Kavli Affiliate: Gregory J. Herczeg
| First 5 Authors: Doug Johnstone, Bhavana Lalchand, Steve Mairs, Hsien Shang, Wen Ping Chen
| Summary:
Short-duration flares at millimeter wavelengths provide unique insights into
the strongest magnetic reconnection events in stellar coronae, and combine with
longer-term variability to introduce complications to next-generation cosmology
surveys. We analyze 5.5 years of JCMT Transient Survey 850 micron submillimeter
monitoring observations toward eight Gould Belt star-forming regions to search
for evidence of transient events or long-duration variability from faint
sources. The eight regions (30 arcmin diameter fields), including ~1200
infrared-selected YSOs, have been observed on average 47 times with
integrations of approximately half an hour, or one day total spread over 5.5
years. Within this large data set, only two robust faint source detections are
recovered: JW 566 in OMC 2/3 and MGM12 2864 in NGC 2023. JW 566, a Class II
TTauri binary system previously identified as an extraordinary submillimeter
flare, remains unique, the only clear single-epoch transient detection in this
sample with a flare eight times bright than our ~4.5 sigma detection threshold
of 55 mJy/beam. The lack of additional recovered flares intermediate between JW
566 and our detection limit is puzzling, if smaller events are more common than
larger events. In contrast, the other submillimeter variable identified in our
analysis, Source 2864, is highly variable on all observed timescales. Although
Source 2864 is occasionally classified as a YSO, the source is most likely a
blazar. The degree of variability across the electromagnetic spectrum may be
used to aid source classification.
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