The Galactic center object G2/DSO

ATel #15103; Florian Peissker, Michal Zajacek, Andreas Eckart, Basel Ali, Vladimir Karas, Nadeen B. Sabha, Rebekka Grellmann, Lucas Labadie, Banafsheh Shahzamanian
on 10 Dec 2021; 22:26 UT
Credential Certification: Florian Peissker (peissker@ph1.uni-koeln.de)

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Around 10 years ago, the Galactic center object G2 was found by Gillessen et al. (2012). The object was classified as a dusty gas cloud by the authors with a mass of about 3 earth_masses. It was predicted, that the cloud gets disrupted during its periapse in 2014 resulting in increased activity by Sgr A*, the supermassive black hole in the center of our Galaxy. Nevertheless, the object continued its trajectory on a Keplerian orbit after its periapse and no firework-like event was observed. In combination with the constant L-band temperature (Witzel et al. 2017), the behavior implied already a stellar nature of G2. Here we report the result of our analysis of the SINFONI data that covers 2005-2019. We find that G2 and its tail consist of 3 individual sources (G2, OS1, OS2) that move on Keplerian orbits around Sgr A*. We also trace the K-band continuum counterpart of G2 on the same orbit as the Doppler-shifted ionized gas emission. The K-band magnitude/temperature of G2 stays constant before and after the periapse in agreement with Witzel et al. (2017). In addition, we analyze the gas distribution in the S-cluster. We come to the conclusion, that the gas which was associated with G2 was in the S-cluster before the object passed by. We inspect position-velocity diagrams and show, that the tail emission is rather an outcome of the used Gaussian filter. In Peißker et al. (2021c), we connect these three sources to the overall population of dusty gaseous emission sources in and close by the S-cluster. With over a dozen sources, G2 seems not an exception but the rule. We speculate, that the Circum Nuclear Disk (CND) may serve as a birthplace for these sources. Cloud-cloud interactions (see Moser et al. 2017; Tsuboi et al. 2017, 2021) could decrease the angular momentum resulting in an infall of the material towards Sgr A* (for simulations of this process, see also Jalali et al. 2014). The overall population implies, that objects like G2, OS1, and OS2 move in groups (see Peißker et al. 2020b; Ciurlo et al. 2020) which would serve as a tracer for the infall of molecular clouds towards Sgr A*. The paper 'The Apparent Tail of the Galactic Center Object G2/DSO' was published today at ApJ (https://iopscience.iop.org/article/10.3847/1538-4357/ac23df) and is also available at arxiv as a preprint (https://arxiv.org/abs/2112.04543). The University of Cologne issued a press release that is attached to the telegram.

Press release of the University of Cologne