scholarly journals Central Compact Objects: some of them could be spinning up?

2018 ◽  
Vol 478 (4) ◽  
pp. 4890-4893 ◽  
Author(s):  
O Benli ◽  
Ü Ertan
Keyword(s):  
Compact Objects ◽  
Central Compact Objects

Time-scales to reach chemical equilibrium in ices at snowline distance around compact objects: the influence of accretion mass in the central object

2021 ◽  
Vol 503 (2) ◽  
pp. 2973-2978
Author(s):  
G A Carvalho ◽  
S Pilling
Keyword(s):  
Time Scales ◽  
Chemical Equilibrium ◽  
Accretion Rate ◽  
Radiation Reaction ◽  
Compact Objects ◽  
Compact Stars ◽  
X Ray ◽  
Accretion Rates ◽  
Central Compact Objects ◽  
Astrophysical Ices

ABSTRACT In this work, we analyse soft X-ray emission due to mass accretion on to compact stars and its effects on the time-scale to reach chemical equilibrium of eventual surrounding astrophysical ices exposed to that radiation. Reaction time-scales due to soft X-ray in water-rich and pure ices of methanol, acetone, acetonitrile, formic acid, and acetic acid were determined. For accretion rates in the range $\dot{m}=10^{-12}\!-\!10^{-8}\,{\rm M}_\odot$ yr−1 and distances in the range 1–3 LY from the central compact objects, the time-scales lie in the range 10–108 yr, with shorter time-scales corresponding to higher accretion rates. Obtained time-scales for ices at snow-line distances can be small when compared to the lifetime (or age) of the compact stars, showing that chemical equilibrium could have been achieved. Time-scales for ices to reach chemical equilibrium depend on X-ray flux and, hence, on accretion rate, which indicates that systems with low accretion rates may not have reached chemical equilibrium.

scholarly journals Central compact objects and their magnetic fields

2012 ◽  
Vol 8 (S291) ◽  
pp. 101-106 ◽  
Author(s):  
Wynn C. G. Ho
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Supernova Remnants ◽  
Compact Objects ◽  
Spectral Measurements ◽  
X Ray ◽  
Surface Field ◽  
Weak Surface ◽  
Central Compact Objects ◽  
Weak Fields

AbstractCentral compact objects (CCOs) are neutron stars that are found near the center of supernova remnants, and their association with supernova remnants indicates these neutron stars are young (≲ 104 yr). Here we review the observational properties of CCOs and discuss implications, especially their inferred magnetic fields. X-ray timing and spectral measurements suggest CCOs have relatively weak surface magnetic fields (~ 1010 − 1011 G). We argue that, rather than being created with intrinsically weak fields, CCOs are born with strong fields and we are only seeing a weak surface field that is transitory and evolving. This could imply that CCOs are one manifestation in a unified picture of neutron stars.

scholarly journals Progenitors and explosion properties of supernova remnants hosting central compact objects: I. RCW 103 associated with the peculiar source 1E 161348−5055

2019 ◽  
Vol 489 (3) ◽  
pp. 4444-4463 ◽  
Author(s):  
C Braun ◽  
S Safi-Harb ◽  
C L Fryer
Keyword(s):  
Supernova Remnants ◽  
Model Fitting ◽  
Plasma Temperature ◽  
Compact Object ◽  
Compact Objects ◽  
Explosion Energy ◽  
Uniform Medium ◽  
Order Of Magnitude ◽  
Central Compact Objects ◽  
Collisional Ionization

ABSTRACT We present a Chandra and XMM–Newton imaging and spectroscopic study of the supernova remnant (SNR) RCW 103 (G332.4−00.4) containing the central compact object 1E 161348−5055. The high-resolution Chandra X-ray images reveal enhanced emission in the south-eastern and north-western regions. Equivalent width line images of Fe L, Mg, Si, and S using XMM–Newton data were used to map the distribution of ejecta. The SNR was sectioned into 56 regions best characterized by two-component thermal models. The harder component (kT ∼ 0.6 keV) is adequately fitted by the VPSHOCK non-equilibrium ionization model with an ionization time-scale net ∼ 1011–1012 cm−3 s, and slightly enhanced abundances over solar values. The soft component (kT ∼ 0.2 keV), fitted by the APEC model, is well described by plasma in collisional ionization equilibrium with abundances consistent with solar values. Assuming a distance of 3.1 kpc and a Sedov phase of expansion into a uniform medium, we estimate an SNR age of 4.4 kyr, a swept-up mass Msw = 16$f_\mathrm{ s}^{-1/2}$ D$_{3.1}^{5/2}$ M⊙, and a low explosion energy E* = 3.7 × 1049 $f_\mathrm{ s}^{-1/2}$ D$_{3.1}^{5/2}$ erg. This energy could be an order of magnitude higher if we relax the Sedov assumption, the plasma has a low filling factor, the plasma temperature is underestimated, or if the SNR is expanding into the progenitor’s wind-blown bubble. Standard explosion models did not match the ejecta yields. By comparing the fitted abundances to the most recent core-collapse nucleosynthesis models, our best estimate yields a low-mass progenitor of around 12–13 M⊙, lower than previously reported. We discuss degeneracies in the model fitting, particularly the effect of altering the explosion energy on the progenitor mass estimate.

scholarly journals Very young neutron stars and millisecond pulsars: the role of the accretion

2012 ◽  
Vol 8 (S290) ◽  
pp. 231-232
Author(s):  
Alexander F. Kholtygin ◽  
Andrei P. Igoshev
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Binary Systems ◽  
Compact Objects ◽  
Millisecond Pulsars ◽  
Know How ◽  
Central Compact Objects ◽  
Low Magnetic Field ◽  
Age Determinations

AbstractWe consider the evolution of the very young neutron stars (NS) with moderate and low magnetic field values around 1E8 G to know how large is the share of the these objects among the those attributed as the millisecond pulsars (MSP). To exclude the contamination of accreted NS and young NS with moderate magnetic fields we study the observational evidences of the accretion on NS in the binary systems and different methods of age determinations. It was concluded that only central compact objects are appropriate candidates for NSs with small initial magnetic fields.

scholarly journals The neutron star in HESS J1731−347: Central compact objects as laboratories to study the equation of state of superdense matter

2014 ◽  
Vol 573 ◽  
pp. A53 ◽  
Author(s):  
D. Klochkov ◽  
V. Suleimanov ◽  
G. Pühlhofer ◽  
D. G. Yakovlev ◽  
A. Santangelo ◽  
...  
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Compact Objects ◽  
Superdense Matter ◽  
Central Compact Objects

scholarly journals Powering central compact objects with a tangled crustal magnetic field

2020 ◽  
Vol 495 (2) ◽  
pp. 1692-1699 ◽  
Author(s):  
Konstantinos N Gourgouliatos ◽  
Rainer Hollerbach ◽  
Andrei P Igoshev
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Initial Conditions ◽  
Supernova Explosion ◽  
Compact Objects ◽  
Dipole Field ◽  
Ohmic Dissipation ◽  
X Ray ◽  
Axisymmetric Structure ◽  
Central Compact Objects

ABSTRACT Central Compact Objects (CCOs) are X-ray sources with luminosity ranging between 1032 and 1034 erg s−1, located at the centres of supernova remnants. Some of them have been confirmed to be neutron stars. Timing observations have allowed the estimation of their dipole magnetic field, placing them in the range ∼1010–1011 G. The decay of their weak dipole fields, mediated by the Hall effect and Ohmic dissipation, cannot provide sufficient thermal energy to power their X-ray luminosity, as opposed to magnetars whose X-ray luminosities are comparable. Motivated by the question of producing high X-ray power through magnetic field decay while maintaining a weak dipole field, we explore the evolution of a crustal magnetic field that does not consist of an ordered axisymmetric structure, but rather comprises a tangled configuration. This can be the outcome of a non-self-excited dynamo, buried inside the crust by fallback material following the supernova explosion. We find that such initial conditions lead to the emergence of the magnetic field from the surface of the star and the formation of a dipolar magnetic field component. An internal tangled magnetic field of the order of 1014 G can provide sufficient Ohmic heating to the crust and power CCOs, while the dipole field it forms is approximately 1010 G, as observed in CCOs.

scholarly journals What causes the absence of pulsations in Central Compact Objects in supernova remnants?

2021 ◽  
Vol 21 (11) ◽  
pp. 294
Author(s):  
Qi Wu ◽  
Adriana M. Pires ◽  
Axel Schwope ◽  
Guang-Cheng Xiao ◽  
Shu-Ping Yan ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Supernova Remnants ◽  
Compact Objects ◽  
Evolutionary Path ◽  
Spectral Components ◽  
Periodic Signals ◽  
The Common ◽  
Central Compact Objects ◽  
Star Surface ◽  
Homogeneous Temperature

Abstract Most young neutron stars belonging to the class of Central Compact Objects (CCOs) in supernova remnants do not have known periodicities. We investigated seven such CCOs to understand the common reasons for the absence of detected pulsations. Making use of XMM-Newton, Chandra, and NICER observations, we perform a systematic timing and spectral analysis to derive updated sensitivity limits for both periodic signals and multi-temperature spectral components that could be associated with radiation from hotspots on the neutron star surface. Based on these limits, we then investigated for each target the allowed viewing geometry that could explain the lack of pulsations. We find that it is unlikely (< 10−6) to attribute that we do not see pulsations to an unfavorable viewing geometry for five considered sources. Alternatively, the carbon atmosphere model, which assumes homogeneous temperature distribution on the surface, describes the spectra equally well and provides a reasonable interpretation for the absence of detected periodicities within current limits. The unusual properties of CCOs with respect to other young neutron stars could suggest a different evolutionary path, as that proposed for sources experiencing episodes of significant fallback accretion after the supernova event.

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