Extended hard-X-ray emission in the inner few parsecs of the Galaxy.
The Galactic Centre hosts a puzzling stellar population in its inner few parsecs, with a high abundance of surprisingly young, relatively massive stars bound within the deep potential well of the central supermassive black hole, Sagittarius A* (ref. 1). Previous studies suggest that the population of objects emitting soft X-rays (less than 10 kiloelectronvolts) within the surrounding hundreds of parsecs, as well as the population responsible for unresolved X-ray emission extending along the Galactic plane, is dominated by accreting white dwarf systems. Observations of diffuse hard-X-ray (more than 10 kiloelectronvolts) emission in the inner 10 parsecs, however, have been hampered by the limited spatial resolution of previous instruments. Here we report the presence of a distinct hard-X-ray component within the central 4 × 8 parsecs, as revealed by subarcminute-resolution images in the 20-40 kiloelectronvolt range. This emission is more sharply peaked towards the Galactic Centre than is the surface brightness of the soft-X-ray population. This could indicate a significantly more massive population of accreting white dwarfs, large populations of low-mass X-ray binaries or millisecond pulsars, or particle outflows interacting with the surrounding radiation field, dense molecular material or magnetic fields. However, all these interpretations pose significant challenges to our understanding of stellar evolution, binary formation, and cosmic-ray production in the Galactic Centre.
1] Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, Room 1027, New York, New York 10027, USA [2] Haverford College, 370 Lancaster Avenue, KINSC L109, Haverford, Pennsylvania 19041, USA.
Kerstin
K
Perez
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, Room 1027, New York, New York 10027, USA.
Charles J
CJ
Hailey
1] Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306, Santiago 22, Chile [2] Millennium Institute of Astrophysics, Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile [3] Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301, USA.
Franz E
FE
Bauer
Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA.
Roman A
RA
Krivonos
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, Room 1027, New York, New York 10027, USA.
Kaya
K
Mori
Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 37-555, Cambridge, Massachusetts 02139, USA.
Frederick K
FK
Baganoff
Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA.
Nicolas M
NM
Barrière
Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA.
Steven E
SE
Boggs
DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby, Denmark.
Finn E
FE
Christensen
1] Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA [2] Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551-0808, USA.
William W
WW
Craig
Cahill Center for Astronomy and Astrophysics, 1200 East California Boulevard, MC 290-17, California Institute of Technology, Pasadena, California 91125, USA.
Brian W
BW
Grefenstette
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-83, Cambridge, Massachusetts 02138, USA.
Jonathan E
JE
Grindlay
Cahill Center for Astronomy and Astrophysics, 1200 East California Boulevard, MC 290-17, California Institute of Technology, Pasadena, California 91125, USA.
Fiona A
FA
Harrison
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-83, Cambridge, Massachusetts 02138, USA.
Jaesub
J
Hong
Cahill Center for Astronomy and Astrophysics, 1200 East California Boulevard, MC 290-17, California Institute of Technology, Pasadena, California 91125, USA.
Kristin K
KK
Madsen
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, Room 1027, New York, New York 10027, USA.
Melania
M
Nynka
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, 4800 Oak Grove Drive, MS 169-221, California 91109, USA.
Daniel
D
Stern
Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA.
John A
JA
Tomsick
NASA Goddard Space Flight Center, 8800 Greenbelt Road, Code 662, Greenbelt, Maryland 20771, USA.
Daniel R
DR
Wik
Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, Room 1027, New York, New York 10027, USA.
Shuo
S
Zhang
NASA Goddard Space Flight Center, 8800 Greenbelt Road, Code 662, Greenbelt, Maryland 20771, USA.
William W
WW
Zhang
Space Science Laboratory, UC Berkeley, 7 Gauss Way, Berkeley, California 94720, USA.
Andreas
A
Zoglauer