxies ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Molecular Gas

AbstractWe present a sample of radio galaxies selected only on the basis of radio continuum emission and we confirm that these galaxies have lower molecular gas mass than other elliptical galaxies with different selection criteria.

scholarly journals Is this an early stage merger? A case study on molecular gas and star formation properties of Arp 240

2020 ◽  
Vol 496 (4) ◽  
pp. 5243-5261 ◽  
Author(s):  
Hao He ◽  
C D Wilson ◽  
Kazimierz Sliwa ◽  
Daisuke Iono ◽  
Toshiki Saito
Keyword(s):  
Star Formation ◽  
Early Stage ◽  
Formation Rate ◽  
Free Fall ◽  
Radio Continuum ◽  
Local Thermal Equilibrium ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Fall Time ◽  
Very Large Array

ABSTRACT We present new high-resolution 12CO J = 1–0, J = 2–1, and 13CO J = 1–0 maps of the early stage merger Arp 240 (NGC 5257/8) obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). Simulations in the literature suggest that the merger has just completed its first passage; however, we find that this system has a lower global gas fraction but a higher star formation efficiency (SFE) compared to typical close galaxy pairs, which suggests that this system may already be in an advanced merger stage. We combine the ALMA data with 12CO J = 3–2 observations from the Submillimeter Array and carry out RADEX modelling on several different regions. Both, the RADEX modelling and a local thermal equilibrium (LTE) analysis show that the regions are most likely to have a CO-to-H2 conversion factor αCO close to or perhaps even smaller than the typical value for (ultra)luminous infrared galaxies. Using 33-GHz data from the Very Large Array to measure the star formation rate, we find that most star-forming regions have molecular gas depletion times of less than 100 Myr. We calculated the SFE per free-fall time for different regions and find some regions appear to have values greater than 100 per cent. We find these regions generally show evidence for young massive clusters (YMCs). After exploring various factors, we argue that this is mainly due to the fact that radio continuum emission in those regions is dominated by that from YMCs, which results in an overestimate of the SFE per free-fall time.

scholarly journals A Survey of OH in the Galactic Centre Region

1996 ◽  
Vol 169 ◽  
pp. 311-316
Author(s):  
P.J. Boyce ◽  
R. J. Cohen
Keyword(s):  
Central Region ◽  
Molecular Clouds ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Molecular Gas ◽  
The Galaxy ◽  
Centre Region ◽  
Line Survey ◽  
The Continuum

The galactic centre contains the largest concentration of molecular clouds in the Galaxy. The clouds in the central region are unusual in having large linewidths and masses, and large non-circular motions. Previous surveys of their distribution in the central region have been carried out in OH (Robinson & McGee 1970; Cohen & Few 1976), H2CO (Whiteoak & Gardner 1979; Cohen & Few 1981), CO (Bania 1977; Dame et al. 1987; Bally et al. 1987, 1988) and CS (Bally et al. 1987, 1988). The OH groundstate lines at 18cm wavelength have certain advantages for such a survey. The OH lines appear in absorption against the galactic centre continuum sources, and against the continuum emission from the disk of the Galaxy. The absorption spectra are sensitive to relatively small molecular column densities. In addition they can give information on the relative positions of the molecular gas and the radio continuum sources. This paper describes results from an absorption line survey of the galactic centre region in the OH main lines at 1667.359 MHz and 1665.402 MHz (Boyce & Cohen 1994).

scholarly journals The Cold Interstellar Medium in Elliptical Galaxies – Observations of HI and Radio Continuum Emission

1987 ◽  
Vol 127 ◽  
pp. 145-154
Author(s):  
G. R. Knapp
Keyword(s):  
Interstellar Medium ◽  
Large Mass ◽  
Elliptical Galaxies ◽  
Current Data ◽  
Solar Neighborhood ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Stellar Kinematics ◽  
Stellar Content ◽  
Continuum Source

About 10% of nearby elliptical galaxies contain HI, with typical values of M(HI) ~ 5 × 108 M⊙ and M(HI)/LB ~ 0.03 M⊙/L⊙. The HI content is unrelated to the stellar content, (unlike the situation in spiral galaxies) suggesting that the HI in early-type galaxies has an external origin and is not produced by mass loss. This conclusion is strengthened by the distribution and kinematics of the HI structures, which lie outside the main optical body of the galaxies, have much larger specific angular momentum than do the stars, and are often highly inclined to the kinematic and distribution axes of the optical bodies.The HI and stellar kinematics show that the rotation curves of E and SO galaxies are approximately flat from small (a few hundred pc) to large (10-20 kpc) radii, as is the case for spirals. Likewise, large mass-to-light ratios are found for some systems. Comparison with mass models derived from X-ray emission suggests that these may in some cases overestimate the mass.The presence of HI is shown to enhance the likelihood that an E/SO galaxy has a nuclear radio continuum source, in agreement with models which suggest that the central engine is fuelled by cold gas. Current data suggest that the gas-to-dust ratio for the cold interstellar medium in ellipticals has a value similar to that found in the solar neighborhood.

scholarly journals Molecular Gas Distribution and Dynamics in the Central Region of Galaxies

1994 ◽  
Vol 140 ◽  
pp. 293-299
Author(s):  
Sumio Ishizuki
Keyword(s):  
High Resolution ◽  
Central Region ◽  
Large Scale ◽  
Starburst Galaxies ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Gas Distribution

AbstractTo investigate the relation between a large-scale stellar bar and circumnuclear starburst, the CO (J=1→0) emission of circumnuclear regions of three starburst galaxies NGC2782, NGC3504, and M83 (NGC5236) have been mapped with the Nobeyama Millimeter Array. The high resolution CO (J=1→0) images indicate that the molecular gas in the three starburst galaxies is located interior to the innermost ends of the paired straight dust lanes. The molecular gas at the small radii is associated with their circumnuclear starburst sites which are indicated by radio continuum emission.

scholarly journals Cold molecular gas and free–free emission from hot, dust-obscured galaxies at z ∼ 3

2020 ◽  
Vol 496 (2) ◽  
pp. 1565-1578
Author(s):  
J I Penney ◽  
A W Blain ◽  
R J Assef ◽  
T Diaz-Santos ◽  
J González-López ◽  
...  
Keyword(s):  
Rest Frame ◽  
Thermal Emission ◽  
Line Emission ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Spectral Energy ◽  
High Signal ◽  
Molecular Gas ◽  
Small Contribution ◽  
Star Forming

ABSTRACT We report on observations of redshifted CO(1–0) line emission and observed-frame $\rm \sim 30\,$GHz radio continuum emission from five ultra-luminous, mid-IR selected hot, Dust-Obscured Galaxies (Hot DOGs) at $z\rm \gtrsim 3$ using the Karl G. Jansky Very Large Array. We detect CO(1–0) line emission in all five Hot DOGs, with one of them at high signal-to-noise ratio. We analyse FIR-radio spectral energy distributions, including dust, free–free, and synchrotron emission for the galaxies. We find that most of the $\rm 115\,$ GHz rest-frame continuum is mostly due to synchrotron or free–free emission, with only a potentially small contribution from thermal emission. We see a deficit in the rest-frame $\rm 115\,$ GHz continuum emission compared to dusty star-forming galaxies and sub-millimetre galaxies (SMGs) at high redshift, suggesting that Hot DOGs do not have similar cold gas reserves compared with star-forming galaxies. One target, W2305−0039, is detected in the FIRST $\rm 1.4\, GHz$ survey, and is likely to possess compact radio jets. We compare to the FIR–radio correlation, and find that at least half of the Hot DOGs in our sample are radio-quiet with respect to normal galaxies. These findings suggest that Hot DOGs have comparably less cold molecular gas than star-forming galaxies at lower, $z\rm \sim 2$ redshifts, and are dominated by powerful, yet radio-quiet AGN.

scholarly journals The Orion Star-Forming Complex

1987 ◽  
Vol 115 ◽  
pp. 123-137 ◽  
Author(s):  
Tetsuo Hasegawa
Keyword(s):  
Dust Emission ◽  
Emission Feature ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Orion Nebula ◽  
Vibrationally Excited ◽  
Star Forming ◽  
H Ii Region ◽  
Co Emission

High resolution images of the Orion Nebula in the millimeter wave emission lines of CS and CO taken with the 45-m telescope at Nobeyama are presented. They cover a field approximately 400″ square with a 15″ – 34″ resolution and reveal a wealth of information on kinematic and density structures. The images of the J=1-0 (49 GHz) and J=2-1 (98 GHz) lines of CS show a long (>1 pc) and narrow (∼0.1 pc) N-S ridge of dense molecular gas. On the ridge, two major clumps are recognized; one is associated with the KL object and the other is 100″ south of it. The images of the J=1-0 (115 GHz) CO line indicate interaction between the molecular cloud and the H II region formed by the Trapezium stars. Bright CO emission is found towards the edges of the denser part of the H II region delineated by radio continuum emission. The CO emission coincides with the emission of vibrationally excited H2 and the 3.3 μm dust emission feature. The CO images reveal filamentary structures (“streamers”) stretching radially from the KL region. On the streamers there are Herbig-Haro objects moving away from the KL region. They may be tracers of weak interaction between the ambient molecular gas and mostly unseen, highly collimated, high-velocity (>200 km/s) jets.

5.21. Molecular gas in the center of the elliptical galaxy NGC759

1998 ◽  
Vol 184 ◽  
pp. 253-254
Author(s):  
T. Wiklind ◽  
F. Combes ◽  
C. Henkel ◽  
F. Wyrowski
Keyword(s):  
Star Formation ◽  
Uv Light ◽  
Elliptical Galaxy ◽  
Large Fraction ◽  
Dust Emission ◽  
Far Infrared ◽  
Elliptical Galaxies ◽  
Infrared Emission ◽  
Continuum Emission ◽  
Molecular Gas

Elliptical galaxies are traditionally defined as gas–free, inert stellar systems. Observations of continuum emission in the far–infrared (FIR) and sub–mm wavelength bands have, however, shown that a large fraction of all ellipticals, ~50% (Jura et al. 1987), contain a dust component. The infrared emission is due to warm dust, in many cases associated with star formation and/or weak AGN activity, while cold dust dominates the long wavelength continuum emission (e.g. Wiklind & Henkel 1995). Some elliptical galaxies also contain a molecular gas component, as seen through CO emission (Lees et al. 1991; Wiklind et al. 1995; Knapp & Rupen 1996). The dust and molecular gas are believed to be associated with each other, but it is not clear what powers the emission: star formation activity and/or AGN activity. Both the molecular gas mass and the FIR luminosity are on average lower in ellipticals than in spiral galaxies of similar luminosities. However, the LFIR/MH2 ratio is larger for the elliptical galaxies. If this ratio is a measure of the star formation efficiency, this suggests that gas is being used up more efficiently in elliptical galaxies than in normal spirals (e.g. Wiklind et al. 1995). Other possibilities is that the FIR dust emission is not only powered by UV–light from young stars, but from other sources as well, or that some dust is not spatially associated with the molecular gas.

Simulated synchrotron emission for the Tycho’s supernova remnants: an asymmetric initial mass model

2020 ◽  
Vol 494 (2) ◽  
pp. 1531-1538
Author(s):  
A Moranchel-Basurto ◽  
P F Velázquez ◽  
G Ares de Parga ◽  
E M Reynoso ◽  
E M Schneiter ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Brightness Distribution ◽  
Radio Continuum ◽  
Initial Mass ◽  
Continuum Emission ◽  
Synchrotron Emission ◽  
Mass Model ◽  
Mhd Simulations ◽  
Tycho’S Snr ◽  
Good Agreement

ABSTRACT We have performed 3D magnetohydrodynamics (MHD) numerical simulations with the aim of exploring the scenario in which the initial mass distribution of a supernova (SN) explosion is anisotropic. The purpose is to analyse if this scenario can also explain the radio-continuum emission and the expansion observed in young supernova remnants (SNRs). To study the expansion, synthetic polarized synchrotron emission maps were computed from the MHD simulations. We found a good agreement (under a number of assumptions) between this expansion study and previous observational results applied to Tycho’s SNR, which represents a good example of asymmetric young SNRs. Additionally, both the observed morphology and the brightness distribution are qualitatively reproduced.

scholarly journals WISDOM project – VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

2021 ◽  
Vol 503 (4) ◽  
pp. 5984-5996
Author(s):  
Mark D Smith ◽  
Martin Bureau ◽  
Timothy A Davis ◽  
Michele Cappellari ◽  
Lijie Liu ◽  
...  
Keyword(s):  
Black Hole ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Supermassive Black Hole ◽  
Gas Kinematics ◽  
Long Baseline ◽  
Gas Measurement ◽  
Strong Gradient

ABSTRACT Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0${^{\prime\prime}_{.}}$11 ($37\,$pc) resolution in the 12CO(2-1) line and $1.3\,$ mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially constant mass-to-light ratio to model the stellar mass distribution. We infer an SMBH mass of $2.5\pm 0.3\times 10^{9}\, \mathrm{M_\odot }$ and a stellar I-band mass-to-light ratio of $4.6\pm 0.2\, \mathrm{M_\odot /L_{\odot ,I}}$ (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionized gas kinematics, which however appears significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.

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