Sizing up the population of gamma-ray binaries

Context. Gamma-ray binaries are thought to be composed of a young pulsar in orbit around a massive O or Be star with their gamma-ray emission powered by pulsar spin-down. The number of such systems in our Galaxy is not known. Aims. We aim to estimate the total number of gamma-ray binaries in our Galaxy and to evaluate the prospects for new detections in the GeV and TeV energy range, taking into account that their gamma-ray emission is modulated on the orbital period. Methods. We modelled the population of gamma-ray binaries and evaluated the fraction of detected systems in surveys with the Fermi-LAT (GeV), H.E.S.S., HAWC and CTA (TeV) using observation-based and synthetic template light curves. Results. The detected fraction depends more on the orbit-average flux than on the light-curve shape. Our best estimate for the number of gamma-ray binaries is 101\hbox{$_{-52}^{+89}$} systems. A handful of discoveries are expected by pursuing the Fermi-LAT survey. Discoveries in TeV surveys are less likely. However, this depends on the relative amounts of power emitted in GeV and TeV domains. There could be as many as ≈ 200 HESS J0632+057-like systems with a high ratio of TeV to GeV emission compared to other gamma-ray binaries. Statistics allow for as many as three discoveries in five years of HAWC observations and five discoveries in the first two years of the CTA Galactic Plane survey. Conclusions. We favour continued Fermi-LAT observations over ground-based TeV surveys to find new gamma-ray binaries. Gamma-ray observations are most sensitive to short orbital period systems with a high spin-down pulsar power. Radio pulsar surveys (SKA) are likely to be more efficient in detecting long orbital period systems, providing a complementary probe into the gamma-ray binary population.

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The Eclipsing Binary WX Eridani

International Astronomical Union Colloquium ◽

10.1017/s0252921100073656 ◽

1979 ◽

Vol 46 ◽

pp. 385

Author(s):

M.B.K. Sarma ◽

K.D. Abhankar

Keyword(s):

Light Curve ◽

Spectral Type ◽

Orbital Period ◽

Primary Component ◽

Light Curves ◽

Absorption Feature ◽

Primary Star ◽

Eclipsing Binary ◽

The Times ◽

Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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The connection between the 15 GHz radio and gamma-ray emission in blazars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315001799 ◽

2014 ◽

Vol 10 (S313) ◽

pp. 17-20

Author(s):

W. Max-Moerbeck ◽

J. L. Richards ◽

T. Hovatta ◽

V. Pavlidou ◽

T. J. Pearson ◽

...

Keyword(s):

Gamma Ray ◽

Statistical Tests ◽

High Energy ◽

Light Curves ◽

Owens Valley ◽

Noise Characteristics ◽

Power Spectral ◽

Emission Models ◽

Gamma Ray Emission ◽

Many Sources

AbstractSince mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope (OVRO 40m). One of the main goals of this programme is to study the relation between the radio and gamma-ray emission in blazars and to use it as a tool to locate the site of high energy emission. Using this large sample of objects we are able to characterize the radio variability, and study the significance of correlations between the radio and gamma-ray bands. We find that the radio variability of many sources can be described using a simple power law power spectral density, and that when taking into account the red-noise characteristics of the light curves, cases with significant correlation are rare. We note that while significant correlations are found in few individual objects, radio variations are most often delayed with respect to the gamma-ray variations. This suggests that the gamma-ray emission originates upstream of the radio emission. Because strong flares in most known gamma-ray-loud blazars are infrequent, longer light curves are required to settle the issue of the strength of radio-gamma cross-correlations and establish confidently possible delays between the two. For this reason continuous multiwavelength monitoring over a longer time period is essential for statistical tests of jet emission models.

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Long-term Photometric Monitoring of FUor and FUor-like Objects

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2018.2.2-240 ◽

2018 ◽

pp. 240-248

Author(s):

E. Semkov ◽

S. Ibryamov ◽

S. Peneva ◽

A. Mutafov

Keyword(s):

Light Curve ◽

Significant Role ◽

Stellar Evolution ◽

Photographic Plate ◽

Light Curves ◽

Curve Shape ◽

Rate Of Increase ◽

Fu Ori ◽

Photometric Monitoring

A phenomenon with a significant role in stellar evolution is the FU Orionis (FUor) type of outburst. The first three (classical) FUors (FU Ori, V1515 Cyg and V1057 Cyg) are well-studied and their light curves are published in the literature. But recently, over a dozen new objects of this type were discovered, whose photometric history we do not know well. Using recent data from photometric monitoring and data from the photographic plate archives we aim to study, the long-term photometric behavior of FUor and FUor-like objects. The construction of the historical light curves of FUors could be very important for determining the beginning of the outburst, the time to reach the maximum light, the rate of increase and decrease in brightness, the pre-outburst variability of the star. So far we have published our results for the light curves of V2493 Cyg, V582 Aur, Parsamian 21 and V1647 Ori. In this paper we present new data that describe more accurate the photometric behavior of these objects. In comparing our results with light curves of the well-studied FUors (FU Ori, V1515 Cyg and V1057 Cyg), we conclude that every object shows different photometric behavior. Each known FUor has a different rate of increase and decrease in brightness and a different light curve shape.

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STUDY OF THE DIFFUSE GAMMA-RAY EMISSION FROM THE GALACTIC PLANE WITH ARGO-YBJ

The Astrophysical Journal ◽

10.1088/0004-637x/806/1/20 ◽

2015 ◽

Vol 806 (1) ◽

pp. 20 ◽

Cited By ~ 28

Author(s):

B. Bartoli ◽

P. Bernardini ◽

X. J. Bi ◽

P. Branchini ◽

A. Budano ◽

...

Keyword(s):

Gamma Ray ◽

Galactic Plane ◽

Gamma Ray Emission

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Precursors of short gamma-ray bursts detected by the INTEGRAL observatory

International Journal of Modern Physics D ◽

10.1142/s0218271818440133 ◽

2018 ◽

Vol 27 (10) ◽

pp. 1844013 ◽

Cited By ~ 1

Author(s):

Pavel Minaev ◽

Alexei Pozanenko ◽

Sergei Molkov

Keyword(s):

Statistical Analysis ◽

Light Curve ◽

Relative Intensity ◽

Gamma Ray ◽

Convincing Evidence ◽

Gamma Ray Bursts ◽

Light Curves ◽

Upper Limits ◽

Short Grbs

We have analyzed the light curves of 527 short gamma-ray bursts (GRBs) registered by the SPI-ACS, SPI and IBIS/ISGRI experiments of INTEGRAL observatory totally to search for precursors. Both the light curves of each 527 individual burst and the averaged light curve of 372 brightest SPI-ACS bursts have been analyzed. In a few cases, we have found and investigated precursor candidates using SPI-ACS, SPI and IBIS/ISGRI of INTEGRAL, GBM and LAT of Fermi data. No convincing evidence for the existence of precursors of short GRBs has been found. A statistical analysis of the averaged light curve for the sample of brightest short bursts has revealed no regular precursor. Upper limits for the relative intensity of precursors have been estimated. We show that the fraction of short GRBs with precursors is less than 0.4% of all short bursts, detected by INTEGRAL.

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Properties of CVSO 30 from TESS measurements: probably a binary T Tauri star with complex light curves and no obvious planets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1038 ◽

2020 ◽

Vol 494 (3) ◽

pp. 4349-4356

Author(s):

C Koen

Keyword(s):

Light Curve ◽

Small Group ◽

T Tauri Stars ◽

Light Curves ◽

Tauri Star ◽

Curve Shape ◽

T Tauri

ABSTRACT ‘Transiting Exoplanet Survey Satellite’ (TESS) photometry of CVSO 30 spanned 21.8 d, with a single large gap of 1.1 d. This allows alias-free determination of the two periodicities in the data. It is confirmed that both of these are non-sinusoidal: the dominant P1 = 0.4990 d has two detectable harmonics and P2 = 0.4486 d has seven. The large number of harmonics in the second periodicity characterizes a very complex light curve shape. One of the features in the light curve is a sharp dip of duration ∼2 h: this is probably the source of the previously claimed planetary transit signature. The star is a member of a small group of T Tauri stars with complex light curves, which have recently been exhaustively studied using Kepler and TESS observations. The two non-commensurate periods are most simply interpreted as being from two stars, i.e. CVSO 30 is probably a binary.

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Using gamma ray monitoring to avoid missing the next Milky Way Type Ia supernova

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz993 ◽

2019 ◽

Vol 486 (2) ◽

pp. 2910-2918 ◽

Cited By ~ 2

Author(s):

Xilu Wang (王夕露) ◽

Brian D Fields ◽

Amy Yarleen Lien (連雅琳)

Keyword(s):

Gamma Rays ◽

Milky Way ◽

Gamma Ray ◽

Galactic Plane ◽

Early Warning Systems ◽

Light Curves ◽

X Rays ◽

Warning Systems ◽

Type Ia Supernova ◽

Type Ia

Abstract A Milky Way Type Ia supernova (SNIa) could be unidentified or even initially unnoticed, being dim in radio, X-rays, and neutrinos, and suffering large optical/IR extinction in the Galactic plane. But SNIa emit nuclear gamma-ray lines from 56Ni → 56Co → 56Fe radioactive decays. These lines fall within the Fermi/GBM energy range, and the 56Ni 158 keV line is detectable by Swift/BAT. Both instruments frequently monitor the Galactic plane, which is transparent to gamma rays. Thus GBM and BAT are ideal Galactic SNIa early warning systems. We simulate SNIa MeV light curves and spectra to show that GBM and BAT could confirm a Galactic SNIa explosion, followed by Swift localization and observation in X-rays and UVOIR band. The time of detection depends sensitively on the 56Ni distribution, and can be as early as a few days if ${\gtrsim } 10{{\ \rm per\ cent}}$ of the 56Ni is present in the surface as suggested by SN2014J gamma data.

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Period-Luminosity-Shape of Light Curve Relation for Cepheids in LMC and SMC

Symposium - International Astronomical Union ◽

10.1017/s0074180900216768 ◽

2005 ◽

Vol 201 ◽

pp. 480-481

Author(s):

P. Ligeza ◽

P. Moskalik ◽

A. Schwarzenberg-Czerny

Keyword(s):

Light Curve ◽

Principal Components Analysis ◽

Principal Components ◽

Fundamental Mode ◽

Light Curves ◽

Analysis Of Covariance ◽

Curve Shape ◽

Long Period ◽

Classical Cepheids ◽

Components Analysis

In this paper we report our analysis of the period-luminosity-shape of light curve (P-L-S) relation. The data we used came from LMC and SMC Cepheid light curves produced by OGLE-II microlensing survey. We used Principal Components Analysis of covariance matrix of the sets for Cepheids in LMC and SMC separately. Our calibrating set was bounded to long period classical Cepheids pulsating in fundamental mode. The results are used to derive a method for estimation of distances from light curve shape.

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Supersoft X-ray phases of recurrent novae as an indicator of their white dwarf masses

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psaa071 ◽

2020 ◽

Vol 72 (5) ◽

Author(s):

Mariko Kato ◽

Izumi Hachisu

Keyword(s):

Light Curve ◽

White Dwarf ◽

Total Duration ◽

Simple Relation ◽

Light Curves ◽

Curve Shape ◽

Plateau Phase ◽

Hydrogen Burning ◽

X Ray ◽

Recurrent Nova

Abstract We have examined the optical/X-ray light curves of seven well-observed recurrent novae, V745 Sco, M31N 2008-12a, LMC N 1968, U Sco, RS Oph, LMC N 2009a, T Pyx, and one recurrent nova candidate LMC N 2012a. Six novae out of the eight show a simple relation that the duration of supersoft X-ray source (SSS) phase is 0.70 times the total duration of the outburst (= X-ray turnoff time), i.e., tSSS = 0.70 toff, the total duration of which ranges from 10 to 260 d. These six recurrent novae show a broad rectangular X-ray light curve shape, the first half-period of which is highly variable in the X-ray count rate. The SSS phase also corresponds to an optical plateau phase that indicates a large accretion disk irradiated by a hydrogen-burning white dwarf (WD). The two other recurrent novae, T Pyx and V745 Sco, show a narrow triangular-shaped X-ray light curve without an optical plateau phase. Their relations between tSSS and toff are rather different from the above six recurrent novae. We also present theoretical SSS durations for recurrent novae with various WD masses and stellar metallicities (Z = 0.004, 0.01, 0.02, and 0.05) and compare them with the observed durations of these recurrent novae. We show that SSS duration is a good indicator of WD mass in recurrent novae with a broad rectangular X-ray light curve shape.

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