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

2013 ◽  
Vol 9 (S303) ◽  
pp. 364-368 ◽  
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.

scholarly journals Galactic Center threads as nuclear magnetohydrodynamic waves

2020 ◽  
Vol 72 (2) ◽  
Author(s):  
Yoshiaki Sofue
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Galactic Center ◽  
Mhd Waves ◽  
Fast Mode ◽  
Magnetohydrodynamic Waves ◽  
Compression Waves ◽  
Sgr A ◽  
The Waves ◽  
The Magnetic Field

Abstract Propagation of fast-mode magnetohydrodynamic (MHD) compression waves is traced in the Galactic Center with a poloidal magnetic cylinder. MHD waves ejected from the nucleus are reflected and guided along the magnetic field, exhibiting vertically stretched fronts. The radio threads and non-thermal filaments are explained as due to tangential views of the waves driven by sporadic activity in Sgr A$^*$, or by multiple supernovae. In the latter case, the threads could be extremely deformed relics of old supernova remnants exploded in the nucleus.

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

2006 ◽  
Vol 638 (2) ◽  
pp. 786-796 ◽  
Author(s):  
Christopher L. Fryer ◽  
Gabriel Rockefeller ◽  
Aimee Hungerford ◽  
Fulvio Melia
Keyword(s):  
Galactic Center ◽  
Supernova Explosion ◽  
X Ray ◽  
Sgr A

scholarly journals Exploring plasma evolution during Sagittarius A* flares

2013 ◽  
Vol 9 (S303) ◽  
pp. 293-297
Author(s):  
S. Dibi ◽  
S. Markoff ◽  
R. Belmont ◽  
J. Malzac ◽  
N. M. Barrière ◽  
...  
Keyword(s):  
Particle Distribution ◽  
Magnetized Plasma ◽  
Flare Event ◽  
X Ray ◽  
Sagittarius A ◽  
Self Consistent ◽  
Infra Red ◽  
Sgr A ◽  
The Magnetic Field ◽  
Specific Particle

AbstractWe present a new way of describing the flares occurring from Sgr A* within a single zone with a self-consistent calculation of the particle distribution. The results allow us to give an interpretation to the flaring events generated very close to the supermassive black hole (SMBH) without assuming a specific particle distribution. We conclude that the flare data are more likely generated by a weakly magnetized plasma in which the particles flow in and out as expected from an accretion flow. Such a plasma, with prescription for non-thermal acceleration, injection, escape, and cooling losses, gives a spectrum with a break between the infra-red and the X-ray, allowing a better simultaneous match in the different wavelengths. The parameters favor the non-thermal synchrotron spectrum, and a decrease/increase of the magnetic field and plasma density are not favored for producing the flare event, but particle acceleration must be happening by other means. We show that under certain conditions, the real particle distribution can differ significantly from the standard distributions used in such studies.

scholarly journals Chandra observations of the X-ray emission from Molecular Clouds at the Galactic Center related to Sgr A* past activity

2013 ◽  
Author(s):  
Maica Clavel ◽  
Regis Terrier ◽  
Andrea Goldwurm ◽  
Mark Morris ◽  
G. Ponti ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Galactic Center ◽  
X Ray ◽  
Sgr A ◽  
Past Activity

scholarly journals Tracing the Milky Way’s Vestigial Nuclear Jet

2021 ◽  
Vol 922 (2) ◽  
pp. 254
Author(s):  
Gerald Cecil ◽  
Alexander Y. Wagner ◽  
Joss Bland-Hawthorn ◽  
Geoffrey V. Bicknell ◽  
Dipanjan Mukherjee
Keyword(s):  
Galactic Center ◽  
Galactic Plane ◽  
Hubble Space Telescope ◽  
Seyfert Galaxy ◽  
Radio Continuum ◽  
X Ray ◽  
Multiple Paths ◽  
Ngc 1068 ◽  
Sgr A ◽  
Hydrodynamical Simulations

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.

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

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.

scholarly journals On the past activity of Sgr A*

2013 ◽  
Vol 9 (S303) ◽  
pp. 333-343 ◽  
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.

scholarly journals Radio Detection of Colliding Wind Binaries

2006 ◽  
Vol 23 (1) ◽  
pp. 50-63 ◽  
Author(s):  
Paula Benaglia ◽  
Bärbel Koribalski ◽  
Juan F. Albacete Colombo
Keyword(s):  
Magnetic Field ◽  
Thermal Emission ◽  
Stellar Systems ◽  
Early Type ◽  
X Ray ◽  
High Energies ◽  
Radio Detection ◽  
Early Type Stars ◽  
The Magnetic Field ◽  
Compact Array

AbstractFour massive, early-type stars, three of which are confirmed binaries, have been observed with the Australia Telescope Compact Array at 1.4, 2.4, 4.8, and 8.6 GHz. The earliest star cataloged so far, HD 93129A, was also observed at 17.8 and 24.5 GHz. Here we present an analysis of the spectra as well as the structure of the stellar systems. All four spectra show clear evidence of non-thermal emission, indicative of a binary system with a colliding wind region. We discuss the magnetic field of the emitting region of HD 93129A and make predictions on the radiation at high energies. Archive X-ray observations towards the target sources are also investigated and interpreted in the light of the non-thermal emission detected.

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

2015 ◽  
Vol 815 (2) ◽  
pp. 132 ◽  
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

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

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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