Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds

Abstract

We present the result of a study of the X-ray emission from the Galactic Centre (GC) Molecular Clouds (MC) within 15 arcmin from Sgr A*. We use XMM-Newton data (about 1.2 Ms of observation time) spanning about 8 years. The MC spectra show all the features characteristic of reflection: i) intense Fe Kalpha, with EW of about 0.7-1 keV, and the associated Kbeta line; ii) flat power law continuum and iii) a significant Fe K edge (tau~0.1-0.3). The diffuse low ionisation Fe K emission follows the MC distribution, nevertheless not all MC are Fe K emitters. The long baseline monitoring allows the characterisation of the temporal evolution of the MC emission. A complex pattern of variations is shown by the different MC, with some having constant Fe K emission, some increasing and some decreasing. In particular, we observe an apparent super-luminal motion of a light front illuminating a Molecular nebula. This might be due to a source outside the MC (such as Sgr A* or a bright and long outburst of a X-ray binary), while it cannot be due to low energy cosmic rays or a source located inside the cloud. We also observe a decrease of the X-ray emission from G0.11-0.11, behaviour similar to the one of Sgr B2. The line intensities, clouds dimensions, columns densities and positions with respect to Sgr A*, are consistent with being produced by the same Sgr A* flare. The required high luminosity (about 1.5~10^39 erg/s) can hardly be produced by a binary system, while it is in agreement with a flare of Sgr A* fading about 100 years ago. The low intensity of the Fe K emission coming from the 50 and the 20 km/s MC places an upper limit of 10^36 erg/s to the mean luminosity of Sgr A* in the last 60-90 years. The Fe K emission and variations from these MC might have been produced by a single flare of Sgr A*.

ApJ in press 17 pages, 14 Figures, 3 tables

References in corpus (17)

• X-ray Properties of Black-Hole Binaries
• A Trigonometric Parallax of Sgr B2
• Discrete sources as the origin of the Galactic X-ray ridge emission
• Galaxy Zoo: The fundamentally different co-evolution of supermassive black holes and their early- and late-type host galaxies
• XMM-Newton study of the complex and variable spectrum of NGC 4051
• Variable accretion and emission from the stellar winds in the Galactic centre
• The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic Center Region: Cosmic Ray Particles
• The Interplay between Star Formation and the Nuclear Environment of our Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet Clusters
• Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
• CAIXA: a Catalogue of AGN In the XMM-Newton Archive II. Multiwavelength correlations
• Resolving the Galactic X-ray background
• An X-Ray Face-on View of the Sgr B Molecular Clouds Observed with Suzaku
• Metal Abundances in the Cool-Cores of Galaxy Clusters
• XMM-Newton and Suzaku analysis of the Fe K complex in the Seyfert 1 galaxy Mrk 509
• Map of the Galaxy in the 6.7 keV emission line
• Non-thermal emission in the core of Perseus: results from a long XMM-Newton observation
• A Viscous Heating Mechanism for the Hot Plasma in the Galactic Center Region

Cited by in corpus (139)

• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• What Drives the Growth of Black Holes?
• Cool Outflows in Galaxies and their Implications
• Black hole variability and the star formation-AGN connection: Do all star-forming galaxies host an AGN?
• A correlation between star formation rate and average black hole accretion in star forming galaxies
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• Observational signatures of particle acceleration in supernova remnants
• Checking the dark matter origin of 3.53 keV line with the Milky Way center
• Photodissociation and X-Ray Dominated Regions
• Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event
• Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center
• Fading hard X-ray emission from the Galactic Centre molecular cloud Sgr B2
• iPTF Discovery of the Rapid "Turn On" of a Luminous Quasar
• The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN
• The XMM-Newton view of the central degrees of the Milky Way
• Impact of low-energy cosmic rays on star formation
• A strongly magnetized pulsar within grasp of the Milky Way's supermassive black hole
• Origin of the Fermi Bubble
• Echoes of multiple outbursts of Sagittarius A* revealed by Chandra
• Herschel observations of EXtraordinary Sources: Analysis of the full Herschel/HIFI molecular line survey of Sagittarius B2(N)
• Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate
• The K-shell Line Distribution of Heavy Elements along the Galactic Plane Observed with Suzaku
• Fossil imprint of a powerful flare at the Galactic Centre along the Magellanic Stream
• Non-Thermal Insights on Mass and Energy Flows Through the Galactic Centre and into the Fermi Bubbles
• Fermi Bubbles in the Milky Way: the closest AGN feedback laboratory courtesy of Sgr A*?
• X-ray bubbles in the circumgalactic medium of TNG50 Milky Way- and M31-like galaxies: signposts of supermassive black hole activity
• Phosphorus-bearing molecules in the Galactic Center
• Relativistic disc reflection in the extreme NLS1 IRAS13224-3809
• Traces of past activity in the Galactic Centre
• Nonthermal X-rays from low-energy cosmic rays: Application to the 6.4 keV line emission from the Arches cluster region
• Galactic Center Research: Manifestations of the Central Black Hole
• The Excitation of HCN and HCO+ in the Galactic Center Circumnuclear Disk
• X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*
• 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
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• The X-ray flaring properties of Sgr A* during six years of monitoring with Swift
• Discovery of the recombining plasma in the south of the Galactic center; a relic of the past Galactic center activity?
• Chemical Features in the Circumnuclear Disk of the Galactic Center
• The wind nebula around magnetar Swift J1834.9-0846
• Hard X-ray Morphological and Spectral Studies of The Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
• On the Fe K absorption - accretion state connection in the Galactic center neutron star X-ray binary AX J1745.6-2901
• The X-ray outburst of the Galactic Centre magnetar SGR J1745-2900 during the first 1.5 year
• Low energy cosmic rays
• New Evidence for High Activity of the Super-Massive Black Hole in our Galaxy
• Not that long time ago in the nearest galaxy: 3D slice of molecular gas revealed by a 110 years old flare of Sgr A*
• Stellar winds pump the heart of the Milky Way
• A New Perspective of the Radio Bright Zone at The Galactic Center: Feedback from Nuclear Activities
• TeV Gamma-ray Observations of The Galactic Center Ridge By VERITAS
• Polarization and long-term variability of Sgr A* X-ray echo
• Diffuse X-Ray Sky in the Galactic Center
• 3 mm spectral line survey of two lines of sight toward two typical cloud complexes in the Galactic Center
• Glimpses of the past activity of Sgr A* inferred from X-ray echoes in Sgr C
• K-shell Emission of Neutral Iron Line from Sgr B2 Excited by Subrelativistic Protons
• The Fermi Bubble as a Source of Cosmic Rays in the Energy Range > 10E15 eV
• INTEGRAL: science highlights and future prospects
• First hard X-ray detection of the non-thermal emission around the Arches cluster: morphology and spectral studies with NuSTAR
• An X-ray survey of the central molecular zone: variability of the Fe Ka emission line
• X-ray polarization evidence for a 200 years-old flare of Sgr A${}^{\ast }$
• Origin of the Galactic Diffuse X-ray Emission: Iron K-shell Line Diagnostics
• Fe Ka line emission from the Arches cluster region - evidence for ongoing particle bombardment?
• The role of feedback in accretion on Low Luminosity AGN: Sgr A* case study
• XMM-Newton observations of the Galactic Centre Region - I: The distribution of low-luminosity X-ray sources
• Gamma rays from the Galactic Centre region: a review
• Origins of Scatter in the Relationship Between HCN 1-0 and Dense Gas Mass in the Galactic Center
• Non-Equilibrium Chemistry and Destruction of CO by X-ray Flares
• 3D simulations of clump formation in stellar wind collisions
• Radio polarimetry of Galactic centre pulsars
• Very-high energy observations of the Galactic center region by VERITAS in 2010-2012
• NuSTAR and Chandra Insight into the Nature of the 3-40 keV Nuclear Emission in NGC 253
• Modelling the thermal X-ray emission around the Galactic Centre from colliding Wolf-Rayet winds
• The Galactic LMXB Population and the Galactic Centre Region
• 74 MHz Nonthermal Emission from Molecular Clouds: Evidence for a Cosmic Ray Dominated Region at the Galactic Center
• Star Formation and Dynamics in the Galactic Centre
• Is SS 433 a misaligned ultraluminous X-ray source? Constraints from its reflected signal in the Galactic plane
• Variation of the X-ray non-thermal emission in the Arches cloud
• Prospects of 3D mapping of the Galactic Centre clouds with X-ray polarimetry
• The 492 GHz emission of Sgr A* constrained by ALMA
• Can Sgr A* flares reveal the molecular gas density PDF?
• Swift J174540.7-290015: a new accreting binary in the Galactic Center
• Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations
• XMM-Newton observations of the Galactic Centre Region - II: The soft thermal emission
• A past capture event at Sagittarius A* inferred from the fluorescent X-ray emission of Sagittarius B clouds
• X-ray Observation of a Magnetized Hot Gas Outflow in the Galactic Center Region
• A Supernova-driven, Magnetically-collimated Outflow as the Origin of the Galactic Center Radio Bubbles
• 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
• The kpc Scale Fe K$\alpha$ Emission in the Compton Thin Seyfert 2 Galaxy NGC 4388 resolved by Chandra
• NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud
• The origin of the 6.4 keV line emission and H${}_2$ ionization in the diffuse molecular gas of the Galactic center region
• The CARMA 3mm Survey of the Inner $0.7^{\circ }\times 0.4^{\circ }$ of the Central Molecular Zone
• Cosmic Rays in a Galactic Breeze
• Probing the clumping structure of Giant Molecular Clouds through the spectrum, polarisation and morphology of X-ray Reflection Nebulae
• Reflection nebulae in the Galactic Center: the case for soft X-ray imaging polarimetry
• Multiple accretion events as a trigger for Sgr A* activity
• Fermi LAT observations of Sagittarius A*: Imaging Analysis
• On the Origin of the 6.4 keV Line in the Galactic Center Region
• The Fossil Nuclear Outflow in the Central 30 pc of the Galactic Center
• Observational tests of the picture of disk accretion
• Investigating the origin of the faint non-thermal emission of the Arches cluster using the 2015-2016 NuSTAR and XMM-Newton X-ray observations
• Multi-phase environment of compact galactic nuclei: the role of the Nuclear Star Cluster
• SRG/eROSITA view of X-ray reflection in the Central Molecular Zone: a snapshot in September-October 2019
• Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
• New Constraints on Cosmic Particle Populations at the Galactic Center using X-ray Observations of the Molecular Cloud Sagittarius B2
• Time-Variability of equivalent width of 6.4 keV line from the Arches Complex: reflected X-rays or charged particles?
• Modelling the time dependence of the TeV Gamma-ray source at the Galactic Centre
• X-ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the nature of AGN variability
• Hard X-ray Irradiation Potentially Drives Negative AGN Feedback by Altering Molecular Gas Properties
• 25 years of XMM-Newton observations of the Sgr A complex: 3D distribution and internal structure of the clouds
• X-raying molecular clouds with a short flare: probing statistics of gas density and velocity fields
• The Galactic Center: Not an Active Galactic Nucleus
• Can a Satellite Galaxy Merger Explain the Active Past of the Galactic Center?
• X-Ray afterglow of SWIFT J1644+57: a Compton echo?
• Evidence for an interaction between the Galactic Center clouds M0.10-0.08 and M0.11-0.11
• X-ray observations of the hot phase in Sgr~A*
• Sculpting the Stellar Cusp in the Galactic Center
• The LLAGN in the centre of the Galaxy
• Atomic Carbon in the Central Molecular Zone of the Milky Way : Possible Cosmic-ray Induced Chemistry or Time-Dependent Chemistry Associated with SNR Sagittarius A East
• Revisit the Circumnuclear X-ray Emission of NGC 2992 in a Historically Low State
• Prospects for the polarimetric mapping of the Sgr A molecular cloud complex with IXPE
• Impact of intrinsic polarisation of Sgr A* historical flares on (polarisation) properties of their X-ray echoes
• Prospects for IXPE and eXTP polarimetric archaeology of the reflection nebulae in the Galactic center
• Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region
• Not gone with the Wind: Survival of High-Velocity Molecular Clouds in the Galactic center
• The Galactic Center compared with nuclei of nearby galaxies
• Mini-spiral as source of material for Sgr A* in bright state
• Iron K-alpha echoes from the circumnuclear disk orbiting Sgr A*
• Galactic Cosmic-Rays in a Breeze
• X-rays from a Central "Exhaust Vent" of the Galactic Center Chimney
• Herschel water maps towards the vicinity of the black hole Sgr A*
• Molecules in the Circumnuclear Disk of the Galactic Center
• Origin of X-ray and gamma-ray emission from the Galactic central region
• The reflection of two past outbursts of Sagittarius A* observed by Chandra during the last decade
• Extreme X-ray Reflection in the Nucleus of the Seyfert Galaxy NGC 5033
• Modelling the thermal X-ray emission around the Galactic centre from colliding Wolf-Rayet winds
• High Energy Emission from the Galactic Center
• Diffuse Hot Plasma in the Interstellar Medium and Galactic Outflows