Breaking the Degeneracy in Magnetic Cataclysmic Variable X-Ray Spectral Modeling Using X-Ray Light Curves

Aims. We aimed to identify the variable X-ray source 3XMM J000511.8+634018, which was serendipitously discovered through routine inspections while the 3XMM catalogue was compiled. Methods. We analysed the archival XMM-Newton observation of the source, obtained BUSCA photometry in three colours, and performed optical spectroscopy with the LBT. These data were supplemented by archival observations from the Zwicky Transient Facility. Results. Based on its optical and X-ray properties, 3XMM J000511.8+634018 is classified as a magnetic cataclysmic variable, or polar. The flux is modulated with a period of 2.22 h (8009.1 ± 0.2 s), which we identify with the orbital period. The bright phases are highly variable in X-ray luminosity from one cycle to the next. The source shows a thermal plasma spectrum typical of polars without evidence of a luminous soft blackbody-like component. It is non-eclipsing and displays one-pole accretion. The X-ray and BUSCA light curves show a stream absorption dip, which suggests an inclination 50° < i < 75°. The phasing of this feature, which occurs at the end of the bright phase, requires a somewhat special accretion geometry with a stream running far around the white dwarf before it is magnetically channelled. The period of this polar falls within the period gap of the cataclysmic variables (2.15−3.18 h), but appears to fall just below the minimum period when only polars are considered.

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A minimal timescale for the continuum in 4U 1608-52 and Aql X-1

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slab004 ◽

2021 ◽

Vol 502 (1) ◽

pp. L72-L78

Author(s):

K Mohamed ◽

E Sonbas ◽

K S Dhuga ◽

E Göğüş ◽

A Tuncer ◽

...

Keyword(s):

Black Hole ◽

Neutron Star ◽

Power Spectra ◽

Light Curves ◽

State Transitions ◽

Strong Positive Correlation ◽

Present Evidence ◽

X Ray ◽

X Ray Binaries ◽

The Continuum

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.

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The study of multipeaked type-I X-ray bursts in the neutron star low-mass X-ray binary 4U 1636 − 536 with RXTE

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3539 ◽

2020 ◽

Vol 501 (1) ◽

pp. 168-178

Author(s):

Chen Li ◽

Guobao Zhang ◽

Mariano Méndez ◽

Jiancheng Wang ◽

Ming Lyu

Keyword(s):

Neutron Star ◽

Flux Ratio ◽

Light Curves ◽

Type I ◽

X Ray ◽

Soft State ◽

Peak Flux ◽

Low Mass ◽

Two Peaks ◽

Second Peak

ABSTRACT We have found and analysed 16 multipeaked type-I bursts from the neutron-star low-mass X-ray binary 4U 1636 − 53 with the Rossi X-ray Timing Explorer (RXTE). One of the bursts is a rare quadruple-peaked burst that was not previously reported. All 16 bursts show a multipeaked structure not only in the X-ray light curves but also in the bolometric light curves. Most of the multipeaked bursts appear in observations during the transition from the hard to the soft state in the colour–colour diagram. We find an anticorrelation between the second peak flux and the separation time between two peaks. We also find that in the double-peaked bursts the peak-flux ratio and the temperature of the thermal component in the pre-burst spectra are correlated. This indicates that the double-peaked structure in the light curve of the bursts may be affected by enhanced accretion rate in the disc, or increased temperature of the neutron star.

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Hydrodynamic Models of Solar and Stellar Flares

International Astronomical Union Colloquium ◽

10.1017/s0252921100031948 ◽

1989 ◽

Vol 104 (1) ◽

pp. 289-298

Author(s):

Giovanni Peres

Keyword(s):

High Resolution ◽

Light Curve ◽

Solar Flares ◽

Impulsive Phase ◽

Light Curves ◽

Physical Parameters ◽

The Sun ◽

Hydrodynamic Models ◽

X Ray ◽

Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

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AN EXTENDED AND MORE SENSITIVE SEARCH FOR PERIODICITIES IN ROSSI X-RAY TIMING EXPLORER /ALL-SKY MONITOR X-RAY LIGHT CURVES

The Astrophysical Journal Supplement Series ◽

10.1088/0067-0049/196/1/6 ◽

2011 ◽

Vol 196 (1) ◽

pp. 6 ◽

Cited By ~ 37

Author(s):

Alan M. Levine ◽

Hale V. Bradt ◽

Deepto Chakrabarty ◽

Robin H. D. Corbet ◽

Robert J. Harris

Keyword(s):

Light Curves ◽

X Ray ◽

Sky Monitor

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TRANSIENT EXTREMELY SOFT X-RAY EMISSION FROM THE UNUSUALLY BRIGHT CATACLYSMIC VARIABLE IN THE GLOBULAR CLUSTER M3: A NEW CV X-RAY LUMINOSITY RECORD?

The Astrophysical Journal ◽

10.1088/0004-637x/732/1/46 ◽

2011 ◽

Vol 732 (1) ◽

pp. 46 ◽

Cited By ~ 9

Author(s):

W. S. Stacey ◽

C. O. Heinke ◽

R. F. Elsner ◽

P. D. Edmonds ◽

M. C. Weisskopf ◽

...

Keyword(s):

Globular Cluster ◽

Cataclysmic Variable ◽

X Ray

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Are the missing X-ray breaks in gamma-ray burst afterglow light curves merely hidden?

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2008.13043.x ◽

2008 ◽

Vol 386 (2) ◽

pp. 859-863 ◽

Cited By ~ 28

Author(s):

P. A. Curran ◽

A. J. van der Horst ◽

R. A. M. J. Wijers

Keyword(s):

Gamma Ray ◽

Light Curves ◽

Gamma Ray Burst ◽

X Ray

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Analysis of IR and X-ray Light Curves of Cyg X-3

Ground-Based Astronomy in Russia. 21st Century. Proceedings of the All-Russian Conference ◽

10.26119/978-5-6045062-0-2_2020_214 ◽

2020 ◽

Author(s):

I. I. Antokhin ◽

A. M. Cherepashchuk ◽

E. A. Antokhina ◽

A. M. Tatarnikov

Keyword(s):

Light Curves ◽

X Ray

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The Intermediate Polars

International Astronomical Union Colloquium ◽

10.1017/s0252921100090291 ◽

1983 ◽

Vol 72 ◽

pp. 155-172

Author(s):

Brian Warner

Keyword(s):

Magnetic Fields ◽

White Dwarf ◽

Variable Star ◽

Theoretical Models ◽

Cataclysmic Variable ◽

General Role ◽

X Ray ◽

Low Mass ◽

Intermediate Polars ◽

X Ray Binaries

Until 1976, cataclysmic variable star research proceeded with few requirements for the inclusion of magnetic fields in theoretical models. Although models for low-mass X-ray binaries stressed the importance of magnetic fields (Lamb et at. 1973) and there was an increasing number of known magnetic single white dwarfs (Angel 1977), and a magnetised white dwarf had been one of the models proposed to explain the rapid oscillations in DQ Her (Herbst et al. 1974, Katz 1975), there was no anticipation of the more general role that magnetic fields now seem destined to play. The two major reviews of the time (Robinson 1976, Warner 1976) scarcely considered the presence of magnetic fields.

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A flare in the optical spotted in the changing-look Seyfert NGC 3516

Astronomy and Astrophysics ◽

10.1051/0004-6361/202037532 ◽

2020 ◽

Vol 638 ◽

pp. A13 ◽

Cited By ~ 1

Author(s):

D. Ilić ◽

V. Oknyansky ◽

L. Č. Popović ◽

S. S. Tsygankov ◽

A. A. Belinski ◽

...

Keyword(s):

Maximum Amplitude ◽

Light Curves ◽

Continuum Emission ◽

X Ray ◽

The Past ◽

Broad Component ◽

High Ionization ◽

Balmer Lines ◽

Activity State ◽

Low Activity

Context. We present observations from the short-term intensive optical campaign (from September 2019 to January 2020) of the changing-look Seyfert NGC 3516. This active galactic nucleus is known to have strong optical variability and has changed its type in the past. It has been in the low-activity state in the optical since 2013, with some rebrightening from the end of 2015 to the beginning of 2016, after which it remained dormant. Aims. We aim to study the photometric and spectral variability of NGC 3516 from the new observations in U- and B-bands and examine the profiles of the optical broad emission lines in order to demonstrate that this object may be entering a new state of activity. Methods. NGC 3516 has been monitored intensively for the past 4 months with an automated telescope in U and B filters, enabling accurate photometry of 0.01 precision. Spectral observations were triggered when an increase in brightness was spotted. We support our analysis of past-episodes of violent variability with the UV and X-ray long-term light curves constructed from the archival Swift/UVOT and Swift/XRT data. Results. An increase of the photometric magnitude is seen in both U and B filters to a maximum amplitude of 0.25 mag and 0.11 mag, respectively. During the flare, we observe stronger forbidden high-ionization iron lines ([Fe VII] and [Fe X]) than reported before, as well as the complex broad Hα and Hβ lines. This is especially seen in Hα, which appears to be double-peaked. It seems that a very broad component of ∼10 000 km s−1 in width in the Balmer lines is appearing. The trends in the optical, UV, and X-ray light curves are similar, with the amplitudes of variability being significantly larger in the case of UV and X-ray bands. Conclusions. The increase of the continuum emission, the variability of the coronal lines, and the very broad component in the Balmer lines may indicate that the AGN of NGC 3516 is finally leaving the low-activity state in which it has been for the last ∼3 years.

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