Distributed Star Formation throughout the Galactic Center Cloud Sgr B2

Ginsburg, Adam; Bally, John; Barnes, Ashley; Bastian, N.; Battersby, Cara; Beuther, H.; Brogan, C. L.; Contreras, Y.; Corby, Joanna F.; Darling, Jeremy; Pree, C. G. De; Galván-Madrid, Roberto; Garay, Guido; Henshaw, Jonathan D.; Hunter, T. R.; Kruijssen, J. M. Diederik; Longmore, Steven N.; Lu, Xing; Meng, Fanyi; Mills, Elisabeth A. C.; Ott, J.; Pineda, Jaime E.; Sánchez-Monge, Á.; Schilke, P.; Schmiedeke, A.; Walker, Daniel; Wilner, David J.

doi:10.3847/1538-4357/aaa6d4

Cited by 104 publications

(146 citation statements)

References 113 publications

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“…The ReMoCA continuum maps are also very similar to the map shown in Fig. 3 of Ginsburg et al (2018), obtained with ALMA at 3 mm with a similar angular resolution (∼0.5 ′′ ). The northeastern part of the maps shown in Fig.…”

Section: Continuum Emissionsupporting

confidence: 78%

“…Kasten & Dreizler (1986) and Kretschmer et al (1996) studied the 14 N hyperfine structure (HFS) in greater detail and determined unsplit rest frequencies with greater accuracy. Godfrey et al (1997) studied the rotational spectra of several isotopologs to determine the structure of urea, in particular the exact shape of the molecule. They also mentioned the identification of transitions pertaining to two excited vibrational states Article number, page 3 of 68 whose vibrational energy they estimated from relative intensities to be ∼155 cm −1 (∼225 K) and ∼365 cm −1 (∼525 K), which they interpreted as the NH 2 wagging fundamental and first overtone states, respectively.…”

Section: Spectroscopymentioning

confidence: 99%

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Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

Беллоче

Garrod

Müller

et al. 2019

A&A

160

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Context. Urea, NH 2 C(O)NH 2 , is a molecule of great importance in organic chemistry and biology. Two searches for urea in the interstellar medium have been reported in the past, but neither were conclusive. Aims. We want to take advantage of the increased sensitivity and angular resolution provided by the Atacama Large Millimeter/submillimeter Array (ALMA) to search for urea toward the hot molecular cores embedded in the high-mass-star-forming region Sgr B2(N). Methods. We used the new spectral line survey named ReMoCA (Re-exploring Molecular Complexity with ALMA) that was performed toward Sgr B2(N) with ALMA in its observing cycle 4 between 84 GHz and 114 GHz. The spectra were analyzed under the local thermodynamic equilibrium approximation. We constructed a full synthetic spectrum that includes all the molecules identified so far. We used new spectroscopic predictions for urea in its vibrational ground state and first vibrationally excited state to search for this complex organic molecule in the ReMoCA data set. We employed the gas-grain chemical kinetics model MAGICKAL to interpret the astronomical observations. Results. We report the secure detection of urea toward the hot core Sgr B2(N1) at a position called N1S slightly offset from the continuum peak, which avoids obscuration by the dust. The identification of urea relies on nine clearly detected transitions. We derive a column density of 2.7 × 10 16 cm −2 for urea, two orders of magnitude lower than the column density of formamide, and one order of magnitude below that of methyl isocyanate, acetamide, and N-methylformamide. The latter molecule is reliably identified toward N1S with 60 clearly detected lines, confirming an earlier claim of its tentative interstellar detection. We report the first interstellar detections of NH 2 CH 18 O and 15 NH 2 CHO. We also report the nondetection of urea toward the secondary hot core Sgr B2(N2) with an abundance relative to the other four species at least one order of magnitude lower than toward the main hot core. Our chemical model roughly reproduces the relative abundances of formamide, methyl isocyanate, acetamide, and N-methylformamide, but it overproduces urea by at least one order of magnitude. Conclusions. Urea is clearly detected in one of the hot cores. Comparing the full chemical composition of Sgr B2(N1S) and Sgr B2(N2) may help understand why urea is at least one order of magnitude less abundant in the latter source.

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Section: Continuum Emissionsupporting

confidence: 78%

Section: Spectroscopymentioning

confidence: 99%

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

Беллоче

Garrod

Müller

et al. 2019

A&A

160

235

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“…Therefore, it is not surprising that most of the 23 detected CH 3 OH masers are associated with known high-mass star formation regions. Among them, 12 out of the 14 CH 3 OH masers in Sgr B2 are associated with UC/HC H II regions De Pree et al 2015) or massive YSOs (Ginsburg et al 2018), while M2 and M11 do not have H II region or YSO counterparts within 1 (see next paragraph). The three masers in the Dust Ridge clouds (M15, M16, and M17) are associated with (UC) H II regions or massive YSOs (Immer et al 2012a;Walker et al 2018;Lu et al 2019).…”

Section: Class II Ch3oh Masers and High-mass Star Formationmentioning

confidence: 99%

“…We apply a column density threshold of 5×10 22 cm −2 (the lowest contour level in Figures 2-5), and search for compact sources above it. This column density threshold is chosen to be the upper limit of the foreground column density toward Sgr B2 (Ginsburg et al 2018;C. Battersby et al in prep.…”

Section: Regionsmentioning

confidence: 99%

A Census of Early-phase High-mass Star Formation in the Central Molecular Zone

Mills

Ginsburg

et al. 2019

ApJS

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We present new observations of C-band continuum emission and masers to assess high-mass (>8 M ) star formation at early evolutionary phases in the inner 200 pc of the Central Molecular Zone (CMZ) of the Galaxy. The continuum observation is complete to free-free emission from stars above 10-11 M in 91% of the covered area. We identify 104 compact sources in the continuum emission, among which five are confirmed ultracompact H II regions, 12 are candidates of ultra-compact H II regions, and the remaining 87 sources are mostly massive stars in clusters, field stars, evolved stars, pulsars, extragalactic sources, or of unknown nature that is to be investigated. We detect class II CH 3 OH masers at 23 positions, among which six are new detections. We confirm six known H 2 CO masers in two high-mass star forming regions, and detect two new H 2 CO masers toward the Sgr C cloud, making it the ninth region in the Galaxy that contains masers of this type. In spite of these detections, we find that current high-mass star formation in the inner CMZ is only taking place in seven isolated clouds. The results suggest that star formation at early evolutionary phases in the CMZ is about 10 times less efficient than expected by the dense gas star formation relation, which is in line with previous studies that focus on more evolved phases of star formation. This means that if there will be any impending, next burst of star formation in the CMZ, it has not yet begun.

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“…As an example, the spatial co-existence of warm ionised regions traced by [Nii] 205 µm , and that of the dense and diffuse molecular gas traced by CO, can be considered similar to the gas phase mixing in the Central Molecular Zone (CMZ) on the scales of 100 pc (Kruijssen & Longmore 2013;Ginsburg et al 2018), and even in the immediate vicinity of Sgr-A* on the scale of 1 pc (Moser et al 2017). Hence, the Galactic centre region may serve as a high-z galaxy analog (see also Swinbank et al 2011;Kruijssen & Longmore 2013).…”

Section: Co-evolution Of Agn/sf In the Rrrmentioning

confidence: 99%

The ‘Red Radio Ring’: ionized and molecular gas in a starburst/active galactic nucleus at z ∼ 2.55

Harrington¹,

Vishwas

Weiß

et al. 2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT We report the detection of the far-infrared (FIR) fine-structure line of singly ionized nitrogen, [N ii] 205 $\mu$m , within the peak epoch of galaxy assembly, from a strongly lensed galaxy, hereafter ‘The Red Radio Ring’; the RRR, at z = 2.55. We combine new observations of the ground-state and mid-J transitions of CO (Jup = 1, 5, 8), and the FIR spectral energy distribution (SED), to explore the multiphase interstellar medium (ISM) properties of the RRR. All line profiles suggest that the H ii regions, traced by [N ii] 205 $\mu$m , and the (diffuse and dense) molecular gas, traced by CO, are cospatial when averaged over kpc-sized regions. Using its mid-IR-to-millimetre (mm) SED, we derive a non-negligible dust attenuation of the [N ii] 205 $\mu$m line emission. Assuming a uniform dust screen approximation results a mean molecular gas column density >1024 cm−2, with a molecular gas-to-dust mass ratio of 100. It is clear that dust attenuation corrections should be accounted for when studying FIR fine-structure lines in such systems. The attenuation corrected ratio of $L_{\rm N\,{\small II}205} / L_{\rm IR(8\!-\!1000\, \mu m)} = 2.7 \times 10^{-4}$ is consistent with the dispersion of local and z > 4 SFGs. We find that the lower limit, [N ii] 205 $\mu$m -based star formation rate (SFR) is less than the IR-derived SFR by a factor of 4. Finally, the dust SED, CO line SED, and $L_{\rm N\,{\small II}205}$ line-to-IR luminosity ratio of the RRR is consistent with a starburst-powered ISM.

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Distributed Star Formation throughout the Galactic Center Cloud Sgr B2

Cited by 104 publications

References 113 publications

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

A Census of Early-phase High-mass Star Formation in the Central Molecular Zone

The ‘Red Radio Ring’: ionized and molecular gas in a starburst/active galactic nucleus at z ∼ 2.55

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