ATTENZIONE! IL REPOSITORY E’ APERTO ESCLUSIVAMENTE ALL’IMMISSIONE DEI RAPPORTI TECNICI (COLLEZIONE 4.01). NON E’ POSSIBILE INSERIRE PRODOTTI IN TUTTE LE ALTRE COLLEZIONI, A CAUSA DI PROBLEMI TECNICI. THE REPOSITORY IS OPEN EXCLUSIVELY FOR THE SUBMISSION OF TECHNICAL REPORTS (COLLECTION 4.01). SUBMISSIONS TO ALL OTHER COLLECTIONS ARE TEMPORARILY UNAVAILABLE, DUE TO TECHNICAL ISSUES.
 

NuSTAR + XMM-Newton monitoring of the neutron star transient AX J1745.6-2901

Journal
Date Issued
2018
Author(s)
•
Bianchi, S.
•
Muñoz-Darias, T.
•
Mori, K.
•
De, K.
•
Rau, A.
•
De Marco, B.
•
Hailey, C.
•
Tomsick, J.
•
Madsen, K. K.
•
Clavel, M.
•
Rahoui, F.
•
Lal, D. V.
•
Roy, S.
•
Stern, D.
DOI
Abstract
AX J1745.6-2901 is a high-inclination (eclipsing) transient neutron star (NS) low-mass X-ray binary showcasing intense ionized Fe K absorption. We present here the analysis of 11 XMM-Newton and 15 NuSTAR new data sets (obtained between 2013 and 2016), therefore tripling the number of observations of AX J1745.6-2901 in outburst. Thanks to simultaneous XMM-Newton and NuSTAR spectra, we greatly improve on the fitting of the X-ray continuum. During the soft state, the emission can be described by a disc blackbody (kT ∼ 1.1-1.2 keV and inner disc radius rDBB ∼ 14 km), plus hot (kT ∼ 2.2-3.0 keV) blackbody radiation with a small emitting radius (rBB ∼ 0.5 - 0.8 km) likely associated with the boundary layer or NS surface, plus a faint Comptonization component. Imprinted on the spectra are clear absorption features created by both neutral and ionized matter. Additionally, positive residuals suggestive of an emission Fe K α disc line and consistent with relativistic ionized reflection are present during the soft state, while such residuals are not significant during the hard state. The hard-state spectra are characterized by a hard (Γ ∼ 1.9-2.1) power law, showing no evidence for a high energy cut-off (kTe > 60-140 keV) and implying a small optical depth (τ < 1.6). The new observations confirm the previously witnessed trend of exhibiting strong Fe K absorption in the soft state that significantly weakens during the hard state. Optical (GROND) and radio (GMRT) observations suggest for AX J1745.6-2901 a standard broad-band spectral energy distribution as typically observed in accreting NSs.
Volume
473
Issue
2
Start page
2304
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2018MNRAS.473.2304P
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

stx2425.pdf

Description
pdf editoriale
Size

3.05 MB

Format

Adobe PDF

Checksum (MD5)

dae70c8bcbd0bd426f4b954dea6f3bb7

Loading...
Thumbnail Image
Name

1709.06571.pdf

Description
preprint
Size

2.43 MB

Format

Adobe PDF

Checksum (MD5)

098da5e81bb5809eae0728e5bc29214e