arXiv subjects

Benjamin Steltner

Publications and source records attributed to Benjamin Steltner.

10 recordsLinked to original sources

arXiv2026

Search for continuous gravitational waves from the pulsar J0435+3233

We perform a search for continuous gravitational waves from J0435+3233 using LIGO O4a public data. J0435+3233 is unique among millisecond pulsars as it exhibits an exceptionally large spin-down and marks the first pulsar observed to date with a spin-down larger than $10^{-12}$ Hz/s in the sub $10$ ms spin period range, making it a potentially strong source of continuous gravitational waves. We target signals at exactly twice the rotation frequency, a narrow band around this frequency, and also signals corresponding to r-modes. Our results are consistent with a non-detection. Our most stringent upper limit on the intrinsic gravitational wave amplitude at 95\% confidence is $h_0=5.8\times10^{-27}$. With an estimated source distance of 1.2 kpc this upper limit constraints the ellipticity to be smaller greater than $1.6\times10^{-8}$. If the observed spin-down is all intrinsic, this is the first source for which the spin-down upper limit is beaten by over an order of magnitude and the ellipticity is constrained to the physically very interesting range of the low $10^{-8}$ region.

gr-qc↗

arXiv2026

Pulsar Discoveries from the TRAPUM UHF Survey of Fermi-LAT Sources

The Fermi Large Area Telescope (LAT) provides advantages for radio pulsar searches by enabling efficient target selection. We can confidently point radio telescopes to the positions of Fermi unidentified gamma-ray sources that have a high probability of hosting a pulsar. As part of Transients and Pulsars with MeerKAT (TRAPUM), we conducted a survey of Fermi-LAT sources using the Ultra High Frequency (UHF; 544-1088 MHz) receiver of the MeerKAT radio telescope. We observed 79 sources that were identified as pulsar-like candidates using a random forest technique from the Fermi-LAT Fourth Source Catalogue. We observed each target for 10 minutes at two separate epochs. As a result, we discovered nine new millisecond pulsars (MSPs) and six slow pulsars. Based on the radio discoveries, we also searched for gamma-ray pulsations, confirming that seven of the newly discovered MSPs are associated with Fermi-LAT sources, and performed joint radio and gamma-ray pulsar timing. Companion mass estimates and evidence of radio eclipses indicate that among the nine MSPs there are three black widows and three redbacks. Lastly, we compared the discovered pulsars in the MeerKAT UHF survey against the previous Fermi sources TRAPUM survey at L band, concluding the superiority of UHF observations in sensitivity to fainter pulsars and in detection rate than L band for finding new gamma-ray MSPs.

astro-ph.HE↗

arXiv2025

High-frequency continuous gravitational waves searched in LIGO O3 public data with Einstein@Home

We search for nearly-monochromatic gravitational wave signals with frequencies $800.0~\textrm{Hz} \leq f \leq 1686.0~\textrm{Hz}$ and spin-down $-2.7\times10^{-9}~\textrm{Hz}\,\textrm{s}^{-1} \leq \dot f \leq 0.2\times 10^{-9}~\textrm{Hz}\,\textrm{s}^{-1}$. We use LIGO O3 public data from the Hanford and Livingston detectors and deploy this search on the Einstein@Home volunteer-computing project. This is the most sensitive search carried out to date in this parameter space. Our results are consistent with a non-detection. We set upper limits on the gravitational wave amplitude $h_{0}$ and translate these to upper limits on neutron star ellipticity and on r-mode amplitude. The most stringent upper limits are at $800~\textrm{Hz}$ with $h_{0} = 1.32\times10^{-25}$, at the $90\%$ confidence level. Searching in the high frequency bands allows us to probe astrophysically interesting ellipticities with our results excluding isolated neutron stars rotating faster than $2.5~\textrm{ms}$ with ellipticities $\epsilon \geq 1.96 \times 10^{-8}\left[\frac{d}{100~\textrm{pc}}\right]$ within a distance $d$ from Earth. Our results also exclude r-mode amplitudes $\alpha \geq 7 \times 10^{-7}\left[\frac{d}{100~\textrm{pc}}\right]$ for neutron stars stars spinning faster than 400 Hz.

gr-qc↗

arXiv2025

Bayesian Framework to Follow-up Continuous Gravitational Wave Candidates from Deep Surveys

Broad all-sky searches for continuous gravitational waves have high computational costs and require hierarchical pipelines. The sensitivity of these approaches is set by the initial search and by the number of candidates from that stage that can be followed up. The current follow-up schemes for the deepest surveys require careful tuning and set-up, have a significant human-labor cost and this impacts the number of follow-ups that can be afforded. Here we present and demonstrate a new follow-up framework based on Bayesian parameter estimation for the rapid, highly automated follow-up of candidates produced by the early stages of deep, wide-parameter space searches for continuous waves.

gr-qc↗

arXiv2025

Einstein@Home all-sky "bucket" search for continuous gravitational waves in LIGO O3 public data

We conduct an all-sky search for continuous gravitational waves using LIGO O3 public data from the Hanford and Livingston detectors. We search for nearly-monochromatic signals with frequencies $30\, \text{Hz} \leq f \leq 250\, \text{Hz}$ and spin-down $-2.7 \times 10^{-9}\, \text{Hz/s} \leq \dot{f} \leq 0.2 \times 10^{-9}\, \text{Hz/s}$. We deploy this search on the Einstein@Home volunteer-computing project and on three super computer clusters; the Atlas supercomputer at the Max Planck Institute for Gravitational Physics, and the two high performance computing systems Raven and Viper at the Max Planck Computing and Data Facility. Our results are consistent with a non-detection. We set upper limits on the gravitational wave amplitude $h_{0}$, and translate these to upper limits on the neutron star ellipticity and on the r-mode amplitude. The most stringent upper limits are at 173 Hz with $h_{0} = 6.5\times 10^{-26}$, at the 90% confidence level.

gr-qc↗

arXiv2022

Density-clustering of continuous gravitational wave candidates from large surveys

Searches for continuous gravitational waves target nearly monochromatic gravitational wave emission from e.g. non-axysmmetric fast-spinning neutron stars. Broad surveys often require to explicitly search for a very large number of different waveforms, easily exceeding $\sim10^{17}$ templates. In such cases, for practical reasons, only the top, say $\sim10^{10}$, results are saved and followed-up through a hierarchy of stages. Most of these candidates are not completely independent of neighbouring ones, but arise due to some common cause: a fluctuation, a signal or a disturbance. By judiciously clustering together candidates stemming from the same root cause, the subsequent follow-ups become more effective. A number of clustering algorithms have been employed in past searches based on iteratively finding symmetric and compact over-densities around candidates with high detection statistic values. The new clustering method presented in this paper is a significant improvement over previous methods: it is agnostic about the shape of the over-densities, is very efficient and it is effective: at a very high detection efficiency, it has a noise rejection of $99.99\%$ , is capable of clustering two orders of magnitude more candidates than attainable before and, at fixed sensitivity it enables more than a factor of 30 faster follow-ups. We also demonstrate how to optimally choose the clustering parameters.

gr-qc↗

arXiv2021

Results from an Einstein@Home search for continuous gravitational waves from G347.3 at low frequencies in LIGO O2 data

We present results of a search for periodic gravitational wave signals with frequency between 20 and 400 Hz, from the neutron star in the supernova remnant G347.3-0.5, using LIGO O2 public data. The search is deployed on the volunteer computing project Einstein@Home, with thousands of participants donating compute cycles to make this endevour possible. We find no significant signal candidate and set the most constraining upper limits to date on the amplitude of gravitational wave signals from the target, corresponding to deformations below $10^{-6}$ in a large part of the band. At the frequency of best strain sensitivity, near $166$ Hz, we set 90\%\ confidence upper limits on the gravitational wave intrinsic amplitude of $h_0^{90\%}\approx 7.0\times10^{-26}$. Over most of the frequency range our upper limits are a factor of 20 smaller than the indirect age-based upper limit.

gr-qc↗

arXiv2021

New searches for continuous gravitational waves from seven fast pulsars

We conduct searches for continuous gravitational waves from seven pulsars, that have not been targeted in continuous wave searches of Advanced LIGO data before. We target emission at exactly twice the rotation frequency of the pulsars and in a small band around such frequency. The former search assumes that the gravitational wave quadrupole is changing phase-locked with the rotation of the pulsar. The search over a range of frequencies allows for differential rotation between the component emitting the radio signal and the component emitting the gravitational waves, for example the crust or magnetosphere versus the core. Timing solutions derived from the Arecibo 327-MHz Drift-Scan Pulsar Survey (AO327) observations are used. No evidence of a signal is found and upper limits are set on the gravitational wave amplitude. For one of the pulsars we probe gravitational wave intrinsic amplitudes just a factor of 3.8 higher than the spin-down limit, assuming a canonical moment of inertia of $10^{38}$ kg m$^2$. Our tightest ellipticity constraint is $1.5 \times 10^{-8}$, which is a value well within the range of what a neutron star crust could support.

astro-ph.HE↗

arXiv2021

Identification and removal of non-Gaussian noise transients for gravitational wave searches

We present a new ${\it{gating}}$ method to remove non-Gaussian noise transients in gravitational wave data. The method does not rely on any a-priori knowledge on the amplitude or duration of the transient events. In light of the character of the newly released LIGO O3a data, glitch-identification is particularly relevant for searches using this data. Our method preserves more data than previously achieved, while obtaining the same, if not higher, noise reduction. We achieve a $\approx$ 2-fold reduction in zeroed-out data with respect to the gates released by LIGO on the O3a data. We describe the method and characterise its performance. While developed in the context of searches for continuous signals, this method can be used to prepare gravitational wave data for any search. As the cadence of compact binary inspiral detections increases and the lower noise level of the instruments unveils new glitches, excising disturbances effectively, precisely, and in a timely manner, becomes more important. Our method does this. We release the source code associated with this new technique and the gates for the newly released O3 data.

gr-qc↗

arXiv2019

Loosely coherent search in LIGO O1 data for continuous gravitational waves from Terzan 5 and the galactic center

We report results of a search for continuous gravitational waves from a region covering the globular cluster Terzan 5 and the galactic center. Continuous gravitational waves are expected from fast-spinning, slightly non-axisymmetric isolated neutron stars as well as more exotic objects. The regions that we target are believed to be unusually abundant in neutron stars. We use a new loosely coherent search method that allows to reach unprecedented levels of sensitivity for this type of search. The search covers the frequency band 475-1500 Hz and frequency time derivatives in the range of [-3e-8, +1e-9] Hz/s, which is a parameter range not explored before with the depth reached by this search. As to be expected with only a few months of data from the same observing run, it is very difficult to make a confident detection of a continuous signal over such a large parameter space. A list of parameter space points that passed all the thresholds of this search is provided. We follow-up the most significant outlier on the newly released O2 data and cannot confirm it. We provide upper limits on the gravitational wave strength of signals as a function of signal frequency.

gr-qc↗