The Sgr B2 X‐Ray Echo of the Galactic Center Supernova Explosion that Produced Sgr A East

Abstract MeerKAT radio continuum and XMM-Newton X-ray images have recently revealed a spectacular bipolar channel at the Galactic Center that spans several degrees (∼0.5 kpc). An intermittent jet likely formed this channel and is consistent with earlier evidence of a sustained, Seyfert-level outburst fueled by black hole accretion onto Sgr A* several Myr ago. Therefore, to trace a now weak jet that perhaps penetrated, deflected, and percolated along multiple paths through the interstellar medium, relevant interactions are identified and quantified in archival X-ray images, Hubble Space Telescope Paschen α images and Atacama Large Millimeter/submillimeter Array millimeter-wave spectra, and new SOAR telescope IR spectra. Hydrodynamical simulations are used to show how a nuclear jet can explain these structures and inflate the ROSAT/eROSITA X-ray and Fermi γ-ray bubbles that extend ± 75° from the Galactic plane. Thus, our Galactic outflow has features in common with energetic, jet-driven structures in the prototypical Seyfert galaxy NGC 1068.

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Molecular gas in the immediate vicinity of Sgr A* seen with ALMA

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012126 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 129-132

Author(s):

Lydia Moser ◽

Álvaro Sánchez-Monge ◽

Andreas Eckart ◽

Miguel A. Requena-Torres ◽

Macarena García-Marin ◽

...

Keyword(s):

Galactic Center ◽

Line Emission ◽

Molecular Gas ◽

Future Studies ◽

X Ray ◽

Circumnuclear Disk ◽

Sgr A ◽

Central Parsec ◽

Cloud Cores ◽

Cold Core

AbstractWe report serendipitous detections of line emission with ALMA in band 3, 6, and 7 in the central parsec of the Galactic center at an up to now highest resolution (<0.7″). Among the highlights are the very first and highly resolved images of sub-mm molecular emission of CS, H13CO+, HC3N, SiO, SO, C2H, and CH3OH in the immediate vicinity (~1″ in projection) of Sgr A* and in the circumnuclear disk (CND). The central association (CA) of molecular clouds shows three times higher CS/X (X: any other observed molecule) luminosity ratios than the CND suggesting a combination of higher excitation - by a temperature gradient and/or IR-pumping - and abundance enhancement due to UV- and/or X-ray emission. We conclude that the CA is closer to the center than the CND is and could be an infalling clump consisting of denser cloud cores embedded in diffuse gas. Moreover, we identified further regions in and outside the CND that are ideally suited for future studies in the scope of hot/cold core and extreme PDR/XDR chemistry and consequent star formation in the central few parsecs.

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On the past activity of Sgr A*

Proceedings of the International Astronomical Union ◽

10.1017/s174392131400088x ◽

2013 ◽

Vol 9 (S303) ◽

pp. 333-343 ◽

Cited By ~ 1

Author(s):

G. Ponti ◽

M. R. Morris ◽

M. Clavel ◽

R. Terrier ◽

A. Goldwurm ◽

...

Keyword(s):

Strong Evidence ◽

Galactic Center ◽

Galactic Disk ◽

X Ray ◽

The Past ◽

Sgr A ◽

Past Activity

AbstractRecent X-ray emission events in the Galactic center would be expected to generate an X-ray reflection response within the surrounding clouds of the central molecular zone, in the Galactic disk and even, if powerful enough, in clouds outside our Galaxy. We review here the current constraints on Sgr A*'s past activity obtained through this method, with particular emphasis on the strong evidence that has been gathered for multiple X-ray flashes during the past few hundred years.

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HARD X-RAY MORPHOLOGICAL AND SPECTRAL STUDIES OF THE GALACTIC CENTER MOLECULAR CLOUD SGR B2: CONSTRAINING PAST SGR A⋆ FLARING ACTIVITY

The Astrophysical Journal ◽

10.1088/0004-637x/815/2/132 ◽

2015 ◽

Vol 815 (2) ◽

pp. 132 ◽

Cited By ~ 31

Author(s):

Shuo Zhang ◽

Charles J. Hailey ◽

Kaya Mori ◽

Maïca Clavel ◽

Régis Terrier ◽

...

Keyword(s):

Molecular Cloud ◽

Galactic Center ◽

Spectral Studies ◽

X Ray ◽

Sgr A

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A new perspective on the radio active zone at the Galactic center – feedback from nuclear activities

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000921 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 364-368 ◽

Cited By ~ 1

Author(s):

J.-H. Zhao ◽

M. R. Morris ◽

W. M. Goss

Keyword(s):

Galactic Center ◽

Detailed Structure ◽

Radio Image ◽

X Ray ◽

Radio Detection ◽

Deep Image ◽

Sgr A ◽

New Perspective ◽

Poloidal Magnetic Fields ◽

The Magnetic Field

AbstractBased on our deep image of Sgr A using broadband data observed with the VLA† at 6 cm, we present a new perspective of the radio bright zone at the Galactic center. We further show the radio detection of the X-ray Cannonball, a candidate neutron star associated with the Galactic center SNR Sgr A East. The radio image is compared with the Chandra X-ray image to show the detailed structure of the radio counterparts of the bipolar X-ray lobes. The bipolar lobes are likely produced by the winds from the activities within Sgr A West, which could be collimated by the inertia of gas in the CND, or by the momentum driving of Sgr A*; and the poloidal magnetic fields likely play an important role in the collimation. The less-collimated SE lobe, in comparison to the NW one, is perhaps due to the fact that the Sgr A East SN might have locally reconfigured the magnetic field toward negative galactic latitudes. In agreement with the X-ray observations, the time-scale of ∼1 × 104 yr estimated for the outermost radio ring appears to be comparable to the inferred age of the Sgr A East SNR.

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Can we infer the past activity of M31⋆ as we do for Sgr A⋆?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316013041 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 253-256

Author(s):

Maïca Clavel ◽

Régis Terrier ◽

Andrea Goldwurm ◽

Mark R. Morris ◽

Gabriele Ponti

Keyword(s):

Black Holes ◽

Molecular Clouds ◽

Galactic Center ◽

Supermassive Black Holes ◽

X Ray ◽

The Past ◽

Upper Limits ◽

History Of ◽

Sgr A ◽

Past Activity

AbstractThe history of supermassive black holes’ activity can be partly constrained by monitoring the diffuse X-ray emission possibly created by the echoes of past events propagating through the molecular clouds of their respective environments. In particular, using this method we have demonstrated that our Galaxy’s supermassive black hole, Sgr A⋆, has experienced multiple periods of higher activity in the last centuries, likely due to several short but very energetic events, and we now investigate the possibility of studying the past activity of other supermassive black holes by applying the same method to M31⋆. We set strong constraints on putative phase transitions of this more distant galactic nucleus but the existence of short events such as the ones observed in the Galactic center cannot be assessed with the upper limits we derived.

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The Hot Gas in the Galactic Bulge

Symposium - International Astronomical Union ◽

10.1017/s0074180900229823 ◽

1996 ◽

Vol 169 ◽

pp. 287-295

Author(s):

K. Koyama ◽

Y. Maeda

Keyword(s):

Galactic Center ◽

Remarkable Feature ◽

Strong Emission ◽

X Ray ◽

Hot Gas ◽

Bright Spots ◽

X Ray Imaging ◽

Soft Spectrum ◽

Sgr A ◽

Extended Emission

X-ray imaging spectroscopic observations near the Galactic center region were carried out with the ASCA satellite. We found two bright spots very close to the Galactic center (Sgr A∗); one is extended and has a soft spectrum associated with strong emission lines from highly ionized irons, while the other is a point-like object with a harder spectrum and a larger absorption. We also found extended emission with K-shell transition lines from highly ionized Si, S, Ar, Ca and Fe. Remarkable feature found with ASCA is an extended emission of 6.4 keV lines of low ionization irons. The 6.4 keV line fluxes are found to be well correlated to the region of cool clouds. We interpret that the 6.4 keV line is due to florescence from the cool clouds irradiated by strong (and obscured from our line of sight) X-ray beams.

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Multiple accretion events as a trigger for Sagittarius A* activity

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000830 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 320-321

Author(s):

D. Kunneriath ◽

B. Czerny ◽

V. Karas ◽

T. K. Das

Keyword(s):

Angular Momentum ◽

Molecular Clouds ◽

Galactic Center ◽

X Ray ◽

Supermassive Black Hole ◽

The Past ◽

Sagittarius A ◽

Enhanced Activity ◽

Show Evidence ◽

Sgr A

AbstractThe Galactic center supermassive black hole is surrounded by orbiting clouds of gas. These clumps of gas may collide with each other, losing angular momentum and plunging towards the center. Observations of X-ray reflection from molecular clouds surrounding the Galactic center show evidence for enhanced activity of Sagittarius A* during the past few hundred years. These observations enable us to place constraints on the nature of past accretion events responsible for this enhanced activity. We model the source intrinsic luminosity of Sgr A* using multiple accretion events occurring at various moments in time, characterized by a range of angular momentum We also applied our scheme to the case of G2 cloud in the Galactic center.

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