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

Avdan, Hasan; Avdan, Senay; Akyüz, A.; Balman, Ş.

doi:10.1007/s10509-014-1888-9

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…In the steep PL or thermal state, most of the Galactic BHBs have relatively higher luminosities than in the hard state. A similar correlation between luminosity and photon index has been found in ULXs X-1 in NGC 1313 (Feng & Kaaret 2006;Dewangan et al 2010) and X37.8+54 in M82 (Jin et al 2010), although there are some ULXs that exhibit the opposite behavior (NGC 1313 X-2, Feng & Kaaret 2006; NGC 4736 X-2, Avdan et al 2014). Additionally, distinct spectral state transitions have been observed in some ULXs (e.g.…”

Section: Introductionsupporting

confidence: 70%

X-Ray Spectral and Optical Properties of a Ulx in NGC 4258 (M106)

Avdan

Akyüz

et al. 2016

ApJ

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We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival XMM-Newton, Chandra, Swift, and Hubble Space Telescope (HST) observations. The source has a peak luminosity of L X ∼ 2 × 10 39 erg sin the XMM-Newton observation of 2004 June. Consideration of the hardness ratios and spectral model parameters shows that the source seems to exhibit possible spectral variations throughout the X-ray observations. In the images from the HST/Advanced Camera for Surveys (ACS), three optical sources have been identified as counterpart candidates within the 1σ error radius of 0 .3. The brightest one has an absolute magnitude of M V ≈ −7.0 and shows extended structure. The remaining two sources have absolute magnitudes of M V ≈ −5.8 and −5.3 mag. The possible spectral types of the candidates from brightest to dimmest were determined as B6−A5, B0−A7, and B2−A3, respectively. The counterparts of the X-ray source possibly belong to a young star cluster. Neither the standard disk model nor the slim disk model provides firm evidence to determine the spectral characteristics of ULX X-6. We argue that the mass of the compact object lies in the range 10 − 15M indicating that the compact source is most likely a stellar-mass black hole.

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Section: Introductionsupporting

confidence: 70%

X-Ray Spectral and Optical Properties of a Ulx in NGC 4258 (M106)

Avdan

Akyüz

et al. 2016

ApJ

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“…However, we might interpret that X-3 exhibits the opposite behavior since the source has a high L X when it is in hard state and a low L X when it is in a thermal state. There are some ULXs that do show similar behavior: NGC 1313 X-2, Feng & Kaaret 1 https://pysynphot.readthedocs.io/en/latest/ (2006); IC 342 X-1, Marlowe et al (2014); NGC 4736 X-2, Avdan et al (2014). As discussed in several studies, when the data quality is low and exposure is short, one-component models should be taken into account statistically.…”

Section: Discussionmentioning

confidence: 96%

The ULX Source X-3 in NGC 4258: A Search for Its X-ray and Optical Properties

Akyuz,

Avdan,

Allak

et al. 2020

Preprint

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We present the results of a search for the nature of ultraluminous X-ray source (ULX) X-3 in the nearby galaxy NGC 4258. We use archival data from XMM-Newton, Chandra, NuSTAR and HST observations. Total X-ray data analysed to find the model parameters of the system is indicative of a stellar mass black hole, ∼ 10 M , as the central compact object. Furthermore, analyses of the optical data from HST reveal two optical candidates with the 90 per cent confidence level of error radius of 0. 28. Assuming the optical emission is dominated by the donor star, both of these candidates are found to have spectral types that lie between B3−F1 with absolute magnitudes of M V ≈ -6.4. Moreover, the age and mass estimates for the candidates are found to be of 10 and 18 Myr and of 13 and 20 M , respectively.

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“…However, X-7 exhibits the opposite behavior since the source has a high L X when it is in a hard state and a low L X when it is in a soft state. There are some ULXs that do show similar correlations like X-2 of NGC 1313, Feng & Kaaret (2006); X-1 of IC 342, Marlowe et al (2014); X-2 of NGC 4736, Avdan et al (2014). X-3 of NGC 925, Earnshaw et al (2020).…”

Section: X-raysmentioning

confidence: 90%

Identification of a New Ultraluminous X-ray Source in NGC 1316

Allak,

Akyuz,

Aksaker

et al. 2020

Preprint

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In this study, we report identification of a new ultraluminous X-ray source (ULX) which we named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.10×10 39 erg s −1 using two recent Chandra archival observations. The X-7 was detected in the Chandra 2001 observation and it was included in the X-ray source list of the NGC 1316 as CXOUJ032240.8-371224 with luminosity of 5.7×10 38 erg s −1 implying a luminosity increase of a factor of ∼ 4. The best fit spectral model parameters indicate that X-7 has a relatively hot disk and hard spectra. The mass of compact object is obtained as ∼ 8 M which is in the range of a stellar-mass black hole. The X-7 shows a relatively long-term count rate variability while no short-term variability is observed. We also identified a unique optical candidate within 0. 22 error circle at 95% confidence level for X-7 using the archival HST/ACS and HST/WFC3 data. Absolute magnitude (M V ) of this candidate is -7.8 mag. Its spectral energy distribution is adequately fitted a blackbody model with a temperature of 3100 K indicating an M type supergiant, assuming the donor star dominates the optical emission. In addition, we identified a transient ULX candidate (XT-1) has a high luminosity of ∼ 10 39 erg s −1 located 6 away from X-7 with no visible counterpart(s).

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

Cited by 5 publications

References 30 publications

X-Ray Spectral and Optical Properties of a Ulx in NGC 4258 (M106)

X-Ray Spectral and Optical Properties of a Ulx in NGC 4258 (M106)

The ULX Source X-3 in NGC 4258: A Search for Its X-ray and Optical Properties

Identification of a New Ultraluminous X-ray Source in NGC 1316

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