Consistent Modeling of GS 1826-24 X-Ray Bursts for Multiple Accretion Rates Demonstrates the Possibility of Constraining rp-process Reaction Rates

ABSTRACT The thermal structure of accreting neutron stars is affected by the presence of urca nuclei in the neutron star crust. Nuclear isobars harbouring urca nuclides can be produced in the ashes of Type I X-ray bursts, but the details of their production have not yet been explored. Using the code MESA, we investigate urca nuclide production in a one-dimensional model of Type I X-ray bursts using astrophysical conditions thought to resemble the source GS 1826-24. We find that high-mass (A ≥ 55) urca nuclei are primarily produced late in the X-ray burst, during hydrogen-burning freeze-out that corresponds to the tail of the burst light curve. The ∼0.4–0.6 GK temperature relevant for the nucleosynthesis of these urca nuclides is much lower than the ∼1 GK temperature most relevant for X-ray burst light curve impacts by nuclear reaction rates involving high-mass nuclides. The latter temperature is often assumed for nuclear physics studies. Therefore, our findings alter the excitation energy range of interest in compound nuclei for nuclear physics studies of urca nuclide production. We demonstrate that for some cases this will need to be considered in planning for nuclear physics experiments. Additionally, we show that the lower temperature range for urca nuclide production explains why variations of some nuclear reaction rates in model calculations impacts the burst light curve but not local features of the burst ashes.

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White Dwarf Masses and Accretion Rates of Recurrent Novae: an X-ray Perspective

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312014962 ◽

2011 ◽

Vol 7 (S281) ◽

pp. 186-189

Author(s):

Koji Mukai ◽

Jennifer L. Sokoloski ◽

Thomas Nelson ◽

Gerardo J. M. Luna

Keyword(s):

White Dwarf ◽

Cataclysmic Variables ◽

The Other ◽

X Ray ◽

Other Hand ◽

Accretion Rates

AbstractWe present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RNe candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab641 ◽

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.

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New Reaction Rates Of 64Ge(p,γ)65As(p,γ)66Se And The Impact On Type I X-ray Bursts

10.22323/1.281.0144 ◽

2017 ◽

Author(s):

Yi Hua Lam ◽

Jianjun He ◽

Hendrik Schatz ◽

B. Alex Brown ◽

Anuj Parikh

Keyword(s):

Reaction Rates ◽

Type I ◽

X Ray ◽

The Impact

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Radiative efficiency of hot accretion flow and the radio/X-ray correlation in X-ray binaries

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315007723 ◽

2014 ◽

Vol 10 (S312) ◽

pp. 139-140

Author(s):

Fu-Guo Xie

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Accretion Rate ◽

Galactic Nuclei ◽

X Ray ◽

Radiative Efficiency ◽

Accretion Flow ◽

Accretion Rates ◽

Distinctive Property ◽

X Ray Binaries

AbstractSignificant progresses have been made since the discovery of hot accretion flow, a theory successfully applied to the low-luminosity active galactic nuclei (LLAGNs) and black hole (BH) X-ray binaries (BHBs) in their hard states. Motivated by these updates, we re-investigate the radiative efficiency of hot accretion flow. We find that, the brightest regime of hot accretion flow shows a distinctive property, i.e. it has a constant efficiency independent of accretion rates, similar to the standard thin disk. For less bright regime, the efficiency has a steep positive correlation with the accretion rate, while for faint regime typical of advection-dominated accretion flow, the correlation is shadower. This result can naturally explain the observed two distinctive correlations between radio and X-ray luminosities in black hole X-ray binaries. The key difference in systems with distinctive correlations could be the viscous parameter, which determines the critical luminosity of different accretion modes.

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X-ray binaries with neutron stars at different accretion stages

Proceedings of the International Astronomical Union ◽

10.1017/s174392131900125x ◽

2018 ◽

Vol 14 (S346) ◽

pp. 219-227

Author(s):

Konstantin A. Postnov ◽

Alexander G. Kuranov ◽

Lev R. Yungelson

Keyword(s):

Magnetic Fields ◽

Neutron Stars ◽

Orbital Period ◽

Population Synthesis ◽

Circular Orbits ◽

X Ray ◽

Accretion Rates ◽

Supercritical Accretion ◽

Binary Evolution ◽

X Ray Binaries

Abstract. Different accretion regimes onto magnetized NSs in HMXBs are considered: wind-fed supersonic (Bondi) regime at high accretion rates <math/> g s-1, subsonic settling regime at lower <math/> and supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs in HMXBs reach equilibrium spin periods P* proportional to binary orbital period Pb. At supercritical accretion stage, the system may appear as a pulsating ULX. Population synthesis of Galactic HMXBs using standard assumptions on the binary evolution and NS formation is presented. Comparison of the model P* – Pb (the Corbet diagram), P* – Lx and Pb – Lx distributions with those for the observed HMXBs (including Be X-ray binaries) and pulsating ULXs suggests the importance of the reduction of P* in non-circular orbits, explaining the location of Be X-ray binaries in the model Corbet diagram, and the universal parameters of pulsating ULXs depending only on the NS magnetic fields.

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ENDPOINT OF rp PROCESS USING RELATIVISTIC MEAN FIELD APPROACH AND A NEW MASS FORMULA

International Journal of Modern Physics E ◽

10.1142/s0218301312500747 ◽

2012 ◽

Vol 21 (08) ◽

pp. 1250074 ◽

Cited By ~ 6

Author(s):

CHIRASHREE LAHIRI ◽

G. GANGOPADHYAY

Keyword(s):

Mass Formula ◽

Optical Potential ◽

Mean Field ◽

Proton Capture ◽

Density Profiles ◽

X Ray ◽

Field Approach ◽

Relativistic Mean Field ◽

Rapid Proton ◽

Rp Process

Densities from relativistic mean field calculations are applied to construct the optical potential and, hence calculate the endpoint of the rapid proton capture (rp) process. Mass values are taken from a new phenomenological mass formula. Endpoints are calculated for different temperature-density profiles of various X-ray bursters. We find that the rp process can produce significant quantities of nuclei upto around mass 95. Our results differ from existing works to some extent.

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Humidity Controlled Diffractometry and its Applications

Advances in X-ray Analysis ◽

10.1154/s0376030800019066 ◽

1992 ◽

Vol 36 ◽

pp. 439-449 ◽

Cited By ~ 1

Author(s):

Radko A. Kühnel ◽

Sjerry J. van der Gaast

Keyword(s):

Structural Changes ◽

Basic Research ◽

Xrd Analysis ◽

Reaction Rates ◽

Hydrous Minerals ◽

X Ray ◽

Special Attachment ◽

Potential Applications ◽

Total Structure ◽

Structure Collapse

AbstractHumidity sensitive mineral phases change their structure when humidity varies resulting in X-ray pattern changes in intensity, position, and shape of lines. These structural changes in hydrous minerals are induced by dehydration and rehydration, which can lead to phase transformations or to steady depletion which may result in a total structure collapse. By means of X-ray diffraction with a special attachment, such reactions can be followed. The controlled relative humidity is provided in situ, in a closed cell, by a flow of moistened helium gas which is flushed through the cell during the XRD analysis. Humidity diffractometry allows studies of reaction rates of dehydration-rehydration reactions and their reversibilities, as well as effects of additives and impurities on these reactions. Potential applications in basic research and in industry are demonstrated using montmorilionite, ettringites, sodium carbonates and calcium sulfates.

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RESONANCE STATES IN 22Mg, 26Si FOR REACTION RATES IN THE RP-PROCESS

Origin of Matter and Evolution of Galaxies 2003 ◽

10.1142/9789812702739_0037 ◽

2004 ◽

Author(s):

Y. SHIMIZU ◽

K. HATANAKA ◽

G.P.A. BERG ◽

M. WIESCHER ◽

H. SCHATZ ◽

...

Keyword(s):

Reaction Rates ◽

Resonance States ◽

Rp Process

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