A multi-transition methanol maser study of the accretion burst source G358.93-0.03-MM1

Abstract

We present the most complete to date interferometric study of the centimeter wavelength methanol masers detected in G358.93-0.03 at the burst and post-burst epochs. A unique, NIR/(sub)mm-dark and FIR-loud MYSO accretion burst was recently discovered in G358.93-0.03. The event was accompanied by flares of an unprecedented number of rare methanol maser transitions. The first images of three of the newly-discovered methanol masers at 6.18, 12.23, and 20.97 GHz are presented in this work. The spatial structure evolution of the methanol masers at 6.67, 12.18, and 23.12 GHz is studied at two epochs. The maser emission in all detected transitions resides in a region of $\sim$0.2${}^{\prime \prime }$ around the bursting source and shows a clear velocity gradient in the north-south direction, with red-shifted features to the north and blue-shifted features to the south. A drastic change in the spatial morphology of the masing region is found: a dense and compact "spiral" cluster detected at epoch I evolved into a disperse, "round" structure at epoch II. During the transition from the first epoch to the second, the region traced by masers expanded. The comparison of our results with the complementary VLA, VLBI, SMA, and ALMA maser data is conducted. The obtained methanol maser data support the hypothesis of the presence of spiral-arm structures within the accretion disk, which was suggested in previous studies of the source.

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• Detection of new methanol maser transitions associated with G358.93-0.03
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Cited by in corpus (10)

• A Keplerian disk with a four-arm spiral birthing an episodically accreting high-mass protostar
• The evolution of the H2O maser emission in the accretion burst source G358.93-0.03
• Identification of the simplest sugar-like molecule glycolaldehyde towards the hot molecular core G358.93-0.03 MM1
• Identification of interstellar cyanamide towards the hot molecular core G358.93-0.03 MM1
• Detection of possible glycine precursor molecule methylamine towards the hot molecular core G358.93$-$0.03 MM1
• Ammonia masers toward G358.931-0.030
• Detection of antifreeze molecule ethylene glycol in the hot molecular core G358.93$-$0.03 MM1
• Observation of Complex Organic Molecules Containing Peptide-like Bonds Toward Hot Core G358.93$-$0.03 MM1
• Identifying the Mechanisms of Water Maser Variability During the Accretion Burst in NGC6334I
• Detections of Compact Radio Continuum toward Methanol Maser Rings Using the VLA