Spectral and accretion evolution of H1743−322 during outbursts in RXTE era

Aims. We study the spectral evolution of the H1743−322 during outbursts in the RXTE era. We aim to connect the variation of the spectral parameters with the accretion parameters along with the progress of the outbursts. We understand the evolution of the accretion parameters and hence the dynamics of the accretion process in light of the irradiated disc instability model. Methods. We provide a comprehensive study of all the outbursts of H1743−322 between 2003 and 2011. We performed spectral modelling of all the RXTE/PCA observations using phenomenological models. Also, we carried out spectral modelling by a hydrodynamic accretion flow model and estimated the accretion parameters. We applied the irradiated disc instability scenario in the presence of both Keplerian and sub-Keplerain accretion components to understand the evolution of accretion parameters. For this purpose, we propose a toy model for the time variation of the accretion rates following a powerlaw during outbursts. Results. All of the outbursts show spectral state transitions in the hardness-intensity diagram. The 2003 and 2004 outbursts are long-duration outbursts and relatively softer than the other outbursts. The 2008b and 2011 outbursts provide a unique opportunity to estimate the critical accretion rate (ṁdc) for triggering an outburst in this system within a narrow range of 0.076 < ṁdc < 0.086 (in Eddington units). In the absence of any dynamical measurement, we attempt to constrain a few orbital parameters of the system using an assumed mass and ṁdc in the range.

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Hysteresis in spectral state transitions – a challenge for theoretical modeling

Astronomy and Astrophysics ◽

10.1051/0004-6361:20041631 ◽

2005 ◽

Vol 432 (1) ◽

pp. 181-187 ◽

Cited By ~ 58

Author(s):

E. Meyer-Hofmeister ◽

B. F. Liu ◽

F. Meyer

Keyword(s):

Theoretical Modeling ◽

State Transitions ◽

Spectral State

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Chemical modification of Ca(2+)-activated potassium channels of GH3 anterior pituitary cells

AJP Cell Physiology ◽

10.1152/ajpcell.1992.263.5.c1081 ◽

1992 ◽

Vol 263 (5) ◽

pp. C1081-C1087 ◽

Cited By ~ 6

Author(s):

A. M. Frace ◽

D. C. Eaton

Keyword(s):

Single Channel ◽

Gh3 Cells ◽

Disulfonic Acid ◽

State Transitions ◽

Trinitrobenzene Sulfonic Acid ◽

Voltage Sensitivity ◽

Pituitary Cells ◽

Amino Groups ◽

Open Probability ◽

Long Duration

The effects of amino group specific reagents were examined on single, large-conductance, Ca(2+)-activated, K+ channels in excised membrane patches from GH3 cells. The reagents used include trinitrobenzene sulfonic acid, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and its 4-acetamido derivative, and sulfophenyl-isothiocyanate. These reagents react covalently with peptide terminal amino groups and the epsilon amino groups of lysine residues, thereby removing positive charge. Internal application of 0.1-1.0 mM reagent to inside-out patches irreversibly increases channel open probability. Single-channel conductance and voltage sensitivity are not affected by modification. Analysis of channel openings and closures shows that the increase in open probability is predominantly due to the loss of long-duration closures of the channel; however, the lengths of long-duration openings are increased. After the modification in the presence of Ca2+ was performed, the channel open probability remains large, regardless of the internal Ca2+ concentration. Transitions among several open and closed states of the modified channel are present in the absence of Ca2+, suggesting that many state transitions are not directly dependent on Ca2+ binding or dissociation.

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Spectral state transitions in low-mass X-ray binaries – the effect of hard and soft irradiation

Astronomy and Astrophysics ◽

10.1051/0004-6361:20053207 ◽

2005 ◽

Vol 442 (2) ◽

pp. 555-562 ◽

Cited By ~ 24

Author(s):

B. F. Liu ◽

F. Meyer ◽

E. Meyer-Hofmeister

Keyword(s):

State Transitions ◽

X Ray ◽

Low Mass ◽

X Ray Binaries ◽

Spectral State

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X-ray Spectral Evolution of High Energy Peaked Blazars

Galaxies ◽

10.3390/galaxies8030062 ◽

2020 ◽

Vol 8 (3) ◽

pp. 62

Author(s):

Haritma Gaur

Keyword(s):

High Energy ◽

Energy Interval ◽

Spectral Studies ◽

Parabolic Model ◽

Spectral Evolution ◽

Spectral Variability ◽

Spectral Parameters ◽

X Ray ◽

Wide Energy ◽

Energy Dependent

The synchrotron hump of the high energy peaked blazars generally lies in the 0.1–10 keV range and such sources show extreme flux and spectral variability in X-ray bands. Various spectral studies showed that the X-ray spectra of high energy peaked blazars are curved and better described by the log-parabolic model. The curvature is attributed to the energy dependent statistical acceleration mechanism. In this work, we review the X-ray spectral studies of high energy peaked blazars. It is found that the log-parabolic model well describes the spectra in a wide energy interval around the peak. The log-parabolic model provides the possibility of investigating the correlation between the spectral parameters derived from it. Therefore, we compiled the studies of correlations between the various parameters derived from the log-parabolic model and their implications to describe the variability mechanism of blazars.

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Spectral State Transitions of the Ultraluminous X-Ray Sources X-1 and X-2 in NGC 1313

The Astrophysical Journal ◽

10.1086/508613 ◽

2006 ◽

Vol 650 (1) ◽

pp. L75-L78 ◽

Cited By ~ 59

Author(s):

Hua Feng ◽

Philip Kaaret

Keyword(s):

State Transitions ◽

X Ray ◽

Spectral State

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The low-luminosity Type II SN 2016aqf: a well-monitored spectral evolution of the Ni/Fe abundance ratio

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1932 ◽

2020 ◽

Vol 497 (1) ◽

pp. 361-377

Author(s):

Tomás E Müller-Bravo ◽

Claudia P Gutiérrez ◽

Mark Sullivan ◽

Anders Jerkstrand ◽

Joseph P Anderson ◽

...

Keyword(s):

Spectral Synthesis ◽

Theoretical Models ◽

Abundance Ratio ◽

Late Time ◽

Type Ii ◽

Spectral Evolution ◽

Spectral Parameters ◽

Bolometric Luminosity ◽

V Band ◽

Explosion Mechanism

ABSTRACT Low-luminosity Type II supernovae (LL SNe II) make up the low explosion energy end of core-collapse SNe, but their study and physical understanding remain limited. We present SN 2016aqf, an LL SN II with extensive spectral and photometric coverage. We measure a V-band peak magnitude of −14.58 mag, a plateau duration of ∼100 d, and an inferred 56Ni mass of 0.008 ± 0.002 M⊙. The peak bolometric luminosity, Lbol ≈ 1041.4 erg s−1, and its spectral evolution are typical of other SNe in the class. Using our late-time spectra, we measure the [O i] λλ6300, 6364 lines, which we compare against SN II spectral synthesis models to constrain the progenitor zero-age main-sequence mass. We find this to be 12 ± 3 M⊙. Our extensive late-time spectral coverage of the [Fe ii] λ7155 and [Ni ii] λ7378 lines permits a measurement of the Ni/Fe abundance ratio, a parameter sensitive to the inner progenitor structure and explosion mechanism dynamics. We measure a constant abundance ratio evolution of $0.081^{+0.009}_{-0.010}$ and argue that the best epochs to measure the ratio are at ∼200–300 d after explosion. We place this measurement in the context of a large sample of SNe II and compare against various physical, light-curve, and spectral parameters, in search of trends that might allow indirect ways of constraining this ratio. We do not find correlations predicted by theoretical models; however, this may be the result of the exact choice of parameters and explosion mechanism in the models, the simplicity of them, and/or primordial contamination in the measured abundance ratio.

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Empirical σ Molecular Orbital Parameters and their Correlation with Rates of Substitution Reactions in Quadrate Cr(III) and Co(III) Complexes

Canadian Journal of Chemistry ◽

10.1139/v71-242 ◽

1971 ◽

Vol 49 (9) ◽

pp. 1497-1501 ◽

Cited By ~ 7

Author(s):

C. H. Langford

Keyword(s):

Field Theories ◽

Complete Analysis ◽

Substitution Reactions ◽

Spectral Parameters ◽

Empirical Measures ◽

Orbital Parameters ◽

Spectral Bands ◽

Leaving Group ◽

The Relationship

Empirical measures of σ bonding involving metal 3d orbitals are derived from Perumareddi's (4) complete analysis of the quartet spectral bands of quadrate complexes in the families Cr(NH3)5Xn+ and Cr(OH2)5Xn+. These are shown to correlate with lability of X in the Cr(III) complexes and in Co(NH3)5Xn+ complexes in a sense indicating that relative reactivity is controlled by variation of ligand metal 3d σ interaction. The relationship between the two Cr(III) series implies that the non-labile ligands can labilize the leaving group in proportion to their σ donor capacities. This observation bears on some well-known difficulties in crystal field theories of reactivity. In evaluating the correlation of spectral parameters with reactivity, the role of solvation in reactivity of Cr(III) and Co(III) complexes is discussed with emphasis on the surprisingly small solvent effects that have been observed.

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