Optical and ultraviolet monitoring of the black hole X-ray binary MAXI J1820+070/ASASSN-18ey for 18 months

Sai, Hanna; Wu, Jianfeng; Lin, Jie; Feng, Hua; Zhang, Tianmeng; Li, Wenxiong; Zhang, Jujia; Mo, Jun; Sun, Tianrui; Ehgamberdiev, S. A.; Mirzaqulov, D. O.; Rui, Liming; Lin, Weili; Zhao, Xulin; Lin, Han; Zhang, Jicheng; Zhang, Xinghan; Zhao, Yi; Li, Xue; Xiang, Danfeng; Wang, Lingzhi; Wu, Chenjie

doi:10.1093/mnras/stab1162

Cited by 7 publications

(8 citation statements)

References 51 publications

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“…The resulting line EW is ∼ 8 eV, similar to that seen in a similar bright low/hard state of GX339-4 (Done & Diaz Trigo 2010). We suggest that this is from the strong optical wind which is seen in this state (Muñoz-Darias et al 2019;Sai et al 2021), and stress that this should be included in all detailed models of the iron line profile.…”

Section: Componentsupporting

confidence: 74%

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

Kawamura,

Axelsson,

Done

et al. 2021

Preprint

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The nature and geometry of the accretion flow in the low/hard state of black hole binaries is currently controversial. While most properties are generally explained in the truncated disc/hot inner flow model, the detection of a broad residual around the iron line argues for strong relativistic effects from an untruncated disc. Since spectral fitting alone is somewhat degenerate, we combine it with the additional information in the fast X-ray variability and perform a full spectral-timing analysis for NICER and NuSTAR data on a bright low/hard state of MAXI J1820+070. For the first time, we model the variability with propagating mass accretion rate fluctuations by combining two separate current insights: that the hot flow is spectrally inhomogeneous, and that there is a discontinuous jump in viscous time-scale between the hot flow and variable disc. Our model naturally gives the 'double hump' shape of the power spectra, and the increasing high frequency variability with energy in the second hump. Including reflection quantitatively reproduces the switch in the lag-frequency spectra, from hard lagging soft at low frequencies (propagation through the variable flow) to the soft lagging hard at the high frequencies (reverberation from the hard X-ray continuum illuminating the disc). The light travel time derived from the model corresponds to a distance of ∼ 45 gravitational radii, supporting the truncated disc model geometry for the low/hard state. The propagation lags allow us to measure the viscous time-scale in the hot flow, and the results favour SANE rather than MAD models for this source.

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Section: Componentsupporting

confidence: 74%

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

Kawamura,

Axelsson,

Done

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The resulting line EW is ∼8 eV, similar to that seen in a similar bright low/hard state of GX339-4 (Done & Diaz Trigo 2010 ). We suggest that this is from the strong optical wind which is seen in this state (Mu ˜ noz- Sai et al 2021 ), and stress that this should be included in all detailed models of the iron line profile (see discussion in Axelsson & Veledina 2021 ).…”

Section: F I T T I N G T H E S P E C T R a L C O M P O N E N T Ssupporting

confidence: 73%

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

Kawamura

Axelsson

Done

et al. 2022

Monthly Notices of the Royal Astronomical Society

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The nature and geometry of the accretion flow in the low/hard state of black hole binaries is currently controversial. While most properties are generally explained in the truncated disc/hot inner flow model, the detection of a broad residual around the iron line argues for strong relativistic effects from an untruncated disc. Since spectral fitting alone is somewhat degenerate, we combine it with the additional information in the fast X-ray variability and perform a full spectral-timing analysis for NICER and NuSTAR data on a bright low/hard state of MAXI J1820+070. We model the variability with propagating mass accretion rate fluctuations by combining two separate current insights: that the hot flow is spectrally inhomogeneous, and that there is a discontinuous jump in viscous time-scale between the hot flow and variable disc. Our model naturally gives the double-humped shape of the power spectra, and the increasing high-frequency variability with energy in the second hump. Including reflection and reprocessing from a disc truncated at a few tens of gravitational radii quantitatively reproduces the switch in the lag-frequency spectra, from hard lagging soft at low frequencies (propagation through the variable flow) to the soft lagging hard at the high frequencies (reverberation from the hard X-ray continuum illuminating the disc). The viscous time-scale of the hot flow is derived from the model, and we show how this can be used to observationally test ideas about the origin of the jet.

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“…MAXIJ1820+070. This source is a black hole XRB, which has been monitored extensively by Swift in recent years (see Sai et al 2021 for an optical and UV monitoring study of this source using only a part of the UVOT data currently avaiable). It was the target of the observations in which our pipeline detected it as a transient.…”

Section: Recovered Known Transientsmentioning

confidence: 99%

“…27 we show the longterm PV lightcurve in optical and UV bands. The primary outburst and several subsequent reflares are clearly visible in the PV lightcurve, most of which have so far not been studied (Sai et al 2021 described only the main outburst and the first reflare). Similar reflaring behaviour has been observed for other neutron star and black hole X-ray transients (e.g.…”

Section: Recovered Known Transientsmentioning

confidence: 99%

TUVOpipe: a pipeline to search for UV transients with Swift-UVOT

Modiano,

Wijnands,

Parikh

et al. 2022

Preprint

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Despite the prevalence of transient-searching facilities operating across most wavelengths, the ultraviolet (UV) transient sky remains to be systematically studied. Therefore, we have recently initiated the Transient Ultraviolet Objects (TUVO) project, with which we search for serendipitous UV transients in data obtained using currently available UV instruments with a strong focus on the UV/Optical (UVOT) telescope aboard the Neil Gehrels Swift Observatory (an overview of the project is described in a companion paper). Here we describe the pipeline (named TUVOpipe) we constructed in order to find such transients in the UVOT data, using difference image analysis. The pipeline is run daily on all new public UVOT data (which are available 6-8 hours after the observations are performed), so we discover transients in near real-time. Transients which last >0.5 days are therefore still active when discovered, allowing for follow-up observations to be performed. From October 1, 2020, to the time of submission, using TUVOpipe we have processed 111 330 individual UVOT images and we currently detect an average rate of ∼100 transient candidates per day. Of these daily candidates, on average ∼30% are real transients (separated by human vetting from the remaining 'bogus' transients which were not discarded automatically within the pipeline). Most of the real transients correspond to known variable stars, though we also detect a significant number of known active galactic nuclei and accreting white dwarfs. TUVOpipe can additionally run in archival mode, whereby all the archival UVOT data of a given field is scoured for 'historical' transients; in this mode we also mostly find variable stars. However, some of the transients we find (in particular in the real-time mode) represent previously unreported new transients, or undiscovered outbursts of previously known transients, predominantly outbursts from cataclysmic variables. In this paper we describe the operation of (both modes of) TUVOpipe and some of the initial results we have so far obtained.

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Optical and ultraviolet monitoring of the black hole X-ray binary MAXI J1820+070/ASASSN-18ey for 18 months

Cited by 7 publications

References 51 publications

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

A full spectral-timing model to map the accretion flow in black hole binaries: the low/hard state of MAXI J1820+070

TUVOpipe: a pipeline to search for UV transients with Swift-UVOT

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