scholarly journals Long-term X-ray variability of the symbiotic system RT Cru based on Chandra spectroscopy

2020 ◽  
Vol 500 (4) ◽  
pp. 4801-4817
Author(s):  
A Danehkar ◽  
M Karovska ◽  
J J Drake ◽  
V L Kashyap
Keyword(s):  
High Resolution ◽  
Thermal Plasma ◽  
High Energy ◽  
Accretion Disc ◽  
Energy Transmission ◽  
Imaging Spectrometer ◽  
Ccd Imaging ◽  
X Ray ◽  
Transmission Grating ◽  
Absorbing Material

ABSTRACT RT Cru belongs to the rare class of hard X-ray emitting symbiotics, whose origin is not yet fully understood. In this work, we have conducted a detailed spectroscopic analysis of X-ray emission from RT Cru based on observations taken by the Chandra Observatory using the Low Energy Transmission Grating (LETG) on the High-Resolution Camera Spectrometer (HRC-S) in 2015 and the High Energy Transmission Grating (HETG) on the Advanced CCD Imaging Spectrometer S-array (ACIS-S) in 2005. Our thermal plasma modelling of the time-averaged HRC-S/LETG spectrum suggests a mean temperature of kT ∼ 1.3 keV, whereas kT ∼ 9.6 keV according to the time-averaged ACIS-S/HETG. The soft thermal plasma emission component (∼1.3 keV) found in the HRC-S is heavily obscured by dense materials (>5 × 1023 cm−2). The aperiodic variability seen in its light curves could be due to changes in either absorbing material covering the hard X-ray source or intrinsic emission mechanism in the inner layers of the accretion disc. To understand the variability, we extracted the spectra in the ‘low/hard’ and ‘high/soft’ spectral states, which indicated higher plasma temperatures in the low/hard states of both the ACIS-S and HRC-S. The source also has a fluorescent iron emission line at 6.4 keV, likely emitted from reflection off an accretion disc or dense absorber, which was twice as bright in the HRC-S epoch compared to the ACIS-S. The soft thermal component identified in the HRC-S might be an indication of a jet that deserves further evaluations using high-resolution imaging observations.

High-resolution x-ray studies of an AXAF high-energy transmission grating

1994 ◽  
Author(s):  
Salim Abdali ◽  
Finn E. Christensen ◽  
Herbert W. Schnopper ◽  
Thomas H. Markert ◽  
Daniel Dewey ◽  
...  
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating

High-Resolution X-Ray Spectra of Capella: Initial Results from the [ITAL]Chandra[/ITAL] High-Energy Transmission Grating Spectrometer

2000 ◽  
Vol 539 (1) ◽  
pp. L41-L44 ◽  
Author(s):  
C. R. Canizares ◽  
D. P. Huenemoerder ◽  
D. S. Davis ◽  
D. Dewey ◽  
K. A. Flanagan ◽  
...  
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating ◽  
Grating Spectrometer ◽  
Initial Results

High-Resolution Spectroscopy of the X-Ray–photoionized Wind in Cygnus X-3 with the [ITAL]Chandra[/ITAL] High-Energy Transmission Grating Spectrometer

2000 ◽  
Vol 533 (2) ◽  
pp. L135-L138 ◽  
Author(s):  
Frits Paerels ◽  
Jean Cottam ◽  
Masao Sako ◽  
Duane A. Liedahl ◽  
A. C. Brinkman ◽  
...  
Keyword(s):  
High Resolution ◽  
High Energy ◽  
High Resolution Spectroscopy ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating ◽  
Grating Spectrometer

The [ITAL]Chandra[/ITAL] High-Energy Transmission Grating Observation of an X-Ray Ionization Cone in Markarian 3

2000 ◽  
Vol 543 (2) ◽  
pp. L115-L118 ◽  
Author(s):  
Masao Sako ◽  
Steven M. Kahn ◽  
Frits Paerels ◽  
Duane A. Liedahl
Keyword(s):  
High Energy ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating

High-Energy Transmission Grating Spectrometer for the Advanced X-ray Astrophysics Facility (AXAF)

1994 ◽  
Author(s):  
Thomas H. Markert ◽  
Claude R. Canizares ◽  
Daniel Dewey ◽  
Michael McGuirk ◽  
Chris S. Pak ◽  
...  
Keyword(s):  
High Energy ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating ◽  
Grating Spectrometer

Discovery of Narrow X-Ray Absorption Lines from NGC 3783 with the [ITAL]Chandra[/ITAL] High Energy Transmission Grating Spectrometer

2000 ◽  
Vol 535 (1) ◽  
pp. L17-L20 ◽  
Author(s):  
Shai Kaspi ◽  
W. N. Brandt ◽  
Hagai Netzer ◽  
Rita Sambruna ◽  
George Chartas ◽  
...  
Keyword(s):  
High Energy ◽  
Absorption Lines ◽  
Energy Transmission ◽  
X Ray ◽  
Transmission Grating ◽  
Grating Spectrometer ◽  
X Ray Absorption

scholarly journals To be or not to be: the case of the hot WHIM absorption in the blazar PKS 2155–304 sight line

2019 ◽  
Vol 621 ◽  
pp. A88 ◽  
Author(s):  
J. Nevalainen ◽  
E. Tempel ◽  
J. Ahoranta ◽  
L. J. Liivamägi ◽  
M. Bonamente ◽  
...  
Keyword(s):  
Absorption Line ◽  
Imaging Spectrometer ◽  
Transient Event ◽  
Ccd Imaging ◽  
X Ray ◽  
Lyman Alpha ◽  
Transmission Grating ◽  
Upper Limits ◽  
Far Ultraviolet

The cosmological missing baryons at z <  1 most likely hide in the hot (T ≳ 105.5 K) phase of the warm hot intergalactic medium (WHIM). While the hot WHIM is hard to detect due to its high ionisation level, the warm (T ≲ 105.5 K) phase of the WHIM has been very robustly detected in the far-ultraviolet (FUV) band. We adopted the assumption that the hot and warm WHIM phases are co-located and therefore used the FUV-detected warm WHIM as a tracer for the cosmologically interesting hot WHIM. We performed an X-ray follow-up in the sight line of the blazar PKS 2155–304 at the redshifts where previous FUV measurements of O VI, Si IV, and broad Lyman-alpha (BLA) absorption have indicated the existence of the warm WHIM. We looked for the O VII Heα and O VIII Lyα absorption lines, the most likely hot WHIM tracers. Despite the very large exposure time (≈1 Ms), the Reflection Grating Spectrometer unit 1 (RGS1) on-board XMM-Newton data yielded no significant detection which corresponds to upper limits of log N(O VII(cm−2)) ≤ 14.5−15.2 and log N(O VIII(cm−2)) ≤ 14.5−15.2. An analysis of the data obtained with the combination of the Low Energy Transmission Grating (LETG) and the High Resolution Camera (HRC) on-board Chandra yielded consistent results. However, the data obtained with the LETG, combined with the Advanced CCD Imaging Spectrometer (ACIS) lead to the detection of an feature resembling an absorption line at λ ≈ 20 Å at simple one-parameter confidence level of 3.7σ, consistent with several earlier LETG/ACIS reports. Given the high statistical quality of the RGS1 data, the possibility of RGS1 accidentally missing the true line at λ ∼ 20 Å is very low: 0.006%. Neglecting this, the LETG/ACIS detection can be interpreted as Lyα transition of O VIII at one of the redshifts (z ≈ 0.054) of FUV-detected warm WHIM. Given the very convincing X-ray spectral evidence for and against the existence of the λ ∼ 20 Å feature, we cannot conclude whether or not it is a true astrophysical absorption line. Considering cosmological simulations, the probability of the LETG/ACIS λ ∼ 20 Å feature being due to the astrophysical O VIII absorber co-located with the FUV-detected O VI absorber is at the very low level of ≲0.1%. We cannot completely rule out the very unlikely possibility that the LETG/ACIS 20 Å feature is due to a transient event located close to the blazar.

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