A Spectral Analysis of the Centimeter Regime of Nearby Galaxies: RRLs, Excited OH, and NH<sub>3</sub>

Eisner, Brian A.; Ott, J.; Meier, David S.; Cannon, John

doi:10.3847/1538-4357/ab3854

Cited by 4 publications

(3 citation statements)

References 105 publications

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“…A likely candidate may be the 4 32 − 4 23 transition of c-C 3 H 2 . c-C 3 H 2 has a widespread presence in the diffuse ISM of the Galaxy (e.g., Lucas & Liszt 2000) and the 2 20 − 2 11 transition has been detected in NGC 4945 (Eisner et al 2019). As an example we plot the velocity of c-C 3 H 2 4 32 − 4 23 relative to H42α in Figure 10.…”

Section: H42α Contaminationmentioning

confidence: 99%

Super Star Clusters in the Central Starburst of NGC 4945

Emig,

Bolatto,

Leroy

et al. 2020

Preprint

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NGC 4945 is a nearby (3.8 Mpc) galaxy hosting a nuclear starburst and Seyfert Type 2 AGN. We use the Atacama Large Millimeter/submillimeter Array (ALMA) to image the 93 GHz (3.2 mm) free-free continuum and hydrogen recombination line emission (H40α and H42α) at 2.2 pc (0.12 ) resolution. Our observations reveal 27 bright, compact sources with FWHM sizes of 1.4-4.0 pc, which we identify as candidate super star clusters. Recombination line emission, tracing the ionizing photon rate of the candidate clusters, is detected in 15 sources, 6 of which have a significant synchrotron component to the 93 GHz continuum. Adopting an age of ∼5 Myr, the stellar masses implied by the ionizing photon luminosities are log 10 (M /M ) ≈ 4.7-6.1. We fit a slope to the cluster mass distribution and find β = −1.8 ± 0.4. The gas masses associated with these clusters, derived from the dust continuum at 350 GHz, are typically an order of magnitude lower than the stellar mass. These candidate clusters appear to have already converted a large fraction of their dense natal material into stars and, given their small free-fall times of ∼0.05 Myr, are surviving an early volatile phase. We identify a point-like source in 93 GHz continuum emission which is presumed to be the AGN. We do not detect recombination line emission from the AGN and place an upper limit on the ionizing photons which leak into the starburst region of Q 0 < 10 52 s −1 .

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Section: H42α Contaminationmentioning

confidence: 99%

Super Star Clusters in the Central Starburst of NGC 4945

Emig,

Bolatto,

Leroy

et al. 2020

Preprint

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“…To our knowledge, these are the spectrally broadest and most spatially compact 6035 and 6030 GHz OH absorption lines ever detected in the ISM. We note that broad absorption lines (>100 km s −1 ) of these OH transitions have been detected in other galaxies, but tracing the overall ensemble of molecular clouds seen in absorption against the continuum of the galaxy rather than from an individual site within a star-forming region (Whiteoak & Wilson 1990;Eisner et al 2019).…”

Section: Vlamentioning

confidence: 75%

Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15

Tan,

Araya,

Rigg

et al. 2023

ApJ

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G34.26 + 0.15 is a region of high-mass star formation that contains a broad range of young stellar objects in different stages of evolution, including a hot molecular core, hypercompact H ii regions, and a prototypical cometary ultracompact H ii region. Previous high-sensitivity single-dish observations by our group resulted in the detection of broad 6035 MHz OH absorption in this region; the line showed a significant blueshifted asymmetry indicative of molecular gas expansion. We present high-sensitivity Karl G. Jansky Very Large Array (VLA) observations of the 6035 MHz OH line conducted to image the absorption and investigate its origin with respect to the different star formation sites in the region. In addition, we report detection of 6030 MHz OH absorption with the VLA and further observations of 4.7 GHz and 6.0 GHz OH lines obtained with the Arecibo Telescope. The 6030 MHz OH line shows a very similar absorption profile as the 6035 MHz OH line. We found that the 6035 MHz OH line absorption region is spatially unresolved at ∼2″ scales, and it is coincident with one of the bright ionized cores of the cometary H ii region that shows broad radio recombination line emission. We discuss a scenario where the OH absorption is tracing the remnants of a pole-on molecular outflow that is being ionized inside-out by the ultracompact H ii region.

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“…The script provided in this article to search for spectral lines and stacking RRLs from continuum VLA data sets should be especially applicable to continuum surveys toward extragalactic objects, in which low velocity resolution spectra would be appropriate for detection of broad lines (e.g., Araya et al 2004;Eisner et al 2019). This is a new discovery tool to explore the rich VLA archive of continuum observations and complement Note.…”

Section: Discussionmentioning

confidence: 99%

Broadband VLA Spectral-line Survey of a Sample of Ionized Jet Candidates

Sanchez-Tovar,

Araya,

Rosero

et al. 2023

ApJS

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The study of the interaction between ionized jets, molecular outflows, and their environments is critical to understanding high-mass star formation, especially because jets and outflows are thought to be key in the transfer of angular momentum outward from accretion disks. We report a low spectral resolution Karl G. Jansky Very Large Array (VLA) survey for OH, NH3, CH3OH, and hydrogen radio recombination lines, toward a sample of 58 high-mass star-forming regions that contain numerous ionized jet candidates. The observations are from a survey designed to detect radio continuum; the novel aspect of this work is to search for spectral lines in broadband VLA data (we provide the script developed in this work to facilitate exploration of other data sets). We report detection of 25 GHz CH3OH transitions toward 10 sources; 5 of them also show NH3 emission. We found that most of the sources detected in CH3OH and NH3 have been classified as ionized jets or jet candidates and that the emission lines are coincident with, or very near (≲0.1 pc), these sources; hence, these molecular lines could be used as probes of the environment near the launching site of jets/outflows. No radio recombination lines were detected, but we found that the rms noise of stacked spectra decreases following the radiometer equation. Therefore, detecting radio recombination lines in a sample of brighter free–free continuum sources should be possible. This work demonstrates the potential of broadband VLA continuum observations as low resolution spectral-line scans.

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A Spectral Analysis of the Centimeter Regime of Nearby Galaxies: RRLs, Excited OH, and NH₃

Cited by 4 publications

References 105 publications

Super Star Clusters in the Central Starburst of NGC 4945

Super Star Clusters in the Central Starburst of NGC 4945

Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15

Broadband VLA Spectral-line Survey of a Sample of Ionized Jet Candidates

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A Spectral Analysis of the Centimeter Regime of Nearby Galaxies: RRLs, Excited OH, and NH3

Cited by 4 publications

References 105 publications

Super Star Clusters in the Central Starburst of NGC 4945

Super Star Clusters in the Central Starburst of NGC 4945

Excited Hydroxyl Outflow in the High-mass Star-forming Region G34.26 + 0.15

Broadband VLA Spectral-line Survey of a Sample of Ionized Jet Candidates

Contact Info

Product

Resources

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A Spectral Analysis of the Centimeter Regime of Nearby Galaxies: RRLs, Excited OH, and NH₃