<b>RobPer</b>: An<i>R</i>Package to Calculate Periodograms for Light Curves Based on Robust Regression

Thieler, Anita Monika; Fried, Roland; Rathjens, Jonathan

doi:10.18637/jss.v069.i09

Cited by 19 publications

(10 citation statements)

References 46 publications

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“…The main problem associated with these measurements is that the classic Fourier periodogram analysis cannot be applied to irregularly sampled databases (e.g. Thieler et al 2013a). For the same reasons, the Deeming (1975) periodogram is not adequate as it is known to react to periodicities in the sampling (see e.g.…”

Section: Discussionmentioning

confidence: 99%

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An eclipsing binary black hole candidate system in the blazar Mrk 421

Benitez,

Cabrera,

Fraija

et al. 2015

Preprint

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Removing outbursts from multiwavelength light curves of the blazar Mrk 421, we construct outburstless time series for this system. A model-independent power spectrum light curve analysis in the optical, hard X-ray and γ-rays for this outburstless state and also the full light-curves, show clear evidence for a periodicity of ≈ 310 days across all wavelengths studied. A subsequent full maximum likelihood analysis fitting an eclipse model confirms a periodicity of 310 ± 1 days. The power spectrum of the signal in the outburstless state of the source does not follow a flicker noise behaviour and so, the system producing it is not self-organised. This and the fact that the periodicity is better defined in the outburstless state, strongly suggests that it is not produced by any internal physical processes associated to the central engine. The simplest physical mechanism to which this periodicity could be ascribed is a dynamical effect produced by an orbiting supermassive black hole companion eclipsing the central engine. Interestingly, the optimal eclipse model infers a brightness enhancement of (136.4 ± 20) %, suggesting an eclipse resulting in a gravitational lensing brightening. Consisting with this interpretation, the eclipse occurs for only (9.7 ± 0.2) % of the orbital period.

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Section: Discussionmentioning

confidence: 99%

“…Cumming et al 1999;Zechmeister & Kürster 2009). The R package RobPer (Thieler et al 2013a), incorporates more complex periodic functions in the fitting process such as periodic splines (e.g. Gaidos et al 1996;Oh et al 2004) which provide more robust results.…”

Section: Discussionmentioning

confidence: 99%

An eclipsing binary black hole candidate system in the blazar Mrk 421

Benitez,

Cabrera,

Fraija

et al. 2015

Preprint

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“…A6 or A8. These calculations were performed with the R package RobPer (Thieler et al 2016). The potentially valid periods were initially determined by a hypothesis test based on a Beta distribution (Thieler et al 2013) or by bootstrapping of the periodogram.…”

Section: Period Determinationmentioning

confidence: 99%

“…For method L2Beta the periodogram and critical value for the hypothesis test are obtained from the R package Robper (Thieler et al 2016). The periodogram for L2Boot is also obtained from the same package, but the critical value is obtained by bootstrapping the periodogram.…”

Section: Data Availability Statementmentioning

confidence: 99%

A survey for variable young stars with small telescopes – IV. Rotation periods of YSOs in IC 5070

Froebrich

Derezea

Scholz

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Studying rotational variability of young stars is enabling us to investigate a multitude of properties of young star-disc systems. We utilize high cadence, multiwavelength optical time series data from the Hunting Outbursting Young Stars citizen science project to identify periodic variables in the Pelican Nebula (IC 5070). A double blind study using nine different period-finding algorithms was conducted and a sample of 59 periodic variables was identified. We find that a combination of four period finding algorithms can achieve a completeness of 85 per cent and a contamination of 30 per cent in identifying periods in inhomogeneous data sets. The best performing methods are periodograms that rely on fitting a sine curve. Utilizing Gaia EDR3 data, we have identified an unbiased sample of 40 periodic young stellar objects (YSOs), without using any colour or magnitude selections. With a 98.9 per cent probability, we can exclude a homogeneous YSO period distribution. Instead, we find a bi-modal distribution with peaks at 3 and 8 d. The sample has a disc fraction of 50 per cent, and its statistical properties are in agreement with other similarly aged YSOs populations. In particular, we confirm that the presence of the disc is linked to predominantly slow rotation and find a probability of 4.8 × 10−3 that the observed relation between period and presence of a disc has occurred by chance. In our sample of periodic variables, we also find pulsating giants, an eclipsing binary, and potential YSOs in the foreground of IC 5070.

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“…The shape parameters of beta distribution were found on the basis of the experimental data by means of the betaCvMfit function of the R [25] package RobPer [26]. The estimation of the mean of plant cover projection was done as follows:…”

Section: Data Analysesmentioning

confidence: 99%

The Small-Scale Variation of Herb-Layer Community Structure in a Riparian Mixed Forest

Zhukova¹,

Demchuk

Yorkina

et al. 2021

ILNS

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The role of spatial variables, soil properties and overstorey structure in spatial variation of the herb-layer community in a riparian mixed forest was shown. The research were conducted in the "Dnipro-Orils’kiy" Nature Reserve (Ukraine). The research polygon was laid in a forest in the floodplain of the River Protich, which is a left inflow of the River Dnipro. Plant abundance was quantified by measuring cover within experimental polygon. The experimental polygon consisted of 7 transects and each transect was made up of 15 test points. The distance between rows in the site was 3 m. At the site we established a plot of 45×21 m, with 105 subplots of 3×3 m organized in a regular grid. Vascular plant species lists were recorded for each 3×3 m subplot along with visual estimates of species cover projection. The plant community was represented by 43 species, of which 18.6% were phanerophytes, 39.5% were hemikriptophytes, 9.3% were therophytes, 7.0% were geophytes. An overall test of random labelling revealed the total nonrandom distribution of the tree stems within the site. Constrained correspondence analysis (CCA) was applied as ordination approach. The forward selection procedure allowed us to select 6 soil variables, which explain 28.3% of the herb-layer community variability. The list of the important soil variables includes soil mechanical impedance (at the depth 0–5, 30–35, 75–80, and 95–10 cm), soil moisture, and soil bulk density. The variation explained by pure spatial variables is equal to 11.0 %. The majority of the tree-distance structured variation in plant community composition was broad-scaled. The significant relationship was found between the pure spatial component of the community variation and a lot of phytoindicator estimations of which the variability of damping and humidity were of the greatest importance. Trees stand was demonstrated to be a considerable factor structuring both the herb-layer community and spatial variation of the physical properties of soil.

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RobPer: AnRPackage to Calculate Periodograms for Light Curves Based on Robust Regression

Cited by 19 publications

References 46 publications

An eclipsing binary black hole candidate system in the blazar Mrk 421

An eclipsing binary black hole candidate system in the blazar Mrk 421

A survey for variable young stars with small telescopes – IV. Rotation periods of YSOs in IC 5070

The Small-Scale Variation of Herb-Layer Community Structure in a Riparian Mixed Forest

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