The X-ray variation of M81* resolved by Chandra and NuSTAR

Abstract

Despite advances in our understanding of low luminosity active galactic nuclei (LLAGNs), the fundamental details about the mechanisms of radiation and flare/outburst in hot accretion flow are still largely missing. We have systematically analyzed the archival Chandra and NuSTAR X-ray data of the nearby LLAGN M81*, whose $L_{\mathrm{bol}}\sim 10^{-5}{L}_{\mathrm{Edd}}$. Through a detailed study of X-ray light curve and spectral properties, we find that the X-ray continuum emission of the power-law shape more likely originates from inverse Compton scattering within the hot accretion flow. In contrast to Sgr A*, flares are rare in M81*. Low-amplitude variation can only be observed in soft X-ray band (amplitude usually $\lesssim 2$). Several simple models are tested, including sinusoidal-like and quasi-periodical. Based on a comparison of the dramatic differences of flare properties among Sgr A*, M31* and M81*, we find that, when the differences in both the accretion rate and the black hole mass are considered, the flares in LLAGNs can be understood universally in a magneto-hydrodynamical model.

11 pages, 8 figures, and 4 tables. Accepted to MNRAS

References in corpus (20)

• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• Numerical Simulation of Hot Accretion Flows (III): Revisiting wind properties using trajectory approach
• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• Predicting the Starquakes in PSR J0537-6910
• Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation
• A Magnetohydrodynamic Model for the Formation of Episodic Jets
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• Exploring plasma evolution during Sagittarius A* flares
• Fundamental Plane of Black Hole Activity in Quiescent Regime
• Towards Self-Consistent Modelling of the Sgr A* Accretion Flow: Linking Theory and Observation
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• ALMA Detection of Bipolar Outflows: Evidence for Low Mass Star Formation within 1pc of Sgr A*
• Discrete Knot Ejection from the Jet in a Nearby Low Luminosity Active Galactic Nucleus, M81*
• A "coronal-mass-ejection'' model for flares in Sagittarius A*
• Formation of episodic jets and associated flares from black hole accretion systems
• A Systematic Chandra study of Sgr A${}^{\star }$: II. X-ray flare statistics
• Kinematics of the Broad Line Region in M81
• The advection-dominated accretion flow+thin accretion disk model for two low-luminosity active galactic nuclei: M81 and NGC4579
• Observational Constraints on Direct Electron Heating in the Hot Accretion Flows in Sgr A* and M87*

Cited by in corpus (1)

• Tracking X-ray Variability in Next Generation EHT LLAGN Targets