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30.08.02. astro-ph za 22 avgusta - 30 avgusta 2002 goda: izbrannye stat'i | ||||
Dlya kazhdogo tipa astronomicheskih istochnikov sushestvuet svoi podhod: kakie-to obychno otkryvayutsya v vidimom diapazone, kakie-to v UF, kakie-to v IK i t.d. Poetomu, kogda naprimer ob'ekt, obychno naibolee yarko proyavlyayushiisya v radiodiapazone otkryvayut v gamma, to eto sobytie, dostoinoe vnimaniya. Kataklizmicheskie peremennye (eto dvoinye sistemy s belym karlikom) obychno otkryvayut v optike, inogda v rentgene (osobenno teper' pri glubokih nablyudeniyah sharovyh skoplenii na Chandre). A vot istochnik J102347.6+003841 otkryli v radio! Voobshe-to radioaktivnost' (ne v smysle yadernoi fiziki) kataklizmikov vesh' izvestnaya: neskol'ko izvestnyh dvoinyh etogo tipa uzhe nablyudalis' v radio. No vot chtoby otkryt'... eto vpervye. Istochnik zametili vo vremya vspyshki. Prichem bol'she s nim takoe poka ne povtoryalos'. Poka neyasno: to li eto istochnik redkogo tipa, to li prosto sluchilas' takaya redkaya sil'naya radiovspyshka. Tak chto nuzhny novye nablyudeniya, chem avtory i sobirayutsya zanyat'sya.
Authors: V.V. Flambaum Comments: 2 pages, RevTex V poslednee vremya intensivno obsuzhdaetsya vopros o vozmozhnom izmenenii vazhnyh fizicheskih konstant (v pervuyu ochered' postoyannoi tonkoi struktury) so vremenem. Nelishne otmetit', chto v nashei strane etimi issledovaniyami aktivno zanimalas' i zanimaetsya gruppa Varshalovicha v FTI im. Ioffe. Postoyannaya tonkoi struktury vybrana nesluchaino. Ee evolyuciyu legko nablyudat' po spektram dalekih vnegalakticheskih ob'ektov (naprimer, kvazarov). Odnako, kak izvestno, v formulu postoyannoi vhodit elementarnyi zaryad, skorost' sveta i postoyannaya Planka. V svyazi s etim obsuzhdaetsya problema "a chto zhe sobstvenno-to izmenyaetsya?" Kto-to govorit, chto izmenyat'sya mogut tol'ko bezrazmernye velichiny, a ostal'noe - ot lukavogo. Kto-to, chto izmenenie elementarnogo zaryada povlechet za soboi umen'shenie entropii chernyh dyr, chto zapresheno (Davies et al. Nature 418). Vot s etoi poslednei tochkoi zreniya i sporit v svoei zametke Flambaum. Ego vyvod takov: model'no-nezavisimye teoreticheskie rassuzhdeniya pro chernye dyry ne mogut dat' nikakih ogranichenii na vozmozhnuyu variaciyu fundamental'nyh konstant.
Authors: Vincent Tatischeff Comments: 46 pages including 16 figures, uses eas.cls, to appear in the proceedings of the Aussois 2001 summer school "Stades Ultimes de l'Evolution Stellaire", EAS Pub. Series V lekciyah opisyvayutsya razlichnye mehanizmy izlucheniya v liniyah v zhestkom diapazone (izluchenie goryachei plazmy, radioaktiyni raspad, annigilyaciya). Svoistva izlucheniya zatem obsuzhdayutsya v svete registracii na sovremennyh sputnikah. Navernoe seichas eto osobenno aktual'no v svyazi s gryadushim zapuskom sputnika Integral, 25 procentov nablyudatel'nogo vremeni kotorogo prinadlezhit Rossii.
Authors: Ronald A. Remillard et al. Comments: 11 pages, 5 figs.; Procs. of the 4th Microquasar Workshop, 2002, eds. Durouchoux, Fuchs, & Rodriguez, (Center for Physics: Kolkata) V rentgenovskom diapazone (da i ne tol'ko v nem) sushestvuyut slozhnosti s opredeleniem parametrov istochnikov. Banal'nyi primer. Na Zemle my izmeryaem potok, no chotby poluchit' svetimost' neobhodimo tochno znat' rasstoyanie, a ono chasto izvestno ploho ili ochen' ploho. Est' problemu so spektrami, osobenno s osobennostyami (liniyami). Spektry chasto okazyvayutsya model'nozavisimymi. I lish' vremennye harakteristiki izmeryayutsya tochno. Poetomu ih vse tak lyubyat. Samye prostye istochniki v etom smysle - rentgenovskie pul'sary. Period pul'sacii - period vrasheniya neitronnoi zvezdy. No est' i vsyakie drugie "zveri", naprimer istochniki s t.n. kvaziperiodicheskimi oscillyaciyami (KPO).
Authors: David R. Smith, Neal Weiner Comments: 4 pages; to appear in the proceedings of 5th International UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe (DM 2002), Marina del Rey, California, 20-22 Feb 2002 Eksperiment DAMA v 2000 g. (Phys. Lett. B 480, 23) zayavil o vozmozhnom obnaruzhenii godichnoi modulyacii signala, kotoraya mozhet svidetel'stvovat' o registracii ustanovkoi chastic temnoi materii (slabovzaimodeistvuyushih massivnyh chastic). Pri etom drugoi eksperiment, CDMS, zayavil ob otsutstvii signala. Avtory stat'i pytayutsya naiti reshenie, pri kotorom dannye obeih ustanovok sovmetimy drug s drugom (pri etom, razumeetsya, DAMA prosto "vidit" chasticy, a CDMS - net, tak chto mozhno rassmatrivat' stat'yu kak popytku spasti reputaciyu Damy).
Authors: S.Mineshige, T.Hosokawa, M.Machida, R.Matsumoto Comments: To appear in PASJ, 15 pages, 2 figures Voobshe govorya, kogda vy stryahivaete gradusnik, to ruka (i gradusnik) izluchayut gravvolny. Tol'ko ochen' slabye (pro gravvolny voobshe i v astrofizike v chastnosti sm., naprimer, stat'yu V.M. Lipunova, a na bolee ser'eznom urovne obzor Grishuka i dr. v UFN ili v astro-ph). V svyazi s vvedeniem v stroi gravdetektorov teoretiki burno obsuzhdayut, chto vo Vselennoi mozhet izluchat' dostatochno sil'nye gravvolny. V dannoi stat'e avtory rassmatrivayut akkrecionnye diski kak vozmozhnye istochniki gravizlucheniya.
Authors: Alice K. Harding Comments: 10 pages, invited paper at XXXVIIth Rencontres de Moriond "The Gamma-Ray Universe", March 9-16, 2002, Les Arcs, France My znaem o neitronnyh zvezdah ochen' mnogo - my znaem o neitronnyh zvezdah ochen' malo. V nastoyashii moment bOl'shaya chast' nablyudaemyh neitronnyh zvezd - radiopul'sary. Odnako, etim vse ne ischerpyvaetsya. Est' samye raznye tipy neitronnyh zvezd. I daleko ne vse iz nih horosho izucheny. Est' nebol'shaya gruppa ob'ektov (7+4 kandidata): neitronnye zvezdy nablyudayushiesya v gamma-diapazone. O nih i rasskazyvaetsya v obsuzhdaemom obzore. Vse sem' istochnikov i chetyre kandidata, obsuzhdaemye v stat'e, yavlyayutsya bolee-menee obychnymi radiopul'sarami. Avtor rassmatrivaet razlichnye mehanizmy izlucheniya, kotorye mogut byt' otvetstvennymi za gamma-izluchenie neitronnyh zvezd. Krome togo rassmatrivayutsya radiotihie neitronnye zvezdy, a takzhe neotozhdestvlennye gamma-istochniki. Ozhidaetsya, chto novye sputniki (GLAST i dr.) smogut uvidet' v gamma-diapazone neskol'ko desyatkov radiopul'sarov.
Authors: Ian Smail et al. Comments: 19 pages, 7 figures, ApJ in press V dannoi stat'e pod ekstremal'no krasnymi ob'ektami (EKO) podrazumevayutsya dalekie galaktiki, kotorye mogut byt' stol' krasnymi kak iz-za pogloshayushei pyli, tak i iz-za obiliya staryh krasnyh zvezd. Avtory stat'i pytayutsya razdelit' eti dve populyacii po nablyudeniyam v raznyh diapazonah (v osobennosti po radionablyudeniyam). Bolee 30 procentov iz vsei vyborki (68 ob'ektov) okazalis' zapylennymi galaktikami s moshnym zvezdoobrazovaniem, vozmozhno, eto chislo dohodit do 75 procentov (sm. takzhe astro-ph/0208486).
Authors: Jonathan Arons Comments: 38 pages, 1 Figure, LaTeX (aastex, epsfig, graphicx, float), submitted to ApJ Avtor pokazyvaet, chto relyativistskii veter ot molodyh magnitarov (trebuetsya pole bol'she 1015 Gauss i period vrasheniya poryadka millisekundy) mozhet uskoryat' chasticy do 1021 eV. Poluchaemyi spektr nahoditsya v grubom sootvetstvii s nablyudaemym u kosmicheskih luchei sverhvysokih energii. Dlya menya ostalos' ne ochen' ponyatnym, kak avtor reshaet problemu otsutstviya korrelyacii kosmicheskih luchei sverhvysokih energii s blizkimi galaktikami.
Authors: Jonathan Mackey, Volker Bromm, Lars Hernquist Comments: 11 pages, 5 figures, submitted to ApJ My ne znaem kogda nachali obrazovyvat'sya pervye zvezdy i kakimi oni byli. Takie ob'ekty nazyvayut zvezdami populyacii III (Pop III). Oni dolzhny byli poyavit'sya na z=10-20. Pri etom izluchenie massivnyh zvezd, a takzhe vzryvy pervyh sverhnovyh dolzhny byli okazat' sushestvennoe vliyanie na zhizn' molodoi vselennoi. Analogov massivnyh zvezd Pop III my seichas ne vidim, t.k. rodivshiesya milliardy let nazad uzhe davno vzorvalis' (napomnyu, chto vremya zhizni massivnyh zvezd ischislyaetsya vsego lish' millionami let), a seichas takie zvezdy ne obrazuyutsya, t.k. mezhzvezdnaya sreda sushestvenno obogashena tyazhelymi elementami v otlichii ot sredy na z=10-20, kogda byli tol'ko vodorod da gelii. Avtory issleduyut zvezdy Pop III i delayut predskazaniya dlya nablyudeniya na kosmicheskom teleskope novogo pokoleniya (Next Generation Space Telescope (NGST)). Takzhe avtory vvodyat novuyu sushnost': zvezdy Pop II.5. Eti zvezdy ne ochen' massivny, i mogli dozhit' v galo nashei Galaktiki do segodnyashnih dnei.
Authors: Janusz Zi\'o{\l}kowski Comments: 6 pages, 1 figure; review presented at Vulcano Workshop: "Multifrequency Behaviour of High Energy Cosmic Sources" (Vulcano, May 21-26, 2001). To be published in Memorie della Societa Astronomica Italiana, 2002 Daetsya obzor tesnyh dvoinyh sistem s Be-zvezdami. Eto massivnye zvezdy s emissionnymi liniyami, chto svyazano s ih bystrym vrasheniem vokrug svoei osi. Pri etom obrauetsya istekayushii disk. Vtorym kompan'onom kak pravilo yavlyaetsya neitronnaya zvezda. Sistemy nablyudayutsya v rentgenovskom diapazone kak tranzientnye istochniki.
Authors: G.F. Marranghello, C.A.Z. Vasconcellos, J.A. de Freitas Pacheco Comments: revtex4, accepted for publication in Phys. Rev. D, 6 pages + figures Kvarkovye vnutrennosti u neitronnyh zvezd voznikayut v rezul'tate fazovogo perehoda. Avtory issleduyut, mozhno li zaregistrirovat' gravitacionno-volnovoi signal ot takogo processa. Predskazaniya okazyvayutsya ne ochen' optimistichnymi. Pervaya ochered' detektorov smozhet registrirovat' signal tol'ko ot galaktik Mestnoi gruppy. I dazhe vtoraya ochered' ne smozhet dotyanut'sya do skopleniya v Deve.
Authors: C. Boehm, T.A. Ensslin, J. Silk Comments: 4 pages. No figure Avtory issleduyut v kakom diapazone mogut nahodit'sya massy chastic temnoi materii. Krome tradicionnyh bol'shih znachenii dlya WIMP (slabovzaimodeistvuyushie massivnye chasticy), avtory predlagayut diapazon ot neskol'kih MeV do 10 GeV.
Authors: Michael Endl et al. Comments: pages, 3 figures, to appear in Conference Proceedings "Scientific Frontiers in Research on Extrasolar Planets", Drake Deming (ed) Obsuzhdaetsya vozmozhnost' obnaruzheniya planet zemnogo tipa u blizkih zvezd. Pokazano, chto esli by u Proksimy Centavra byli takie planety v "obitaemoi" zone, to ih by uzhe obnaruzhili (krome sluchaev malen'kih uglov naklona ploskosti orbity planety k luchu zreniya). Takzhe poyavilas' stat'ya Vol'fa i dr. astro-ph/0208461, posvyashennaya vozmozhnosti obnaruzheniya planet-gigantov v okolozvezdnyh diskah po nablyudeniyam v IK i submillimetrovoi oblasti.
Authors: Duncan K. Galloway et al. Comments: 13 pages, 7 figures, submitted to ApJ Odna iz vazhnyh zadach v astronomii - poisk t.n. "standartnyh svechei". Esli vy uvereny v svetimosti ob'ekta, to, znaya potok na Zemle, mozhno opredelit' rasstoyanie. V dannoi stat'e avtory predlagayut ispol'zovat' rentgenovsike barstery v kachestve standartnyh svechei. Na primere istochnika 4U 1728-34 Gellouei i dr. popytalis' opredelit' "standart", i po ih slovam eto udalos' sdelat' s 3-h procentnoi tochnost'yu. Edinstvennoi sushestvennoi neopredelennost'yu, po mneniyu avtorov, okazalas' neizvestnaya massa neitronnoi zvezdy. K schast'yu, diapazon etot ne velik, i ocenka rasstoyaniya do istochnika s uchetom neopredelennostei okazavaetsya ravnoi 5.2-5.6 kpk.
Authors: W. Becker, B. Aschenbach Comments: 23 pages, 22 figures, 4 tables. To appear in the Proceedings of the 270.WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants, Jan 21-25, Physikzentrum Bad Honnef, eds W. Becker, H. Lesch & J. Truemper. Proceedings available as MPE-Report 278. The paper with high resolution images can be obtained from ftp://ftp.xray.mpe.mpg.de/people/web/Becker_Aschenbach.pdf Dan obzor nablyudenii neitronnyh zvezd i pul'sarov na sputnike HMM-N'yuton.
astro-ph/0208475 Chandra X-ray Observation of the Orion Nebula Cluster. Authors: E. Flaccomio et al. Comments: 36 pages, 10 figures; to be published in ApJ; for online tables see http://www.astropa.unipa.it/~ettoref (astro-ph/0208474) 31 pages, 17 figures; to be published in ApJ ((astro-ph/0208475) V dvuh stat'yah opisyvayutsya rezul'taty rentgenovskih nablyudenii zvezdnogo skopleniya v tumannosti Oriona na sputnike Chandra. Zaregistrirovano 742 istochnika. V osnovnom eto malomassivnye zvezdy.
Authors: Bradley E. Schaefer, Suzanne W. Tourtellotte Comments: 13 pages, 2 figures, submitted to Icarus Zagadki v nauke byvayut raznye. Est' "velikie zagadki", vekami muchayushie lyudei ("chto bylo, kogda nichego ne bylo). Est' "zhguchie tainy" (kak gamma-vspleski), vozmozhno oni ne imeyut superfundamental'nogo znacheniya, no sotni issledovatelei imi zanimayutsya, vse o nih znayut. Est' "klyuchevye problemy" (naprimer, chto takoe temnaya materiya). A est' malen'kie interesnye tainy, i tut est' chem razvlech' "malen'kie serye kletochki". Nereida - sputnik Neptuna. Iz-za ee neobychnoi orbity polagayut, chto eto zahvachennyi ob'ekt poyasa Koipera. Taina Nereidy takova: nablyudayutsya haoticheskie izmeneniya ee bleska na raznyh masshtabah. Ideyu o haoticheskom vrashenii prishlos' otbrosit', t.k. harakternoe vremya dolzhno byt' ne menee dvuh nedel'. Avtory predstavlyayut detal'nuyu krivuyu bleska Nereidy. Nu a prichiny peremennosti tak i ostayutsya neyasnymi....
Authors: Scott A. Hughes, Roger D. Blandford Comments: 4 pages, 1 figure, submitted to ApJLetters V astrofizike sverhmassivnyh chernyh dyr est' eshe ochen' mnogo voprosov. Neizvestno kak oni obrazuyutsya, kak evolyucioniruyut. Odna iz vozmozhnostei rosta chernyh dyr - sliyaniya galaktik, v centrah kotoryh uzhe est' chernye dyry. Avtory issleduyut kak pri etom izmenyaetsya vrashenie chernyh dyr. Okazyvaetsya, chto v srednem chernye dyry posle sliyanii zamedlyayutsya. Dlya uskoreniya vrasheniya nuzhno sochetanie dovol'no redkih parametrov. Nablyudeniya zhe ukazyvayut, chto mnogie sverhmassivnye chernye dyry dovol'no bystro vrashayutsya. Esli eto deistvitel'no tak, to eto mozhet nakladyvat' vazhnye ogranicheniya na rol' sliyanii v roste massy chernyh dyr v centrah galaktik.
Authors: Peter Goldreich, Yoram Lithwick, Re'em Sari Zametnaya dolya ob'ektov poyasa Koipera yavlyaetsya dvoinymi. V stat'e avtory rassmatrivayut mehanizm obrazovaniya takih sistem. Naibolee mnogoobeshayushim mehanizmom yavlyaetsya besstolknovitel'nyi. Na pervom etape obrazuetsya vremennaya para iz dvuh massivnyh tel posle togo kak kazhdoe popalo v sferu Hilla partnera. Zatem nuzhno kak-to izbavit'sya ot lishnei energii. Eto mozhno sdelat' za schet tret'ego massivnogo tela ili za schet neskol'kih malomassivnyh. Avtory sravnivayut razlichnye mehanizmy i dayut chislennye ocenki parametrov sistem v poyase Koipera.
Authors: B. Aschenbach Comments: 13 pages, 18 figures. To appear in the Proceedings of the 270. WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants, Jan. 21-25, 2002, Physikzentrum Bad Honnef, eds W. Becker, H. Lesch & J. Truemper. Proceedings are available as MPE-Report 278 astro-ph/0208498 Radio Observations of Supernova Remnants Authors: W. Reich (MPIfR) Comments: 12 pages, 15 figures. To appear in the Proceedings of the 270. WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants, Jan. 21-25, 2002, Physikzentrum Bad Honnef, eds W. Becker, H. Lesch & J. Truemper. Proceedings are available as MPE-Report 278
Authors: A.O. Petters Comments: 8 pages, 4 figures Odinochnye chernye dyry mozhno obnaruzhivat' po effektu mikrolinzirovaniya (sm. Agol i dr. 2002 astro-ph/0203257). Odnako, v etom sluchae tradicionnye formuly mikrolinzirovaniya (vypisyvaemye dlya ob'ektov tipa obychnyh zvezd ili planet) nuzhdayutsya v utochnenii. Petters rassmatrivaet relyativistskie popravki dlya mikrolinzirovaniya na chernyh dyrah.
Authors: F.W. Stecker Comments: Text of Lectures for the D. Chalonge International School of Astrophysics - 9th Course of Astrofundamental Physics, Palermo, Sept. 2002, to be published in the proceedings, 49 pages with 17 ps figures Daetsya obzor nedavnih dostizhenii v astrofizike kosmicheskih luchei vysokih energii. Osoboe vnimanie udelyaetsya vysokoenergichnym neitrino.
Authors: Eric V. Linder Comments: 4 pages, 3 figures, submitted to Phys. Rev. Letters Naskol'ko horosho po imeyushimsya nablyudatel'nym dannym mozhno razlichit' kosmologicheskie modeli? Imenno eto yavlyaetsya temoi korotkoi stat'i Erika Lindera. Osobye nadezhdy on vozlagaet na sleduyushee pokolenie obzorov sverhnovyh tipa Ia (oni "propishut" Vselennuyu do z=1.7). Sm. takzhe ob etoi rabote v kosmologicheskih obzorah Sergeya Pavlyuchenko.
Authors: Antoine Letessier-Selvon Comments: 6 pages, 6 figures, 1 table. Talk given at the neutrino 2002 conference. To be published in Nuclear Physics B (Proceedings Supplement) Ozhidanie lyubogo krupnogo nablyudatel'nogo proekta soprovozhdaetsya mnozhestvom statei na temu "chto zhe my uvidim, i kak eto budet zdorovo!". Proekt Ozhe (Auger) zdes' ne isklyuchenie. V svoei stat'e avtor rassuzhdaet o vozmozhnostyah registracii neitrino sverhvysokih energii (1018 eV). Predskazyvaetsya, chto v blizhaishie 5 let takie chasticy budut zaregistrirovany.
Authors: Marco Lombardi Comments: 14 pages, 4 figures, A&A in press Dovol'no special'naya stat'ya, posvyashennaya interpolyacii i sglazhivaniyu (v pervuyu ochered' v astronomicheskih primeneniyah). Odnako, pri etom stat'ya interesna ne tol'ko astronomam, a vsem, komu prihodit'sya stalkivat'sya s sootvetstvuyushimi metodami v svoih issledovaniyah.
Authors: George B. Rybicki Comments: 26 pages, 5 figures, submitted to ApJ Daetsya novoe kineticheskoe uravnenie dlya komptonovskogo rasseyaniya (otlichnoe ot uravneniya Kompaneica). Pokazano, chto pri ispol'zovanii novogo uravneniya ne voznikaet bol'shih tehnicheskih trudnostei i pri etom daet bolee akkuratnye rezul'taty.
Authors: Massimo Stiavelli Comments: 14 pages, 10 figures. To appear in the proceedings of the SPIE conference 4835 "Future research directions and visions for astronomy" held in Waikaloa, HI on August 25-26, 2002, A. Dressler Ed. Needs spie.cls (included) Daetsya obzor po reionizacii Vselennoi, osobenno na vklade pervyh massivnyh zvezd maloi metallichnosti. Obsuzhdayutsya nablyudatel'nye perspektivy v etoi oblasti. Arhiv statei, voshedshih v predydushie vypuski.
Razdely arhiva (s iyulya 2002 g.): Poleznye astronomicheskie ssylki. Obzornye stat'i v astro-ph s 2001 g. |
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