RADIO SYNCHROTRON EMISSION FROM A BOW SHOCK AROUND THE GAS CLOUD G2 HEADING TOWARD THE GALACTIC CENTER

AbstractThe radio flux from the synchrotron emission of electrons accelerated in the forward bow shock of G2 is expected to have peaked when the forward shock passes close to the pericenter from the Galactic center, around autumn of 2013. This radio flux is model dependent. We find that if G2 were to be a momentum-supported bow shock of a faint star with a strong wind, the radio synchrotron flux from the forward-shock heated ISM is well below the quiescent radio flux of Sgr A*. By contrast, if G2 is a diffuse cloud, the radio flux is predicted to be much larger than the quiescent radio flux and therefore should have already been detected or will be detected shortly. No such radiation has been observed to date. Radio measurements can reveal the nature of G2 well before G2 completes its periapsis passage.

Download Full-text

3D moving mesh simulations of Galactic center cloud G2

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000829 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 318-319 ◽

Cited By ~ 1

Author(s):

P. C. Fragile ◽

P. Anninos ◽

S. D. Murray

Keyword(s):

Feeding Rate ◽

Galactic Center ◽

Equations Of State ◽

Accretion Rate ◽

Three Dimensional ◽

Light Curves ◽

Moving Mesh ◽

Future Evolution ◽

Sgr A ◽

Gas Cloud

AbstractUsing three-dimensional, moving-mesh simulations, we investigate the future evolution of the recently discovered gas cloud G2 traveling through the galactic center. From our simulations we expect an average feeding rate onto Sgr A* in the range of (5−19) × 10−8M⊙ yr−1 beginning in 2014. This accretion varies by less than a factor of three on timescales ∼ 1 month, and shows no more than a factor of 10 difference between the maximum and minimum observed rates within any given model. These rates are comparable to the current estimated accretion rate in the immediate vicinity of Sgr A*, although they represent only a small (< 10%) increase over the current expected feeding rate at the effective inner boundary of our simulations (racc = 750 RS ∼ 1015 cm). We also explore multiple possible equations of state to describe the gas. In examining the Br-γ light curves produced from our simulations, we find that all of our isothermal models predict significant (factor of 10) enhancements in the luminosity of G2 as it approaches pericenter, in conflict with observations. Models that instead allow the cloud to heat as it is compressed do better at matching observations.

Download Full-text

Large-Scale Fragmentation of Gas Cloud Rotating at The Galactic Center

Fragmentation of Molecular Clouds and Star Formation ◽

10.1007/978-94-011-3384-5_24 ◽

1991 ◽

pp. 215-217

Author(s):

M. Fujimoto ◽

Y. Tatematsu

Keyword(s):

Large Scale ◽

Galactic Center ◽

Gas Cloud

Download Full-text

XMM-Newton and Geminga

Symposium - International Astronomical Union ◽

10.1017/s007418090018101x ◽

2004 ◽

Vol 218 ◽

pp. 215-218

Author(s):

Patrizia Caraveo ◽

Andrea De Luca ◽

Sandro Mereghetti ◽

Alberto Pellizzoni ◽

Giovanni Bignami ◽

...

Keyword(s):

Magnetic Field ◽

Surrounding Medium ◽

Matter Density ◽

Bow Shock ◽

Synchrotron Emission ◽

Electron Synchrotron ◽

X Ray ◽

Injection Energy ◽

Pulsar Wind ◽

Supersonic Motion

A deep XMM-Newton/EPIC observation of the field of the Geminga pulsar unveiled the presence of two elongated parallel X-ray tails trailing the neutron star. They are aligned with the object's supersonic motion, extend for ∼ 2′, and have a nonthermal spectrum produced by electron-synchrotron emission in the bow shock between the pulsar wind and the surrounding medium. Such a first ever X-ray detection of a pulsar bow shock allows us to gauge the pulsar electron injection energy and the shock magnetic field while constraining the angle of Geminga's motion and the local matter density.

Download Full-text

The Nature of the Galactic Center Arc

Symposium - International Astronomical Union ◽

10.1017/s0074180900229768 ◽

1996 ◽

Vol 169 ◽

pp. 263-269 ◽

Cited By ~ 1

Author(s):

E. Serabyn

Keyword(s):

Magnetic Field ◽

Strong Magnetic Field ◽

Galactic Center ◽

Magnetic Energy ◽

Linear Structure ◽

High Energy ◽

Molecular Gas ◽

Synchrotron Emission ◽

Interferometric Imaging ◽

Relativistic Particles

Ever since the Galactic Center Arc was resolved into its component filaments a decade ago, it has been clear that its linear structure arises from the influence of a strong magnetic field. However, the origin and nature of the contributory phenomena have remained elusive. Since what is seen is synchrotron emission from relativistic particles, of prime interest is a knowledge of the acceleration mechanism involved. Interferometric imaging of the molecular gas in the vicinity of the Arc has now provided a tantalizing clue to the Arc's origin: molecular clumps coinciding with the endpoints of a number of the Arc's filaments point to these clumps as the source of the relativistic particles. This suggests that as dense molecular clumps course through the ambient magnetic field at the Galactic Center, magnetic energy is liberated in their leading layers via field reconnection, precipitating rapid acceleration of free charges to high energy.

Download Full-text

3D ADAPTIVE MESH REFINEMENT SIMULATIONS OF THE GAS CLOUD G2 BORN WITHIN THE DISKS OF YOUNG STARS IN THE GALACTIC CENTER

The Astrophysical Journal ◽

10.1088/0004-637x/811/2/155 ◽

2015 ◽

Vol 811 (2) ◽

pp. 155 ◽

Cited By ~ 11

Author(s):

M. Schartmann ◽

A. Ballone ◽

A. Burkert ◽

S. Gillessen ◽

R. Genzel ◽

...

Keyword(s):

Adaptive Mesh Refinement ◽

Galactic Center ◽

Mesh Refinement ◽

Adaptive Mesh ◽

Young Stars ◽

Gas Cloud

Download Full-text

A new MIR bow shock source in the Galactic center

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000428 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 150-152 ◽

Cited By ~ 1

Author(s):

N. Sabha ◽

M. Zamaninasab ◽

A. Eckart ◽

L. Moser

Keyword(s):

Black Hole ◽

Symmetry Axis ◽

Galactic Center ◽

Bow Shock ◽

Shock Source ◽

Stellar Cluster ◽

Supermassive Black Hole ◽

Sgr A ◽

Central Parsec

AbstractWe find a convex-like feature at a distance of 0.68 pc (17″) from the position of the supermassive black hole, Sgr A*, at the center of the nuclear stellar cluster. This feature resembles a stellar bow shock with a symmetry axis pointing to the center. We discuss the possible nature of the feature and the implications of its alignment with other dusty comet-like objects inside the central parsec.

Download Full-text

The bow shock structure of IRS 7 - Wind-wind collision near the Galactic center

The Astrophysical Journal ◽

10.1086/186273 ◽

1992 ◽

Vol 385 ◽

pp. L41 ◽

Cited By ~ 44

Author(s):

Farhad Yusef-Zadeh ◽

Fulvio Melia

Keyword(s):

Galactic Center ◽

Shock Structure ◽

Bow Shock

Download Full-text

Large-scale fragmentation of gas cloud rotating at the Galactic center

Symposium - International Astronomical Union ◽

10.1017/s0074180900198936 ◽

1991 ◽

Vol 147 ◽

pp. 215-217

Author(s):

M. Fujimoto ◽

Y. Tatematsu

Keyword(s):

Gravitational Potential ◽

Large Scale ◽

Galactic Center ◽

Major Axis ◽

Matter Density ◽

The Self ◽

Dynamical Structure ◽

Gas Density ◽

Self Gravity ◽

Gas Cloud

A rotating and slowly-contracting gas cloud is followed in the deep gravitational potential of the galactic center. When the gas density increases as high as (102 — 103)H2 cm—3, which is more than twenty times as large as the background matter density, the self-gravity of the cloud becomes dominant to govern its dynamical structure. The cloud elongates and then splits into two separated objects, as observed at the centers of IC342, NGC6946, and Maffei 2 where we have two symmetric peaks on the major axis of the 12CO (J=1-0) cloud.

Download Full-text