scholarly journals Prospects for IXPE and eXTP polarimetric archaeology of the reflection nebulae in the Galactic center

2020 ◽  
Vol 643 ◽  
pp. A52
Author(s):  
L. Di Gesu ◽  
R. Ferrazzoli ◽  
I. Donnarumma ◽  
P. Soffitta ◽  
E. Costa ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Galactic Center ◽  
Region Of Interest ◽  
Polarization Degree ◽  
Polarization Angle ◽  
Diffuse Emission ◽  
X Ray ◽  
X Ray Imaging ◽  
Spread Function ◽  
Reflection Nebulae

The X-ray polarization properties of the reflection nebulae in the Galactic center inform us about the direction of the illuminating source (through the polarization angle) and the cloud position along the line of sight (through the polarization degree). However, the detected polarization degree is expected to be lowered because the polarized emission of the clouds is mixed with the unpolarized diffuse emission that permeates the Galactic center region. In a real observation, also the morphological smearing of the source due to the point spread function and the unpolarized instrumental background contribute in diluting the polarization degree. So far, these effects have never been included in the estimation of the dilution. We evaluate the detectability of the X-ray polarization predicted for the MC2, Bridge-B2, G0.11-0.11, Sgr B2, Sgr C1, Sgr C2, and Sgr C3 molecular clouds with modern X-ray imaging polarimeters such as the Imaging X-ray Polarimetry Explorer (IXPE), which is expected to launch in 2021, and the Enhanced X-ray Timing and Polarimetry mission (eXTP), whose launch is scheduled for 2027. We perform realistic simulations of X-ray polarimetric observations considering (with the aid of Chandra maps and spectra) the spatial, spectral, and polarization properties of all the diffuse emission and background components in each region of interest. We find that in the 4.0–8.0 keV band, where the emission of the molecular clouds outshines the other components, the dilution of the polarization degree, including the contribution due to the morphological smearing of the source, ranges between ~19% and ~55%. We conclude that for some distance values reported in the literature, the diluted polarization degree of G0.11-0.11, Sgr B2, Bridge-B2, Bridge-E, Sgr C1, and Sgr C3 may be detectable in a 2 Ms long IXPE observations. With the same exposure time, and considering the whole range of possible distances reported in the literature, the enhanced capabilities of eXTP may allow detecting the 4.0–8.0 keV of all the targets considered here.

scholarly journals Reflection nebulae in the Galactic center: soft X-ray imaging polarimetry

2015 ◽  
Vol 576 ◽  
pp. A19 ◽  
Author(s):  
F. Marin ◽  
F. Muleri ◽  
P. Soffitta ◽  
V. Karas ◽  
D. Kunneriath
Keyword(s):  
Galactic Center ◽  
X Ray ◽  
X Ray Imaging ◽  
Imaging Polarimetry ◽  
Reflection Nebulae

scholarly journals Warped disks during type II outbursts in Be/X-ray binaries: evidence from optical polarimetry

2018 ◽  
Vol 619 ◽  
pp. A19 ◽  
Author(s):  
P. Reig ◽  
D. Blinov
Keyword(s):  
Neutron Star ◽  
Structural Changes ◽  
Degree Of Polarization ◽  
Polarization Degree ◽  
Polarization Angle ◽  
Similar Amount ◽  
Type Ii ◽  
Line Profiles ◽  
X Ray ◽  
X Ray Binaries

Context. Current models that explain giant (type II) X-ray outbursts in Be/X-ray binaries (BeXB), are based on the idea of highly distorted disks. They are believed to occur when a misaligned and warped disk becomes eccentric, allowing the neutron star to capture a large amount of material. The BeXB 4U 0115+63 underwent two major outbursts in 2015 and 2017. Aims. Our aim is to investigate whether the structural changes in the disk expected during type II outbursts can be detected through optical polarimetry. Methods. We present the first optical polarimetric observations and new optical spectra of the BeXB 4U 0115+63 covering the period 2013–2017. We study in detail the shape of the Hα line profile and the polarization parameters before, during, and after the occurrence of a type II X-ray outburst. Results. We find significant changes in polarization degree and polarization angle and highly distorted line profiles during the 2017 X-ray outburst. The degree of polarization decreased by ∼1%, while the polarization angle, which is supposed to be related with the disk orientation, first increased by ∼10° in about two months and then decreased by a similar amount and on a similar timescale once the X-ray activity ceased. Conclusions. We interpret the polarimetric and spectroscopic variability as evidence for the presence of a warped disk.

scholarly journals X-ray polarimetry – A new Window on Black Hole Systems

2016 ◽  
Vol 12 (S324) ◽  
pp. 338-341
Author(s):  
René W. Goosmann
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Galactic Center ◽  
Galactic Nuclei ◽  
High Energy ◽  
X Ray ◽  
X Ray Imaging ◽  
History Of ◽  
Imaging Polarimetry ◽  
High Energy Emission

AbstractThree dedicated X-ray polarimetry mission projects are currently under phase A study at NASA and ESA. The need for this new observational window is more apparent than ever. On behalf of the consortium behind the X-ray Imaging Polarimetry Explorer (XIPE) we present here some prospects of X-ray polarimetry for our understanding of supermassive and stellar mass black hole systems. X-ray polarimetry is going to discriminate between leptonic and hadronic jet models in radio-loud active galactic nuclei. For leptonic jets it also puts important constraints on the origin of the seed photons that constitute the high energy emission via Comptonization. Another important application of X-ray polarimetry allows us to clarify the accretion history of the supermassive black hole at the Galactic Center. In a few Black Hole X-ray binary systems, X-ray polarimetry allows us to estimate in a new, independent way the angular momentum of the black hole.

scholarly journals Chandra observations of the X-ray emission from Molecular Clouds at the Galactic Center related to Sgr A* past activity

2013 ◽  
Author(s):  
Maica Clavel ◽  
Regis Terrier ◽  
Andrea Goldwurm ◽  
Mark Morris ◽  
G. Ponti ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Galactic Center ◽  
X Ray ◽  
Sgr A ◽  
Past Activity

TU-EE-A4-04: A New Antiscatter Grid for High-Resolution Region-Of-Interest (ROI) X-Ray Imaging

2007 ◽  
Vol 34 (6Part18) ◽  
pp. 2563-2563
Author(s):  
G Yadava ◽  
S Rudin ◽  
A Kuhls ◽  
D Bednarek
Keyword(s):  
High Resolution ◽  
Region Of Interest ◽  
X Ray ◽  
X Ray Imaging ◽  
Antiscatter Grid

scholarly journals NuSTARHARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

2015 ◽  
Vol 814 (2) ◽  
pp. 94 ◽  
Author(s):  
Kaya Mori ◽  
Charles J. Hailey ◽  
Roman Krivonos ◽  
Jaesub Hong ◽  
Gabriele Ponti ◽  
...  
Keyword(s):  
Galactic Center ◽  
Diffuse Emission ◽  
X Ray ◽  
Center Region ◽  
Region I

scholarly journals Can we infer the past activity of M31⋆ as we do for Sgr A⋆?

2016 ◽  
Vol 11 (S322) ◽  
pp. 253-256
Author(s):  
Maïca Clavel ◽  
Régis Terrier ◽  
Andrea Goldwurm ◽  
Mark R. Morris ◽  
Gabriele Ponti
Keyword(s):  
Black Holes ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Supermassive Black Holes ◽  
X Ray ◽  
The Past ◽  
Upper Limits ◽  
History Of ◽  
Sgr A ◽  
Past Activity

AbstractThe history of supermassive black holes’ activity can be partly constrained by monitoring the diffuse X-ray emission possibly created by the echoes of past events propagating through the molecular clouds of their respective environments. In particular, using this method we have demonstrated that our Galaxy’s supermassive black hole, Sgr A⋆, has experienced multiple periods of higher activity in the last centuries, likely due to several short but very energetic events, and we now investigate the possibility of studying the past activity of other supermassive black holes by applying the same method to M31⋆. We set strong constraints on putative phase transitions of this more distant galactic nucleus but the existence of short events such as the ones observed in the Galactic center cannot be assessed with the upper limits we derived.

scholarly journals The Hot Gas in the Galactic Bulge

1996 ◽  
Vol 169 ◽  
pp. 287-295
Author(s):  
K. Koyama ◽  
Y. Maeda
Keyword(s):  
Galactic Center ◽  
Remarkable Feature ◽  
Strong Emission ◽  
X Ray ◽  
Hot Gas ◽  
Bright Spots ◽  
X Ray Imaging ◽  
Soft Spectrum ◽  
Sgr A ◽  
Extended Emission

X-ray imaging spectroscopic observations near the Galactic center region were carried out with the ASCA satellite. We found two bright spots very close to the Galactic center (Sgr A∗); one is extended and has a soft spectrum associated with strong emission lines from highly ionized irons, while the other is a point-like object with a harder spectrum and a larger absorption. We also found extended emission with K-shell transition lines from highly ionized Si, S, Ar, Ca and Fe. Remarkable feature found with ASCA is an extended emission of 6.4 keV lines of low ionization irons. The 6.4 keV line fluxes are found to be well correlated to the region of cool clouds. We interpret that the 6.4 keV line is due to florescence from the cool clouds irradiated by strong (and obscured from our line of sight) X-ray beams.

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