Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations

Abstract

In the centre of our galaxy lies a super-massive black hole, identified with the radio source Sagittarius A*. This black hole has an estimated mass of around 4 million solar masses. Although Sagittarius A* is quite dim in terms of total radiated energy, having a luminosity that is a factor of $10^{10}$ lower than its Eddington luminosity, there is now compelling evidence that this source was far brighter in the past. Evidence derived from the detection of reflected X-ray emission from the giant molecular clouds in the galactic centre region. However, the interpretation of the reflected emission spectra cannot be done correctly without detailed modelling of the reflection process. Attempts to do so can lead to an incorrect interpretation of the data. In this paper we present the results of a Monte Carlo simulation code we developed in order to fully model the complex processes involved in the emerging reflection spectra. The simulated spectra can be compared to real data in order to derive model parameters and constrain the past activity of the black hole. In particular we apply our code to observations of Sgr B2, in order to constrain the position and density of the cloud and the incident luminosity of the central source. The results of the

Accepted to MNRAS, 13 pages

References in corpus (28)

• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre
• A Catalog of Galaxy Clusters Observed by XMM-Newton
• A 100-parsec elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the Galactic Center
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• A Trigonometric Parallax of Sgr B2
• Diffuse X-ray Emission in a Deep Chandra Image of the Galactic Center
• Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
• Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
• Fading hard X-ray emission from the Galactic Centre molecular cloud Sgr B2
• Equivalent width, shape and proper motion of the iron fluorescent line emission from the molecular clouds as an indicator of the illuminating source X-ray flux history
• Echoes of multiple outbursts of Sagittarius A* revealed by Chandra
• Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
• Chandra Observations of Diffuse X-Rays from the Sagittarius B2 Cloud
• Traces of past activity in the Galactic Centre
• Herschel observations of the Sgr B2 cores: Hydrides, warm CO, and cold dust
• X-ray Diagnostics of Giant Molecular Clouds in the Galactic Center Region and Past Activity of Sgr A*
• The X-ray lightcurve of Sgr A* over the past 150 years inferred from Fe-Ka line reverberation in Galactic Centre molecular clouds
• Hard X-ray Morphological and Spectral Studies of The Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
• An X-Ray Face-on View of the Sgr B Molecular Clouds Observed with Suzaku
• Spectral imaging of the Sagittarius B2 region in multiple 7-mm molecular lines
• Unusual Properties of X-Ray Emission near the Galactic Center
• Variation of the X-ray non-thermal emission in the Arches cloud
• Interpretation of radio continuum and molecular line observations of Sgr B2: free-free and synchrotron emission, and implications for cosmic rays
• A thin diffuse component of the Galactic Ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries
• Probing the clumping structure of Giant Molecular Clouds through the spectrum, polarisation and morphology of X-ray Reflection Nebulae
• Sub-Arcsecond Near-Infrared Images of Massive Star Formation Region NGC 6334 V

Cited by in corpus (14)

• Polarization and long-term variability of Sgr A* X-ray echo
• Glimpses of the past activity of Sgr A* inferred from X-ray echoes in Sgr C
• An X-ray survey of the central molecular zone: variability of the Fe Ka emission line
• Non-Equilibrium Chemistry and Destruction of CO by X-ray Flares
• Can Sgr A* flares reveal the molecular gas density PDF?
• NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud
• New Constraints on Cosmic Particle Populations at the Galactic Center using X-ray Observations of the Molecular Cloud Sagittarius B2
• Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
• Time-Variability of equivalent width of 6.4 keV line from the Arches Complex: reflected X-rays or charged particles?
• Prospects for IXPE and eXTP polarimetric archaeology of the reflection nebulae in the Galactic center
• Prospects for the polarimetric mapping of the Sgr A molecular cloud complex with IXPE
• Galactic Cosmic Rays - Theory and Interpretation
• Tree-based solvers for adaptive mesh refinement code FLASH -- IV: An X-ray radiation scheme to couple discrete and diffuse X-ray emission sources to the thermochemistry of the interstellar medium
• High Energy Emission from the Galactic Center