BeppoSAX and RXTE spectral study of the low-mass X-ray binary 4U 1705-44. Spectral hardening during the banana branch

Seiﬁna, E.; Titarchuk, L.; Shrader, C.; Shaposhnikov, N.

Статья опубликована в высокорейтинговом журнале

Информация о цитировании статьи получена из Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 26 декабря 2015 г.

Авторы: Elena Seiﬁna, Lev Titarchuk, Chris Shrader, Nikolai Shaposhnikov
Журнал: Astrophysical Journal
Том: 808
Год издания: 2015
Издательство: University of Chicago Press
Местоположение издательства: United States
Первая страница: 142
Последняя страница: 158
DOI: 10.1088/0004-637X/808/2/142
Аннотация: We analyze the X-ray spectra of the atoll 4U 1705-44 when the source undergoes the island−banana state transition. We use the Rossi X-ray Timing Explorer (RXTE) and BeppoSAX observations for this analysis. We demonstrate that the broad-band energy spectral distributions for all evolutionary states can be ﬁtted by a model, consisting two Comptonized components. One arises from the seed photons coming from a neutron star (NS) atmosphere at a temperature kTs1<=1.5 keV (herein Comptb1) and a second resulting from the seed photons of Ts2 ∼1.1−1.3 keV coming from the disk (herein Comptb2). We found that we needed to add a low-temperature Blackbody and an iron-line (Gaussian) component to the model in order to obtain high quality ﬁts. The data analysis using this model indicates that the power-law photon index Γ1 of our model is always about 2, independently of the spectral state. Another parameter, Γ2 demonstrates a two-phase behavior depending on the spectral state. Γ2 is quasi-constant at Γ2 ∼ 2 when the electron temperature kTe(2) < 80 keV and Γ2 is less than 2, in the range of 1.3 < Γ2 < 2, when kTe(2) > 80 keV. This phase is similar to that was previously found in the Z-source Sco X-1. We interpret the decreasing index phase using a model in which a super-Eddington radiation pressure from the neutron star causes an expansion of the Compton cloud similar to that found previously in Sco X-1 during the Flaring branch.
Добавил в систему: Сейфина Елена Викторовна

	ИСТИНА	Войти в систему Регистрация
	ИСТИНА ИНХС РАН
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

ИСТИНА ИНХС РАН

BeppoSAX and RXTE spectral study of the low-mass X-ray binary 4U 1705-44. Spectral hardening during the banana branchстатья

Прикрепленные файлы