THE PLERIONIC SUPERNOVA REMNANT G21.5-0.9 POWERED BY PSR J1833-1034: NEW SPECTROSCOPIC AND IMAGING RESULTS REVEALED WITH THE CHANDRA X-RAY OBSERVATORY

Journal Article · Sat Nov 20 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/724/1/572· OSTI ID:21471179

Matheson, Heather ^[1]; Safi-Harb, Samar ^[2]

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1. Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 (Canada)
2. Canada Research Chair. (Canada)

In 1999, the Chandra X-ray Observatory revealed a 150'' radius halo surrounding the 40'' radius pulsar wind nebula (PWN) G21.5-0.9. A 2005 imaging study of G21.5-0.9 showed that the halo is limb-brightened and suggested that this feature is a candidate for the long-sought supernova remnant (SNR) shell. We present a spectral analysis of SNR G21.5-0.9, using the longest effective observation to date (578.6 ks with the Advanced CCD Imaging Spectrometer (ACIS) and 278.4 ks with the High-Resolution Camera (HRC)) to study unresolved questions about the spectral nature of remnant features, such as the limb brightening of the X-ray halo and the bright knot in the northern part of the halo. The Chandra analysis favors the non-thermal interpretation of the limb. Its spectrum is fit well with a power-law model with a photon index {Gamma} = 2.13 (1.94-2.33) and a luminosity of L{sub x} (0.5-8 keV) = (2.3 {+-} 0.6) x 10{sup 33} erg s{sup -1} (at an assumed distance of 5.0 kpc). An srcut model was also used to fit the spectrum between the radio and X-ray energies. While the absence of a shell in the radio still prohibits constraining the spectrum at radio wavelengths, we assume a range of spectral indices to infer the 1 GHz flux density and the rolloff frequency of the synchrotron spectrum in X-rays and find that the maximum energy to which electrons are accelerated at the shock ranges from {approx}60 to 130 TeV (B/10 {mu}G){sup -1/2}, where B is the magnetic field in units of {mu}G. For the northern knot, we constrain previous models and find that a two-component power-law (or srcut) + pshock model provides an adequate fit, with the pshock model requiring a very low ionization timescale and solar abundances for Mg and Si. Our spectroscopic study of PSR J1833-1034, the highly energetic pulsar powering G21.5-0.9, shows that its spectrum is dominated by hard non-thermal X-ray emission with some evidence of a thermal component that represents {approx}9% of the observed non-thermal emission and that suggests non-standard rapid cooling of the neutron star. Finally, the ACIS and HRC-I images provide the first evidence for variability in the PWN, a property observed in other PWNe such as the Crab and Vela.

• OSTI ID: 21471179
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 724; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
COSMIC RADIATION
COSMIC RADIO SOURCES
ELECTRONS
ELEMENTARY PARTICLES
EMISSION
ENERGY RANGE
FERMIONS
FLUX DENSITY
IONIZATION
IONIZING RADIATIONS
LEPTONS
LUMINOSITY
MAGNETIC FIELDS
MEASURING INSTRUMENTS
NEBULAE
NEUTRON STARS
OPTICAL PROPERTIES
PHOTON EMISSION
PHYSICAL PROPERTIES
PULSARS
RADIATIONS
SPECTROMETERS
STARS
SUPERNOVA REMNANTS
TEV RANGE