ASCA Observations Research Articles

ASCA and ROSAT observations of NGC 5548: discrepant spectral indices

We report on simultaneous ASCA and ROSAT observations of the Seyfert galaxy NGC 5548 made during the ASCA Performance Verification phase. Spectral features due to a warm absorber and reflection are clearly seen in the X-ray spectra. We find that the continuum spectral shape differs between the ASCA and ROSAT data sets. The photon-index obtained from the ROSAT PSPC exceeds that from the ASCA SIS ΔΓ≈0.4. The discrepancy is clear even in the 0.5–2 keV energy band over which both detectors are sensitive. The spectra cannot be made consistent by choosing a more complex model. The problem likely lies in the response curve (estimated effective area) of one, or both, detectors. There may be important consequences for a wide range of published results.

The X-ray nature of AX J2049.6+2939

AX J2049.6+2939 is a compact source in the vicinity of the southern blow-up region of the Cygnus Loop super-nova remnant (Miyata 1998). This source is the brightest X-ray source found during the ASCA survey of the Cygnus Loop. The X-ray spectrum could be well fitted by a power-law function with an index of 2.1 ± 0.1. Timing analysis was performed and no coherent pulsation was found. Taking into account the X-ray properties, we conclude that AX J2049.6+2939 is either an AGN or a spin-powered pulsar. We again observed AX J2049.6+2939 with ASCA. The GIS count rate was a factor of 40 lower than that of the first ASCA observation. This suggests that AX J2049.6+2939 is not likely to be an ordinary rotation-powered pulsar. The X-ray intensity of the third ASCA observation is consistent with that of the second observation. The nature of AX J2049.6+2939 is still unclear and further observation with a wide energy band is strongly required.

The X-ray nature of AX J2049.6+2939

AX J2049.6+2939 is a compact source in the vicinity of the southern blow-up region of the Cygnus Loop super-nova remnant (Miyata 1998). This source is the brightest X-ray source found during the ASCA survey of the Cygnus Loop. The X-ray spectrum could be well fitted by a power-law function with an index of 2.1 ± 0.1. Timing analysis was performed and no coherent pulsation was found. Taking into account the X-ray properties, we conclude that AX J2049.6+2939 is either an AGN or a spin-powered pulsar. We again observed AX J2049.6+2939 with ASCA. The GIS count rate was a factor of 40 lower than that of the first ASCA observation. This suggests that AX J2049.6+2939 is not likely to be an ordinary rotation-powered pulsar. The X-ray intensity of the third ASCA observation is consistent with that of the second observation. The nature of AX J2049.6+2939 is still unclear and further observation with a wide energy band is strongly required.

Recent ASCA and SAX observations of intermediate BL Lac objects

Astronomische NachrichtenVolume 320, Issue 4-5 p. 315-315 Original Paper Recent ASCA and SAX observations of intermediate BL Lac objects J. Siebert, J. Siebert MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorW. Brinkmann, W. Brinkmann MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorM. Gliozzi, M. Gliozzi MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorS.A. Laurent-Muehleisen, S.A. Laurent-Muehleisen IGPP/LLNL, Livermore, CA 94550, USASearch for more papers by this authorM. Matsuoka, M. Matsuoka RIKEN, 2-1 Hirosawa, Wako, 351-01 Saitama, JapanSearch for more papers by this author J. Siebert, J. Siebert MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorW. Brinkmann, W. Brinkmann MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorM. Gliozzi, M. Gliozzi MPI für extraterrestrische Physik, Postfach 1603, 85740 Garching, GermanySearch for more papers by this authorS.A. Laurent-Muehleisen, S.A. Laurent-Muehleisen IGPP/LLNL, Livermore, CA 94550, USASearch for more papers by this authorM. Matsuoka, M. Matsuoka RIKEN, 2-1 Hirosawa, Wako, 351-01 Saitama, JapanSearch for more papers by this author First published: 03 July 2001 https://doi.org/10.1002/1521-3994(199908)320:4/5<315::AID-ASNA315>3.0.CO;2-3Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume320, Issue4-5August 1999Pages 315-315 RelatedInformation

The broad Fe K line in MCG–6‐30‐15: results from the second ASCA long‐look

We report results on the broad iron emission line of the Seyfert galaxy MCG–6-30-15, obtained from the second long ASCA observation in 1997. The time-averaged profile of the broad line is very similar to that seen with ASCA in 1994. A bright flare is seen in the light curve, during which the emission line peaks around 5 keV and most of its emission is shifted below 6 keV with no component detected at 6.4 keV (EW < 60 eV). This can be interpreted as the result of an extraordinarily large gravitational redshift due to a dominant flare occurring very close to the black hole.

Discovery of a New X-Ray Pulsar, AX J0049-729, in the Small Magellanic Cloud with ASCA

Abstract We report on the results of two ASCA observations on an X^ray source, AX J0049–729 (= RX J0049.1–7250), in the Small Magellanic Cloud. A sinusoidal pulsation with a barycentric period of 74.676±0.022 s was found. The pulse fraction was ∼ 70%, independent of the X-ray energy. The spectrum was hard with an absorbed power-law having a photon index of ∼ 1. The X-ray flux was 1.1×10−11 erg s−1 cm−2, and then declined to 1.6×10∼12 erg s−1 cm−2 from the first to the second observations, separated by about one month. Together with the previous results of the Einstein and ROSAT satellites, we found that AX J0049–729 has been in quiescent states, but occasionally showing flare activities. The flux variability, long-pulse period, and hard spectrum support the idea that AX J0049-729 is an X-ray binary pulsar, most likely a Be star binary.

The broad Fe K line in MCG–6-30-15: results from the second ASCA long-look

We report results on the broad iron emission line of the Seyfert galaxy MCG–6-30-15, obtained from the second long ASCA observation in 1997. The time-averaged profile of the broad line is very similar to that seen with ASCA in 1994. A bright flare is seen in the light curve, during which the emission line peaks around 5 keV and most of its emission is shifted below 6 keV with no component detected at 6.4 keV (EW < 60 eV). This can be interpreted as the result of an extraordinarily large gravitational redshift due to a dominant flare occurring very close to the black hole.

X-ray lobes of W 50/SS 433 system

The X-ray lobes lie on both sides (east and west) of SS 433, and are presumably produced by the interaction of the jets of SS 433 with the surrounding SNR W 50. The non-thermal nature of the east lobe has been reported by Yamauchi et al. (1994) using ASCA data. With the further ASCA observations, we studied the spectra and morphology of both the east and west lobes in detail. Their spectra have no emission lines, and are well described by power-law models with interstellar absorption. The X-ray emission becomes softer on both sides with increasing distance from SS 433. The X-ray surface brightness peaks closer to SS 433 in the high-energy band than in the low energy band, suggesting that the high energy electrons in the X-ray lobes lose energies by synchrotron emission as the travel away from SS 433. We estimate the magnetic field and the total energy of the high energy electrons to be ∼2 μG and ∼5 × 1046 erg, respectively.

ASCA observation of ultra-luminous X-ray sources and interpretation of their nature

ASCA observation of ultra-luminous X-ray sources and interpretation of their nature

ASCA observations of non-thermal emissions from groups of galaxies

ASCA observations of non-thermal emissions from groups of galaxies

ASCA observations of LINERs without broad Hα emission

ASCA observations of LINERs without broad Hα emission

ASCA observation of the polar V834 Cen: detection of resonance scattering ?

Astronomische NachrichtenVolume 320, Issue 4-5 p. 352-352 Original Paper ASCA observation of the polar V834 Cen: detection of resonance scattering ? M. Ishida, M. Ishida Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, JAPANSearch for more papers by this authorR. Fujimoto, R. Fujimoto Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, JAPANSearch for more papers by this author M. Ishida, M. Ishida Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, JAPANSearch for more papers by this authorR. Fujimoto, R. Fujimoto Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, JAPANSearch for more papers by this author First published: 03 July 2001 https://doi.org/10.1002/1521-3994(199908)320:4/5<352::AID-ASNA352>3.0.CO;2-%23Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume320, Issue4-5August 1999Pages 352-352 RelatedInformation

The X-ray spectrum of millisecond pulsar PSR J2124–3358 observed with ASCA

We report results for the X-ray spectrum of a millisecond pulsar, PSR J2124–3358 observed with ASCA. This pulsar is an isolated 4.9 ms pulsar (Bailes et al 1997). Its X-ray pulsation was detected with ROSAT HRI in the 0.1 - 2.4 keV band(Becker & Trümper 1998). The pulse profile was broad, and there is an indication of a secondary peak. Due to the lack of spectral information, the nature of the X-ray emission was unclear. An ASCA observation of this pulsar was carried out in May 1998, and provided the X-ray spectrum in the energy band from 0.5 to 10.0 keV. Due to poor statistics, the X-ray pulsation was not confirmed by ASCA.

ASCA Observation of 3C129 cluster of galaxies

Astronomische NachrichtenVolume 320, Issue 4-5 p. 299-299 Original Paper ASCA Observation of 3C129 cluster of galaxies Y. Ogasaka, Y. Ogasaka Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorK. Yamashita, K. Yamashita Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorF. Akimoto, F. Akimoto Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorA. Furuzawa, A. Furuzawa Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this author Y. Ogasaka, Y. Ogasaka Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorK. Yamashita, K. Yamashita Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorF. Akimoto, F. Akimoto Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this authorA. Furuzawa, A. Furuzawa Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, JapanSearch for more papers by this author First published: 03 July 2001 https://doi.org/10.1002/1521-3994(199908)320:4/5<299::AID-ASNA299>3.0.CO;2-XAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume320, Issue4-5August 1999Pages 299-299 RelatedInformation

ASCA observation of the Virgo cluster of galaxies

ASCA observation of the Virgo cluster of galaxies

ASCA observation of ultra-luminous X-ray sources and interpretation of their nature

ASCA observation of ultra-luminous X-ray sources and interpretation of their nature

ASCA observations of Galactic relativistic jet sources

ASCA observations of Galactic relativistic jet sources

ASCA observations of the spiral galaxy M108 with HI supershell structure

ASCA observations of the spiral galaxy M108 with HI supershell structure

ASCA observations of ultra luminous infrared galaxies — evolution from starburst to AGN ?

We made a series of ASCA observations of Ultra Luminous Infrared Galaxies (ULIRGs), to reveal the origin of their luminosities and to test a proposed evolutionary scenario of ULIRGs. We discovered embedded AGN in some galaxies, but the relative contribution of AGN activity to the total luminosity varies significantly from galaxy to galaxy and has no correlation with the evolutionary sequence as mergers.

ASCA observations of massive medium-distant clusters of galaxies

ASCA observations of massive medium-distant clusters of galaxies