VLA Survey of Dense Gas in Extended Green Objects: Prevalence of 25 GHz Methanol Masers

Journal Article · Thu Jun 01 04:00:00 EDT 2017 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.3847/1538-4365/AA73D8· OSTI ID:22872617

Towner, A. P. M.; Brogan, C. L.; Hunter, T. R.; McGuire, B. A.; Indebetouw, R. ^[1]; Cyganowski, C. J. ^[2]; Friesen, R. K. ^[3]; Chandler, C. J. ^[4]

---

1. National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville, VA 22903 (United States)
2. Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)
3. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St George St., Toronto, ON, M5S 3H4 (Canada)
4. National Radio Astronomy Observatory, 1003 Lopezville Rd., Socorro, NM 87801 (United States)

We present ∼1″–4″ resolution Very Large Array (VLA) observations of four CH{sub 3}OH J{sub 2}--J{sub 1}-E 25 GHz transitions (J = 3, 5, 8, 10) along with the 1.3 cm continuum toward 20 regions of active massive star formation containing Extended Green Objects (EGOs), 14 of which we have previously studied with the VLA in the Class I 44 GHz and Class II 6.7 GHz maser lines. Sixteen regions are detected in at least one 25 GHz line (J = 5), with 13 of 16 exhibiting maser emission. In total, we report 34 new sites of CH{sub 3}OH maser emission and 10 new sites of thermal CH{sub 3}OH emission, significantly increasing the number of 25 GHz Class I CH{sub 3}OH masers observed at high angular resolution. We identify probable or likely maser counterparts at 44 GHz for all 15 of the 25 GHz masers for which we have complementary data, providing further evidence that these masers trace similar physical conditions despite uncorrelated flux densities. The sites of thermal and maser emission of CH{sub 3}OH are both predominantly associated with the 4.5 μm emission from the EGO, and the presence of thermal CH{sub 3}OH emission is accompanied by 1.3 cm continuum emission in 9 out of 10 cases. Of the 19 regions that exhibit 1.3 cm continuum emission, it is associated with the EGO in 16 cases (out of a total of 20 sites), 13 of which are new detections at 1.3 cm. Twelve of the 1.3 cm continuum sources are associated with 6.7 GHz maser emission and likely trace deeply embedded massive protostars.

• OSTI ID: 22872617
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 2 Vol. 230; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DETECTION
EMISSION
FLUX DENSITY
GHZ RANGE
MASERS
METHANOL
PROTOSTARS