Near- and Mid-infrared Observations in the Inner Tenth of a Parsec of the Galactic Center Detection of Proper Motion of a Filament Very Close to Sgr A*

Peißker, F.; Eckart, A.; Sabha, Nesrin; Bhat, Harshitha

doi:10.3847/1538-4357/ab9826

Cited by 21 publications

(16 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is also supported by the multiphase medium of Sgr A* on the scale of one parsec (Moser et al 2017), which could also be A105, page 10 of 17 present on smaller scales due to for example thermal instability (Różańska et al 2017). In particular, Peißker et al (2020a) report a detection of the proper motion of a Brγ filament, whose estimated distance is close to the Bondi radius at ∼0.2 pc. At comparable scales, Royster et al (2019) used the H30α line to trace a blueshifted, ionised gas with a velocity of between −480 and −300 km s −1 , which appears to be outflowing.…”

Section: Discussionmentioning

confidence: 64%

“…However, the detection by Murchikova et al (2019) is questionable, especially the association of the recombination double-peak line of H30α at 1.3 mm with the gaseous material at milliparsec spatial scales; it is especially controversial given that near-infrared (NIR) line maps, for example of the recombination Brγ line that can trace ionised material of 10 4 K, do not seem to imply any existence of such a compact disc-like structure. On the other hand, there are indications of denser material traced by the Brγ line (Peißker et al 2020a) and the blueshifted H30α line (Royster et al 2019) at larger spatial scales closer to the Bondi radius, which the study of Murchikova et al (2019) could be associated with. This underlines the need for better and independent constraints on the accretion-flow density at the intermediate range of radii.…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Constraining the accretion flow density profile near Sgr A* using theL′-band emission of the S2 star

Hosseini

Eckart

Sabha

et al. 2020

A&A

Self Cite

View full text Add to dashboard Cite

Context. The density of the ambient medium around a supermassive black hole (SMBH) and the way it varies with distance plays an important role in our understanding of the inflow-outflow mechanisms in the Galactic centre (GC). This dependence is often fitted by spherical power-law profiles based on observations in the X-ray, infrared (IR), submillimetre (submm), and radio domains. Aims. Nevertheless, the density profile is poorly constrained at the intermediate scales of 1000 Schwarzschild radii (R s). Here we independently constrain the spherical density profile using the stellar bow shock of the star S2 which orbits the SMBH at the GC with the pericentre distance of 14.4 mas (∼1500 R s). Methods. Assuming an elliptical orbit, we apply celestial mechanics and the theory of bow shocks that are at ram pressure equilibrium. We analyse the measured IR flux density and magnitudes of S2 in the L-band (3.8 micron) obtained over seven epochs in the years between 2004-2018. We put an upper limit on the emission from S2's associated putative bow shock and constrain the density profile of the ambient medium. Results. We detect no significant change in S2 flux density until the recent periapse in May 2018. The intrinsic flux variability of S2 is at the level of 2-3%. Based on the dust-extinction model, the upper limit on the number density at the S2 periapse is ∼1.87 × 10 9 cm −3 , which yields a density slope of at most 3.20. Using the synchrotron bow-shock emission, we obtain the ambient density of 1.01 × 10 5 cm −3 and a slope of 1.47. These values are consistent with a wide variety of media from hot accretion flows to potentially colder and denser media comparable in properties to broad-line-region clouds. However, a standard thin disc can be excluded at the distance of S2's pericentre. Conclusions. With the current photometry sensitivity of 0.01 mag, we are not able to make stringent constraints on the density of the ambient medium in the GC using S2-star observations. We can distinguish between hot accretion flows and thin, cold discs, where the latter can be excluded at the scale of the S2 periapse. Future observations of stars in the S cluster using instruments such as Mid-IR Extremely Large Telescope Imager and Spectrograph at Extremely Large Telescope with the photometric sensitivity of as much as 10 −3 mag will allow the GC medium to be probed at intermediate scales at densities as low as ∼700 cm −3 in case of non-thermal bow-shock emission. The new instrumentation, in combination with discoveries of stars with smaller pericentre distances, will help to independently constrain the density profile around Sagittarius A* (Sgr A*).

show abstract

Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 97%

Constraining the accretion flow density profile near Sgr A* using theL′-band emission of the S2 star

Hosseini

Eckart

Sabha

et al. 2020

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The gas has complex, multi-component emission extended in space and velocity. We can identify one component to the West, associated with radio source Epsilon (Yusef-Zadeh et al 1990), two in the northeast and southeast corners associated with bright Wolf-Rayet stars (IRS16 C and IRS16 SW) and one featuring an almost linear feature immediately adjacent to the position of Sgr A* along the line of sight (Schödel et al 2011;Peißker et al 2020). More details on this extended gas emission are reported in Appendix E.…”

Section: Discussionmentioning

confidence: 93%

Upper Limit on Brackett-gamma Emission from the Immediate Accretion Flow onto the Galactic Black Hole

Ciurlo,

Morris,

Campbell

et al. 2021

Preprint

View full text Add to dashboard Cite

We present the first observational constraint on the Brγ recombination line emission associated with the supermassive black hole at the center of our Galaxy, known as Sgr A*. By combining 13 years of data with the Adaptive Optics fed integral field spectrograph OSIRIS at the W. M. Keck Observatory obtained as part of the Galactic Center Orbits Initiative, we extract the near-infrared spectrum within ∼0."2 of the black hole and we derive an upper limit on the Brγ flux. The aperture was set to match the size of the disk-like structure that was recently reported based on millimeter-wave ALMA observations of the hydrogen recombination line, H30α. Our stringent upper limit is at least a factor of 80 (and up to a factor of 245) below what would be expected from the ALMA measurements and strongly constrains possible interpretation of emission from this highly under-luminous supermassive black hole.

show abstract

“…GRAVITY Collaboration et al (2020) studied the polarization data of SGR A* during a bright NIR flare observed with the GRAVITY on July 28, 2018, the beam depolarized like emission indicated the flares' emission region resolves the magnetic field structure near the blackhole. Peißker et al (2020) through the observations of near-and mid-infrared of VISIR, find a proper motion of the filamentary emission which is very close to SGR A*. Also, Khabibullin et al (2020) found the bright flares of X-ray emission of SGR A*, combining these data with measurements of polarization can indicate that SGR A* is the primary source and the emission of the flares is polarization properties.…”

Section: Introductionmentioning

confidence: 82%

“…Yuan et al (2009b) has calculated the images of the ADAF surrounding a Kerr black hole with the observational wavelengths, with primary analysis by comparison with the observed sizes of SGR A* suggests that the disk around the central of SGR A* is highly inclined, or the central black hole is rotating fast. SGR A* is the most observed supermassive black hole and the most suitable observable object in many instruments such as ESO VLT (Paranal/Chile) and SINFONI and VISIR (Peißker et al 2020). The Event Horizon Telescope Event Horizon Telescope (EHT) will soon provide its first high-resolution images (Fromm et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Radiative energy from a reconnection region around massive black hole

Zhao,

Kumar

2021

Preprint

View full text Add to dashboard Cite

In the previous numerical study, we find the blob formation and ejection in the presence of magnetic reconnection in the environment of the hot flow of the accretion disk. Based on those encouraging results, in the present work, we calculate the energy and the spectrum of the emission in the different bands around Sgr A*. We assume the electrons in the magnetic reconnection region are non-thermal and emits synchrotron radiation. The electrons in the other region are thermal, which follows the thermal distribution, and the thermal electron emission mechanism is thermal synchrotron radiation. During the whole process of the magnetic evolution and reconnection, we find two peaks in the temporal light curve in the recently observed Radio frequencies (230 GHz and 43 GHz) and NIR wavelengths (3.8𝜇𝑚 and 2.2𝜇𝑚). Although, the light curve of the NIR band is most prominent in a single peak. The first peak appears because of the blob in the plasma flow, which is formed due to the magnetic reconnection. The second peak appears due to the production of the non-thermal electrons with the evolution of the magnetic flux. Both peaks reach luminosity more than 10 26 erg/s for a single plasmoid/blob. For the NIR band, the highest luminosity can reach more than 10 28 erg/s.These luminosities can be high for the large simulation area and the stronger magnetic field with the multiple blobs. We infer that the observed flares are a group of magnetic reconnection phenomena, not a single one.

show abstract

Near- and Mid-infrared Observations in the Inner Tenth of a Parsec of the Galactic Center Detection of Proper Motion of a Filament Very Close to Sgr A*

Cited by 21 publications

References 63 publications

Constraining the accretion flow density profile near Sgr A* using theL′-band emission of the S2 star

Constraining the accretion flow density profile near Sgr A* using theL′-band emission of the S2 star

Upper Limit on Brackett-gamma Emission from the Immediate Accretion Flow onto the Galactic Black Hole

Radiative energy from a reconnection region around massive black hole

Contact Info

Product

Resources

About