• 한국컴퓨터정보학회지
• /
• 제25권1호
• /
• pp.1-6
• /
• 2017

• 천문학회보
• /
• 제32권1호
• /
• pp.57-57
• /
• 2007

• Kyungpook Mathematical Journal
• /
• 제22권1호
• /
• pp.123-129
• /
• 1982

• Kyungpook Mathematical Journal
• /
• 제22권1호
• /
• pp.53-54
• /
• 1982

• 대한치과마취과학회:학술대회논문집
• /
• 대한치과마취과학회 2004년도 제4차 정기총회 및 학술대회
• /
• pp.37-39
• /
• 2004

• 천문학회보
• /
• 제40권1호
• /
• pp.75.1-75.1
• /
• 2015

Environments (field, galaxy groups, and galaxy clusters) can affect galaxy evolution due to galaxy interaction which is controlled by different galaxy number densities and velocity dispersions. Since the galaxy interaction or merger triggers both star formation and AGN, AGN fraction can be used to understand the effect of environment. We detected X-ray AGN fraction in a nearby galaxy cluster, Abell 133, using Chandra X-ray image and optical spectra. We found ~600 X-ray point sources in the field of Abell 133 using the 2.8 Msec exposure Chandra images. We determined 3 cluster members based on the redshifts derived from optical spectra obtained from Magellan IMACS observation. The AGN fraction in Abell 133 is similar to that of other environments, i.e., COSMOS and CDFS. We will discuss the results by comparing Abell 133 with other environments.

• Journal of Astronomy and Space Sciences
• /
• 제30권3호
• /
• pp.127-132
• /
• 2013

Here we review the effort of Fermi Asian Network (FAN) in exploring the supernova remnants (SNRs) with state-of-art high energy observatories, including Fermi Gamma-ray Space Telescope and Chandra X-ray Observatory, in the period of 2011- 2012. Utilizing the data from Fermi LAT, we have discovered the GeV emission at the position of the Galactic SNR Kes 17 which provides evidence for the hadronic acceleration. Our study also sheds light on the propagation of cosmic rays from their acceleration site to the intersteller medium. We have also launched an identification campaign of SNR candidates in the Milky Way, in which a new SNR G308.3-1.4 have been uncovered with our Chandra observation. Apart from the remnant, we have also discovered an associated compact object at its center. The multiwavelength properties of this X-ray source suggest it can possibly be the compact binary that survived a supernova explosion.

• 천문학회지
• /
• 제38권2호
• /
• pp.211-214
• /
• 2005

We performed a spatially resolved spectroscopic study of the thermal composite supernova remnant 3C 391 by the Chandra observation. Broad- and narrow-band X-ray images show a southeast-northwest elongated morphology and unveil a highly clumpy structure of the remnant. The spectral analysis for. the small-scale features indicates normal metal abundance and uniform temperature for the interior gas. The properties of the hot gas are largely in agreement with the cloudlet evaporation model as a main mechanism for the 'thermal composite' X-ray appearance, though radiative rim and thermal conduction may also be effective. An unresolved X-ray source, with a power-law spectrum, is observed on the northwest border. The equivalent width images reveal a faint finger-like protrusion in Si and S lines out of the southwest radio border.

• 천문학회보
• /
• 제43권1호
• /
• pp.55.3-55.3
• /
• 2018

Magnetars are neutron stars powered by strong magnetic field (B > $10^{14}G$). Their spin period is in the range of 2 - 12s. The magnetic stress in the star may distort the crust (observed as outbursts), so magnetars (especially in outbursts) may emit gravitational waves. There are 29 magnetars known (potential gravitational waves sources), and increasing the number will increase the chance of detecting low-frequency gravitational waves. In addition, magnetars can be used for studying matter under extreme condition. In this study, we searched for more magnetars using extensive Chandra archival data and found 11 candidates. Due to the limited sensitivity of Chandra, form identification cannot be made, and more sensitivity X-ray data are needed.

• Journal of Astronomy and Space Sciences
• /
• 제19권3호
• /
• pp.173-180
• /
• 2002

Images taken with the Chandra X-ray telescope have for the the first time revealed the central, wind-driven, hot bubble (Chu et al. 2001), while Hubble Space Telescope (HST) WFPC2 images of the Cat's Eye nebula, NGC 6543, show that the temperature of the halo region of angular radius ~ 20", is much higher than that of the inner bright H II region. With the coupling of a photoionization calculation to a hydrodynamic simulation, we predict the observed 〔O III〕 line intensities of the halo region with the same O abundance as in the core H II region: oxygen abundance gradient does not appear to exist in the NGC 6543 inner halo. An interaction between a (leaky) fast stellar wind and halo gas may cause the higher excitation temperatures in the halo region and the inner hot bubble region observed with the Chandra X-ray telescope.