J
		
		2021
			
	    
Dragged surfaces. On the accretion tori in the ergoregion
	    PUGLIESE, Daniela and Zdeněk STUCHLÍK
	
	
	
	    
	
     
 
	
	Basic information
	
		Original name
		Dragged surfaces. On the accretion tori in the ergoregion
	 
			
				Edition
				 Publications Of The Astronomical Society Of Japan, England, 2021, 0004-6264
			 
		
Other information
		
	
		
			Type of outcome
			Article in a journal
		 
	
		
			Field of Study
			10308 Astronomy
		 
	
		
			Country of publisher
			United Kingdom of Great Britain and Northern Ireland
		 
	
		
			Confidentiality degree
			is not subject to a state or trade secret
		 
	
			
		
			
				Impact factor
				Impact factor: 3.310
			 
		
		
			RIV identification code
			RIV/47813059:19630/21:A0000149
		 
	
			
				Organization unit
				Institute of physics in Opava
			 
		
			
		
		
			EID Scopus
			2-s2.0-85122462049
		 
		
			Keywords in English
			accretion; accretion disks;black hole physics;galaxies: active;galaxies: jets;hydrodynamics
		 
			Tags
			International impact, Reviewed
		 
			
			
				
					In the original language
					We discuss the conditions for the existence of extended matter configurations orbiting in the ergoregion or close to the outer ergosurface of the Kerr black hole ("dragged" configurations). The co-rotating tori under consideration are perfect fluid configurations with barotropic equations of state, orbiting on the equatorial plane of the central Kerr black hole. The possibility of magnetized tori with a toroidal magnetic field is also discussed. Indications on the attractors where dragged tori can be observed are provided with the analysis of the fluid characteristics and geometrical features, relevant for the torus stability and their observations. QPO emissions from the inner edges of the dragged tori are also discussed. We argue that the smaller dragged tori could be subjected to a characteristic instability: the effect of the frame-dragging. This possibility is thoroughly explored. This can finally lead to the destruction of the torus (disk exfoliation) which can combine with accretion and processes present in the region very close to the black hole horizon. Tori are characterized according to the central attractor dimensionless spin. These structures can be observed in orbiting black holes with dimensionless spin a > 0.9897 M.
				  
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