scholarly journals Discovery of soft and hard X-ray time lags in low-mass AGNs

2021 ◽  
Vol 503 (3) ◽  
pp. 3775-3783
Author(s):  
L Mallick ◽  
D R Wilkins ◽  
W N Alston ◽  
A Markowitz ◽  
B De Marco ◽  
...  
Keyword(s):  
Scaling Relations ◽  
Average Height ◽  
Time Lags ◽  
Lower Mass ◽  
Coronal Emission ◽  
Low Frequencies ◽  
X Ray ◽  
Band Emission ◽  
Normal Mass ◽  
Low Mass

ABSTRACT The scaling relations between the black hole (BH) mass and soft lag properties for both active galactic nuclei (AGNs) and BH X-ray binaries (BHXRBs) suggest the same underlying physical mechanism at work in accreting BH systems spanning a broad range of mass. However, the low-mass end of AGNs has never been explored in detail. In this work, we extend the existing scaling relations to lower mass AGNs, which serve as anchors between the normal-mass AGNs and BHXRBs. For this purpose, we construct a sample of low-mass AGNs ($M_{\rm BH}\lt 3\times 10^{6} \, \mathrm{M}_{\odot }$) from the XMM–Newton archive and measure frequency-resolved time-delays between the soft (0.3–1 keV) and hard (1–4 keV) X-ray emissions. We report that the soft band lags behind the hard band emission at high frequencies ∼[1.3−2.6] × 10−3 Hz, which is interpreted as a sign of reverberation from the inner accretion disc in response to the direct coronal emission. At low frequencies (∼[3−8] × 10−4 Hz), the hard-band lags behind the soft-band variations, which we explain in the context of the inward propagation of luminosity fluctuations through the corona. Assuming a lamppost geometry for the corona, we find that the X-ray source of the sample extends at an average height and radius of ∼10rg and ∼6rg, respectively. Our results confirm that the scaling relations between the BH mass and soft lag amplitude/frequency derived for higher mass AGNs can safely extrapolate to lower mass AGNs, and the accretion process is indeed independent of the BH mass.

scholarly journals The redshift evolution of X-ray and Sunyaev–Zel’dovich scaling relations in the fable simulations

2019 ◽  
Vol 489 (2) ◽  
pp. 2439-2470 ◽  
Author(s):  
Nicholas A Henden ◽  
Ewald Puchwein ◽  
Debora Sijacki
Keyword(s):  
High Redshift ◽  
Scaling Relations ◽  
Observational Constraints ◽  
Lower Mass ◽  
X Ray ◽  
Galaxy Groups ◽  
Mass Scaling ◽  
Low Mass ◽  
Hydrodynamical Simulations ◽  
Intrinsic Scatter

Abstract We study the redshift evolution of the X-ray and Sunyaev–Zel’dovich (SZ) scaling relations for galaxy groups and clusters in the fable suite of cosmological hydrodynamical simulations. Using an expanded sample of 27 high-resolution zoom-in simulations, together with a uniformly sampled cosmological volume to sample low-mass systems, we find very good agreement with the majority of observational constraints up to z ∼ 1. We predict significant deviations of all examined scaling relations from the simple self-similar expectations. While the slopes are approximately independent of redshift, the normalizations evolve positively with respect to self-similarity, even for commonly used mass proxies such as the YX parameter. These deviations are due to a combination of factors, including more effective active galactic nuclei feedback in lower mass haloes, larger binding energy of gas at a given halo mass at higher redshifts, and larger non-thermal pressure support from kinetic motions at higher redshifts. Our results have important implications for cluster cosmology from upcoming SZ surveys such as SPT-3G, ACTpol, and CMB-S4, as relatively small changes in the observable–mass scaling relations (within theoretical uncertainties) have a large impact on the predicted number of high-redshift clusters and hence on our ability to constrain cosmology using cluster abundances. In addition, we find that the intrinsic scatter of the relations, which agrees well with most observational constraints, increases at lower redshifts and for lower mass systems. This calls for a more complex parametrization than adopted in current observational studies to be able to accurately account for selection biases.

4U 1608–52 as a quasi-persistent X-ray source

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Accretion Disk ◽  
Time Segment ◽  
X Ray ◽  
Band Emission ◽  
Heating And Cooling ◽  
Soft State ◽  
Cyclic Variations ◽  
Low Mass ◽  
X Ray Binaries ◽  
Disk Region

Abstract 4U 1608–52 is a soft X-ray transient. The analysis presented here of a particular part of its X-ray activity uses observations of RXTE/ASM and Swift/BAT. We show a time segment (MJD 54262–MJD 55090) (828 d) in which 4U 1608–52 behaved as a quasi-persistent X-ray source with a series of bumps, with a complicated relation between the evolution of fluxes in the soft (1.5–12 keV) and the hard (15–50 keV) X-ray regions. We ascribe these bumps to a series of propagations of heating and cooling fronts over the inner disk region without any transitions to the true quiescence. 4U 1608–52 oscillated around the boundary between the dominance of the Comptonized component and the dominance of the multicolor accretion disk in its luminosity. Only some of the bumps in this series were accompanied by a transition from the hard to the soft state; if it occurred, it displayed a strong hysteresis effect. The hard-band emission with the dominant Comptonized component was present for most of this active state and showed a cycle of about 40 d. We argue that the cyclic variations of flux come from the inner disk region, not, e.g., from a jet. We also discuss the observed behavior of 4U 1608–52 in the context of other quasi-persistent low-mass X-ray binaries.

scholarly journals Aperiodic variability of low-mass X-ray binaries at very low frequencies

2003 ◽  
Vol 398 (3) ◽  
pp. 1103-1110 ◽  
Author(s):  
P. Reig ◽  
I. Papadakis ◽  
N. D. Kylafis
Keyword(s):  
Low Frequencies ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Activity and Rotation in the Young Cluster h Per

2013 ◽  
Vol 9 (S302) ◽  
pp. 102-105
Author(s):  
C. Argiroffi ◽  
M. Caramazza ◽  
G. Micela ◽  
E. Moraux ◽  
J. Bouvier
Keyword(s):  
Main Sequence ◽  
Activity Relationship ◽  
Central Field ◽  
Activity Levels ◽  
Rotational Period ◽  
Main Sequence Stars ◽  
Lower Mass ◽  
Significant Evidence ◽  
X Ray ◽  
Low Mass

AbstractWe study the rotation-activity relationship for low-mass members of the young cluster h Persei, a ~13 Myr old cluster. h Per, thanks to its age, allows us to link the rotation-activity relation observed for main-sequence stars to the still unexplained activity levels of very young clusters.We constrained the activity levels of h Per members by analyzing a deep Chandra/ACIS-I observation pointed to the central field of h Per. We combined this X-ray catalog with the catalog of h Per members with measured rotational period, presented by Moraux et al. (2013). We obtained a final catalog of 202 h Per members with measured X-ray luminosity and rotational period. We investigate the rotation-activity relation of h Per members considering different mass ranges. We find that stars with 1.3 M⊙ > M 1.4 M⊙ show significant evidence of supersaturation for short periods. This phenomenon is instead not observed for lower mass stars.

Structural Characterization of Nickel Oxide

1991 ◽  
Vol 46 (6) ◽  
pp. 503-512 ◽  
Author(s):  
V. Massarotti ◽  
D. Capsoni ◽  
V. Berbenni ◽  
R. Riccardi ◽  
A. Marini ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Structural Parameters ◽  
Powder Diffraction Data ◽  
Lower Mass ◽  
X Ray ◽  
Low Mass ◽  
Refinement Procedure ◽  
Structural Characterizations ◽  
The Ideal

AbstractIt is known from the literature that a slight distortion of the ideal cubic cell is present in the NiO structure. This work shows that such a distortion can be accurately evaluated by means of a refinement of the structural and profile parameters of X-ray powder diffraction data. Moreover, since only small amounts of products are sometimes at disposal to perform structural characterizations, it was thought useful to extend the refinement procedure to X-ray data collected on NiO samples of much lower mass (15-60 mg) than those usually utilized in X-ray diffractometric studies. The results obtained show that reliable structural parameters can be obtained from low mass samples too

scholarly journals Magnetic Braking in Cataclysmic and Low-Mass X-Ray Binaries

1984 ◽  
Vol 80 ◽  
pp. 287-294
Author(s):  
O. Vilhu
Keyword(s):  
Mass Transfer ◽  
Binary Stars ◽  
Cataclysmic Variables ◽  
Turnover Time ◽  
Coronal Emission ◽  
X Ray ◽  
Compact Binaries ◽  
Gradual Loss ◽  
Low Mass ◽  
Magnetic Braking

AbstractThe chromospheric-coronal emission of lower Main-Sequence single and binary stars can be correlated with an activity parameter of type R = g(B-V)P-1 where P is the rotation or orbital period and g(B-V) a function of the color resembling the convective turnover time. Observations indicate that the active region area coverage filling factor grows as R2, and the whole stellar surface becomes filled with closed loop structures at R ≂ 3. A braking formula is proposed (Equation 4) to include all periods (0.d1 ≲ R ≳ 30d) and spectral types F-M. On the basis of this equation, the mass transfer rates in compact binaries (driven by the gradual loss of orbital angular momentum) are discussed. It is concluded that the magnetic braking has good chances of being that mechanism which drives the mass transfer in cataclysmic variables and galactic bulge X-ray sources.

scholarly journals X-ray variability analysis of a large series of XMM–Newton +NuSTAR observations of NGC 3227

2020 ◽  
Vol 494 (4) ◽  
pp. 5056-5074 ◽  
Author(s):  
A P Lobban ◽  
T J Turner ◽  
J N Reeves ◽  
V Braito ◽  
L Miller
Keyword(s):  
Maximum Likelihood ◽  
Power Spectra ◽  
Low Frequency ◽  
Light Curves ◽  
Scaling Relations ◽  
Time Lags ◽  
Likelihood Methods ◽  
X Ray ◽  
Variability Analysis ◽  
Maximum Likelihood Methods

ABSTRACT We present a series of X-ray variability results from a long XMM–Newton + NuSTAR campaign on the bright, variable AGN NGC 3227. We present an analysis of the light curves, showing that the source displays typically softer-when-brighter behaviour, although also undergoes significant spectral hardening during one observation which we interpret as due to an occultation event by a cloud of absorbing gas. We spectrally decompose the data and show that the bulk of the variability is continuum-driven and, through rms variability analysis, strongly enhanced in the soft band. We show that the source largely conforms to linear rms-flux behaviour and we compute X-ray power spectra, detecting moderate evidence for a bend in the power spectrum, consistent with existing scaling relations. Additionally, we compute X-ray Fourier time lags using both the XMM–Newton and – through maximum-likelihood methods – NuSTAR data, revealing a strong low-frequency hard lag and evidence for a soft lag at higher frequencies, which we discuss in terms of reverberation models.

scholarly journals Testing the low-mass end of X-ray scaling relations with a sample ofChandragalaxy groups

2011 ◽  
Vol 535 ◽  
pp. A105 ◽  
Author(s):  
H. J. Eckmiller ◽  
D. S. Hudson ◽  
T. H. Reiprich
Keyword(s):  
Scaling Relations ◽  
X Ray ◽  
Low Mass
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