Failed Experiment ReportOpen accessPhysics
D. Bojiloff, M. Tajmar · 2015 · arXiv
In the year 2002 publications of A.V.M. Khachatourian and A.O. Wistrom were released, in which the existence of an electrostatic torque has been claimed. This moment of force should act in a three sphere configuration, where one sphere is held at a constant electric potential. This claim was based on an observed rotation and was supported by a mathematical solution derived by Wistrom and Khachatourian. The theoretical work of Wistrom and Khachatourian as well as the interpretation of the observed rotation were criticized by several scientists who offered alternative explanations for the rotati
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Kim-Vy H. Tran, Simon J. Lilly, David Crampton et al. · 2004 · arXiv
We present results from a deep spectroscopic search in the 9150A atmospheric window for z~6.5 Lyman-alpha emitting galaxies using the VLT/FORS2. Our multi-slit+narrow-band filter survey covers a total spatial area of 17.6 sq. arcmin in four different fields and reaches fluxes down to 5x10^(-18) erg/s/cm^2 (7 sigma detection). Our detection limit is significantly fainter than narrow-band searches at this redshift and fainter also than the unlensed brightness of Hu et al.'s HCM6A at z=6.56, and thus provides better overlap with surveys at much lower redshifts. Eighty secure emission line galaxie
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A. T. Deller, J. P. W. Verbiest, S. J. Tingay et al. · 2008 · arXiv
Using the recently upgraded Long Baseline Array, we have measured the trigonometric parallax of PSR J0437-4715 to better than 1% precision, the most precise pulsar distance determination made to date. Comparing this VLBI distance measurement to the kinematic distance obtained from pulsar timing, which is calculated from the pulsar's proper motion and apparent rate of change of orbital period, gives a precise limit on the unmodeled relative acceleration between the Solar System and PSR J0437-4715, which can be used in a variety of applications. Firstly, it shows that Newton's gravitational cons
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Hao Wei, Minzi Feng · 2019 · arXiv
LIGO/Virgo S190814bv is the first high-probability neutron star - black hole (NSBH) merger candidate, whose gravitational waves (GWs) triggered LIGO/Virgo detectors at 21:10:39.012957 UT, 14 August 2019. It has a probability $>99\%$ of being an NSBH merger, with a low false alarm rate (FAR) of 1 per 1.559e+25 years. For an NSBH merger, electromagnetic counterparts (especially short gamma-ray bursts (GRBs)) are generally expected. However, no electromagnetic counterpart has been found in the extensive follow-up observing campaign. In the present work, we propose a novel explanation to this null
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Björn Ahlgren, Josefin Larsson · 2020 · arXiv
Macrolensing of gamma-ray bursts (GRBs) is expected to manifest as a GRB recurring with the same light curve and spectrum as a previous one, but with a different flux and a slightly offset position. Identifying such lensed GRBs may give important information about the lenses, cosmology, as well as the GRBs themselves. Here we present a search for lensed GRBs among $\sim 2700$ GRBs observed by the Fermi Gamma-ray Burst Monitor (GBM) during 11 years of operations. To identify lensed GRBs, we perform initial cuts on position, time-averaged spectral properties and relative duration. We then use th
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N. Kains, D. M. Bramich, K. C. Sahu et al. · 2016 · arXiv
We discuss the potential of the gravitational microlensing method as a unique tool to detect unambiguous signals caused by intermediate-mass black holes in globular clusters. We select clusters near the line of sight to the Galactic Bulge and the Small Magellanic Cloud, estimate the density of background stars for each of them, and carry out simulations in order to estimate the probabilities of detecting the astrometric signatures caused by black hole lensing. We find that for several clusters, the probability of detecting such an event is significant with available archival data from the Hubb
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Eli Visbal, Rupert A. C. Croft · 2007 · arXiv
The UV radiation from a quasar leaves a characteristic pattern in the distribution of ionized hydrogen throughout the surrounding space. This pattern or light echo propagates through the intergalactic medium at the speed of light, and can be observed by its imprint on the Ly-alpha forest spectra of background sources. As the echo persists after the quasar has switched off, it offers the possibility of searching for dead quasars, and constraining their luminosities and lifetimes. We outline a technique to search for and characterize these light echoes. To test the method, we create artificial L
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J. T. Wright, R. Griffith, S. Sigurðsson et al. · 2014 · arXiv
We describe the framework and strategy of the Ĝ infrared search for extraterrestrial civilizations with large energy supplies, which will use the wide-field infrared surveys of WISE and Spitzer to search for these civilizations' waste heat. We develop a formalism for translating mid-infrared photometry into quantitative upper limits on extraterrestrial energy supplies. We discuss the likely sources of false positives, how dust can and will contaminate our search, and prospects for distinguishing dust from alien waste heat. We argue that galaxy-spanning civilizations may be easier to distinguis
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Marcus Högås, Edvard Mörtsell, Harry Desmond et al. · 2025 · arXiv
We revisit the local distance ladder measurement of the Hubble constant in models where gravity is modified by a fifth force, an additional long-range interaction. In many such theories the force is screened; suppressed in dense environments but potentially active in galaxies used for distance calibration. We model this environmental dependence using three quantities that characterize each galaxy's large-scale gravitational environment: the external gravitational potential $Φ$, acceleration $a$, and curvature $K$. Our baseline analysis recalibrates the SH0ES-team's Cepheid-supernova distance l
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David J. Armstrong, Ares Osborn, Remo Burn et al. · 2025 · arXiv
NCORES was a large observing program on the ESO HARPS spectrograph, dedicated to measuring the masses of Neptune-like and smaller transiting planets discovered by the TESS satellite using the radial velocity technique. This paper presents an overview of the programme, its scientific goals and published results, covering 35 planets in 18 planetary systems. We present spectrally derived stellar characterisation and mass constraints for five additional TOIs where radial velocity observations found only marginally significant signals (TOI-510.01, $M_p=1.08^{+0.58}_{-0.55}M_\oplus$), or found no si
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Joonho Kim, Marios Karouzos, Myungshin Im et al. · 2018 · arXiv
Active Galactic Nucleus (AGN) variability can be used to study the physics of the region in the vicinity of the central black hole. In this paper, we investigated intra-night optical variability of AGN in the COSMOS field in order to understand the AGN instability at the smallest scale. Observations were performed using the KMTNet on three separate nights for 2.5-5 hour at a cadence of 20-30 min. We find that the observation enables the detection of the short-term variability as small as $\sim$ 0.02 and 0.1 mag for $R \sim$ 18 and 20 mag sources, respectively. Using four selection methods (X-r
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Rodger I. Thompson, Jill Bechtold, John H. Black et al. · 2009 · arXiv
In an effort to resolve the discrepancy between two measurements of the fundamental constant mu, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the molecular hydrogen absorption lines in archival VLT/UVES spectra of the damped Lyman alpha systems in the QSOs Q0347-383 and Q0405-443 yields a combined measurement of a (Delta mu)/mu value of (-7 +/- 8) x 10^{-6}, consistent with no change in the value of mu over a time span of 11.5 gigayears. Here we define (Delta mu) as (mu_z - mu_0) where mu_z is the valu
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T. Liu, K. Rolfs, I. Fan et al. · 2020 · arXiv
By measuring the nuclear magnetic spin precession frequencies of polarized $^{129}$Xe and $^{3}$He, a new upper limit on the $^{129}$Xe atomic electric dipole moment (EDM) $ d_\mathrm{A} (^{129}\mathrm{Xe})$ was reported in Phys. Rev. Lett. 123, 143003 (2019). Here, we propose a new evaluation method based on global phase fitting (GPF) for analyzing the continuous phase development of the $^{3}$He-$^{129}$Xe comagnetometer signal. The Cramer-Rao Lower Bound on the $^{129}$Xe EDM for the GPF method is theoretically derived and shows the potential benefit of our new approach. The robustness of t
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Yun-Jing Huang, Yuji Urata, Kuiyun Huang et al. · 2020 · arXiv
We present the result of a search for orphan Gamma-Ray Burst (GRB) afterglows in the Pan-STARRS1 (PS1) COSMOS survey. There is extensive theoretical and observational evidence suggesting that GRBs are collimated jets; the direct observation of orphan GRB afterglows would further support this model. An optimal survey strategy is designed by coupling the PS1 survey with the Subaru/Hyper-Suprime-Cam (HSC) survey. The PS1 COSMOS survey, one of the survey fields in the PS1 Medium Deep Survey (PS1/MDS), searches a field of 7 deg$^2$ from December 2011 to January 2014, reaching a limiting magnitude R
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G. Sardin · 2004 · arXiv
A novel experiment to test special relativity via Lorentz symmetry has become factible thanks to three recent technological achievements: huge Michelson-like set-up with arms 3 km long (Virgo) and 4 km (Ligo) with beam paths respectively reaching 120 km and 200 km through multiple reflections, ultrashort laser pulses of 10-15 s and ultrafast detectors of 10-12 s resolution. The alliance of these three elements would allow checking the equality of the time-of-flight of the two orthogonal beams with a resolution high enough to allow prospecting in a novel way the equivalency of inertial system p
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P. M. Phillips, I. W. A. Browne, P. N. Wilkinson · 2000 · arXiv
We present the results of an unbiased radio search for gravitational lensing events with image separations between 15 and 60 arcsec, which would be associated with clusters of galaxies with masses >10^{13-14}M_{\sun}. A parent population of 1023 extended radio sources stronger than 35 mJy with stellar optical identifications was selected using the FIRST radio catalogue at 1.4 GHz and the APM optical catalogue. The FIRST catalogue was then searched for companions to the parent sources stronger than 7 mJy and with separation in the range 15 to 60 arcsec. Higher resolution observations of the res
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Natalie R. Hinkel, Stephen R. Kane, Genady Pilyavsky et al. · 2015 · arXiv
The current goal of exoplanetary science is not only focused on detecting but characterizing planetary systems in hopes of understanding how they formed, evolved, and relate to the Solar System. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) combines both radial velocity (RV) and photometric data in order to achieve unprecedented ground-based precision in the fundamental properties of nearby, bright, exoplanet-hosting systems. Here we discuss HD 6434 and its planet, HD 6434b, which has a M_p*sin(i) = 0.44 M_J mass and orbits every 22.0170 days with an eccentricity of 0.146. We
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Kelly Lepo, Marten van Kerkwijk · 2011 · arXiv
Missing from the usual considerations of nuclear burning white dwarfs as Type Ia supernova progenitors are systems with very higher mass transfer rates, where more material than is needed for steady burning accretes on the white dwarf. This will move out the photosphere of the white dwarf, causing it to emit at longer wavelengths. Thus, we propose the name ultra-soft source (USS) for these objects. We present a VLT/FLAMES survey looking for USS in the SMC, selected to be bright in the far UV and with blue far UV-V colors. While we find some unusual objects, and recover known planetary nebula a
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Yi-Fan Wang, Alexander H. Nitz, Collin D. Capano et al. · 2022 · arXiv
The recent discovery of a kilonova associated with an apparent long-duration gamma-ray burst has challenged the typical classification that long gamma-ray bursts originate from the core collapse of massive stars and short gamma-ray bursts are from compact binary coalescence. The kilonova indicates a neutron star merger origin and suggests the viability of gravitational-wave and long gamma-ray burst multimessenger astronomy. Gravitational waves play a crucial role by providing independent information for the source properties. This work revisits the archival 2015-2020 LIGO/Virgo gravitational-w
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J. V. Hernandez Santisteban, C. Knigge, M. L. Pretorius et al. · 2017 · arXiv
Binary evolution theory predicts that accreting white dwarfs with sub-stellar companions dominate the Galactic population of cataclysmic variables (CVs). In order to test these predictions, it is necessary to identify these systems, which may be difficult if the signatures of accretion become too weak to be detected. The only chance to identify such "dead" CVs is by exploiting their close binary nature. We have therefore searched the Sloan Digital Sky Survey (SDSS) Stripe 82 area for apparently isolated white dwarfs that undergo eclipses by a dark companion. We found no such eclipses in either
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Thomas Fitoussi, Gustavo Medina-Tanco, Juan-Carlos D'Olivo · 2019 · arXiv
Almost three decades ago, the Fly's Eye experiment recorded the most energetic cosmic-ray ever observed. With an energy of 320 EeV, this event is well beyond the suppression region of the ultra-high energy cosmic rays (UHECR) spectrum. Modern and larger observatories, with an exposure up to 60 times larger, have never observed an event with even remotely comparable energy. Thus, if the energy of the Fly's Eye event was indeed well measured, as strongly suggested by the data, then it remains a great mystery or an unbelievable stroke of luck. At such high energies, the Universe is very opaque to
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O. Kochukhov, A. M. Amarsi, A. Lavail et al. · 2024 · arXiv
The A-type metallic-line (Am) stars are typically considered to be non-magnetic or possessing very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature, most commonly for the bright hot Am star o Peg. Several studies claimed to detect 1-2 kG field of unknown topology in this object, possibly indicating a new process of magnetic field generation in intermediate-mass stars. In this study, we revisit the evidence of a strong magnetic field in o Peg using new high-resolution spectropolarimetric observations and advanced spectral fitting techniques. The mean magnet
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Stefano Profumo, Kally Wen · 2025 · arXiv
We present a systematic search for signatures of terminal black-hole evaporation in short gamma-ray burst (sGRB) catalogs. An exploding primordial black hole (PBH) undergoing final-stage Hawking radiation is predicted to produce a distinctive "backwards burst"-a very short, spectrally hard transient with monotonically increasing flux and little or no longer-wavelength afterglow. We develop a forward-modeling framework that directly compares theoretical PBH evaporation light curves, computed with full Standard Model particle content and detector response folding, against empirical GRB pulse tem
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D. Abriola, F. T. Avignone, R. L. Brodzinski et al. · 1998 · arXiv
Data collected during three years with a germanium spectrometer at the Sierra Grande underground laboratory have been analyzed for distinctive features of annual modulation of the signal induced by WIMP dark matter candidates. The main motivation for this analysis was the recent suggestion by the DAMA/NaI Collaboration that a yearly modulation signal could not be rejected at the 90% confidence level when analyzing data obtained with a high-mass low-background scintillator detector. We performed two different analyses of the data: First, the statistical distribution of modulation-significance v
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Pasquale Galianni, Martin Feix, Hongsheng Zhao et al. · 2011 · arXiv
A unique signature of the modified Newtonian dynamics (MOND) paradigm is its peculiar behavior in the vicinity of the points where the total Newtonian acceleration exactly cancels. In the Solar System, these are the saddle points of the gravitational potential near the planets. Typically, such points are embedded into low-acceleration bubbles where modified gravity theories a` la MOND predict significant deviations from Newton's laws. As has been pointed out recently, the Earth-Sun bubble may be visited by the LISA Pathfinder spacecraft in the near future, providing a unique occasion to put th
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Khun Sang Phukon, Gregory Baltus, Sarah Caudill et al. · 2021 · arXiv
We perform a search for binary black hole mergers with one subsolar mass black hole and a primary component above $2 M_\odot$ in the second observing run of LIGO/Virgo. Our analysis therefore extends previous searches into a mass region motivated by the presence of a peak in any broad mass distribution of primordial black holes (PBHs) around $[2-3] M_\odot$ coming from the equation of state reduction at the QCD transition. Four candidate events are found passing a false alarm rate (FAR) threshold of 2 per year, although none are statistically significant enough for being clear detections. We f
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Víctor Navas-Portella, Abigail Jiménez, Álvaro Corral · 2018 · arXiv
Coulomb-stress theory has been used for years in seismology to understand how earthquakes trigger each other. Whenever an earthquake occurs, the stress field changes, and places with positive increases are brought closer to failure. Earthquake models that relate earthquake rates and Coulomb stress after a main event, such as the rate-and-state model, assume that the magnitude distribution of earthquakes is not affected by the change in the Coulomb stress. By using different slip models, we calculate the change in Coulomb stress in the fault plane for every aftershock after the Landers event (C
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Ziv Meir, Tomas Sikorsky, Ruti Ben-shlomi et al. · 2016 · arXiv
Ultra-cold atom-ion mixtures are gaining increasing interest due to their potential applications in quantum chemistry, quantum computing and many-body physics. Here, we studied the dynamics of a single ground-state cooled ion during few, to many, Langevin (spiraling) collisions with ultra-cold atoms. We measured the ion's energy distribution and observed a clear deviation from Maxwell-Boltzmann to a Tsallis characterized by a power-law tail of high energies. Unlike previous experiments, the energy scale of atom-ion interactions is not determined by either the atomic cloud temperature or the io
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Paolo Barletta · 2008 · arXiv
This paper presents a comparative analysis of complexes made of one Rare Gas (Rg) atom and molecular hydrogen, for all five stable Rg atoms. In particular, the vibrational band origins have been calculated, as well as the structural properties of the associated wavefunctions. The study is extended to cold Rg-H$_2$ scattering. The molecular systems are studied variationally using a very simple, yet effective, trial wavefunction. A large number of Potential Energy Surfaces available from the literature is considered. A comparative analysis shows that differences of up to two orders of magnitude
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Ulrich H. E. Hansmann · 1997 · arXiv
We discuss the use of Tsallis generalized mechanics in simulated annealing algorithms. For a small peptide it is shown that older implementations are not more effective than regular simulated annealing in finding ground state configurations. We propose a new implementation which leads to an improvement over regular simulated annealing.
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