SOFT X-RAY SPECTROSCOPY OF THE CYGNUS LOOP SUPERNOVA REMNANT

The Cygnus X-Ray Emission Spectroscopic Survey (CyXESS) sounding rocket payload was launched from White Sands Missile Range on 2006 November 20 and obtained a high-resolution spectrum of the Cygnus Loop supernova remnant in the soft X-ray. The novel X-ray spectrograph incorporated a wire-grid collimator feeding an array of gratings in the extreme off-plane mount that ultimately dispersed the spectrum onto gaseous electron multiplier (GEM) detectors. This instrument recorded 65 s of usable data between 43 and 49.5 A in two prominent features. The first feature near 45 A is dominated by the He-like triplet of O VII in second order with contributions from Mg X and Si IX-Si XII in first order, while the second feature near 47.5 A is first-order S IX and S X. Fits to the spectra give an equilibrium plasma at log (T) = 6.2 (kTe = 0.14 keV) and near cosmic abundances. This is consistent with previous observations, which demonstrated that the soft X-ray emission from the Cygnus Loop is dominated by interactions between the initial blast wave and the walls of a precursor-formed cavity surrounding the Cygnus Loop and that this interaction can be described using equilibrium conditions.

[1]  Randall L. McEntaffer,et al.  CHANDRA IMAGING AND SPECTROSCOPY OF THE EASTERN XA REGION OF THE CYGNUS LOOP SUPERNOVA REMNANT , 2011, 1103.5648.

[2]  S. Reynolds,et al.  Maximum Energies of Shock-accelerated Electrons in Young Shell Supernova Remnants , 1999 .

[3]  D. Leahy.  X-ray spectrum variations in the south-west Cygnus Loop , 2004 .

[4]  S. P. Reynolds,et al.  Supernova Remnants in the Sedov Expansion Phase: Thermal X-Ray Emission , 2000 .

[5]  Dan McCammon,et al.  Interstellar photoelectric absorption cross-sections, 0.03-10 keV , 1983 .

[6]  K. Long,et al.  Einstein Observations of the Cygnus Loop , 1984 .

[7]  R. Petre,et al.  Evidence for shock acceleration of high-energy electrons in the supernova remnant SN1006 , 1995, Nature.

[8]  J. Blondin,et al.  On the X-ray spectrum of Kepler's supernova remnant , 1994 .

[9]  D. Liedahl,et al.  Collisional Plasma Models with APEC/APED: Emission-Line Diagnostics of Hydrogen-like and Helium-like Ions , 2001, astro-ph/0106478.

[10]  N. Gehrels.  Confidence limits for small numbers of events in astrophysical data , 1986 .

[11]  Xin Zhou,et al.  The origin of the X-ray-emitting plasma in the eastern edge of the Cygnus Loop , 2010, 1003.3424.

[12]  M. Arnaud,et al.  Iron ionization and recombination rates and ionization equilibrium , 1992 .

[13]  Motohide Kokubun,et al.  Detection of Highly-Ionized Carbon and Nitrogen Emission Lines from the Cygnus Loop Supernova Remnant with the Suzaku Observatory , 2007 .

[14]  A. Hamilton,et al.  X-ray line emission from supernova remnants. I - Models for adiabatic remnants , 1983 .

[15]  R. Kirshner,et al.  Spectrophotometry of the Cygnus Loop , 1982 .

[16]  J. Graham,et al.  The ROSAT HRI X-Ray Survey of the Cygnus Loop , 1997, astro-ph/9703092.

[17]  S. Rappaport,et al.  A soft X-ray survey of the galactic plane from Cygnus to Norma. , 1972 .

[18]  N. Nemes,et al.  The Plasma Structure of the Cygnus Loop from the Northeastern Rim to the Southwestern Rim , 2007, 0710.1135.

[19]  J. Raymond,et al.  Hubble Space Telescope Imaging of the Primary Shock Front in the Cygnus Loop Supernova Remnant , 2005 .

[20]  R. McCray,et al.  The Violent Interstellar Medium , 1979 .

[21]  L. Spitzer.  Physical processes in the interstellar medium , 1998 .

[22]  N. Grevesse,et al.  Abundances of the elements: Meteoritic and solar , 1989 .

[23]  Barham W. Smith,et al.  Soft X-ray spectrum of a hot plasma. , 1977 .

[24]  D. McCammon,et al.  Photoelectric absorption cross sections with variable abundances , 1992 .

[25]  S. Reynolds.  Models of Synchrotron X-Rays from Shell Supernova Remnants , 1998 .

[26]  J. Ostriker,et al.  A theory of the interstellar medium - Three components regulated by supernova explosions in an inhomogeneous substrate , 1977 .

[27]  J. Vink,et al.  Characterizing the Nonthermal Emission of Cassiopeia A , 2008, 0806.3748.

[28]  S. Katsuda,et al.  Ejecta Distributions of Heavy Elements in the Cygnus Loop , 2009, 0901.3433.

[29]  John P. Hughes,et al.  A Deep Chandra Observation of Kepler’s Supernova Remnant: A Type Ia Event with Circumstellar Interaction , 2007, 0708.3858.

[30]  J. Graham,et al.  Panoramic Views of the Cygnus Loop , 1998, astro-ph/9805008.

[31]  R. C. Catura,et al.  X-Ray Objective Grating Spectrograph , 1988, Optics & Photonics.

[32]  E. Salpeter,et al.  On the physics of dust grains in hot gas. , 1979 .

[33]  S. Katsuda,et al.  LINE-OF-SIGHT SHELL STRUCTURE OF THE CYGNUS LOOP , 2009, 0910.3731.

[34]  E. Salpeter,et al.  Destruction mechanisms for interstellar dust , 1979 .

[35]  W C Cash.  X-ray optics. 2: A technique for high resolution spectroscopy. , 1991, Applied optics.

[36]  R. Arendt,et al.  Infrared emission from X-ray and optically emitting regions in the Cygnus Loop supernova remnant , 1992 .

[37]  J. Graham,et al.  Shell Shock and Cloud Shock: Results from Spatially Resolved X-Ray Spectroscopy with Chandra in the Cygnus Loop , 2002, astro-ph/0205191.

[38]  J. Graham,et al.  The Cygnus Loop: A Soft-shelled Supernova Remnant , 1999 .

[39]  Eric Schindhelm,et al.  The Diffuse Interstellar Cloud Experiment (DICE): integration and first-look data , 2010, Astronomical Telescopes + Instrumentation.

[40]  C. Canizares,et al.  High-resolution X-ray spectroscopic evidence of nonequilibrium conditions in the Cygnus Loop , 1986 .

[41]  H. Tsunemi,et al.  Reflection-shocked Gas in the Cygnus Loop Supernova Remnant , 2001, astro-ph/0101558.

[42]  Duane A. Liedahl,et al.  New Calculations of Fe L-Shell X-Ray Spectra in High-Temperature Plasmas , 1995 .