Large velocity dispersion of molecular gas in bars of strongly barred galaxies NGC 1300 and NGC 5383

Maeda, Fumiya; Ohta, Kouji; Fujimoto, Yusuke; Habe, Asao; Baba, Junichi

doi:10.1093/pasj/psy028

Cited by 22 publications

(28 citation statements)

References 42 publications

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“…CO observations towards NGC 1300 with a single-dish telescope of Nobeyama 45-m show the higher velocity dispersion in bar regions than in arm regions at a kpc-scale resolution (Maeda et al 2018). This result suggests the relative velocity among the clouds in the bar regions is larger than that in the arm regions and is qualitatively consistent with the fast CCC scenario in the bar region.…”

Section: Discussionmentioning

confidence: 96%

“…Our ALMA observations did not recover the total CO(1 − 0) flux due to the lack of Atacama Compact Array (ACA) measurements. To estimate the recovery fraction of the total CO(1 − 0) flux, we compared the CO(1 − 0) flux obtained from ALMA with those from Nobeyama 45-m single-dish telescope by Maeda et al (2018), which presented single-pointing observations of several regions in NGC 1300. First, we convolved the CO(1 − 0) data cube to 13 .5, the beam size of the Nobeyama 45-m telescope at 115 GHz.…”

Section: Impact Of the Missing Fluxmentioning

confidence: 99%

“…1). Maeda et al (2018) carried out 12 CO(1 − 0) observations toward the bar and arm region of NGC 1300 with a single dish telescope of Nobeyama 45-m telescope. They find that the Σ H 2 in the bar region is comparable to that in the arm region (Σ H 2 ∼ 10 M pc −2 ), indicating the star formation activity in the bar region is clearly suppressed.…”

Section: Introductionmentioning

confidence: 99%

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Properties of giant molecular clouds in the strongly barred galaxy NGC 1300

Maeda

Ohta

Fujimoto

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Star formation activity depends on galactic-scale environments. To understand the variations in star formation activity, comparing the properties of giant molecular clouds (GMCs) among environments with different star formation efficiency (SFE) is necessary. We thus focus on a strongly barred galaxy to investigate the impact of the galactic environment on the GMCs properties, because the SFE is clearly lower in bar regions than in arm regions. In this paper, we present the 12 CO(1 − 0) observations toward the western bar, arm and bar-end regions of the strongly barred galaxy NGC 1300 with ALMA 12-m array at a high angular resolution of ∼40 pc. We detected GMCs associated with the dark lanes not only in the arm and bar-end regions but also in the bar region, where massive star formation is not seen. Using the CPROPS algorithm, we identified and characterized 233 GMCs across the observed regions. Based on the Kolmogorov-Smirnov test, we find that there is virtually no significant variations in GMC properties (e.g., radius, velocity dispersion, molecular gas mass, and virial parameter) among the bar, arm and bar-end region. These results suggest that systematic differences in the physical properties of the GMCs are not the cause for SFE differences with environments, and that there should be other mechanisms which control the SFE of the GMCs such as fast cloud-cloud collisions in NGC 1300.

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Section: Discussionmentioning

confidence: 96%

Section: Impact Of the Missing Fluxmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Properties of giant molecular clouds in the strongly barred galaxy NGC 1300

Maeda

Ohta

Fujimoto

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Bigiel et al (2008) find average values of Σ mol for disks of local non-barred spiral galaxies of ∼10-15 M pc −2 . At the bar region, Σ mol is typically in the range ≈20-90 M pc −2 (Reynaud & Downes 1998;Regan et al 1999;Kuno et al 2007;Muraoka et al 2016;Maeda et al 2018Maeda et al , 2020Yajima et al 2019), under the assumption of a common α CO = 3.2 M (K km s −1 pc −2 ) −1 , as used here. Our use of a bigger sample reveals a somewhat larger range: Σ mol varies by ≈1.5−2 orders of magnitude between the probed galaxies.…”

Section: Integrated Co Spectra and Molecular Gas Massmentioning

confidence: 99%

Molecular gas and star formation within 12 strong galactic bars observed with IRAM-30 m

Díaz-García

Lisenfeld

Pérez

et al. 2021

A&A

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Context. While some galactic bars show recent massive star formation (SF) along them, some others do not. Whether bars with low level of SF are a consequence of low star formation efficiency, low gas inflow rate, or dynamical effects remains a matter of debate. Aims. In order to study the physical conditions that enable or prevent SF, we perform a multi-wavelength analysis of 12 strongly barred galaxies with total stellar masses log10(M⋆/M⊙)∈[10.2, 11], chosen to host different degrees of SF along the bar major axis without any prior condition on gas content. We observe the CO(1–0) and CO(2–1) emission within bars with the IRAM-30 m telescope (beam sizes of 1.7–3.9 kpc and 0.9–2.0 kpc, respectively; 7–8 pointings per galaxy on average). Methods. We estimated molecular gas masses (Mmol) from the CO(1–0) and CO(2–1) emissions. SF rates (SFRs) were calculated from GALEX near-ultraviolet (UV) and WISE 12 μm images within the beam-pointings, covering the full bar extent (SFRs were also derived from far-UV and 22 μm). Results. We detect molecular gas along the bars of all probed galaxies. Molecular gas and SFR surface densities span the ranges log10(Σmol/[M⊙ pc−2]) ∈ [0.4,2.4] and log10(ΣSFR/[M⊙ pc−1 kpc−2]]) ∈ [−3.25, −0.75], respectively. The star formation efficiency (SFE; i.e., SFR/Mmol) in bars varies between galaxies by up to an order of magnitude (SFE ∈[0.1, 1.8] Gyr−1). On average, SFEs are roughly constant along bars. SFEs are not significantly different from the mean value in spiral galaxies reported in the literature (∼0.43 Gyr−1), regardless of whether we estimate Mmol from CO(1–0) or CO(2–1). Interestingly, the higher the total stellar mass of the host galaxy, the lower the SFE within their bars. In particular, the two galaxies in our sample with the lowest SFE and ΣSFR (NGC 4548 and NGC 5850, SFE ≲ 0.25 Gyr−1, ΣSFR ≲ 10−2.25 M⊙ yr−1 kpc−2, M⋆ ≳ 1010.7 M⊙) are also those hosting massive bulges and signs of past interactions with nearby companions. Conclusions. We present a statistical analysis of the SFE in bars for a sample of 12 galaxies. The SFE in strong bars is not systematically inhibited (either in the central, middle, or end parts of the bar). Both environmental and internal quenching are likely responsible for the lowest SFEs reported in this work.

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“…An extremely unproductive region for massive star formation is seen in such a strong bar; prominent Hii regions are mostly not seen although there are remarkable dust lanes along the stellar bar. Towards nearby strongly barred galaxies NGC1300 and NGC5383, sensitive CO observations were recently made and a large amount of molecular gas is proven to be present in the bar, even though they are not associated active star-forming regions (Maeda et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Fast cloud–cloud collisions in a strongly barred galaxy: suppression of massive star formation

Fujimoto

Maeda

Habe

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Recent galaxy observations show that star formation activity changes depending on galactic environments. In order to understand the diversity of galactic-scale star formation, it is crucial to understand the formation and evolution of giant molecular clouds in an extreme environment. We focus on observational evidence that bars in strongly barred galaxies lack massive stars even though quantities of molecular gas are sufficient to form stars. In this paper, we present a hydrodynamical simulation of a strongly barred galaxy, using a stellar potential which is taken from observational results of NGC1300, and we compare cloud properties between different galactic environments: bar, bar-end and spiral arms. We find that the mean of cloud's virial parameter is α vir ∼ 1 and that there is no environmental dependence, indicating that the gravitationally-bound state of a cloud is not behind the observational evidence of the lack of massive stars in strong bars. Instead, we focus on cloud-cloud collisions, which have been proposed as a triggering mechanism for massive star formation. We find that the collision speed in the bar is faster than those in the other regions. We examine the collision frequency using clouds' kinematics and conclude that the fast collisions in the bar could originate from random-like motion of clouds due to elliptical gas orbits shifted by the bar potential. These results suggest that the observed regions of lack of active star-formation in the strong bar originate from the fast cloudcloud collisions, which are inefficient in forming massive stars, due to the galactic-scale violent gas motion.

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Large velocity dispersion of molecular gas in bars of strongly barred galaxies NGC 1300 and NGC 5383

Cited by 22 publications

References 42 publications

Properties of giant molecular clouds in the strongly barred galaxy NGC 1300

Properties of giant molecular clouds in the strongly barred galaxy NGC 1300

Molecular gas and star formation within 12 strong galactic bars observed with IRAM-30 m

Fast cloud–cloud collisions in a strongly barred galaxy: suppression of massive star formation

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