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by: Miss Jayde Monahan


Miss Jayde Monahan
GPA 3.82


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Class Notes
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This 15 page Class Notes was uploaded by Miss Jayde Monahan on Thursday October 22, 2015. The Class Notes belongs to WRIT 1 at University of California Santa Barbara taught by Staff in Fall. Since its upload, it has received 34 views. For similar materials see /class/226974/writ-1-university-of-california-santa-barbara in Writing at University of California Santa Barbara.


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Date Created: 10/22/15
Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 1 lUltracompact Xray Binaries lin Globular Clusters Lee Homer University of Washington Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 2 Introduction What is an ultracornpact Xray binary Observational results to date are ultracornpacts over abundant in globular clusters GCs relative to the eld Formation and evolution scenarios in GO environrnents Future prospects Conclusions Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 3 What is an ultracompact Xray binary interacting binary With a neutron star accretor for purposes of this talk at least so compact that Roche lobe lling star cannot be lower rnain sequence H burning E POM lt 80min7 a S 06 R9 donor must be at least partially degenerate and in part H depleted best studied case7 eld LMXB pulsar X1627i673 appears to have 002 MG 3 0 or O Ne Mg White dwarf the fractionated core of a formally more massive WD relevance to GCs possible over abundance7 relating to unique forrnation channels Ultracompact Xray Binaries in Globular Clusters edetermined o X16277673 41 min 0 XTE 1117517305 42 min 0 XTE 1109297314 44 min 0 X19167053 50 min 1 well determined o NGC 6624 X18207303 11 min 1 to be con rmed o NGC 6712 X18507087 21 min k I Observational Results KITP UC Santa Barbara 2005 4 Number of LMXBS X1627 X1751 X0929 100 Orbital period hrs Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 5 Consideration of relation between L X Lopt and system size7 as parameterized by van Paradijs amp McClintock 1994 enables prediction of nominal period and upper limits 1probable o NGC 1851 X0512e401 0 g 5m139n 7 585 min 2 potential 1 if g NGC 7078X2 CXOU E J21295817121002 46 min 2 11 i 547 hr 2m 7 7 460 6624 3 7 o NGC 6440CX1 CXOU V mean J17485217202132 60 min 4 g hr sooty1 2 NGC 707 fx2 another 2 possible measured 5 L o NGC 6652A X18327330 6 W8 50 min 01quot 2244 hr 2o L1 5 do l d5 olo olsl l 10 logZ Absolute magnitude of LMXBs versusZ LXLEdd12P1hr23 Field LMXBS from Van Paradijs amp McClintock 1994 are marked by symbols Adapted from Deutsch 1998 K Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 6 Note Further 2 eld LMXBs X0918 549 and X1543 624 have very high LXLopt and show excess Ne absorption in X ray spectra similar to the known ultracompact X1627 673 Juett et al 2002 gt candidate ultracompacts Notwithstanding the small number statistics 7 Ratio of systems With PM lt 80 min to those with P0 lt 1000 hr 0 Field 4 9 CD l M15X2 NGC 6440CX1 l o GCs 30 60 Number of LMXBS NG C 1551 NGC 66523 NGC 6652A 39 NGC 66522A 39 gt Suggests possible over abundance 2 of ultracompact LMXBs in GCs lllm llH lllwml lllwml llwm 0 1 1 10 100 1000 104 Orbital period hrs K Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 7 lFormation amp Evolution Scenarios in GCsi At least four scenarios have been put forward 1 Direct collision of neutron star NS With red giant RG gt spiral in of NS and loss of giant s envelope gt NS WD former core of RG binary Eventually brought into contact by gravitational radiation GR angular momentum AM loss Verbunt 1987 Problem probable complete disruption of HG before spiral in 7 Rasio 81 Shapiro 1991 Bailyn 1988 2 Tidal capture of MS star by NS gt MS NS binary Donor only lls Roche lobe when evolves off MS7 then mass transfer unstable gt formation of common envelope CE gt spiralin and then as for 1 Bailyn amp Grindlay 1987 3 Exchange encounter of NS into primordial binary gt MSNS binary then as for 2 Rasio7 Pfahl amp Rappaport 20007 RPR00 4 Tidal capture of lowmass MS star by NS gt short period 5 18 hr MS NS binary gt mass transfer starts near or at point of central H exhaustion gt degenerate He star donor gt stable mass transfer with decreasing PM continues Fedorova amp Ergma 19897 Podsiadlovvski7 Rappaport amp Pfahl 20027 PRP02 K Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 8 As a step en route to forming the short period millisecond pulsars observed in GCs eg gt20 in 47 Tuc RPROO examined ways to produce NS WD binaries with ultrashort periods started out with population of primordial binaries and NSs gt migrate to core due to mass segregation interact togetheri too hard gt ejection too soft gt disruption remainder form NS MS binary via exchange interaction Note MS star has 173 MG typically as earlier in life of cluster with expansion as secondary evolves off MS gt 12 of systems enter CE phase gt formation of close NS WD binary if P0 5 8hr GR AM losses gt contact and Roche lobe over ow short lived 106 107 yr X ray bright phase as ultracompact like X18207303 Problems 0 Mostly robust but details of CE phase still very uncertain K Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 9 gt con rmed formation path for ultracompact binaries If initial binary period at which mass trans fer comences below bifurcation value 18 hr7 systems evolve to shorter periods For Pmit Z 5 hr7 minimum period within the range of ultracompact With mass transfer onset around time of end of core H burning gt donor becomes degen erate He star gt PM as short as N5 min One particular binary sequence able to ac count for periods of most of GC LMXBsi from A0211 with 171 hr to X1820 303 with 11 min PRP02 undertook a systematic study of evolution of LMXBs and IMXBs7 determining 100 binary evolution sequences spanning full range of likely initial secondary masses and periods 3 I O 9 39 0 Pminm1neo O v I s I Mm I 111 quot O M11110 I I I 39 1o 15 D I 39 39 log dMg I I t a H I I 39 1o 15 0 o39 39 surface I N o39 I I I I 10 r r 15 1111 Formation of ultracornpact LMXBs all calculations start With 114M NS and 1M Dashed curves represent limits of fully conservative upper donorl or nonconservative mass transfer lovverl duced from PRPOZ Repro Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 10 Of special note 0 initial period range 10718 hrs preferentially attained following tidal capture of MS star by NS gt could account for the possible over abundance of ultracornpacts in GCs 0 exchange interactions do not generally lead to such initial conditions Caveats 0 during tidal capture7 total energy to be dissipated in MS star wits binding energy gt disruption 0 hence range of possible initial MS NS periods may well be further constrained 0 value of bifurcation period strongly dependent on magnetic braking7 eg change of ef ciency by factor of 5 leads to values of 20 hr and N5 hr instead K Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 11 Future Prospects Determining the period distribution 0 Con rmdetermine X1850 087 and NGC 66522A amp B periods with further HST or ground based A0 time series photometry o For known optical counterparts NGC 64402CX1 M15 X 2 attempt time series photometry 0 Via colour HST photometry seek identi cations of all LMXBs extremely dif cult for either remaining persistent sources in highly reddened clusters or the new quiescent LMXBs being uncovered by Chandra Ultracompact Xray Binaries in Globular Clusters KITP UC Santa Barbara 2005 12 Nature of secondaries o High resolution X ray With Chandra or XMM spectroscopy may well provide more detailed information on elemental abundances of transferred material cf X1627 673 X0918 549 and X1543 624 in the eld 0 Multi epoch orbital determinations to measure P 0 Taken together these may be used to test formationevolutionary channels andor constrain current phase of given system eg by comparison With the predictions of P and abundances in the sequences of PRP02 Ultracompact X ray Binaries in Globular Clusters KITP UC Santa Barbara 2005 13 0 General progress in modelling of GC stellar dynamics and evolution gt improved understanding of relative importance of exchange encounters versus tidal capture 0 Speci c constraints on the nature of the resulting stellar systems7 together With a full binary population synthesis studies gt prediction of period distribution for GO LMXBs o Improvements still needed in understanding processes of tidal capture and CE evolutioni indeed comparisons of observational and theoretical period results may provide useful constraints Home Work 1 Two pages Reading assignments don7t have to be turned in You can choose to do the problems in this homework or the exercises in sections 21 25 of my notes posted on the class web site 1 Reading assignment Read chapters 17 2 and 3 of Dym7s book 2 Reading assignment Read chapter 2 of the notes posted on the class web site 3 Find a way to represent complex numbers as 2 gtlt 2 real matrices7 such that arithmetic operations 1L7 7 gtlt7 and on complex numbers becomes equivalent to arithmetic operations on their matrix representations instead That is7 if Tz is the 2 gtlt 2 real matrix representing the complex number 2 then T21 22 T21 T227 T21 7 22 T21 7 T227 T2122 T21T227 TQM22 T22 1T217 for all complex numbers 21 and 22 Hint The entries of Tz will depend on the real and imaginary parts of 2 Look at the expression for the product of two complex numbers and two 2 gtlt 2 matrices 4 A Show that the exchange operator which exchanges the 24th and j th components of a vector leaVing all others untouched7 is a linear operator US Find a matrix representation for EU 0 Show that the permutation operator


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