Universität zu Köln

Peissker, F., Zajacek, M., Eckart, A., Sabha, N. B., Shahzamanian, B. and Parsa, M. (2019). New bow-shock source with bipolar morphology in the vicinity of Sgr A*. Astron. Astrophys., 624. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. We find an extended source in the direct vicinity of Sgr A* with an approximate projected mean distance of 425 +/- 26 mas. Its sky-projected elongated shape can be described by an averaged spatial extension of x = 110 +/- 20 mas and y = 180 +/- 20 mas. With this, the observed object points in the analyzed SINFONI data sets between 2006 and 2016 directly toward the supermassive black hole. We discuss different possible scenarios that could explain the detected blueshifted line emission source. Aims. Here we present a detailed and extensive analysis of the adaptive optics corrected SINFONI data between 2006 and 2016 with a spatial pixel scale of 0.'' 025 and a corresponding field of view of 0.'' 8 x 0.'' 8 per single data cube with the focus on the newly discovered source. We spectroscopically identify the source, which we name X8, in the blueshifted Br gamma line maps. Additionally, an upper limit for the continuum magnitude can be derived from the close-by S-star S41. Methods. We applied the standard reduction procedure with the SINFONI/EsoRex pipeline for the analysis. We applied pre- and post-data correction in order to establish various calibration procedures. For the sharpened images, we used the Lucy-Richardson algorithm with a low iteration number. For the high-pass filtered images, we used the smooth-subtracting process in order to increase the signal-to-noise ratio. Results. We are able to detect the elongated line emission source in quantified data sets between 2006 and 2016. We find a lower limit for the infrared continuum magnitude of K-s >= 17.0 +/- 0.1. The alignment of X8 toward Sgr A* can be detected in data sets that fulfill a sufficient number of observations with a defined quality level. A more detailed analysis of the results shows indications of a bipolar outflow source that might be associated with either a young stellar object, or with a post-AGB star or young planetary nebula. Conclusions. The near-infrared excess source X8 close to S24, S25, and S41 can be detected between 2006 and 2016. In addition to an apparent bow-shock morphology, the source shows clear signatures of a bipolar outflow that is consistent with both a young stellar object and a post-AGB star. If confirmed, this would be the closest ever detected bipolar outflow source to the supermassive black hole. Similar to the case of the DSO/G2 source and other dusty sources, it further supports the in situ star formation in the direct vicinity of Sgr A*. If X8 were a bow-shock source, it would be the third object of this type that can be found in projection in the mini-cavity. This scenario would support the idea that the cavity is created by a wind from Sgr A*.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Peissker, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zajacek, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Eckart, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sabha, N. B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Shahzamanian, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Parsa, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-150628
DOI:	10.1051/0004-6361/201834947
Journal or Publication Title:	Astron. Astrophys.
Volume:	624
Date:	2019
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language GALACTIC-CENTER; BLACK-HOLE; STAR-FORMATION; PROPER MOTIONS; EMISSION; CLUSTER; RESOLUTION; OUTFLOW; ORBITS; LINES Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/15062