Multimission Observations of GS 1354-64 during the 2025-2026 Outburst: First Results

Abstract

The Galactic transient black hole GS 1354-64 recently showed a new outburst, which has been continuously monitored by {\it MAXI}, {\it NuSTAR} and {\it Insight-HXMT} missions. The ongoing $2025$--$2026$ outburst shows a slow rise with an unusually short period ($\sim 3$~days) of X-ray flare of peak flux $\sim 1.4$~Crab, followed by another relatively weak flare of intensity $\sim 0.8$ Crab. The source was observed to evolve through ``canonical'' spectral states in a hardness-intensity diagram (HID) during rising phase of the outburst, but the subsequent outburst profile during this study, the source did not follow the reverse trend of the HID. A rapid evolution of quasi-periodic oscillation (QPO) frequencies ($\sim 0.07-4$ Hz) is observed during hard and intermediate spectral states without any signature of QPOs in the soft state. The evolution of the observed low frequency QPOs shows a monotonically increasing (rising phase) signature as well as decreasing (decay phase) one, these are further studied with the propagating oscillatory shock model to understand the nature of the evolution of the shock wave responsible for the origin of the observed QPOs. The broadband energy spectra from {\it NuSTAR} ($3-70$ keV) and {\it Insight-HXMT} ($2-60$ keV) are well described by thermal (\textit{diskbb}) and reflection (\textit{relxill}) model components, indicating a strong signature of a relativistic reflection feature. Using ``canonical'' observations of a softer state, we found the source to be maximally rotating with $a_k\sim 0.998$ and inclination angle to be as $i\sim 63^{\circ }-70^{\circ }$, which are consistent with earlier reports.

arXiv comment12 pages, 5 figures, 2 tables

References in corpus (44)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• X-ray Properties of Black-Hole Binaries
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Towards a unified model for black hole X-ray binary jets
• Modelling the behaviour of accretion flows in X-ray binaries
• Constraining Black Hole Spin Via X-ray Spectroscopy
• Spectral Properties of Accretion Disks Around Galactic and Extragalactic Black Holes
• The evolution of the timing properties of the black-hole transient GX 339-4 during its 2002/2003 outburst
• The evolution of black hole states
• Measuring Black Hole Spin using X-ray Reflection Spectroscopy
• The ABC of low-frequency quasi-periodic oscillations in Black-Hole Candidates: analogies with Z-sources
• X-ray reflected spectra from accretion disk models. I. Constant density atmospheres
• WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries
• Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite
• Resonance Oscillation Of Radiative Shock Waves In Accretion Disks Around Compact Objects
• Grand Unification of Solutions of Accretion and Winds around Black Holes and Neutron Stars
• Correlations between X-ray and radio spectral properties of accreting black holes
• Accretion flow dynamics during the evolution of timing and spectral properties of GX 339-4 during its 2010-11 outburst
• Mechanisms for High-frequency QPOs in Neutron Star and Black Hole Binaries
• Towards precision measurements of accreting black holes using X-ray reflection spectroscopy
• Tracing the power-law component in the energy spectrum of black hole candidates as a function of the QPO frequency
• Accretion Processes On a Black Hole
• Zero Energy Rotating Accretion Flows near a Black Hole
• Evolution of the quasi-periodic oscillation frequency in GRO J1655-40 -- Implications for accretion disk dynamics
• Thermal synchrotron radiation and its Comptonization in compact X-ray sources
• Determination of mass of IGR J17091-3624 from "Spectro-Temporal" variations during onset-phase of the 2011 outburst
• Accretion flow dynamics of MAXI J1836-194 during its 2011 outburst from TCAF solution
• On the Spectral Slopes of Hard X-ray Emission from Black Hole Candidates
• Properties of the propagating shock wave in the accretion flow around GX 339-4 in the 2010 outburst
• Characterization of GX 339-4 outburst of 2010-11: analysis by xspec using two component advective flow model
• A self-consistent hybrid Comptonization model for broad-band spectra of accreting supermassive black holes
• Accretion-ejection instability in magnetized disks: Feeding the corona with Alfven waves
• Evolution of the temporal and the spectral properties in 2010 and 2011 outbursts of H 1743-322
• Discovery of photon index saturation in the black hole binary GRS 1915+105
• Evidence for a Black Hole in the X-ray transient GS 1354-64 (=BW Cir)
• Accretion Flow Dynamics During 1999 Outburst of XTE J1859+226 - Modeling of Broadband Spectra and Constraining the Source Mass
• Relations between X-ray timing features and spectral parameters of Galactic black hole X-ray binaries
• Accretion Flow Properties of Swift J1753.5-0127 during its 2005 outburst
• NuSTAR Observations of the Black Hole GS 1354-645: Evidence of Rapid Black Hole Spin
• 'Spectro-temporal' variabilities and possible physical mechanism for Jet ejections
• Delayed Outburst of H 1743--322 in 2003 and relation with its other outbursts
• Constraining the mass of the black hole GX 339-4 using spectro-temporal analysis of multiple outbursts
• Relation Between Quiescence and Outbursting Properties of GX 339-4
• A Machine Learning approach for classification of accretion states of Black hole binaries