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

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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Tidally-disrupted Molecular Clouds falling to the Galactic Center

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012047 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 115-118 ◽

Cited By ~ 1

Author(s):

Masato Tsuboi ◽

Yoshimi Kitamura ◽

Kenta Uehara ◽

Ryosuke Miyawaki ◽

Atsushi Miyazaki

Keyword(s):

Molecular Cloud ◽

Molecular Clouds ◽

Galactic Center ◽

Outer Region ◽

Recombination Line ◽

Ionized Gas ◽

Boundary Area ◽

Gas Streams ◽

Uv Emission ◽

Sgr A

AbstractWe found a molecular cloud connecting from the outer region to the “Galactic Center Mini-spiral (GCMS)” which is a bundle of the ionized gas streams adjacent to Sgr A*. The molecular cloud has a filamentary appearance which is prominent in the CSJ=2-1 emission line and is continuously connected with the GCMS. The velocity of the molecular cloud is also continuously connected with that of the ionized gas in the GCMS observed in the H42α recombination line. The morphological and kinematic relations suggest that the molecular cloud is falling from the outer region to the vicinity of Sgr A*, being disrupted by the tidal shear of Sgr A* and ionized by UV emission from the Central Cluster. We also found the SiOJ=2-1 emission in the boundary area between the filamentary molecular cloud and the GCMS. There seems to exist shocked gas in the boundary area.

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The Deuterium Abundance In The Galactic Center 50 km/s Molecular Cloud: Evidence For A Cosmological Origin Of D

Symposium - International Astronomical Union ◽

10.1017/s0074180900166550 ◽

2000 ◽

Vol 198 ◽

pp. 167-175

Author(s):

D. A. Lubowich ◽

Jay M. Pasachoff ◽

Robert P. Galloway ◽

Thomas J. Balonek ◽

Christy Tremonti ◽

...

Keyword(s):

Molecular Cloud ◽

Galactic Center ◽

Reaction Model ◽

Baryon Density ◽

The Galaxy ◽

Chemical Reaction Model ◽

Sgr A ◽

Galactic Sources ◽

Continuous Injection ◽

The Universe

We confirm that deuterium exists in the Galactic Center (GC) and estimate that D/H = 3 × 10−6 using a new 5192-chemical reaction model. This is the lowest D/H ratio observed in the Galaxy, five times lower than the local ISM D/H = 1.5 × 10−5 but 106 × larger than D/H predicted by GC models. We detected DCN in the GC Sgr A 50 km/s molecular cloud located 10 pc from the GC with the NRAO 12m telescope and obtained T*R = 0.061 ± 0.007 K and 0.04 ± 0.02 K for the J = 1-0 and 2-1 lines. The most likely source of the GC D is continuous injection from the infall of primordial matter with D/H = 5 × 10−5 with the D/H determined by astration and mixing. Thus there are no significant Galactic sources of D and no recent quasar or AGN activity in the GC. This primordial D/H implies that the baryon density is less than the density necessary to close the Universe; most of the baryons are in dark matter; and there are fewer than four ν families.

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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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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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