Twelve Years of Spectroscopic Monitoring in the Galactic Center: The Closest Look at S-stars near the Black Hole

Habibi, M.; Gillessen, S.; Martins, F.; Eisenhauer, F.; Plewa, P. M.; Pfuhl, O.; George, E. M.; Dexter, Jason; Waisberg, I.; Ott, Thomas; Fellenberg, S. von; Bauböck, M.; Jiménez-Rosales, A.; Genzel, R.

doi:10.3847/1538-4357/aa876f

Cited by 128 publications

(173 citation statements)

References 69 publications

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“…In the published literature, 24 RV measurements, beginning in the year 2000, have been reported from WMKO (Ghez et al 2003(Ghez et al , 2005(Ghez et al , 2008Boehle et al 2016) and 40 measurements, beginning in 2003, have been reported from the VLT (Eisenhauer et al 2005;Gillessen et al 2009aGillessen et al , 2017Habibi et al 2017). Many of the RV measurements are based on multiple nights of observations.…”

Section: Previously Reported Datamentioning

confidence: 99%

“…This limit depends on the total mass M tot used in Equation (5). In this work, two extreme values for M tot are considered: (i) a low value of M tot = 10 M e (Habibi et al 2017 reported the mass of S0-2 as 13.6 1.8…”

Section: Is S0-2 a Binary?mentioning

confidence: 99%

“…In particular, it has provided proof of the existence of a supermassive black hole (SMBH), the characterization of the SMBH properties (mass and distance), and the laws of gravitation (Ghez et al 2005(Ghez et al , 2008Gillessen et al 2009bGillessen et al , 2017Boehle et al 2016;. S0-2 is also notable because spectroscopic studies have revealed that it, along with most of the "S-stars" located within 1″ of the black hole, is a young main-sequence B star (Ghez et al 2003;Eisenhauer et al 2005;Martins et al 2008;Habibi et al 2017). This discovery raised questions about their formation mechanism, since traditional star formation would be disrupted by the tidal forces of the black hole (Morris 1993).…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

Chu

Hees

et al. 2018

ApJ

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The star S0-2, which orbits the supermassive black hole (SMBH) in our Galaxy with a period of 16 years, provides the strongest constraint on both the mass of the SMBH and the distance to the Galactic center. S0-2 will soon provide the first measurement of relativistic effects near a SMBH. We report the first limits on the binarity of S0-2 from radial velocity (RV) monitoring, which has implications for both understanding its origin and robustness as a probe of the central gravitational field. With 87 RV measurements, which include 12 new observations that we present, we have the requisite data set to look for RV variations from S0-2′s orbital model. Using a Lomb-Scargle analysis and orbit-fitting for potential binaries, we detect no RV variation beyond S0-2′s orbital motion and do not find any significant periodic signal. The lack of a binary companion does not currently distinguish different formation scenarios for S0-2. The upper limit on the mass of a companion star (M comp ) still allowed by our results has a median upper limit of M comp sini1.6 M e for periods between 1 and 150 days, the longest period to avoid tidal break-up of the binary. We also investigate the impact of the remaining allowed binary system on the measurement of the relativistic redshift at S0-2′s closest approach in 2018. While binary star systems are important to consider for this experiment, we find that plausible binaries for S0-2 will not alter a 5σ detection of the relativistic redshift.

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Section: Previously Reported Datamentioning

confidence: 99%

Section: Is S0-2 a Binary?mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

Chu

Hees

et al. 2018

ApJ

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“…In contrast, Morris & Serabyn (1996) suggested that the constant inflow of gas might trigger star formation that could play a role when accretion processes are investigated. Followed by this, the detection of young stars in the Galactic Center, mostly O/B and Wolf Rayet WR stars, indicate a recent star-forming epoch (Eisenhauer et al 2005;Habibi et al 2017). Ghez et al (2003) formulated the 'paradox of youth' where the authors reflect the contrary situation.…”

Section: Introductionmentioning

confidence: 97%

Monitoring dusty sources in the vicinity of Sagittarius A*

Peißker

Hosseini

Eckart

et al. 2020

A&A

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Context. We trace several dusty infrared sources on their orbits around Sgr A* with SINFONI and NACO mounted at the VLT/Chile. These sources show near-infrared excess and Doppler-shifted line emission. We investigate these sources in order to clarify their nature and compare their relationship to other observed NIR objects close to Sgr A*. Aims. By using SINFONI, we are able to determine the spectroscopic properties of the investigated dusty infrared sources. Furthermore, we extract spatial and velocity information of these objects. We are able to identify X7, X7.1, X8, G1, DSO/G2, D2, D23, D3, D3.1, D5, and D9 in the Doppler-shifted line maps of the SINFONI H+K data. From our K-and L -band NACO data, we derive the related magnitudes of the brightest sources located west of Sgr A*. Methods. For determining the line of sight velocity information and to investigate single emission lines, we use the near-infrared integral field spectrograph SINFONI data-sets between 2005 and 2015. For the kinematic analysis, we use NACO data-sets between 2002 and 2018. This study is done in the H, K s , and L band. From the 3D SINFONI data-cubes, we extract line-maps in order to derive positional information of the sources. In the NACO images, we identify the dusty counterpart of the objects. If possible, we determine Keplerian orbits and apply a photometric analysis.Results. The spectrum of the investigated objects show a Doppler-shifted Brγ and HeI line emission. For some objects west of Sgr A*, we find additionally [Fe III] line emission that can be clearly distinguished from the background. A one-component blackbody model fits the extracted near-infrared flux for the majority of the investigated objects, with the characteristic dust temperature of 500 K. The photometric derived H-and K S -band magnitudes are between mag H > 22.5 and mag K = 18.1 +0.3 −0.8 for the dusty sources. For the H-band magnitudes we can provide an upper limit. For the bright dusty sources D2, D23, and D3, the Keplerian orbits are elliptical with a semi-major axis of a D2 = (749 ± 13) mas, a D23 = (879 ± 13), and a D3 = (880 ± 13) mas. For the DSO/G2, a single-temperature and a two-component blackbody model is fitted to the H-, K-, L -, and M-band data, while the two-component model that consists of a star and an envelope fits its SED better than an originally proposed single-temperature dusty cloud. Conclusions. The spectroscopic analysis indicates, that the investigated objects could be dust embedded pre-main-sequence stars. The Doppler-shifted [Fe III] line can be spectroscopically identified in several sources that are located between 17:45:40.05 and 17:45:42.00 in DEC. However, the sources with a DEC less than 17:45:40.05 show no [Fe III] emission. Therefore, these two groups show different spectroscopic features that could be explained by the interaction with a non-spherical outflow that originates at the position of Sgr A*. Followed by this, the hot bubble around Sgr A* consists out of isolated sources with [Fe III] line emission that can partially ...

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“…Of a particular interest is the inner cluster within the projected radius of ∼1 ′′ ≃ 0.04 pc, which consists of ∼30 mostly B-type bright stars -the so-called S cluster (Eckart & Genzel 1996, 1997Ghez et al 1998;Gillessen et al 2009Gillessen et al , 2017Habibi et al 2017). These stars have nearly isotropic distribution of elliptical orbits with considerable eccentricities and pericenter distances of ∼1,500 Schwarzschild radii and orbital velocities at the periapse of several thousand kilometers per second.…”

Section: Introductionmentioning

confidence: 99%

A stellar fly‐by close to the Galactic center: Can we detect stars on highly relativistic orbits?

Tursunov

2018

Astron Nachr

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The Galactic center Nuclear Star Cluster is one of the densest stellar clusters in the Galaxy. The stars in its inner portions orbit the supermassive black hole associated with the compact radio source Sgr A* at the orbital speeds of several thousand kilometers per second. The B‐type star S2 is currently the best case to test the general relativity as well as other theories of gravity, based on its stellar orbit. Yet, its orbital period of ∼16 years and the eccentricity of ∼0.88 yields the relativistic pericenter shift of ∼11′, which is observationally still difficult to reliably measure due to possible Newtonian perturbations as well as reference‐frame uncertainties. A naive way to solve this problem is to find stars with smaller pericenter distances, rp ≲ 1529 Schwarzschild radii (120 AU), and thus with more prominent relativistic effects. In this paper, we show that to detect stars on relativistic orbits is progressively less likely, given the volume shrinkage and the expected stellar density distributions. Finally, one arrives at a sparse region where the total number of bright stars is expected to fall below 1. One can, however, still potentially detect stars crossing this region. In this paper, we provide a simple formula for the detection probability of a star crossing a sparse region. We also examine an approximate timescale in which the star reappears in the sparse region, i.e., a “waiting” timescale for observers.

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Twelve Years of Spectroscopic Monitoring in the Galactic Center: The Closest Look at S-stars near the Black Hole

Cited by 128 publications

References 69 publications

Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

Monitoring dusty sources in the vicinity of Sagittarius A*

A stellar fly‐by close to the Galactic center: Can we detect stars on highly relativistic orbits?

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