X-ray, Optical, and Near-infrared Monitoring of the New X-ray Transient MAXI J1820+070 in the Low/hard State

Abstract

We report X-ray, optical, and near-infrared monitoring of the new X-ray transient MAXI J1820$+$070 discovered with MAXI on 2018 March 11. Its X-ray intensity reached $\sim 2$ Crab in 2--20 keV at the end of March, and then gradually decreased until the middle of June. In this period, the X-ray spectrum was described by Comptonization of the disk emission, with a photon index of $\sim$1.5 and an electron temperature of $\sim$50 keV, which is consistent with a black hole X-ray binary in the low/hard state. The electron temperature and the photon index were slightly decreased and increased with increasing flux, respectively. The source showed significant X-ray flux variation on timescales of seconds. This short-term variation was found to be associated with changes in the spectral shape, and the photon index became slightly harder at higher fluxes. This suggests that the variation was produced by a change in the properties of the hot electron cloud responsible for the strong Comptonization. Modeling a multi-wavelength SED around the X-ray flux peak at the end of March, covering the near-infrared to X-ray bands, we found that the optical and near-infrared fluxes were likely contributed substantially by the jet emission. Before this outburst, the source was never detected in the X-ray band with MAXI (with a 3$\sigma$ upper limit of $\sim$0.2 mCrab in 4--10 keV, obtained from the 7-year data in 2009--2016), whereas weak optical and infrared activity was found at their flux levels $\sim$3 orders of magnitude lower than the peak fluxes in the outburst.

arXiv comment14 pages, 9 figures, accepted for publication in ApJ

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Cited by in corpus (27)

• An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070
• Discovery of oscillations above 200 keV in a black hole X-ray binary with Insight-HXMT
• Gaia DR2 Distances and Peculiar Velocities for Galactic Black Hole Transients
• MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries
• Insight-HXMT observations of jet-like corona in a black hole X-ray binary MAXI J1820+070
• Hard-state accretion disk winds from black holes: the revealing case of MAXI J1820+070
• X-ray and Optical Monitoring of State Transitions in MAXI J1820+070
• Measuring fundamental jet properties with multi-wavelength fast timing of the black hole X-ray binary MAXI J1820+070
• INTEGRAL/IBIS 17-yr hard X-ray all-sky survey
• X-ray dips and a complex UV/X-ray cross-correlation function in the black hole candidate MAXI J1820+070
• A timing-based estimate of the spin of the black hole in MAXI J1820+070
• Observations of the Disk/Jet Coupling of MAXI J1820+070 During its Descent to Quiescence
• Chasing the break: Tracing the full evolution of a black hole X-ray binary jet with multi-wavelength spectral modeling
• Broad-band spectral study of X-ray transient MAXI J1820+070 using Swift/XRT and NuSTAR
• Evidence for Disk Truncation at Low Accretion States of the Black Hole Binary MAXI J1820+070 Observed by NuSTAR and XMM-Newton
• A broadband view on microquasar MAXI J1820+070 during the 2018 outburst
• Multiwavelength observations of MAXI J1820+070 during its outburst decay and subsequent mini-outburst
• Accretion Scenario of MAXI J1820+070 during 2018 Outbursts with Multi-mission Observations
• Low Frequency Quasi-periodic Oscillation in MAXI J1820+070: Revealing distinct Compton and Reflection Contributions
• Synchronous X-ray/Optical QPOs from the Black Hole LMXB MAXI J1820+070
• Multiwavelength Observations of the Black Hole X-ray Binary MAXI J1820$+$070 in the Rebrightening Phase
• Intermittent QPO properties of MAXI J1820+070 revealed by Insight-HXMT
• Evolution of Accretion Disk Structure of the Black Hole X-ray Binary MAXI J1820$+$070 during the Rebrightening Phase
• Tracking optical variability and outflows across the accretion states of the black hole transient MAXI J1820+070
• Tracking the evolution of the accretion flow in MAXI J1820+070 during its hard state with the JED-SAD model
• Large optical modulations during 2018 outburst of MAXI J1820+070 reveal evolution of warped accretion disc through X-ray state change
• Evolution of X-ray and optical rapid variability during the low/hard state in the 2018 outburst of MAXI J1820+070 = ASASSN-18ey