Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT

Motoko Serino, Megumi Shidatsu, Yoshihiro Ueda, Masaru Matsuoka, Hitoshi Negoro, Kazutaka Yamaoka, Jamie A. Kennea, Kosuke Fukushima, Takahiro Nagayama

Research output: Contribution to journalArticle

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Abstract

Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ∼ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm -2 s -1 . By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.

Original languageEnglish (US)
Article number30
JournalPublications of the Astronomical Society of Japan
Volume67
Issue number2
DOIs
StatePublished - Jan 27 2015

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slits
sky
monitors
cameras
telescopes
gases
gas
x rays
outburst
bursts
OSO
photons
neutron stars
hardness
observatory
luminosity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Serino, M., Shidatsu, M., Ueda, Y., Matsuoka, M., Negoro, H., Yamaoka, K., ... Nagayama, T. (2015). Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT. Publications of the Astronomical Society of Japan, 67(2), [30]. https://doi.org/10.1093/pasj/psv003
Serino, Motoko ; Shidatsu, Megumi ; Ueda, Yoshihiro ; Matsuoka, Masaru ; Negoro, Hitoshi ; Yamaoka, Kazutaka ; Kennea, Jamie A. ; Fukushima, Kosuke ; Nagayama, Takahiro. / Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT. In: Publications of the Astronomical Society of Japan. 2015 ; Vol. 67, No. 2.
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abstract = "Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ∼ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm -2 s -1 . By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.",
author = "Motoko Serino and Megumi Shidatsu and Yoshihiro Ueda and Masaru Matsuoka and Hitoshi Negoro and Kazutaka Yamaoka and Kennea, {Jamie A.} and Kosuke Fukushima and Takahiro Nagayama",
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Serino, M, Shidatsu, M, Ueda, Y, Matsuoka, M, Negoro, H, Yamaoka, K, Kennea, JA, Fukushima, K & Nagayama, T 2015, 'Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT', Publications of the Astronomical Society of Japan, vol. 67, no. 2, 30. https://doi.org/10.1093/pasj/psv003

Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT. / Serino, Motoko; Shidatsu, Megumi; Ueda, Yoshihiro; Matsuoka, Masaru; Negoro, Hitoshi; Yamaoka, Kazutaka; Kennea, Jamie A.; Fukushima, Kosuke; Nagayama, Takahiro.

In: Publications of the Astronomical Society of Japan, Vol. 67, No. 2, 30, 27.01.2015.

Research output: Contribution to journalArticle

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T1 - Low-mass X-ray binary MAXI J1421-613 observed by MAXI GSC and Swift XRT

AU - Serino, Motoko

AU - Shidatsu, Megumi

AU - Ueda, Yoshihiro

AU - Matsuoka, Masaru

AU - Negoro, Hitoshi

AU - Yamaoka, Kazutaka

AU - Kennea, Jamie A.

AU - Fukushima, Kosuke

AU - Nagayama, Takahiro

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Y1 - 2015/1/27

N2 - Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ∼ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm -2 s -1 . By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.

AB - Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC (Gas Slit Camera) and the Swift XRT (X-Ray Telescope) follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is ∼ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm -2 s -1 . By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc. The position of this source is contained by the large error regions of two bright X-ray sources detected with Orbiting Solar Observatory-7 (OSO-7) in the 1970s. Besides this, no past activities at the XRT position are reported in the literature. If MAXI J1421-613 is the same source as (one of) these, the outburst observed with MAXI may have occurred after a quiescence of 30-40 years.

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