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The R.A.P. Project (Reviews of Astro-Ph) 2003

Akkreciya
(Arhiv Akkreciya:
v.2, 2004, v.1, 2002-2003)

Vypusk 62. 01-15 dekabrya 2003

miniobzor astro-ph/0312170 Doplerovskaya tomografiya akkrecii v dvoinyh (Doppler tomography of accretion in binaries)
Authors: D. Steeghs
Comments: 5 pages, two color figures, to appear in the proceedings of IAU JD9, "Astro-tomography", eds. A.Cameron, A.Schwope and S.Vrielmann, movies available at http://hea-www.harvard.edu/~dsteeghs/wzsge/movies.html

Neposredstvenno uvidet' akkrecionnyi disk v tesnoi dvoinoi sisteme poka nel'zya: slishkom daleki ot nas eti ob'ekty. Odnako, est' metodika, kotoraya pozvolyaet postroit' kartu diska. Nazyvaetsya eto - doplerovskaya tomografiya.


Sistema WZ Sge. Sleva pokazana karta v linii ionizovannogo geliya, a sprava - v linii vodoroda Hβ

Sut' metoda zaklyuchaetsya v issledovanii profilei emissionnyh linii v zavisimosti ot orbital'noi fazy dvoinoi sistemy. Issleduyutsya raznye tipy dvoinyh sistem, naprimer, kataklizmicheskie peremennye. V obzore kratko opisyvaetsya sut' metodiki i dayutsya primery (odin iz nih pokazan na risunke).


Vypusk 58. 01-17 oktyabrya 2003

astro-ph/0310224 Akkreciya na bystrye rentgenovskie pul'sary (Accretion Onto Fast X-Ray Pulsars)
Authors: S.A.Rappaport et al.
Comments: 10 pages, 5 figures, submitted to ApJ

V poslednie desyat' let byli otkryty akkreciruyushie rentgenovskie pul'sary s millisekundnymi periodami. V standartnoi modeli akkrecii voznikayut nekotorye problemy s ob'yasneniem nablyudaemyh svoistv etih ob'ektov. Naprimer, s ob'yasneniem togo, chto temp akkrecii u nih razlichaetsya pochti na dva poryadka velichiny, ili chto eti ob'ekty demonstriruyut ochen' vysokie tempy tormozheniya.

Dlya ob'yasneniya nablyudaemyh yavlenii avtory predlagayut modificirovannuyu model' diska u kotorogo vneshnyaya granica raspolozhena na radiuse korotacii. Razmer takogo diska zavisit ot perioda vrasheniya neitronnoi zvezdy.


Vypusk 56. 13-20 sentyabrya 2003

miniobzor astro-ph/0309347 Nablyudatel'nyi obzor akkreciruyushih millisekundnyh rentgenovskih pul'sarov (An observational review of accretion-driven millisecond X-ray pulsars)
Authors: Rudy Wijnands
Comments: 10 pages, 6 figures.

Segodnya izvestno pyat' akkreciruyushih millisekundnyh rentgenovskih pul'sarov. Bol'shuyu chast' obzora zanimaet pul'sar SAX J1808.4-3658 - on byl otkryt pervym i yavlyaetsya samym izuchennym ob'ektom v dannoi gruppe. Ot nego k segodnyashnemu dnyu nablyudalis' uzhe chetyre vspyshki. Poslednyaya iz nih proizoshla v oktyabre 2002 g. i vyzvala osobyi interes, poskol'ku v hode nee u ob'ekta nablyudalis' kilogercovye kvaziperiodicheskie oscillyacii (QPO) odnovremenno na dvuh chastotah i pochti kogerentnye (periodicheskie) pul'sacii vo vremya rentgenovskoi vspyshki pervogo tipa. Do sih por kilogercovye QPO nablyudalis' tol'ko u rentgenovskih novyh - kandidatov v chernye dyry, t.e. v sistemah s kompaktnym ob'ektom ne obladayushim sobstvennym tochno izmerennym periodom vrasheniya. Ostal'nye chetyre ob'ekta etogo klassa byli otkryty v poslednie dva goda, k nastoyashemu vremeni opublikovany rezul'taty tol'ko nebol'shogo kolichestva ih nablyudenii. Vozmozhno, v blizhaishee vremya my poluchim novye interesnye rezul'taty, kasayushiesya etih pul'sarov.

Bolee razvernutuyu i obnovlyaemuyu versiyu dannogo obzora mozhno naiti na saite avtora http://zon.wins.uva.nl/~rudy/admxp/

Ob'ektu SAX J1808.4-3658 takzhe posvyashena stat'ya astro-ph/0309345 "Aperiodicheskoe vremennoe povedenie akkreciruyushego millisekundnogo pul'sara SAX J1808.4-3658"


astro-ph/0309458 Model' dlya vysokochastotnyh kvaziperiodicheskih oscillyacii v Akkreciruyushih chernyh dyrah (A Model for High Frequency Quasi-periodic Oscillations from Accreting Black Holes)
Authors: Jeremy D. Schnittman and Edmund Bertschinger
Comments: 25 pages, 13 figures, submitted to ApJ

Nablyudeniya s borta rentgenovskogo sputnika RXTE obnaruzhili vysokochastotnye kvaziperiodicheskie oscillyacii (QPO) u ryada akkreciruyushih rentgenovskih sistem s chernymi dyrami. Po krainei mere u dvuh sistem kolebaniya proishodyat na dvuh chastotah, otnosyashihsya kak 2:3. Dlya ob'yasneniya etogo yavleniya avtory predlozhili model' yarkogo pyatna vo vnutrennei chasti akkrecionnogo diska vokrug kerrovskoi chernoi dyry. Vblizi vnutrennego kraya diska, okolo poslednei ustoichivoi krugovoi orbity, chastoty radial'nyh kolebanii obrashayusheisya chasticy sostavlyayut 1/3 orbital'noi chastoty. Nablyudenie podobnogo pyatna pod nekotorym uglom k disku dolzhno porozhdat' kvaziperiodicheskie oscillyacii s otnosheniyami chastot 2:3 ili 3:4.


Vypusk 55. 01-12 sentyabrya 2003

astro-ph/0309321 Model' diska pri vozvratnoi akkrecii dlya ul'tramoshnyh istochnikov (A Fallback Disk Model for Ultraluminous X-ray Sources)
Authors: Xiang-Dong Li
Comments: 6 pages, accepted for publication in ApJL

Napomnim, ul'tramoshnye istochniki (UMI) - eto ob'ekty, nablyudaemye obychno v rentgenovskom diapazone, potok izlucheniya ot kotoryh sotvetstvuet izotropnoi svetimosti bolee 1039 erg/s. Eta svetimost' sootvetstvuet akkrecii na chernuyu dyru s massoi 10 mass Solnca. Esli my vidim bOl'shii potok, to ili massa chernoi dyry bol'she (a otkuda ih vzyat'?), ili izluchenie ne izotropno - dzhet.

Nablyudeniya ukazyvayut, chto ul'tramoshnye istochniki obychno nahodyatsya tam zhe, gde i molodye massivnye zvezdy (hotya vidyat istochniki i v ellipticheskih galaktikah). Nekotorye iz UMI sovpadayut s ostatkami sverhnovyh. Eto privelo avtora stat'i k mysli, chto istochnikom veshestva dlya akkrecii mozhet byt' tozhe samoe veshestvo, chto bylo vybrosheno pri vzryve sverhnovoi.

Davno bylo pokazano, chto posle vzryva znachitel'naya chast' veshestva mozhet vypadat' obratno. Takoi process poluchil nazvanie vozvratnaya akkreciya (fall-back). Veshestvo mozhet obrazovyvat' disk, chto mozhet privodit' k anizotropii izlucheniya i obrazovaniyu dzhetov. No po vidimomu vpervye ideyu vozvratnoi akkrecii primenyayut dlya ob'yasneniya ul'tramoshnyh istochnikov (u menya eta rabota vyzvala reakciyu: "Pochemu zhe ya-to ne dogadalsya?!" - S.P.). Avtor ne pretenduet na ob'yasnenie vseh izvestnyh ob'ektov etogo tipa, t.k. stadiya vozvratnoi akkrecii so stol' vysokim energovydeleniem yavlyaetsya dostatochno korotkoi (okolo 100000 let). Odnako mozhno ob'yasnit' poryadka 10 procentov istochnikov, naprimer te, chto "sidyat" v ostatkah sverhnovyh.


Vypusk 48. 23-30 iyunya 2003


astro-ph/0306614 Struinodominirovannye sostoyaniya: al'ternativa advekcii cherez gorizont chernoi dyry v "spokoinyh" rentgenovskih dvoinyh (Jet-dominated states: an alternative to advection across black hole event horizons in uiescent' X-ray binaries)
Authors: R.P. Fender, E. Gallo, P.G. Jonker
Comments: 6 pages, Accepted for publication as a letter in MNRAS

Seichas izvestno dostatochno mnogo kandidatov v chernye dyry v tesnyh dvoinyh sistemah (sm. obzor Cherepashuka v UFN). Nekotorye iz etih sistem mogut nahodit'sya v t.n. "spokoinyh" sostoyaniyah, kogda ih svetimost' stanovitsya chrezvychaino nizkoi. Prichiny etogo neyasny. Odnoi iz naibolee populyarnyh gipotez yavlyaetsya advekcionnaya: v etom sluchae goryachee veshestvo utekaet pod gorizont, i ne proishodit vydeleniya energii v vide elektromagnitnogo izlucheniya. V dannoi stat'e avtory predlagayut al'ternativu: "vse uhodit v svistok". Energiya uhodit v kineticheskuyu energiyu strui, b'yushih perpendikulyarno akkrecionnomu disku.

Vypusk 47. 16-21 iyunya 2003

astro-ph/0306328 Porozhdaemyi vyazkost'yu veter ot magnitnyh akkrecionnyh diskov (Viscosity-Driven Winds from Magnetized Accretion Disks)
Authors: Daizo Maruta, Osamu Kaburaki
Comments: accepted for publication in ApJ

Chto proishodit s akkrecionnym diskom, kotoryi pronizyvaetsya global'nym magnitnym polem? Hod akkrecii v nem kontroliruetsya odnovremenno dvumya processami - magnitnym polem i vyazkost'yu plazmy. Avtoram dannoi raboty udalos' postroit' analiticheskuyu model' dlya takogo diska v advekcionno-dominirovannom sluchae (kogda osnovnaya chast' vydelyaemogo v vyazkih processah tepla perenositsya po radiusu potokom veshestva, a ne diffundiruet poperek diska, kak v standartnoi modeli). Silovye linii polya, poperechno peresekayushie disk, porozhdayut magnitnyi veter - chasticy veshestva s poverhnosti diska uskoryayutsya vdol' silovyh linii. Vdol' osi vrasheniya diska pri etom obrazuyutsya dzhetopodobnye struktury. Vse eti detali izobrazheny na predstavlennoi sheme.


"Konceptual'naya shema" zamagnichennogo akkrecionnogo diska


Vypusk 46. 1-15 iyunya 2003

obzor astro-ph/0306184 Dvumernye adiabaticheskie potoki na chernye dyry. I. Gidrodinamicheskaya akkreciya (Two Dimensional Adiabatic Flows onto a Black Hole: I. Fluid Accretion)
Authors: Roger D. Blandford and Mitchell C. Begelman
Comments: 21 pages, 9 figures, submitted to MNRAS

Vsem, vsem, vsem, kto interesuetsya akkreciei!

Rodzher Blenford - zhivoi klassik sovremennoi astrofiziki, ego soavtor - Mitchel Begel'man, takzhe ochen' izvestnyi issledovatel'. Predstavlennaya imi rabota sochetaet v sebe original'nye rezul'taty s obzorom sovremennogo sostoyaniya gidrodinamicheskoi akkrecii (bez sushestvennogo vliyaniya magnitnyh polei).

Pri akkrecii na chernye dyry veshestvo izluchaet ochen' neeffektivno. Diski okazyvayutsya polnost'yu konvektivnymi. Avtorami poluchena seriya 2-mernyh avtomodel'nyh reshenii dlya konvektivnyh diskov.


Raspredelenie fizicheskih parametrov v akkrecionnom diske bez konvekcii. Pokazany poverhnosti postoyannyh znachenii (snizu vverh na risunke) plotnosti p, davleniya P, sfericheskogo radiusa r, uglovoi skorosti W, cilindricheskogo radiusa R, udel'nogo uglovogo momenta L, integrala Bernulli B i entropii S. Vse poverhnosti prohodyat cherez odnu i tu zhe tochku na ekvatore diska.

V obzore rassmotreny takzhe sleduyushie temy: odno- i dvumernoe opisanie diskov, cirkulyaciya i ottok veshestva v diskah, otkloneniya ot avtomodel'nosti vo vnutrennih i vneshnih chastyah diskov, al'ternativnye modeli adiabaticheskoi akkrecii (nekonvektivnye diski, advekcionno-dominirovannye diski, polnost'yu konvektivnye diski, slabo svyazannye diski).


astro-ph/0306208 Perenos uglovogo momenta v akkrecionnyh diskah (Enhanced Angular Momentum Transport in Accretion Disks)
Author: Steven A. Balbus (Dept. of Astronomy, University of Virginia)
Comments: 43 pages, 2 figures, to appear v.43 A.R.A.A. October 2003

Fundamental'ny astrofizicheskii obzor, kotoryi vyidet v tome Annual Reviews etogo goda.

Za poslednie desyatiletie astrofizika sushestvenno prodvinulas', kak v ponimanii klyuchevyh fizicheskih processov diskovoi akkrecii, tak i v nablyudeniyah akkreciruyushih rentgenovskih istochnikov.

V obzore rassmotreny sleduyushie voprosy: sovremennaya teoriya akkrecii s uchetom nelineinyh fluktuacii, gidrodinamicheskie volny v diskah, gidrodinamicheskie neustoichivosti, rol' MGD turbulentnosti i ee chislennoe modelirovanie, 2- i 3-mernoe modelirovanie diskov.


Shema akkrecionnogo diska s malym vkladom davleniya izlucheniya


Vypusk 45. 26-31 maya 2003

astro-ph/0305421 Akkreciya Bondi i problema nedostayushih odinochnyh neitronnyh zvezd (Bondi Accretion and the Problem of the Missing Isolated Neutron Stars)
Authors: R.Perna, R.Narayan, G.Rybicki, L.Stella, A.Treves
Comments: accepted to ApJ; 19 pages, 4 figures

V galaktike dolzhno nahodit'sya 108-109 neitronnyh zvezd, rodivshihsya za vremya ee zhizni. Bol'shinstvo iz nih slishkom holodnye, chtoby mozhno bylo zametit' ih sobstvennoe izluchenie, no oni mogli by svetit za schet akkrecii iz mezhzvezdnoi sredy. Raschety, provodivshiesya pered zapuskom rentgenovskoi observatorii ROSAT (primerno v 1990 g.), pokazyvali, chto ona dolzhna byla uvidet' sotni i tysyachi podobnyh slabyh odinochnyh istochnikov, a obnaruzheny byli edinicy (tochnee, dostoverno ne otkryto ni odnogo, est' sem' ob'ektov-kandidatov). Kuda delis' ostal'nye? Kakie faktory byli uchteny nepravil'no?

Okazyvaetsya ih bylo naskol'ko.

  1. Okazalos', chto prostranstvennye skorosti neitronnyh zvezd v srednem sushestvenno vyshe, chem predpolagalos' v 1990 g.
  2. Dlya pravil'noi ocenki akkrecionnoi svetimosti neitronnyh zvezd neobhodimo uchityvat' vliyanie ih atmosfer.
  3. Dlya ocenki tempa akkrecii ispol'zovalas' klassicheskaya formula Bondi, kotorye avtory predlagayut modificirovat'. Delo v tom, chto pri akkrecii energiya magnitnyh polei, vmorozhennyh v mezhzvezdnoe veshestvo, vozrastaet bystree vsego. Na nekotorom rasstoyanii ot neitronnoi zvezdy eta energiya stanovitsya sravnimoi s kineticheskoi energii veshestva i akkreciya nachinaet tormozit'sya.
Vtoroi iz ukazannyh faktorov povyshaet akkrecionnuyu svetimost' neitronnyh zvezd, no pervyi i tretii ee sushestvenno sil'nee ponizhayut (avtory osobenno upirayut na tret'yu prichinu), chto i vyzyvaet snizhenie chisla zaregistrirovannyh istochnikov.

Vypusk 44. 17-23 maya 2003

astro-ph/0305335 Shema edinogo opisaniya malomoshnyh akkreciruyushih chernyh dyr - struino-dominirovannye akkrecionnye potoki i korrelyaciya radio i rentgenovskogo izlucheniya (A Scheme to Unify Low-Power Accreting Black Holes - Jet-Dominated Accretion Flows and the Radio/X-Ray Correlation)
Authors: Heino Falcke et al.
Comments: Astronomy & Astrophysics, submitted, A&A LaTex, 7 pages, 3 figures, also available at this URL

Odna iz celei nauchnogo podhoda - opisanie nablyudaemyh yavlenii s tochki zreniya naibolee obshego (edinogo ) podhoda. Otsyuda poiski "teorii vsego", "Velikoe ob'ekdinenie" i t.d. Pohozhie veshi proishodyat vo vseh oblastyah nauki. V astronomii, naprimer, pytayutsya ob'yasnit' aktivnost' galaktik raznyh tipov v terminah evolyucionnyh stadii sverhmassivnyh chernyh dyr.

Akkreciruyushie chernye dyry vstrechayutsya ne tol'ko v yadrah galaktik. Est' takie ob'ekty v tesnyh dvoinyh sistemah. Po vsei vidimosti est' chernye dyry promezhutochnyh mass. Dolzhny byt' odinochnye chernye dyry, akkreciruyushie veshestvo mezhzvezdnoi sredy... Processy dolzhny byt' v kakoi-to stepeni pohozhi (o raznyh tipah chernyh dyr sm., naprimer, obzory Cherepashuka v UFN). V dannoi stat'e avtory predstavlyayut popytku edinogo opisaniya razlichnyh ob'ektov, soderzhashih akkreciruyushie chernye dyry, ch'ya svetimost' sushestvenno men'she eddingtonovskoi. Raznica v tom, chto pri svetimosti poryadka eddingtonovskoi dominiruet vklad diska, a pri sushestvenno men'shei svetimosti - neteplovoe izluchenie relyativistskogo dzheta. Kandidatov v takoe sostoyanie mnogo: ot tesnyh dvoinyh do aktivnyh i neaktivnyh yader galaktik.

Osnovnye predpolozheniya avtorov svodyatsya k tomu, chto
dzhet vsegda prisutstvuet,
pri nekotorom tempe akkrecii (menee neskol'kih procentov ot eddingtonovskogo) disk perestaet byt' sushestvennym istochnikom izlucheniya,
esli my smotrim "v zherlo", to vklad dzheta bol'she vklada diska.

Sravnenie s nablyudeniyami pokazyvaet rabotosposobnost' modeli, odnako yasno, chto ona nuzhdaetsya v dal'neishem razvitii i novyh proverkah, poskol'ku ochevidno, chto real'nost' ustroena neskol'ko slozhnee, chem prosto tonkii disk + dzhet.


Vypusk 38. 1-11 aprelya 2003

astro-ph/0304045 Psevdo-n'yutonovskii potencial dlya relyativistskogo akkrecionnogo diska vokrug vrashayushegosya central'nogo ob'ekta s tverdoi poverhnost'yu (Pseudo-Newtonion potential for the relativistic accretion disk around rotating central objects having hard surface)
Author: Shubhrangshu Ghosh
Commets: 8 pages, aa.cls style; Accepted for publication in Astronomy and Astrophysics (A&A)

Gravitacionnoe pole vokrug bystro vrashayusheisya neitronnoi ili strannoi zvezdy imeet bolee slozhnyi vid, dazhe chem pole Kerrovskoi chernoi dyry. Teper' mozhno ne reshat' uravneniya Einshteina, a vospol'zovat'sya formulami, vyvedennymi avtorom dannoi stat'i, kotorye pravil'no uchityvayut vse fizicheskie effekty. Esli, konechno, vas udovletvoryaet 10% tochnost'.


astro-ph/0304157 Global'noe reshenie dlya vyazkogo akkrecionnogo diska vokrug vrashayushihsya kompaktnyh ob'ektov: psevdo-relyativistskii podhod (Global solution of viscous accretion disk around rotating compact objects: a pseudo-general-relativistic study)
Author: Banibrata Mukhopadhyay and Shubhrangshu Ghosh
Commets: 25 pages including 5 figures; to appear in MNRAS
astro-ph/0304157 Global'noe reshenie dlya vyazkogo akkrecionnogo diska vokrug vrashayushihsya kompaktnyh ob'ektov: psevdo-relyativistskii podhod (Global solution of viscous accretion disk around rotating compact objects: a pseudo-general-relativistic study)
Author: Banibrata Mukhopadhyay and Shubhrangshu Ghosh
Commets: 25 pages including 5 figures; to appear in MNRAS

Reshat' zadachi akkrecii neposredstvenno v ramkah OTO dostatochno tyazhelo. Poetomu vmesto iskrivlennogo prostranstva mozhno popytat'sya vvesti psevdo-N'yutonovskii potencial v kotorom dvizhenie chastic opisyvaetsya pravil'no. Eto udaetsya sdelat' dlya Shvarcshil'dovskogo gravitacionnogo polya, kotoroe sushestvuet vokrug nevrashayushihsya neitronnyh zvezd i chernyh dyr. Dlya vrashayushihsya ob'ektov oboitis' odnim potencialom ne udaetsya. Avtory podrobno rassmatrivayut kak edinym obrazom mozhno vvesti takie potencialy i v kakih sluchayah dannyh podhod rabotaet. Eta stat'ya dopolnyaet vyshedshuyu v proshlom mesyace:


(Arhiv Akkreciya:
v.2, 2004, v.1, 2002-2003)

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