scholarly journals Shock structure and shock heating in the Galactic central molecular zone

2013 ◽  
Vol 9 (S303) ◽  
pp. 104-105 ◽  
Author(s):  
Jürgen Ott ◽  
Michael Burton ◽  
Paul Jones ◽  
David S. Meier
Keyword(s):  
High Energy ◽  
Molecular Gas ◽  
Star Formation Region ◽  
Formation Region ◽  
Heating Source ◽  
Supermassive Black Hole ◽  
Shock Heating ◽  
Sgr A ◽  
Morphological Differences ◽  
High Energy Emission

AbstractWe present maps of a large number of dense molecular gas tracers across the central molecular zone of our Galaxy. The data were taken with the CSIRO/CASS Mopra telescope in Large Projects in the 1.3 cm, 7 mm, and 3 mm wavelength regimes. Here, we focus on the brightness of the shock tracers SiO and HNCO, molecules that are liberated from dust grains under strong (SiO) and weak (HNCO) shocks. The shocks may have occurred when the gas enters the bar regions and the shock differences could be due to differences in the moving cloud masses. Based on tracers of ionizing photons, it is unlikely that the morphological differences are due to selective photo-dissociation of the molecules. We also observe direct heating of molecular gas in strongly shocked zones, with high SiO/HNCO ratios, where temperatures are determined from the transitions of ammonia. Strong shocks appear to be the most efficient heating source of molecular gas, apart from high energy emission emitted by the central supermassive black hole Sgr A* and the processes within the extreme star formation region Sgr B2.

scholarly journals Acceleration of particles up to PeV energies at the galactic centre

2016 ◽  
Vol 12 (S324) ◽  
pp. 317-321
Author(s):  
Stefano Gabici ◽  
Felix A. Aharonian ◽  
Emmanuel Moulin ◽  
Aion Viana
Keyword(s):  
Black Hole ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Galactic Centre ◽  
Acceleration Of Particles ◽  
Supermassive Black Hole ◽  
Centre Region ◽  
Very High Energy ◽  
Sgr A ◽  
Very High

AbstractRecent very high energy observations of the galactic centre region performed by H.E.S.S. revealed the presence of a powerful PeVatron. This is the first of such objects detected, and its most plausible counterpart seems to be associated to Sgr A*, the supermassive black hole in the centre of our galaxy. The implications of this discovery will be discussed, in particular in the context of the problem of the origin of galactic cosmic rays.

TeV observations of the Galactic center and starburst galaxies

2013 ◽  
Vol 9 (S303) ◽  
pp. 29-42
Author(s):  
Mathieu de Naurois
Keyword(s):  
Black Hole ◽  
Cosmic Rays ◽  
Galactic Center ◽  
High Energy ◽  
Starburst Galaxies ◽  
Energy Emission ◽  
Very High Energy ◽  
Sgr A ◽  
High Energy Emission ◽  
Very High

AbstractThe vicinity of the Galactic center harbors many potential accelerators of cosmic rays (CR) that could shine in very-high-energy (VHE) γ-rays, such as pulsar wind nebulae, supernova remnants, binary systems and the central black hole Sgr A*, and is characterized by high gas density, large magnetic fields and a high rate of starburst activity similar to that observed in the core of starburst galaxies. In addition to these astrophysical sources, annihilation of putative WIMPs concentrated in the gravitational well could lead to significant high-energy emission at the Galactic center. The Galactic center region has been observed by atmospheric Cherenkov telescopes, and in particular by the H. E. S. S. array in Namibia for the last ten years above 150 GeV. This large data set, comprising more than 200 hours of observations, led to the discovery of a point-like source spatially compatible with the supermassive black hole Sgr A*, and to an extended diffuse emission, correlated with molecular clouds and attributed to the interaction of cosmic rays with the interstellar medium. Over the same time period, two starburst galaxies, namely M 82 and NGC 253, were detected at TeV energies after very deep exposures. Results from these ten years of observations of the Galactic center region and starburst galaxies at TeV energies are presented, and implications for the various very-high-energy emission mechanisms are discussed.

scholarly journals High-energy Emission from Supernovae and Remnants

2000 ◽  
Vol 195 ◽  
pp. 135-142
Author(s):  
R. A. Chevalier
Keyword(s):  
Supernova Remnants ◽  
High Energy ◽  
Molecular Gas ◽  
X Ray ◽  
Sn 1987A ◽  
Energy Emission ◽  
Energetic Radiation ◽  
Γ Ray ◽  
Composition Structure ◽  
High Energy Emission

An early burst of energetic radiation is expected from a supernova at the time of shock breakout. This emission has not been directly observed but has been inferred from the photoionization around SN 1987A. X-ray emission has been detected from core-collapse supernovae in the days to years after the explosion as they interact with their circumstellar winds. Young Galactic supernova remnants provide the possibility of determining the composition structure of the ejecta through X-ray spectroscopy. An exciting finding for older remnants is that a number of remnants that appear to be interacting with molecular gas may be sources of high-energy γ-ray emission. The clumpy structure of molecular clouds has implications for the structure expected in high-energy emission. Finally, the field of γ-ray-line spectroscopy is beginning to yield results relevant to the explosive nucleosynthesis of radionuclides in supernovae.

Molecular Gas in the NGC 6334 Star Formation Region

1999 ◽  
Vol 124 (2) ◽  
pp. 439-463 ◽  
Author(s):  
Kathleen E. Kraemer ◽  
James M. Jackson
Keyword(s):  
Star Formation ◽  
Molecular Gas ◽  
Star Formation Region ◽  
Formation Region ◽  
Ngc 6334

Central kiloparsec of NGC 1326 observed with SINFONI

2020 ◽  
Vol 638 ◽  
pp. A53
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Andreas Eckart ◽  
Françoise Combes ◽  
Persis Misquitta ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Stellar Content ◽  
Stellar Rotation ◽  
Supermassive Black Hole ◽  
Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

High‐Energy Emission from the TeV Blazar Markarian 501 during Multiwavelength Observations in 1996

1999 ◽  
Vol 514 (1) ◽  
pp. 138-147 ◽  
Author(s):  
J. Kataoka ◽  
J. R. Mattox ◽  
J. Quinn ◽  
H. Kubo ◽  
F. Makino ◽  
...  
Keyword(s):  
High Energy ◽  
Energy Emission ◽  
High Energy Emission ◽  
Multiwavelength Observations

scholarly journals WISDOM project – VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

2021 ◽  
Vol 503 (4) ◽  
pp. 5984-5996
Author(s):  
Mark D Smith ◽  
Martin Bureau ◽  
Timothy A Davis ◽  
Michele Cappellari ◽  
Lijie Liu ◽  
...  
Keyword(s):  
Black Hole ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Supermassive Black Hole ◽  
Gas Kinematics ◽  
Long Baseline ◽  
Gas Measurement ◽  
Strong Gradient

ABSTRACT Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0${^{\prime\prime}_{.}}$11 ($37\,$pc) resolution in the 12CO(2-1) line and $1.3\,$ mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially constant mass-to-light ratio to model the stellar mass distribution. We infer an SMBH mass of $2.5\pm 0.3\times 10^{9}\, \mathrm{M_\odot }$ and a stellar I-band mass-to-light ratio of $4.6\pm 0.2\, \mathrm{M_\odot /L_{\odot ,I}}$ (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionized gas kinematics, which however appears significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.

scholarly journals HIGH-ENERGY EMISSION OF GRB 130427A: EVIDENCE FOR INVERSE COMPTON RADIATION

2013 ◽  
Vol 776 (2) ◽  
pp. 95 ◽  
Author(s):  
Yi-Zhong Fan ◽  
P. H. T. Tam ◽  
Fu-Wen Zhang ◽  
Yun-Feng Liang ◽  
Hao-Ning He ◽  
...  
Keyword(s):  
High Energy ◽  
Energy Emission ◽  
Inverse Compton ◽  
High Energy Emission
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