{
  "id": "0906.4169",
  "version": "v2",
  "published": "2009-06-23T06:38:40.000Z",
  "updated": "2009-12-08T09:55:52.000Z",
  "title": "Spectral and temporal changes associated with flux enhancement in 4U 1626-67",
  "authors": [
    "Chetana Jain",
    "Biswajit Paul",
    "Anjan Dutta"
  ],
  "comment": "7 pages, accepted for publication in MNRAS with minor changes",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "4U 1626-67 is an accretion powered X-ray pulsar that shows remarkably stable X-ray luminosity above hours timescale and gradual intensity variation on a few years timescale. Here we report a significant increase in the X-ray intensity in the long term RXTE-ASM light curve of 4U 1626-67. Similar enhancement in the X-ray flux has also been detected in the Swift-BAT light curve. The increase in the X-ray flux took place over a long period of about 100 days and there appears to be two episodes of flux enhancement. We have investigated the spectral and timing features of 4U 1626-67 during its current state of enhanced flux emission with data obtained from the Proportional Counter Array and the High-Energy X-ray Timing Explorer on board the Rossi X-ray Timing Explorer. The source has entered a new spin-up phase with a spin-up rate of 4.02(5) $\\times$ 10$^{-13}$ Hz s$^{-1}$. The present spin-up rate is almost half of the earlier spin-up and spin-down trends. A significant excess in soft X-ray photon emission is observed during the enhanced flux state, which is similar to the energy spectrum obtained during the spin-up era of the pulsar before 1990. We also report detection of a significant broadening in the wings of the 130 mHz peak and a change in the shape of the continuum of the power spectrum.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2009-12-08T09:55:52.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "flux enhancement",
      "temporal changes",
      "x-ray timing explorer",
      "long term rxte-asm light curve",
      "x-ray flux took place"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "doi": "10.1111/j.1365-2966.2009.16170.x",
      "journal": "Monthly Notices of the Royal Astronomical Society",
      "year": 2010,
      "month": "Apr",
      "volume": 403,
      "number": 2,
      "pages": 920
    },
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable",
      "inspire": 823865,
      "adsabs": "2010MNRAS.403..920J"
    }
  }
}