First results from the NuSTAR “mini-survey” of the Galactic center region

2013 ◽  
Vol 9 (S303) ◽  
pp. 439-443
Author(s):  
Charles J. Hailey ◽  
Keyword(s):  
Galactic Center ◽  
Galactic Plane ◽  
Pulsar Wind Nebulae ◽  
Telescope Array ◽  
X Ray ◽  
Center Region ◽  
First Results ◽  
Pulsar Wind ◽  
Sgr A

AbstractOne of the major science objectives of the Nuclear Spectroscopic Telescope Array (NuSTAR) observatory is to perform the first sub-arcminute, hard X-ray survey of several square degrees of the Galactic plane, centered on a region near the Galactic center. As a prelude to the full survey, which began in July 2013, NuSTAR conducted a ∼500 ks, 0.3 × 0.4° “mini-survey” focused on Sgr A* and its environs. We present analysis of several candidate pulsar wind nebulae and filaments, which are revealed to be intense sources of X-ray emission at >10 keV.

scholarly journals Detailed distributions of the CO J = (2 − 1)/J = (1 − 0) intensity ratios toward a large area of the central molecular zone

2013 ◽  
Vol 9 (S303) ◽  
pp. 106-108
Author(s):  
Kazufumi Torii ◽  
Rei Enokiya ◽  
Yasuo Fukui ◽  
Hiroaki Yamamoto ◽  
Akiko Kawamura ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Galactic Center ◽  
Galactic Plane ◽  
Area Coverage ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Large Area ◽  
First Results ◽  
Intensity Ratios ◽  
Sgr A

AbstractWe present the first results of the new CO J = (2 − 1) observations toward the central molecular zone (CMZ) using the NANTEN2 telescope at an angular resolution of 100″. Large area coverage of 4° × 2° in l and b and a high angular resolution of 100″ enable us to investigate detailed structures of the molecular gas in the CMZ including peculiar molecular filaments perpendicularly to the Galactic plane to b > |0.5°|. The major components of the CMZ, e.g., Sgr A, Sgr B and Sgr C cloud complexes, show high CO J = (2 − 1)/J = (1 − 0) ratios around 0.9, indicating highly excited conditions of the molecular gas, while the local foreground components show less than 0.4. The molecular filaments show the typical ratios of 0.6–0.7 indicate that they are indeed located in the Galactic center.

scholarly journals Nonthermal filamentary radio features within 20 pc of the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 369-373 ◽  
Author(s):  
M. R. Morris ◽  
J.-H. Zhao ◽  
W. M. Goss
Keyword(s):  
Galactic Center ◽  
Galactic Plane ◽  
Pulsar Wind Nebulae ◽  
Flux Tubes ◽  
Deep Imaging ◽  
Point Reflection ◽  
Predominant Orientation ◽  
Magnetic Flux Tubes ◽  
Field Lines ◽  
Sgr A

AbstractDeep imaging of the Sgr A complex at 6 cm wavelength with the B and C configurations of the Karl G. Jansky VLA† has revealed a new population of faint radio filaments. Like their brighter counterparts that have been observed throughout the Galactic center on larger scales, these filaments can extend up to ∼10 parsecs, and in most cases are strikingly uniform in brightness and curvature. Comparison with a survey of Paschen-α emission reveals that some of the filaments are emitting thermally, but most of these structures are nonthermal: local magnetic flux tubes illuminated by synchrotron emission. The new image reveals considerable filamentary substructure in previously known nonthermal filaments (NTFs). Unlike NTFs previously observed on larger scales, which tend to show a predominant orientation roughly perpendicular to the Galactic plane, the NTFs in the vicinity of the Sgr A complex are relatively randomly oriented. Two well-known radio sources to the south of Sgr A – sources E and F – consist of numerous quasi-parallel filaments that now appear to be particularly bright portions of a much larger, strongly curved, continuous, nonthermal radio structure that we refer to as the “Southern Curl”. It is therefore unlikely that sources E and F are Hii regions or pulsar wind nebulae. The Southern Curl has a smaller counterpart on the opposite side of the Galactic center – the Northern Curl – that, except for its smaller scale and smaller distance from the center, is roughly point-reflection symmetric with respect to the Southern Curl. The curl features indicate that some field lines are strongly distorted, presumably by mass flows. The point symmetry about the center then suggests that the flows originate near the center and are somewhat collimated.

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 10.7. Absorption columns with bright X-ray sources near the galactic center: — mass estimation in the Galactic center region

1998 ◽  
Vol 184 ◽  
pp. 443-444 ◽  
Author(s):  
Masaaki Sakano ◽  
Mamiko Nishiuchi ◽  
Yoshitomo Maeda ◽  
Katsuji Koyama ◽  
Jun Yokogawa
Keyword(s):  
Simple Form ◽  
Total Mass ◽  
Column Density ◽  
Galactic Center ◽  
Galactic Plane ◽  
Angular Distance ◽  
Mass Determination ◽  
Mass Estimation ◽  
X Ray ◽  
Center Region

We report the column density distribution to the Galactic Center region using the X-ray binary observations with the X-ray satellite ASCA, and demonstrate a new method of the total mass determination near the Galactic Center. The column densities are given by a simple form as a function of the angular distance from the Galactic Plane. Assuming a disklike mass distribution of 500 pc radius, we estimate the total mass to be ~ 6 × 107M⊙.

scholarly journals New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations

2017 ◽  
Vol 470 (1) ◽  
pp. 512-516 ◽  
Author(s):  
Roman A. Krivonos ◽  
Sergey S. Tsygankov ◽  
Ilya A. Mereminskiy ◽  
Alexander A. Lutovinov ◽  
Sergey Yu. Sazonov ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Sky Survey ◽  
The Galaxy ◽  
Pulsar Wind

Abstract The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) continues to successfully work in orbit after its launch in 2002. The mission provides the deepest ever survey of hard X-ray sources throughout the Galaxy at energies above 20 keV. We report on a catalogue of new hard X-ray source candidates based on the latest sky maps comprising 14 yr of data acquired with the IBIS telescope onboard INTEGRAL in the Galactic Plane (|b| < 17.5°). The current catalogue includes in total 72 hard X-ray sources detected at S/N > 4.7σ and not known to previous INTEGRAL surveys. Among them, 31 objects have also been detected in the on-going all-sky survey by the BAT telescope of the Swift observatory. For 26 sources on the list, we suggest possible identifications: 21 active galactic nuclei, two cataclysmic variables, two isolated pulsars or pulsar wind nebulae and one supernova remnant; 46 sources from the catalogue remain unclassified.

scholarly journals X-RAY DIAGNOSTICS OF GIANT MOLECULAR CLOUDS IN THE GALACTIC CENTER REGION AND PAST ACTIVITY OF Sgr A*

2011 ◽  
Vol 740 (2) ◽  
pp. 103 ◽  
Author(s):  
Hirokazu Odaka ◽  
Felix Aharonian ◽  
Shin Watanabe ◽  
Yasuyuki Tanaka ◽  
Dmitry Khangulyan ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Galactic Center ◽  
Giant Molecular Clouds ◽  
X Ray ◽  
Center Region ◽  
Sgr A ◽  
Past Activity

scholarly journals The contribution of Galactic TeV pulsar wind nebulae to Fermi-LAT diffuse emission

2021 ◽  
Author(s):  
Vittoria Vecchiotti ◽  
Giulia Pagliaroli ◽  
Francesco Villante
Keyword(s):  
Cosmic Rays ◽  
Energy Range ◽  
Spectral Index ◽  
Large Scale ◽  
Galactic Center ◽  
Galactic Plane ◽  
Diffuse Emission ◽  
Pulsar Wind Nebulae ◽  
Γ Ray ◽  
Pulsar Wind

Abstract The large-scale diffuse γ−ray flux observed by Fermi-LAT in the 1-100 GeV energy range, parameterized as ∝ E−Γ, has a spectral index Γ that depends on the distance from the Galactic center. This feature, if attributed to the diffuse emission produced by cosmic rays (CR) interactions with the interstellar gas, can be interpreted as the evidence of a progressive CR spectral hardening towards the Galactic center. This interpretation challenges the standard cosmic rays diffusion paradigm. We report on the implications of TeV Pulsar Wind Nebulae observed by the HESS Galactic Plane Survey in the 1-100 TeV energy range for the interpretation of Fermi-LAT data. We argue that a relevant fraction of this population cannot be resolved by Fermi-LAT in the GeV domain providing a relevant contribution to the large-scale diffuse emission, viz. the 30% of the total diffuse γ-ray emission in the inner Galaxy. This additional component naturally accounts for a large part of the spectral index variation observed by Fermi-LAT, weakening the evidence of CR spectral hardening in the inner Galaxy.

scholarly journals The H.E.S.S. Galactic Plane Survey

2009 ◽  
Vol 5 (H15) ◽  
pp. 808-808
Author(s):  
Emma de Oña-Wilhelmi
Keyword(s):  
Supernova Remnants ◽  
Binary Systems ◽  
Galactic Plane ◽  
Giant Molecular Clouds ◽  
Pulsar Wind Nebulae ◽  
Compact Binary ◽  
Pulsar Wind ◽  
Star Formation Regions ◽  
Galactic Sources ◽  
Gps Observations

AbstractThe H.E.S.S. Galactic Plane Survey (GPS) has revealed a large number of Galactic Sources, including Pulsar Wind Nebulae (PWN), Supernova Remnants (SNRs), giant molecular clouds, star formation regions and compact binary systems, as well as a number of unidentified objects, or dark sources, for which no obvious counterparts at other wavelengths have yet been found. We will review the latest results from the GPS observations and discuss the most interesting cases.

X-ray bursts from the source A1742-294 in the Galactic-center region

2001 ◽  
Vol 27 (8) ◽  
pp. 501-506 ◽  
Author(s):  
A. A. Lutovinov ◽  
S. A. Grebenev ◽  
M. N. Pavlinsky ◽  
R. A. Sunyaev
Keyword(s):  
Galactic Center ◽  
X Ray ◽  
Center Region

scholarly journals Sgr A* and Company—Multiwavelength Observations of Sgr A* and VLA Search for “Sgr A*’s” in LINERs

1998 ◽  
Vol 164 ◽  
pp. 323-324
Author(s):  
H. Falcke ◽  
W. M. Goss ◽  
L. C. Ho ◽  
H. Matsuo ◽  
P. Teuben ◽  
...  
Keyword(s):  
Low Power ◽  
Galactic Center ◽  
First Results ◽  
Liner Galaxies ◽  
Sgr A ◽  
Multiwavelength Observations

AbstractWe report first results from a multiwavelength campaign to measure the simultaneous spectrum of Sgr A* from cm to mm wavelengths. The observations confirm that the previously detected submm-excess is not due to variability; the presence of an ultracompact component with a size of a few Schwarzschild radii is inferred. In a VLA survey of LINER galaxies, we found Sgr A*-like nuclei in one quarter of the galaxies searched, suggesting a link between those low-power AGN and the Galactic Center.

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