Monitor of All-sky X-ray Image (MAXI)

Mihara, T.; Matsuoka, M.; Kawai, N.; Yoshida, A.; Tsunemi, H.; Miyata, Emi; Negoro, H.; Torii, K.; Ueno, S.; Sugizaki, M.; Tomida, H.; Sakurai, Ikuya; Shirasaki, Y.; Yamauchi, M.

doi:10.1063/1.1302478

Cited by 10 publications

(7 citation statements)

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“…It provides us with a unique opportunity to discover new objects and study their transient behaviors. In fact, we have discovered 31 new X-ray objects including 14 black hole binaries, 13 neutron star binaries, and one white dwarf binary, that appeared in our Galaxy and the Small Magellanic Cloud (e.g., Mihara et al 2022). The data also enable us to study their variabilities on time scales from hours to over 12 yr. To uncover the nature of these new transient objects, prompt follow-up observations with large-area X-ray telescopes as well as multi-wavelength observations from both space and ground observatories are essential.…”

Section: Introductionmentioning

confidence: 95%

Discovery of a new supergiant fast X-ray transient MAXI J0709−159 associated with the Be star LY Canis Majoris

Sugizaki

Mihara

Kobayashi

et al. 2022

Publications of the Astronomical Society of Japan

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We report on the discovery of a new supergiant fast X-ray transient (SFXT), MAXI J0709−159, and its identification with LY CMa (also known as HD 54786). On 2022 January 25, a new flaring X-ray object, named MAXI J0709−159, was detected by the Monitor of All-sky X-ray Image (MAXI). Two flaring activities were observed in two scans ∼3 hr apart, where the 2–10 keV flux reached 5 × 10−9 erg cm−2 s−1. During the period, the source exhibited a large spectral change, suggesting that the absorption column density NH increased from 1022 to 1023 cm−2. A NuSTAR follow-up observation on January 29 identified a new X-ray source with a flux of 6 × 10−13 erg cm−2 s−1 at a position consistent with LY CMa, which has been identified as a B supergiant as well as a Be star, located at a 3 kpc distance. The observed X-ray activity, characterized by short (≲several hours) duration, rapid (≲ a few seconds) variabilities accompanied by spectral changes, and a large luminosity swing (1032–1037 erg s−1), agree with those of SFXTs. On the other hand, optical spectroscopic observations of LY CMa reveal a broad Hα emission line, which may indicate the existence of a Be circumstellar disk. These results suggest that the optical companion, LY CMa, certainly has a complex circumstellar medium including dense clumps.

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Section: Introductionmentioning

confidence: 95%

Discovery of a new supergiant fast X-ray transient MAXI J0709−159 associated with the Be star LY Canis Majoris

Sugizaki

Mihara

Kobayashi

et al. 2022

Publications of the Astronomical Society of Japan

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“…In fact, we have discovered 31 new X-ray objects including 14 black-hole binaries, 13 neutron-star binaries, and one white-dwarf binary, that appeared in our Galaxy and the Small Magellanic Cloud (e.g. Mihara et al 2022). The data also enable us to study their variabilities in time scales from hours to over the 12 years.…”

Section: Introductionmentioning

confidence: 95%

Discovery of a new supergiant fast X-ray transient MAXI J0709-159 associated with the Be star LY CMa

Sugizaki,

Mihara,

Kobayashi

et al. 2022

Preprint

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“…The sensitivity is 7 mCrab (5 σ level) in one scan and 1 mCrab in one-week accumulation [1,3]. The purposes of the all-sky monitor are not only the discoveries of new X-ray sources, but also the challenge to the cosmology models by measuring the large scale structure of the universe via the distribution of distant active galaxies as well as the cosmic X-ray background.…”

Section: Monitor Of All-sky X-ray Image (Maxi)mentioning

confidence: 99%

“…For on-axis scanning (φ = 0 deg) this yields ∼ 10 c s −1 per GSC in 1-30 keV when averaged over the scan time. 3, and should be taken as a reference value only. Then the average count rate is ∼ 40 c s −1 .…”

Section: Crab Count Rate and In-orbit Data Ratementioning

confidence: 99%

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<title>Performance of the GSC engineering counter for MAXI/ISS</title>

et al. 2002

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We are developing Monitor of All Sky X-ray Image (MAXI) which will be mounted on the Japanese Experiment Module of the International Space Station. MAXI is an all-sky X-ray monitor which scans the sky in every 90 minutes. The sensitivity will be as high as 7 mCrab (5 σ level) in one scan and 1 mCrab in one-week accumulation. The GSC (Gas Slit Camera) instrument consists of twelve one-dimensional position sensitive proportional counters using the Xe+CO 2 gas and the carbon fiber anodes of 10µm diameter. The window size is 272 × 190 mm. The position is obtained by the charge division method. It is used to identify the source in the long rectangular field-ofview (1.5 × 80 degrees). Three cameras will be set to cover the 1.5 × 160 degrees arc. The position resolution is essentially important, which becomes better in the higher gas gain. We have tested gas mixtures of Xe+CO 2 with CO 2 = 0.2%, 0.5%, 1%, and 3%. The CO 2 = 0.5% showed the most uniform gas gain, but has a little after pulses. We chose the Xe (99%) + CO 2 (1%) combination for the flight counters. It can achieve the uniform gas gain in the cell and negligible after-pulse in high operating voltage. The engineering model of the counter (EM1) was build. We have tested the position resolution and the energy resolution across the counter. The position resolution and the energy resolution depend on the X-ray energy. On the basis of these results, together with the collimator response, we performed a realistic simulation. MONITOR OF ALL-SKY X-RAY IMAGE (MAXI)Monitor of All-sky X-ray Image (MAXI) is the first astronomical payload to be placed on the International Space Station (ISS)'s Japanese Experimental Module (JEM) in 2005 ( Fig. 1 left) [1, 2, 3, 4]. MAXI has the size of 0.8 × 1.2 × 1.85 m and the weight of 500kg. Power, communication, and cooling fluid are supplied from the JEM/ISS. MAXI has two X-ray observational instruments, Gas Slit Camera (GSC) and Solid-state Slit Camera (SSC, Miyata in this meeting). The GSC uses gas counters which is sensitive in 2-30 keV. The SSC uses X-ray CCDs sensitive in the soft X-ray (0.5-10 keV). Both instruments are slit-cameras and have a long rectangular field-of-view (FOV) (Fig. 1 middle). With the combination of one-dimensional X-ray detector, the positions of the X-ray sources in the FOV are determined (Fig. 1 right). The narrow FOV scans across the sky with the 90-minute orbital rotation of the ISS. The GSC has two identical FOVs, one is facing forward and the other zenithal. The forward FOV is tilted up by 6 degrees to avoid the earth and the atmosphere completely. There are non-operational periods in the orbit, such as the South Atlantic Anomaly and the high-radiation polar regions. Although one FOV cannot observe the portion of the sky which to be observed from there, the other FOV can cover that region after or before 21 minutes, because it is offset by 84 degrees. Thus MAXI can monitor almost the whole sky in every 90 minutes, twice in most part.As an all-sky monitor MAXI has unprecedented sensitivity in the hard...

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Monitor of All-sky X-ray Image (MAXI)

Cited by 10 publications

References 14 publications

Discovery of a new supergiant fast X-ray transient MAXI J0709−159 associated with the Be star LY Canis Majoris

Discovery of a new supergiant fast X-ray transient MAXI J0709−159 associated with the Be star LY Canis Majoris

Discovery of a new supergiant fast X-ray transient MAXI J0709-159 associated with the Be star LY CMa

<title>Performance of the GSC engineering counter for MAXI/ISS</title>

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