scholarly journals Kiso Hα Imaging Observations of Nearby Galaxies

1998 ◽  
Vol 15 (1) ◽  
pp. 149-151
Author(s):  
T. Hasegawa ◽  
S. Sakamoto ◽  
S. Nishiura ◽  
Y. Ohyama ◽  
Y. Sofue
Keyword(s):  
Star Formation ◽  
Compact Group ◽  
Spiral Galaxy ◽  
Clear Correlation ◽  
Nuclear Region ◽  
Diffuse Emission ◽  
Schmidt Telescope ◽  
Group System ◽  
Nearby Galaxies ◽  
Formation Efficiency

AbstractWe report Hα imaging observations of nearby galaxies with the Kiso Schmidt telescope. For spiral galaxy NGC 628, we found no clear correlation between Hα and CO intensities, and we discuss the star formation efficiency of this galaxy. No nuclear Hα emission in this galaxy was detected. This is consistent with spectroscopic observations which indicate that the nuclear region is in the post starburst phase. We also describe the Hα image of Hickson's compact group 92 in which diffuse emission is detected extending within the group system.

scholarly journals Molecular Gas in Hickson Compact Groups

1999 ◽  
Vol 186 ◽  
pp. 414-414
Author(s):  
S. Leon ◽  
F. Combes ◽  
T.K. Menon
Keyword(s):  
Star Formation ◽  
Compact Group ◽  
Gas Flow ◽  
Control Sample ◽  
Gas Content ◽  
Cloud Formation ◽  
Molecular Gas ◽  
Compact Groups ◽  
Hickson Compact Groups ◽  
Formation Efficiency

Compact groups are ideal sites to study the influence of strong dynamical evolution due to environment on molecular cloud formation and star formation efficiency. We have observed 70 galaxies belonging to 45 Hickson compact groups (HCGs) in the 12CO(1→0) and 12CO(2→1) lines, in order to determine their molecular content. We compare the gas content relative to blue and LFIR luminosities of galaxies in compact groups with respect to other samples in the literature, including various environments and morphological types. We find that there is some hint, of enhanced MH2/LB and Mdust/LB ratios in the galaxies from compact group with respect to our control sample, especially for the most compact groups, suggesting that tidal interactions can drive the gas component inwards, by removing its angular momentum, and concentrating it in the dense central regions, where it is easily detected. The threshold at 20–30 kpc in mean galaxy separation for the enhancement of H2 suggests that it must correspond to an acceleration of the merging process and a significant inward gas flow. The molecular gas content in compact group galaxies is similar to that in pairs and starburst samples. However, the total LFIR luminosity of HCGs is quite similar to that of the control sample, and therefore the star formation efficiency appears lower than in the control galaxies. However this assumes that the FIR spatial distributions are similar in both samples which is not the case at radio frequencies. Higher spatial resolution FIR data are needed to make a valid comparison. Given their short dynamical friction time-scale, it is possible that some of these systems are in the final stage before merging, leading to ultraluminous starburst phases. We also find for all galaxy samples that the H2 content (normalized to blue luminosity) is strongly correlated with LFIR, while the total gas content (H2+HI) is not.

scholarly journals The ALMaQUEST Survey – II. What drives central starbursts at z ∼ 0?

2020 ◽  
Vol 492 (4) ◽  
pp. 6027-6041 ◽  
Author(s):  
Sara L Ellison ◽  
Mallory D Thorp ◽  
Hsi-An Pan ◽  
Lihwai Lin ◽  
Jillian M Scudder ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Stellar Mass ◽  
Starburst Galaxies ◽  
Molecular Gas ◽  
Central Regions ◽  
Primary Driver ◽  
Nearby Galaxies ◽  
Field Unit ◽  
Formation Efficiency

ABSTRACT Starburst galaxies have elevated star formation rates (SFRs) for their stellar mass. In Ellison et al., we used integral field unit maps of SFR surface density (ΣSFR) and stellar mass surface density (Σ⋆) to show that starburst galaxies in the local universe are driven by SFRs that are preferentially boosted in their central regions. Here, we present molecular gas maps obtained with the Atacama Large Millimeter Array (ALMA) observatory for 12 central starburst galaxies at z ∼ 0 drawn from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The ALMA and MaNGA data are well matched in spatial resolution, such that the ALMA maps of molecular gas surface density ($\Sigma _{\rm H_2}$) can be directly compared with MaNGA maps at kpc-scale resolution. The combination of $\Sigma _{\rm H_2}$, Σ⋆ and ΣSFR at the same resolution allow us to investigate whether central starbursts are driven primarily by enhancements in star formation efficiency (SFE) or by increased gas fractions. By computing offsets from the resolved Kennicutt-Schmidt relation ($\Sigma _{\rm H_2}$ versus ΣSFR) and the molecular gas main sequence (Σ⋆ versus $\Sigma _{\rm H_2}$), we conclude that the primary driver of the central starburst is an elevated SFE. We also show that the enhancement in ΣSFR is accompanied by a dilution in O/H, consistent with a triggering that is induced by metal poor gas inflow. These observational signatures are found in both undisturbed (9/12 galaxies in our sample) and recently merged galaxies, indicating that both interactions and secular mechanisms contribute to central starbursts.

scholarly journals Star Formation Efficiency per Free-fall Time in nearby Galaxies

2018 ◽  
Vol 861 (2) ◽  
pp. L18 ◽  
Author(s):  
Dyas Utomo ◽  
Jiayi Sun ◽  
Adam K. Leroy ◽  
J. M. Diederik Kruijssen ◽  
Eva Schinnerer ◽  
...  
Keyword(s):  
Star Formation ◽  
Free Fall ◽  
Fall Time ◽  
Nearby Galaxies ◽  
Formation Efficiency

scholarly journals DYNAMO: An upclose view of turbulent, clumpy galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 317-317
Author(s):  
Deanne Fisher
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Velocity Dispersion ◽  
Molecular Gas ◽  
Rotating Disks ◽  
Giant Star ◽  
Star Forming ◽  
Nearby Galaxies ◽  
Formation Efficiency ◽  
The Universe

AbstractOver 2/3 of all star formation in the Universe occurs in gas-rich, super-high pressure clumpy galaxies in the epoch of redshift z ∼ 1 – 3. However, because these galaxies are so distant we are limited in the information available to study the properties of star formation and gas in these systems. I will present results using a sample of extremely rare, nearby galaxies (called DYNAMO) that are very well matched in gas fraction (fgas ∼ 20 – 80%), kinematics (rotating disks with velocity dispersions ranging 20 – 100 km/s), structure (exponential disks) and morphology (clumpy star formation) to high-z main-sequence galaxies. We therefore use DYNAMO galaxies as laboratories to study the processes inside galaxies in the dominate mode of star formation in the Universe. In this talk I will report on results from our programs with HST, ALMA, Keck, and NOEMA for DYNAMO galaxies that are aimed at testing models of star formation. We have discovered of an inverse relationship between gas velocity dispersion and molecular gas depletion time. This correlation is directly predicted by theories of feedback-regulated star formation; conversely, predictions of models in which turbulence is driven by gravity only are not consistent with our data. I will also show that feedback-regulated star formation can explain the redshift evolution of galaxy star formation efficiency. I will also present results from a recently acquired map of CO(2-1) in a clumpy galaxy with resolution less than 200 pc. With maps such as these we can begin to study these super giant star forming clumps at scales that are more comparable to local surveys. I will show results for the star formation efficiency of clumps, the boundedness of clumps of molecular gas, and discuss links between star formation efficiency and formation of clumps of stellar mass. The details of clumpy systems are a direct constraint of the results of simulations, especially on the nature of feedback in the high density environments of star formation that dominate the early Universe.

scholarly journals THE STAR FORMATION EFFICIENCY IN NEARBY GALAXIES: MEASURING WHERE GAS FORMS STARS EFFECTIVELY

2008 ◽  
Vol 136 (6) ◽  
pp. 2782-2845 ◽  
Author(s):  
Adam K. Leroy ◽  
Fabian Walter ◽  
Elias Brinks ◽  
Frank Bigiel ◽  
W. J. G. de Blok ◽  
...  
Keyword(s):  
Star Formation ◽  
Nearby Galaxies ◽  
Formation Efficiency

scholarly journals The EDGE-CALIFA Survey: The Resolved Star Formation Efficiency and Local Physical Conditions

2021 ◽  
Vol 923 (1) ◽  
pp. 60
Author(s):  
V. Villanueva ◽  
A. Bolatto ◽  
S. Vogel ◽  
R. C. Levy ◽  
S. F. Sánchez ◽  
...  
Keyword(s):  
Star Formation ◽  
High Surface ◽  
Formation Rate ◽  
Radial Dependence ◽  
Clear Correlation ◽  
Physical Parameters ◽  
Equilibrium Pressure ◽  
Star Formation Activity ◽  
Formation Efficiency ◽  
Co Emission

Abstract We measure the star formation rate (SFR) per unit gas mass and the star formation efficiency (SFEgas for total gas, SFEmol for the molecular gas) in 81 nearby galaxies selected from the EDGE-CALIFA survey, using 12CO (J = 1–0) and optical IFU data. For this analysis we stack CO spectra coherently by using the velocities of Hα detections to detect fainter CO emission out to galactocentric radii r gal ∼ 1.2r 25 (∼3R e) and include the effects of metallicity and high surface densities in the CO-to-H2 conversion. We determine the scale lengths for the molecular and stellar components, finding a close to 1:1 relation between them. This result indicates that CO emission and star formation activity are closely related. We examine the radial dependence of SFEgas on physical parameters such as galactocentric radius, stellar surface density Σ⋆, dynamical equilibrium pressure P DE, orbital timescale τ orb, and the Toomre Q stability parameter (including star and gas Q star+gas). We observe a generally smooth, continuous exponential decline in the SFEgas with r gal. The SFEgas dependence on most of the physical quantities appears to be well described by a power law. Our results also show a flattening in the SFEgas–τ orb relation at log [ τ orb ] ∼ 7.9 – 8.1 and a morphological dependence of the SFEgas per orbital time, which may reflect star formation quenching due to the presence of a bulge component. We do not find a clear correlation between SFEgas and Q star+gas.

scholarly journals STAR FORMATION EFFICIENCY IN THE BARRED SPIRAL GALAXY NGC 4303

2010 ◽  
Vol 721 (1) ◽  
pp. 383-394 ◽  
Author(s):  
Rieko Momose ◽  
Sachiko K. Okumura ◽  
Jin Koda ◽  
Tsuyoshi Sawada
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Barred Spiral Galaxy ◽  
Formation Efficiency

scholarly journals A panchromatic spatially resolved analysis of nearby galaxies – II. The main sequence – gas relation at sub-kpc scale in grand-design spirals

2020 ◽  
Vol 496 (4) ◽  
pp. 4606-4623 ◽  
Author(s):  
L Morselli ◽  
G Rodighiero ◽  
A Enia ◽  
E Corbelli ◽  
V Casasola ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Formation Rate ◽  
Molecular Gas ◽  
Spatially Resolved ◽  
Grand Design ◽  
Nearby Galaxies ◽  
Formation Efficiency ◽  
H2 Molecule ◽  
Intense Star Formation

ABSTRACT In this work, we analyse the connection between gas availability and the position of a region with respect to the spatially resolved main-sequence (MS) relation. Following the procedure presented in Enia et al. (2020), for a sample of five face-on, grand design spiral galaxies located on the MS we obtain estimates of stellar mass and star formation rate surface densities (Σ⋆ and ΣSFR) within cells of 500 pc size. Thanks to H i 21cm and 12CO(2–1) maps of comparable resolution, within the same cells we estimate the surface densities of the atomic (ΣH i) and molecular ($\Sigma _{\rm {H_2}}$) gas and explore the correlations among all these quantities. Σ⋆, ΣSFR, and $\Sigma _{\rm {H_2}}$ define a 3D relation whose projections are the spatially resolved MS, the Kennicutt–Schmidt law and the molecular gas MS. We find that $\Sigma _{\rm {H_2}}$ steadily increases along the MS relation and is almost constant perpendicular to it. ΣH i is nearly constant along the MS and increases in its upper envelope. As a result, ΣSFR can be expressed as a function of Σ⋆ and ΣH i, following the relation log ΣSFR = 0.97log Σ⋆ + 1.99log ΣH i − 11.11. We show that the total gas fraction significantly increases towards the starburst regions, accompanied by a weak increase in star formation efficiency. Finally, we find that H2/H i varies strongly with the distance from the MS, dropping dramatically in regions of intense star formation, where the UV radiation from newly formed stars dissociates the H2 molecule, illustrating the self-regulating nature of the star formation process.

scholarly journals CO Multi-line Imaging of Nearby Galaxies (COMING). III. Dynamical effect on molecular gas density and star formation in the barred spiral galaxy NGC 4303

2019 ◽  
Vol 71 (Supplement_1) ◽  
Author(s):  
Yoshiyuki Yajima ◽  
Kazuo Sorai ◽  
Nario Kuno ◽  
Kazuyuki Muraoka ◽  
Yusuke Miyamoto ◽  
...  
Keyword(s):  
Star Formation ◽  
Spiral Galaxy ◽  
Galactic Disk ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Spiral Arms ◽  
Nearby Galaxies ◽  
Barred Spiral Galaxy ◽  
Barred Spiral Galaxies ◽  
Line Imaging

AbstractWe present the results of $^{12}\textrm{C}$$\textrm{O}$(J = 1–0) and $^{13}\textrm{C}$$\textrm{O}$(J = 1–0) simultaneous mappings toward the nearby barred spiral galaxy NGC 4303 as part of the CO Multi-line Imaging of Nearby Galaxies (COMING) project. Barred spiral galaxies often show lower star-formation efficiency (SFE) in their bar region compared to the spiral arms. In this paper, we examine the relation between the SFEs and the volume densities of molecular gas n(H2) in the eight different regions within the galactic disk with $\textrm{C}$$\textrm{O}$ data combined with archival far-ultraviolet and 24 μm data. We confirmed that SFE in the bar region is lower by 39% than that in the spiral arms. Moreover, velocity-alignment stacking analysis was performed for the spectra in the individual regions. Integrated intensity ratios of $^{12}\textrm{C}$$\textrm{O}$ to $^{13}\textrm{C}$$\textrm{O}$ (R12/13) ranging from 10 to 17 were the results of this stacking. Fixing a kinetic temperature of molecular gas, $n(\rm {H_2})$ was derived from R12/13 via non-local thermodynamic equilibrium (non-LTE) analysis. The density n(H2) in the bar is lower by 31%–37% than that in the arms and there is a rather tight positive correlation between SFEs and n(H2), with a correlation coefficient of ∼0.8. Furthermore, we found a dependence of $n(\rm {H}_2)$ on the velocity dispersion of inter-molecular clouds (ΔV/sin i). Specifically, n(H2) increases as ΔV/sin i increases when ΔV/sin i < 100 km s−1. On the other hand, n(H2) decreases as ΔV/sin i increases when ΔV/sin i > 100 km s−1. These relations indicate that the variations of SFE could be caused by the volume densities of molecular gas, and the volume densities could be governed by the dynamical influence such as cloud–cloud collisions, shear, and enhanced inner-cloud turbulence.

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