scholarly journals Extended X-ray emission from the classic nova DQ Her – on the possible presence of a magnetized jet

2020 ◽  
Vol 495 (4) ◽  
pp. 4372-4379
Author(s):  
J A Toalá ◽  
M A Guerrero ◽  
E Santamaría ◽  
G Ramos-Larios ◽  
L Sabin
Keyword(s):  
Major Axis ◽  
Bipolar Structure ◽  
X Ray ◽  
North East ◽  
South West ◽  
Optical Images ◽  
Photon Index ◽  
Careful Revision ◽  
Nova Shell ◽  
Thin Plasma

ABSTRACT We present an analysis of archival Chandra and XMM–Newton observations of the magnetically active cataclysmic variable DQ Her and the shell around it ejected in a nova event in 1934. A careful revision of the Chandra observations confirms previous claims on the presence of extended X-ray emission around DQ Her and reveals that it actually corresponds to a bipolar jet-like structure extending ≃32 arcsec along a direction from north-east to south-west. Therefore, this X-ray emission extends beyond the optical nova shell and is perpendicular to its major axis. The XMM–Newton observations confirm the presence of the extended X-ray emission detected by Chandra, suggesting the additional presence of a diffuse X-ray emission from a hot bubble filling the nova shell. This hot bubble was very likely produced by the explosion that created the nebular shell detected in optical images. The bipolar feature can be modelled by the combination of an optically thin plasma emission component with temperature T ≈ 2 × 106 K and a power-law component with a photon index of Γ = 1.1 ± 0.9. Its X-ray luminosity in the 0.3–5 keV energy range is LX = (2.1 ± 1.3) × 1029 erg s−1, for an electron density ne ≈ 2 cm−3 and a mass mX ≈ 3 × 10−6 M⊙. We suggest that the X-ray bipolar structure in DQ Her is a jet and interpret its non-thermal X-ray emission in terms of a magnetized jet.

scholarly journals Numerically investigating the morphology of the supernova remnant SN 1006 in the ambient medium with a density discontinuity

2019 ◽  
Vol 491 (2) ◽  
pp. 2460-2464 ◽  
Author(s):  
Jun Fang ◽  
Jingwen Yan ◽  
Lu Wen ◽  
Chunyan Lu ◽  
Huan Yu
Keyword(s):  
Supernova Remnant ◽  
Ambient Medium ◽  
X Rays ◽  
X Ray ◽  
North West ◽  
Density Discontinuity ◽  
North East ◽  
The North ◽  
South West ◽  
Type Ia

ABSTRACT Multiband observations on the Type Ia supernova remnant SN 1006 indicate peculiar properties in its morphologies of emission in the radio, optical, and X-ray bands. In the hard X-rays, the remnant is bilateral with two opposite bright limbs with prominent protrusions. Moreover, a filament has been detected at the radio, optical, and soft X-ray wavelengths. The reason for these peculiar features in the morphologies of the remnant is investigated using 3D HD simulations. With the assumption that the supernova ejecta are evolved in the ambient medium with a density discontinuity, the radius of the remnant’s boundary is smaller in the tenuous medium, and the shell consists of two hemispheres with different radii. Along particular line of sights, protrusions appear on the periphery of the remnants since the emission from the edge of the hemisphere with a larger radius is located outside that from the shell of the small hemisphere. Furthermore, the north-west filament of SN 1006 arises as a result of the intersection of the line of sight and the shocked material near the edges of the two hemispheres. It can be concluded that the protrusions on the north-east and south-west limbs and the north-west filament in the morphologies of SN 1006 can be reproduced as the remnants interacting with the medium with a density discontinuity.

scholarly journals Close-up view of an ongoing merger between the NGC 4839 group and the Coma cluster – a post-merger scenario

2019 ◽  
Vol 485 (2) ◽  
pp. 2922-2934 ◽  
Author(s):  
N Lyskova ◽  
E Churazov ◽  
C Zhang ◽  
W Forman ◽  
C Jones ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Coma Cluster ◽  
The South ◽  
X Ray ◽  
Sheath Region ◽  
North East ◽  
South West ◽  
Ram Pressure ◽  
Cool Gas ◽  
Optical Centre

ABSTRACT We study a merger of the NGC 4839 group with the Coma cluster using X-ray observations from the XMM–Newton and Chandra telescopes. X-ray data show two prominent features: (i) a long (∼600 kpc in projection) and bent tail of cool gas trailing (towards south-west) the optical centre of NGC 4839, and (ii) a ‘sheath’ region of enhanced X-ray surface brightness enveloping the group, which is due to hotter gas. While at first glance the X-ray images suggest that we are witnessing the first infall of NGC 4839 into the Coma cluster core, we argue that a post-merger scenario provides a better explanation of the observed features and illustrate this with a series of numerical simulations. In this scenario, the tail is formed when the group, initially moving to the south-west, reverses its radial velocity after crossing the apocenter, the ram pressure ceases and the ram pressure-displaced gas falls back towards the centre of the group and overshoots it. Shortly after the apocenter passage, the optical galaxy, dark matter, and gaseous core move in a north-east direction, while the displaced gas continues moving to the south-west. The ‘sheath’ is explained as being due to interaction of the re-infalling group with its own tail of stripped gas mixed with the Coma gas. In this scenario, the shock, driven by the group before reaching the apocenter, has already detached from the group and would be located close to the famous relic to the south-west of the Coma cluster.

scholarly journals Progressive steepening of the SNR RX J1713.7–3946 X-ray spectrum from XMM–Newton to INTEGRAL

2019 ◽  
Vol 489 (2) ◽  
pp. 1828-1836 ◽  
Author(s):  
Ekaterina Kuznetsova ◽  
Roman Krivonos ◽  
Eugene Churazov ◽  
Natalia Lyskova ◽  
Alexander Lutovinov
Keyword(s):  
Energy Range ◽  
Supernova Remnant ◽  
X Rays ◽  
X Ray ◽  
North West ◽  
South West ◽  
Photon Index ◽  
Coded Mask ◽  
First Time ◽  
Single Emission

ABSTRACT In this work, we present the first detailed analysis of the supernova remnant RX J1713.7–3946 in the hard X-ray energy range with the Imager on Board the INTEGRAL Satellite (IBIS) coded-mask telescope onboard the INTEGRAL observatory. The shell-type morphology of the entire remnant is mapped in hard X-rays for the first time and significantly detected up to 50 keV. The IBIS sky image of RX J1713.7–3946, accumulated over 14 yr of operations, demonstrates two extended hard X-ray sources. These sources are spatially consistent with north-west and south-west rims of RX J1713.7–3946 and are also clearly visible at energies below 10 keV with XMM–Newton. This points to a single emission mechanism operating in soft and hard X-rays. The INTEGRAL 17–120 keV spectrum of RX J1713.7–3946 is characterized by a power-law continuum with the photon index of Γ ≈ 3 that is significantly softer than Γ ≈ 2 determined by XMM–Newton in the 1–10 keV energy range, suggesting a progressive steepening of the spectrum with the energy.

scholarly journals XMM-Newton detection of the 2.1 ms coherent pulsations from IGR J17379–3747

2018 ◽  
Vol 616 ◽  
pp. L17 ◽  
Author(s):  
A. Sanna ◽  
E. Bozzo ◽  
A. Papitto ◽  
A. Riggio ◽  
C. Ferrigno ◽  
...  
Keyword(s):  
Inclination Angle ◽  
Major Axis ◽  
Black Body ◽  
Orbital Evolution ◽  
Semi Major Axis ◽  
Companion Star ◽  
X Ray ◽  
Orbital Parameters ◽  
Photon Index ◽  
Soft Disk

We report the detection of X-ray pulsations at 2.1 ms from the known X-ray burster IGR J17379–3747 using XMM-Newton. The coherent signal shows a clear Doppler modulation from which we estimate an orbital period of ~1.9 h and a projected semi-major axis of ~8 lt-ms. Taking into account the lack of eclipses (inclination angle of <75°) and assuming a neutron star mass of 1.4 M⊙, we have estimated a minimum companion star of ~0.06 M⊙. Considerations on the probability distribution of the binary inclination angle make the hypothesis of a main-sequence companion star less likely. On the other hand, the close correspondence with the orbital parameters of the accreting millisecond pulsar SAX J1808.4–3658 suggests the presence of a bloated brown dwarf. The energy spectrum of the source is well described by a soft disk black-body component (kT ~ 0.45 keV) plus a Comptonisation spectrum with photon index ~1.9. No sign of emission lines or reflection components are significantly detected. Finally, combining the source ephemerides estimated from the observed outbursts, we obtained a first constraint on the long-term orbital evolution of the order of Ṗorb = (−2.5 ± 2.3) × 10−12 s s−1.

scholarly journals X-ray cavities in the G50 bright group-centered galaxy NGC 5846

2021 ◽  
pp. 17-24
Author(s):  
Anil Kyadampure ◽  
N.D. Vagshette ◽  
M.K. Patil
Keyword(s):  
Black Hole ◽  
Accretion Rate ◽  
Black Hole Mass ◽  
Radio Luminosity ◽  
X Ray ◽  
Supermassive Black Hole ◽  
North East ◽  
The North ◽  
South West ◽  
Group A

We present results based on analysis of the currently available 29.86 ks Chandra data on the Bright Group-Centered Galaxy (BGG) NGC 5846 of G50 group. A pair of X-ray cavities have been detected within a radius ? 1 kpc along the North-East and South-West directions. The analysis yielded the average cavity energy, ages and mechanical power equal to ~ 3:1 x 1048 erg, 0:61 x 107 yr and, 3:78 x 1041 erg s-1, respectively. The luminosity of X-ray emitting gas within the cooling radius (20 kpc) was found to be 2.4 x 1041 erg s??1, in agreement with the mechanical cavity power. The ratio of radio luminosity to mechanical cavity power is found to be 10??4. The Bondi accretion rate of the central supermassive black hole (SMBH) is ~ 5:95 x 10-5 M? yr-1 and the black-hole mass derived using the Bondi-accretion rate was found to be ~ 3:74 x 108 M?.

scholarly journals Discovery of 105 Hz coherent pulsations in the ultracompact binary IGR J16597–3704

2018 ◽  
Vol 610 ◽  
pp. L2 ◽  
Author(s):  
A. Sanna ◽  
A. Bahramian ◽  
E. Bozzo ◽  
C. Heinke ◽  
D. Altamirano ◽  
...  
Keyword(s):  
Neutron Star ◽  
Energy Spectrum ◽  
Binary System ◽  
Broad Band ◽  
Major Axis ◽  
Semi Major Axis ◽  
Band Energy ◽  
X Ray ◽  
Neutron Star Mass ◽  
Photon Index

We report the discovery of X-ray pulsations at 105.2 Hz (9.5 ms) from the transient X-ray binary IGR J16597–3704 using NuSTAR and Swift. The source was discovered by INTEGRAL in the globular cluster NGC 6256 at a distance of 9.1 kpc. The X-ray pulsations show a clear Doppler modulation that implies an orbital period of ~46 min and a projected semi-major axis of ~5 lt-ms, which makes IGR J16597–3704 an ultracompact X-ray binary system. We estimated a minimum companion mass of 6.5 × 10−10 M⊙, assuming a neutron star mass of 1.4 M⊙, and an inclination angle of <75° (suggested by the absence of eclipses or dips in its light curve). The broad-band energy spectrum of the source is well described by a disk blackbody component (kT ~ 1.4 keV) plus a comptonised power-law with photon index ~2.3 and an electron temperature of ~30 keV. Radio pulsations from the source were unsuccessfully searched for with the Parkes Observatory.

scholarly journals Brightest cluster galaxies: the centre can(not?) hold

2020 ◽  
Vol 500 (1) ◽  
pp. 310-318
Author(s):  
Roberto De Propris ◽  
Michael J West ◽  
Felipe Andrade-Santos ◽  
Cinthia Ragone-Figueroa ◽  
Elena Rasia ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Environment ◽  
Major Axis ◽  
Theoretical Models ◽  
Dark Matter Halo ◽  
Gas Distribution ◽  
X Ray ◽  
Cluster Galaxies ◽  
Peculiar Velocities ◽  
Brightest Cluster Galaxies

ABSTRACT We explore the persistence of the alignment of brightest cluster galaxies (BCGs) with their local environment. We find that a significant fraction of BCGs do not coincide with the centroid of the X-ray gas distribution and/or show peculiar velocities (they are not at rest with respect to the cluster mean). Despite this, we find that BCGs are generally aligned with the cluster mass distribution even when they have significant offsets from the X-ray centre and significant peculiar velocities. The large offsets are not consistent with simple theoretical models. To account for these observations BCGs must undergo mergers preferentially along their major axis, the main infall direction. Such BCGs may be oscillating within the cluster potential after having been displaced by mergers or collisions, or the dark matter halo itself may not yet be relaxed.

scholarly journals X-ray properties of reverberation-mapped AGNs with super-Eddington accreting massive black holes

2019 ◽  
Vol 15 (S356) ◽  
pp. 143-143
Author(s):  
Jaya Maithil ◽  
Michael S. Brotherton ◽  
Bin Luo ◽  
Ohad Shemmer ◽  
Sarah C. Gallagher ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Accretion Rate ◽  
Time Lags ◽  
Black Hole Mass ◽  
Host Galaxies ◽  
Massive Black Holes ◽  
X Ray ◽  
Photon Index ◽  
The Impact

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

scholarly journals X-ray Properties of 3C 111: Separation of Primary Nuclear Emission and Jet Continuum

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 219
Author(s):  
Elena Fedorova ◽  
B.I. Hnatyk ◽  
V.I. Zhdanov ◽  
A. Del Popolo
Keyword(s):  
Accretion Disk ◽  
Power Law ◽  
Line Emission ◽  
High Energy ◽  
Power Law Model ◽  
X Ray ◽  
Additional Information ◽  
Observational Dataset ◽  
Simple Power ◽  
Photon Index

3C111 is BLRG with signatures of both FSRQ and Sy1 in X-ray spectrum. The significant X-ray observational dataset was collected for it by INTEGRAL, XMM-Newton, SWIFT, Suzaku and others. The overall X-ray spectrum of 3C 111 shows signs of a peculiarity with the large value of the high-energy cut-off typical rather for RQ AGN, probably due to the jet contamination. Separating the jet counterpart in the X-ray spectrum of 3C 111 from the primary nuclear counterpart can answer the question is this nucleus truly peculiar or this is a fake “peculiarity” due to a significant jet contribution. In view of this question, our aim is to estimate separately the accretion disk/corona and non-thermal jet emission in the 3C 111 X-ray spectra within different observational periods. To separate the disk/corona and jet contributions in total continuum, we use the idea that radio and X-ray spectra of jet emission can be described by a simple power-law model with the same photon index. This additional information allows us to derive rather accurate values of these contributions. In order to test these results, we also consider relations between the nuclear continuum and the line emission.

Sign in / Sign up

Export Citation Format

Share Document