CRIT READING RHET
CRIT READING RHET Writing 39
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This 18 page Class Notes was uploaded by Jamal Crooks on Saturday September 12, 2015. The Class Notes belongs to Writing 39 at University of California - Irvine taught by Staff in Fall. Since its upload, it has received 35 views. For similar materials see /class/201888/writing-39-university-of-california-irvine in Writing at University of California - Irvine.
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Date Created: 09/12/15
Tidal Disruption of Stars as Probes of IMBHs Enrico Ramlrez Rulz UCSC UCI Mar 2009 Collabnmtnrs Guillnchnn UCSC S Rnsswog Blemen D Kasen UCSC W Rix ORNL Tidal Disruption of Stars by IMBHs One would like some independent corroboration of the black hole hypothesis or conversely some way of ruling it out The best diagnostic for a black hole s presence would be some inevitable concomitant that cannot be explained in any other way A candidate may be distinctive manifestations of tidal disruption and ignition of white dwarfs Tidal Disruption of Stars Basics As stellar orbits diffuse in phase space it therefore seems inevitable that some may wander sufficiently close to the hole that they suffer tidal disruption AZ orbital plane tidal radius I I pericentre R M 13 For solartype stars RT 2 5 X 1012M 63 f lt cm Q hl f d WD 11 13 R d M d 43 w i e or egenerate s 37 2 12 x 10 4M lt W gt lt W gt cm 109cm 06MQ Tidal Disruption of WDs Relevance to IMBHs The domain of astrophysical relevance of tidal disruption of a white dwarf by a black hole RT 723 Rwd de 713 03M X IQ h 101ngt lt06A1 gt Black Hole Enters White Dwarf Entersi White Dwarf BlaCk Hole 16 MMQZM i B de 14 MD 10 No Disruption l 102 1o3 104 105 MWMg Tidal Disruption of WDs Explosive Energy Release Although WD should account for l0 of all disruptions there is the possibility of explosive energy release 1 08 08 04 02 m a a M 0 ll ID NI2K NMK Nlz k N 16K Relative Fraction Baumgardt et al 2004 Relative fraction of disrupted stars for cluster simulations containing a black hole with an initial mass of I03 M Events in the Brief Life of a Tidally Disrupted WD A 02 M He WD approaching a IO3 M IMBH with l3l2 68 sec 103 sec pmin pmax 70 sec log p 3 x101ocm 3D SPH method Rosswog et al 2008 using a realistic equation of state and a 7 nuclear species 0network Rix et al I998 Tidal Pinching 0 WEm fa wwf pg mg W HU W m m Em 1ng M tujg g mfg my Umgg i Hm th Wi ag jiEF E SWGQEFCQU mgymgg im a m mcg SEmO 68 sec 72 sec log T Tidal Pinching OThig m mg M m m do ag Eh mm mimcg pgl W i fEX mcgfi m m mm E h mw g p mo 714 sec Shock Heating 2x108 4x108 6x108 720 sec 726 sec Nuclear Burning A large fraction of Fegroup nuclei are freshly synthesised log mass M 1 A Peculiar Type Ia Supernovae 0 20 1 106 sec A Peculiar Type Ia Supernovae The mass fraction that is ejected though less spectacular than typical Ia supernovae could nevertheless have distinctive observational characteristics oit should be seen in association with a globular cluster odegenerate stars should be on average lighter the light curve should be rather unique as a result of the material being highly squeezed into the orbital plane othe ejected debris would be expelled with speeds gt I 04 kms A Peculiar Type la Supernovae39 Absolute Bolometric Magnitude A Peculiar Type Ia Supernovae 4 s S 3 Relative Flux plus offset 3 10 15 Days Since Explosion K 555555 Olllll 2000 3000 4000 5000 6000 Wave ength Angstroms 7000 8000 Unbound debris The required energy to tear the WD apart is supplied at the expense of the orbital kinetic energy which at Rt is larger by Mhde23 300 39393939393939393939 0015 dMds 0005 30 specific energy a On average the debris would be bound to the hole although several effects impart a spread in orbital binding energy Swallowing Bound Debris The returning gas does not immediately produce a flare of activity from the black hole First material must enter circular orbits and form an accretion torus Angular momentum redistribution shock After passage the outflowing gas is in an orbit which will collide with the infalling stream damping the vertical motion Nozzle As the stream approaches pericenter radial focusing act as an effective nozzle 1372 sec 713 723 a N 300l173 dengwd G rg log 2 log T Swallowing Bound Debris 437 sec 118ec Timescale for Swallowing Bound Debris The infalling debris forms a torus within which radiation pressure is dominant its subsequent flow would be controlled by viscosity cooling and winds 5 log M Mgs ta N 150a300rg32M2 s 8I 0 04 08 12 16 2 24 28 Iogtmin A luminosity LEddlo4th3 erg s I can only be maintained for at most a year with an effective surface temperature 0l keV
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