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RXTE/PCA confirms an X-ray pulsation from MAXI J1409-619

ATEL # 3070; Takayuki Yamamoto (RIKEN), Motoki Nakajima (Nihon U.), Kazutaka Yamaoka (AGU), Philip E. Kaaret (Univ. of Iowa), Jamie A. Kennea (PSU), Satoshi Nakahira, Ichiro Takahashi, Atsumasa Yoshida (AGU), Mikio Morii, Nobuyuki Kawai (Tokyo Tech.), Hitoshi Negoro (Nihon U.), Yoshihiro Ueda (Kyoto U.), and Motoko Serino (RIKEN)
on 7 Dec 2010; 0:13 UT
Password Certification: Kazutaka Yamaoka (yamaoka@phys.aoyama.ac.jp)

Subjects: X-ray, Binaries, Neutron Stars, Pulsars
Referred to by ATEL #: 3082

Following the current re-brightening of the new X-ray transient MAXI J1409-619 (Kennea et al. ATel #3060, Ueno et al. ATel #3067), we performed two pointed RXTE ToO observations on December 4, 2010 with a net exposure of 8.5 ksec.

The averaged X-ray flux was 7.6e-10 and 8.1e-10 erg cm^-2 s^-1 (about 32 and 34 mCrab) in the 2-10 keV band, respectively, which is 6-7 times higher than previous RXTE/PCA flux (Yamaoka et al. ATel #2969). The PCA light curve confirms a strong X-ray pulsation with a period of 506 +/- 1 seconds. This is consistent with results measured by Swift/XRT (503 +/- 10 seconds on Nov. 30; Kennea et al. ATel #3060) and Fermi/GBM (506.93 seconds on Dec. 3; Camero-Arranz et al. ATel #3069). So we conclude that MAXI J1409-619 is a long period pulsar.

The summed PCA spectrum in the 3-50 keV range is well explained by a cutoff powerlaw with a partially covered absorption or a reflection plus a narrow iron line. The best-fit parameters for former model are the hydrogen column density N_H: (5.6 +/- 0.5)e22 cm^-2, covering factor of the absorber: 0.18 +/- 0.04, N_H of the partially covered absorber: (1.3 +/- 0.6)e24 cm^-2, the photon index: 1.34 (-0.08, +0.13), and the e-folding energy: 28 (-5, +9) keV (chi^2/dof = 58.8/72), and for latter model are N_H: (5.2 +/- 0.3)e22 cm^-2, the reflection scaling factor: 0.52 +/- 0.18, the photon index: 1.29 +/- 0.05, and the e-folding energy: 25 +/- 4 keV (chi^2/dof = 69.1/73). No clear cyclotron absorption features are seen in the PCA spectrum.

We thank the RXTE team for accepting our proposal and prompt scheduling of ToO observations.


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