X‐Ray Observations of the Compact Source in CTA 1

Abstract

The point source RX J0007.0+7302, at the center of supernova remnant CTA 1, was studied using the X-Ray Multi-mirror Mission (XMM-Newton). The X-ray spectrum of the source is consistent with a neutron star interpretation, and is well described by a power law with the addition of a soft thermal component that may correspond to emission from hot polar cap regions or to cooling emission from a light element atmosphere over the entire star. There is evidence of extended emission on small spatial scales which may correspond to structure in the underlying synchrotron nebula. No pulsations are observed. Extrapolation of the nonthermal spectrum of RX J0007.0+7302 to gamma-ray energies yields a flux consistent with that of EGRET source 3EG J0010+7309, supporting the proposition that there is a gamma-ray emitting pulsar at the center of CTA 1. Observations of the outer regions of CTA 1 with the Advanced Satellite for Cosmology and Astrophysics confirm earlier detections of thermal emission from the remnant and show that the synchrotron nebula extends to the outermost reaches of the SNR. Subject headings: stars: neutron -stars: individual (RX J0007.0+7302, 3EG J0010+7309) -ISM: individual (CTA 1) -supernova remnants -X-rays: ISM

VERITAS observation of CTA1

“…From the X-ray observation, the spin down energy of the pulsar is estimated to be ~4. 5 × 10 35 ergs per second [1]. Deep searches in optical and radio wavelengths could not find a counterpart to RX J0007.0+7302.…”

“…The distance to the SNR is estimated to be 1.4 ± 0.3 kpc based on the association of an H1 shell on the northwest part of the remnant [6]. The age of SNR is ~1.3 × 10 4 years [1]. The X-ray observation of CTA1 suggests that the extended non-thermal emission around the radio quiet, gamma-ray pulsar is a synchrotron PWN.…”

Comparing Neutron Star Kicks to Supernova Remnant Asymmetries

“…Non-thermal X-rays in CTA 1 reveal the presence of a PWN with a central radio pulsar RX J0007.0+7303 that exhibits jet-like structure (Slane et al 1997;Halpern et al 2004). Slane et al (2004) initially modeled the ASCA spectra of CTA 1 as an absorbed power-law and discovered that a thermal CIE component was required to fit the data below ≈1 keV. They found a column density of N H ≈ 2.8×10 21 cm −2 , a spectral index of Γ ≈ 2.3, and a plasma temperature of kT ≈ 0.27 keV.…”

The Fermi Gamma-Ray Space Telescope Discovers the Pulsar in the Young Galactic Supernova Remnant CTA 1

“…The radio and X-ray characteristics of CTA 1 imply that it is 1.4±0.3 kpc away (6) and it exploded 5000 to 15000 years ago (6,10,11).…”

“…A particle-heated polar cap could be a possibility. Alternatively, if the NS has a light element atmosphere and cools through a direct URCA process, a cooling age of (1-2)×10 4 years is also possible (11). Although no signs of periodicity could be found in the X-ray data (11) the energetics of the PWN lead to typical requirements for the time-averaged spin-down power of the putative pulsar of 10 36 -10 37 erg/s.…”