A search for periodicities from a ULX in the LINER galaxy NGC 4736

Abstract

We report our findings on a new quasi-periodic oscillation (QPO) and a long period from the ultraluminous X-ray source (ULX) X-2 in nearby galaxy NGC 4736 based on the Chandra and XMM-Newton archival data. To examine the timing properties, power density spectra of the source have been obtained using Fast Fourier Transform. Also the spectral parameters of the source have been calculated by obtaining and fitting the energy spectra. Power density spectrum of this source reveals a QPO peak at $0.73_{-0.14}^{+0.16}$ mHz with an fractional rms variability of 16% using the Chandra data (in the year 2000-lower state of the source). The XMM-Newton data analysis indicates a peak at $0.53_{-0.35}^{+0.09}$ mHz with a fractional rms variation of 5% (in the year 2006-higher state of the source). These recovered QPOs overlap within errors and may be the same oscillation. In addition, we detect a long periodicity or a QPO in the Chandra data of about $(5.2\pm 2.0)\times 10^{-5}$ Hz ($\sim$ 5.4 hrs) over 3 $\sigma$ confidence level. If this is a QPO, it is the lowest QPO detected from a ULX. The mass of the compact object in ULX X-2 is estimated using the Eddington luminosity and a disk blackbody model in the range (10$-$80) M_{\sun}.

arXiv comment6 pages, 4 Figures; Accepted for publication in Astrophysics and Space Science

References in corpus (26)

• X-ray Properties of Black-Hole Binaries
• Ultraluminous X-Ray Sources in External Galaxies
• Super-Eddington Fluxes from Thin Accretion Disks?
• Intermediate-Mass Black Holes
• Ultraluminous X-ray Sources in the Chandra and XMM-Newton Era
• Discovery of X-ray QPOs from an Ultra-luminous X-ray Source in M82: Evidence Against Beaming
• XMM-Newton Archival Study of the ULX Population in Nearby Galaxies
• Quasi-Periodic Variability in NGC 5408 X-1
• Chandra Acis Survey of X-Ray Point Sources in 383 Nearby Galaxies I. the Source Catalog
• Black Hole Mass of the Ultraluminous X-ray source M82 X-1
• A Systematic Study of Variability in a Sample of Ultraluminous X-ray Sources
• Spectral State Transitions of the Ultraluminous X-ray Sources X-1 and X-2 in NGC 1313
• A variable Quasi-Periodic Ocillation in M82 X-1. Timing and spectral analysis of XMM-Newton and RossiXTE observations
• The Birth of an Ultra-Luminous X-ray Source in M83
• Origin of the X-ray Quasi-Periodic Oscillations and Identification of a Transient Ultraluminous X-Ray Source in M82
• Discovery of mHz X-ray Oscillations in a Transient Ultraluminous X-ray Source in M82
• Quasi Periodic Oscillations and Strongly Comptonized X-ray emission from Holmberg IX X-1
• Detection of Strong Short-Term Variability in NGC 6946 X-1
• A Multi-epoch Timing and Spectral Study of the Ultraluminous X-Ray Source NGC 5408 X-1 with XMM-Newton
• CXOM31 J004253.1+411422: The first ultra-luminous X-ray transient in M 31
• Different types of ultraluminous X-ray sources in NGC 4631
• A Two Hour Quasi-Period in an Ultra-luminous X-Ray source in NGC628
• Discovery of a Highly Variable Dipping Ultraluminous X-ray source in M94
• The fading of two transient ULXs to below the stellar mass Eddington limit
• XMM-Newton Observations of Luminous Sources in the Nearby Galaxies: NGC 4395, NGC 4736, and NGC 4258
• Frequency Resolved Spectroscopy of XB 1323-619 Using XMM-Newton data: Detection of a Reflection Region in the Disk

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