The Apparent Tail of the Galactic Center Object G2/DSO

Abstract Observations of the near-infrared excess object G2/DSO increased attention toward the Galactic center and its vicinity. The predicted flaring event in 2014 and the outcome of the intense monitoring of the supermassive black hole in the center of our Galaxy did not fulfill all predictions about a significantly enhanced accretion event. Subsequent observations addressed the question concerning the nature of the object because of its compact shape, especially during its periapse in 2014. Theoretical approaches have attempted to answer the contradictory behavior of the object, resisting the expected dissolution of a gaseous cloud due to tidal forces in combination with evaporation and hydrodynamical instabilities. However, assuming that the object is instead a dust-enshrouded young stellar object seems to be in line with the predictions of several groups and observations presented in numerous publications. Here we present a detailed overview and analysis of the observations of the object that have been performed with SINFONI (VLT) and we provide a comprehensive approach to clarify the nature of G2/DSO. We show that the tail emission consists of two isolated and compact sources with different orbital elements for each source rather than an extended and stretched component as it appeared in previous representations of the same data. Considering our recent publications, we propose that the monitored dust-enshrouded objects are remnants of a dissolved young stellar cluster whose formation was initiated in the circumnuclear disk. This indicates a shared history, which agrees with our analysis of the D- and X-sources.

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Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic center

Astronomy and Astrophysics ◽

10.1051/0004-6361/201219994 ◽

2013 ◽

Vol 551 ◽

pp. A18 ◽

Cited By ~ 49

Author(s):

A. Eckart ◽

K. Mužić ◽

S. Yazici ◽

N. Sabha ◽

B. Shahzamanian ◽

...

Keyword(s):

Near Infrared ◽

Galactic Center ◽

Proper Motions ◽

Infrared Excess

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Infrared Excess Sources in the Galactic Center Stellar Cluster

Science with Adaptive Optics - ESO Astrophysics Symposia ◽

10.1007/10828557_49 ◽

2005 ◽

pp. 279-285

Author(s):

Andreas Eckart ◽

J. Moultaka ◽

T. Viehmann ◽

C. Straubmeier ◽

N. Mouawad ◽

...

Keyword(s):

Galactic Center ◽

Infrared Excess ◽

Stellar Cluster

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Detection of polarized continuum emission of the Dusty S-cluster Object (DSO/G2)

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011819 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 233-234

Author(s):

B. Shahzamanian ◽

M. Zajaček ◽

M. Valencia-S. ◽

F. Peissker ◽

A. Eckart ◽

...

Keyword(s):

Near Infrared ◽

Galactic Center ◽

Continuum Emission ◽

Polarization Angle ◽

Imaging Data ◽

Intrinsic Geometry ◽

Infrared Excess ◽

Geometrical Properties ◽

Sgr A ◽

First Time

AbstractA peculiar source in the Galactic center known as the Dusty S-cluster Object (DSO/G2) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014. Its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry. For the first time, we use near-infrared polarimetric imaging data to obtain constraints about the geometrical properties of the DSO. We find out that DSO is an intrinsically polarized source, based on the significance analysis of polarization parameters, with the degree of the polarization of ~30% and an alternating polarization angle as it approaches the position of Sgr A*. Since the DSO exhibits a near-infrared excess of Ks-L′ > 3 and remains rather compact in emission-line maps, its main characteristics may be explained with the model of a pre-main-sequence star embedded in a non-spherical dusty envelope.

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Mini-Spiral at the Galactic Center: A Link between its Structure and the Value of a Central Point Mass

Symposium - International Astronomical Union ◽

10.1017/s0074180900229744 ◽

1996 ◽

Vol 169 ◽

pp. 241-246

Author(s):

A.M. Fridman ◽

O.V. Khoruzhii ◽

V.V. Lyakhovich ◽

L. Ozernoy ◽

L. Blitz

Keyword(s):

Galactic Center ◽

Density Wave ◽

Neutral Hydrogen ◽

Wave Model ◽

Molecular Gas ◽

Stellar Cluster ◽

Nonthermal Radio ◽

H Ii Region ◽

Circumnuclear Disk ◽

Sgr A

The innermost 2 pc contain a rotating ring (“circumnuclear disk”) of molecular gas, neutral hydrogen, and dust with an embedded H II region called Sgr A West; a dense stellar cluster; and a compact nonthermal radio source Sgr A∗ (for a recent review, see Blitz et al. 1993). The clumped, spiral-shaped morphology of Sgr A West, sometimes called lthe mini-spiral”, has been a subject of numerous speculations concerning its origin (for a review, see Genzel & Townes 1987). Lacy et al. (1991) demonstrated that both the kinematics and shape of a part of Sgr A West can be fairly well approximated using an one-armed density-wave model.

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FIR Spectroscopy of the Galactic Center: Hot and Warm Molecular Gas

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012072 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 168-169

Author(s):

Javier R. Goicoechea ◽

Mireya Etxaluze ◽

José Cernicharo ◽

Maryvonne Gerin ◽

Jerome Pety ◽

...

Keyword(s):

Angular Resolution ◽

Galactic Center ◽

Rotational Line ◽

Molecular Gas ◽

Central Cavity ◽

Stellar Cluster ◽

Line Intensities ◽

The Galaxy ◽

Circumnuclear Disk ◽

Sgr A

AbstractThe angular resolution (~10″) achieved by the Herschel Space Observatory ~3.5 m telescope at FIR wavelengths allowed us to roughly separate the emission toward the inner parsec of the galaxy (the central cavity) from that of the surrounding circumnuclear disk (the CND). The FIR spectrum toward Sgr A* is dominated by intense [O iii], [O i], [C ii], [N iii], [N ii], and [C i] fine-structure lines (in decreasing order of luminosity) arising in gas irradiated by the strong UV field from the central stellar cluster. The high-J CO rotational line intensities observed at the interface between the inner CND and the central cavity are consistent with a hot isothermal component at Tk ≈ 103.1 K and n(H2)≈ 104 cm−3. They are also consistent with a distribution of lower temperatures at higher gas density, with most CO at Tk≈300 K. The hot CO component (either the bulk of the CO column density or just a small fraction depending on the above scenario) likely results from a combination of UV and shock-driven heating. If UV-irradiated and heated dense clumps do not exist, shocks likely dominate the heating of the hot molecular gas component. Although this component is beam diluted in our FIR observations, it may be resolved at much higher angular resolution. An ALMA project using different molecular tracers to characterize UV-irradiated shocks in the innermost layers of the CND is ongoing.

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