X-RAY SIGNATURES: NEW TIME SCALES AND SPECTRAL FEATURES

X-ray photon correlation spectroscopy (XPCS) enables the study of sample dynamics between micrometer and atomic length scales. As a coherent scattering technique, it benefits from the increased brilliance of the next-generation synchrotron radiation and Free-Electron Laser (FEL) sources. In this article, we will introduce the XPCS concepts and review the latest developments of XPCS with special attention on the extension of accessible time scales to sub-μs and the application of XPCS at FELs. Furthermore, we will discuss future opportunities of XPCS and the related technique X-ray speckle visibility spectroscopy (XSVS) at new X-ray sources. Due to its particular signal-to-noise ratio, the time scales accessible by XPCS scale with the square of the coherent flux, allowing to dramatically extend its applications. This will soon enable studies over more than 18 orders of magnitude in time by XPCS and XSVS.

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Transient absorption spectroscopy using high harmonic generation: a review of ultrafast X-ray dynamics in molecules and solids

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0463 ◽

2019 ◽

Vol 377 (2145) ◽

pp. 20170463 ◽

Cited By ~ 28

Author(s):

Romain Geneaux ◽

Hugo J. B. Marroux ◽

Alexander Guggenmos ◽

Daniel M. Neumark ◽

Stephen R. Leone

Keyword(s):

Time Scales ◽

Harmonic Generation ◽

Absorption Spectroscopy ◽

Transient Absorption ◽

High Harmonic ◽

High Harmonic Generation ◽

Transient Absorption Spectroscopy ◽

Spectroscopic Techniques ◽

X Rays ◽

X Ray

Attosecond science opened the door to observing nuclear and electronic dynamics in real time and has begun to expand beyond its traditional grounds. Among several spectroscopic techniques, X-ray transient absorption spectroscopy has become key in understanding matter on ultrafast time scales. In this review, we illustrate the capabilities of this unique tool through a number of iconic experiments. We outline how coherent broadband X-ray radiation, emitted in high-harmonic generation, can be used to follow dynamics in increasingly complex systems. Experiments performed in both molecules and solids are discussed at length, on time scales ranging from attoseconds to picoseconds, and in perturbative or strong-field excitation regimes. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

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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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X-ray variability time scales in active galactic nuclei

Astronomy and Astrophysics ◽

10.1051/0004-6361/200911958 ◽

2009 ◽

Vol 504 (1) ◽

pp. 61-66 ◽

Cited By ~ 8

Author(s):

W. Ishibashi ◽

T. J.-L. Courvoisier

Keyword(s):

Active Galactic Nuclei ◽

Time Scales ◽

Galactic Nuclei ◽

X Ray

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Hydration Dynamics at Femtosecond Time Scales and Angstrom Length Scales from Inelastic X-Ray Scattering

Physical Review Letters ◽

10.1103/physrevlett.103.237402 ◽

2009 ◽

Vol 103 (23) ◽

Cited By ~ 14

Author(s):

Robert H. Coridan ◽

Nathan W. Schmidt ◽

Ghee Hwee Lai ◽

Rahul Godawat ◽

Michael Krisch ◽

...

Keyword(s):

Time Scales ◽

Length Scales ◽

X Ray ◽

X Ray Scattering ◽

Hydration Dynamics ◽

Ray Scattering

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Systematic study of magnetar outbursts

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317007323 ◽

2017 ◽

Vol 13 (S337) ◽

pp. 326-327

Author(s):

Francesco Coti Zelati

Keyword(s):

Time Scales ◽

Systematic Study ◽

Decay Time ◽

Temporal Evolution ◽

Triggering Mechanism ◽

X Ray ◽

Characteristic Decay Time

AbstractWe present the results of a systematic study of all magnetar outbursts observed to date through a reanalysis of data acquired in about 1100 X-ray observations. We track the temporal evolution of the luminosity for all these events, model empirically their decays, and estimate the characteristic decay time-scales and the energy involved. We study the link between different parameters, and reveal several correlations between different quantities. We discuss our results in the framework of the models proposed to explain the triggering mechanism and evolution of magnetar outbursts.

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New Time Scales: Removing Ambiguities

Highlights of Astronomy ◽

10.1007/978-94-010-9374-3_38 ◽

1995 ◽

pp. 255-255

Author(s):

V. A. Brumberg

Keyword(s):

Time Scales ◽

New Time

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Review of GRANAT Observations of AGNs

Symposium - International Astronomical Union ◽

10.1017/s0074180900174856 ◽

1994 ◽

Vol 159 ◽

pp. 63-72 ◽

Cited By ~ 2

Author(s):

E. Churazov ◽

M. Gilfanov ◽

A. Finoguenov ◽

R. Sunyaev ◽

M. Chernyakova ◽

...

Keyword(s):

Time Scales ◽

Gamma Ray ◽

Broad Band ◽

Band 3 ◽

X Rays ◽

X Ray ◽

X Ray Background

Brief review of AGNs observations in the X-ray / soft gamma-ray bands with the orbital observatory GRANAT is presented.For three well known bright objects (3C273, NGC4151 and Cen A) broad band (3 keV–few hundreds keV) spectra have been obtained. Imaging capabilities allowed accurate (several arcminutes) identification of these objects with sources of hard X-rays.The spectrum of NGC4151 above ≈ 50 keV was found to be much steeper than that in most of the previous observations, while in standard X-ray band the spectrum agrees with observed previously. The comparison of the observed spectra with that of the X-Ray Background (XRB) indicates that sources similar to NGC4151 could reproduce the shape of XRB spectrum in 3–60 keV band.Cen A was observed in the very low state during most of observations in 1990–1993, except for two observations in 1991. The variability of the hard X-ray flux has been detected on the time scales of several days.

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MHD Aspects of Coronal Transients

Symposium - International Astronomical Union ◽

10.1017/s007418090006770x ◽

1980 ◽

Vol 91 ◽

pp. 263-277 ◽

Cited By ~ 1

Author(s):

U. Anzer

Keyword(s):

Solar Corona ◽

Time Scales ◽

White Light ◽

Solar Flares ◽

Great Length ◽

X Ray

If one defines coronal transients as events which occur in the solar corona on rapid time scales (≲ several hours) then one would have to include a large variety of solar phenomena: flares, sprays, erupting prominences, X-ray transients, white light transients, etc. Here we shall focus our attention on the latter two phenomena; solar flares have been discussed at great length in a recent Skylab workshop and IAU Colloqium No. 44 was devoted to the study of prominences. Coronal transients, in the narrower sense, were first seen with the instruments on board of Skylab, both in the optical and the X-ray part of the spectrum.

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Thermonuclear Processes on Accreting Neutron Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900073939 ◽

1981 ◽

Vol 93 ◽

pp. 207-227

Author(s):

Paul C. Joss

Keyword(s):

Spatial Distribution ◽

Neutron Stars ◽

Time Scales ◽

Decay Time ◽

Stellar Population ◽

Effective Radius ◽

X Ray ◽

Burst Maximum ◽

Many Sources ◽

S Peak

The observed properties of X-ray burst sources have recently been reviewed by Lewin and Clark (1980) and Lewin and Joss (1980). About thirty-five such sources are presently known, and they have a spatial distribution reminiscent of stellar Population II (see Figure 1). The salient features of these sources include burst rise times of ≲ls, decay time scales of ~3–100 s, peak luminosities of ~1039 ergs per burst, spectra that can generally be well fitted by blackbody emission from a surface with a constant effective radius of ~10 km and a peak temperature of ~3 × 107 K, and “tails” of softer X-ray emission that may persist for several minutes after the burst maximum. Profiles of bursts from some typical burst sources are shown in Figure 2. The intervals between bursts from a given source may be regular or erratic and are typically in the range of ~104−105 s; many sources undergo burst-inactive phases that can last for weeks or months. Most burst sources are also sources of persistent X-ray emission, and the ratio of average persistent luminosity to time-averaged burst luminosity is typically ~102 during burst-active phases. (The properties of the “Rapid Burster,” MXB1730-335, are different from those of all other known burst sources and will be discussed separately in §VI below.) There are few correlations among the burst flux, burst intervals, and persistent X-ray flux from any given source, and the detailed burst shapes vary from one source to another and often vary with time in a given source.

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