Monitoring the Dusty S-Cluster Object (Dso/G2) on Its Orbit Toward the Galactic Center Black Hole

Valencia-S., M.; Eckart, A.; Zajaček, Michal; Peißker, F.; Parsa, M.; Grosso, N.; Mossoux, E.; Porquet, D.; Jalali, Bahram; Karas, V.; Yazici, S.; Shahzamanian, B.; Sabha, Nesrin; Saalfeld, R.; Smajić, Semir; Grellmann, R.; Moser, Lydia; Horrobin, M.; Borkar, A.; García-Marín, M.; Dovčiak, Michal; Kunneriath, D.; Karssen, G. D.; Bursa, Michal; Straubmeier, C.; Bushouse, H.

doi:10.1088/0004-637x/800/2/125

Cited by 61 publications

(136 citation statements)

References 82 publications

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“…These limits on accretion rates, which are always substantially lower than the total mass of G2 (with details depending on which structure of G2 is assumed), are consistent with the observed kinematics of G2 during its pericenter passage: as noted by several studies, the orbit was purely Keplerian even after the pericenter passage (Witzel et al 2014;Pfuhl et al 2015;Valencia et al 2015). This indicates that G2 did not experience a notable loss of angular momentum and energy, which indicates rather weak interactions with the hot gas around Sgr A*.…”

Section: Discussionsupporting

confidence: 87%

“…The second possibility under discussion is that G2 is a circumstellar cloud around a star that provides stabilizing gravity and continuously replenishes the gas. Studies supporting this scenario highlighted that the tail might only be a fore-or background feature and might not be physically connected to G2 (Phifer et al 2013;Valencia et al 2015). Recent observations have also shown that G2 survived its pericenter passage as a compact source, which might be a clue that G2 is a star enshrouded by gas and/or dust (Witzel et al 2014;Valencia et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Studies supporting this scenario highlighted that the tail might only be a fore-or background feature and might not be physically connected to G2 (Phifer et al 2013;Valencia et al 2015). Recent observations have also shown that G2 survived its pericenter passage as a compact source, which might be a clue that G2 is a star enshrouded by gas and/or dust (Witzel et al 2014;Valencia et al 2015). This scenario was modeled analytically (Miralda-Escudé 2012; Scoville & Burkert 2013) and explored with the help of numerical simulations (Ballone et al 2013;De Colle et al 2014;Zajaček et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

Park

Trippe

Krichbaum

et al. 2015

A&A

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The gas cloud G2 that falls toward Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, is assumed to provide valuable information on the physics of accretion flows and the environment of the black hole. We observed Sgr A* with four European stations of the Global Millimeter Very Long Baseline Interferometry Array (GMVA) at 86 GHz on 1 October 2013 when parts of G2 had already passed the pericenter. We searched for a possible transient asymmetric structure -such as jets or winds from hot accretion flows -around Sgr A* that might be caused by accretion of material from G2. The interferometric closure phases remained zero within errors during the observation time. We therefore conclude that Sgr A* did not show significant asymmetric (in the observer frame) outflows in late 2013. Using simulations, we constrain the size of the outflows that we could have missed to ≈2.5 mas along the major axis and ≈0.4 mas along the minor axis of the beam, corresponding to approximately 232 and 35 Schwarzschild radii, respectively; we thus probe spatial scales on which the jets of radio galaxies are thought to convert magnetic into kinetic energy. Because probably less than 0.2 Jy of the flux from Sgr A* can be attributed to accretion from G2, the effective accretion rate is ηṀ 1.5 × 10 9 kg s −1 ≈ 7.7 × 10 −9 M ⊕ yr −1 for material from G2. Exploiting the relation of kinetic jet power to accretion power of radio galaxies shows that the rate of accretion of matter that is finally deposited in jets is limited toṀ 10 17 kg s −1 ≈ 0.5 M ⊕ yr −1 . Accordingly, G2 appears to be mostly stable against loss of angular momentum and subsequent (partial) accretion at least on timescales 1 yr.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

Park

Trippe

Krichbaum

et al. 2015

A&A

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“…Another scenario for the non-spherical geometry of the source can be the prolongation of the gaseous environment due the tidal forces rather than the described model. However, the tidal stretching of the source along its orbit was not observed in continuum and line emission during its periapse passage [8,12].…”

Section: Analysis and Resultsmentioning

confidence: 93%

“…The increase of a Brγ line width also shows that it is a young accreting star surrounded by a dusty envelope [8]. It is an infrared-excess source compared to the main-sequence stars and has a magnitude of 18.5 in K s -band (2.2 µm) continuum [6,9].…”

Section: Introductionmentioning

confidence: 88%

Polarization: A Method to Reveal the True Nature of the Dusty S-Cluster Object (DSO/G2)

et al. 2018

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Abstract:There have been different scenarios describing the nature of a dusty source, noted as Dusty S-cluster Object (DSO) or G2, orbiting around the Galactic centre super-massive black hole. Observing the polarized continuum emission of this source provides information on its nature and geometry. We show that this source is intrinsically polarized with polarization degree of 30%, implying that it has a non-spherical geometry, and a varying polarization angle in the ambient medium of the black hole. Its main observable properties can be well described and modeled with a pre-main-sequence star forming a bow shock as it approaches the Sgr A* position.

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Possible Alternatives to the Supermassive Black Hole at the Galactic Center

Zakharov

2015

J Astrophys Astron

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Monitoring the Dusty S-Cluster Object (Dso/G2) on Its Orbit Toward the Galactic Center Black Hole

Cited by 61 publications

References 82 publications

No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2

Polarization: A Method to Reveal the True Nature of the Dusty S-Cluster Object (DSO/G2)

Possible Alternatives to the Supermassive Black Hole at the Galactic Center

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