Physics Commons^™

Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares, Icecube, And The Pierre Auger Observatory, Antares Collaboration, The Icecube Collaboration, The Pierre Auger Collaboration, Ligo Scientific Collaboration, Virgo Collaboration, Karen Andeen

Physics Faculty Research and Publications

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the FermiGamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory(INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV–EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. …

Measurement Of The Multi-Tev Neutrino Interaction Cross-Section With Icecube Using Earth Absorption, Karen Andeen, The Icecube Collaboration

Physics Faculty Research and Publications

Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino–nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators^1,2. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to …

Mito-Apocynin Prevents Mitochondrial Dysfunction, Microglial Activation, Oxidative Damage, And Progressive Neurodegeneration In Mitopark Transgenic Mice, Monica Langley, Anamitra Ghosh, Adhithiya Charli, Souvarish Sarkar, Muhammet Ay, Jie Luo, Jacek Zielonka, Timothy Brenza, Brian Bennett, Huajun Jin, Shivani Ghaisas, Benjamin Schlichtmann, Dongsuk Kim, Vellareddy Anantharam, Arthi Kanthasamy, Balaji Narasimhan, Balaraman Kalyanaraman, Anumantha G. Kanthasamy

Physics Faculty Research and Publications

Aims: Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive motor deficits and degeneration of dopaminergic neurons. Caused by a number of genetic and environmental factors, mitochondrial dysfunction and oxidative stress play a role in neurodegeneration in PD. By selectively knocking out mitochondrial transcription factor A (TFAM) in dopaminergic neurons, the transgenic MitoPark mice recapitulate many signature features of the disease, including progressive motor deficits, neuronal loss, and protein inclusions. In the present study, we evaluated the neuroprotective efficacy of a novel mitochondrially targeted antioxidant, Mito-apocynin, in MitoPark mice and cell culture models of neuroinflammation and mitochondrial dysfunction.

Results: …

Multiwavelength Follow-Up Of A Rare Icecube Neutrino Multiplet, Karen Andeen

Physics Faculty Research and Publications

On February 17, 2016, the IceCube real-time neutrino search identified, for the first time, three muon neutrino candidates arriving within 100 s of one another, consistent with coming from the same point in the sky. Such a triplet is expected once every 13.7 years as a random coincidence of background events. However, considering the lifetime of the follow-up program the probability of detecting at least one triplet from atmospheric background is 32%. Follow-up observatories were notified in order to search for an electromagnetic counterpart. Observations were obtained by Swift’s X-ray telescope, by ASAS-SN, LCO and MASTER at optical wavelengths, …

Constraints On Galactic Neutrino Emission With Seven Years Of Icecube Data, Karen Andeen

Physics Faculty Research and Publications

The origins of high-energy astrophysical neutrinos remain a mystery despite extensive searches for their sources. We present constraints from seven years of IceCube Neutrino Observatory muon data on the neutrino flux coming from the Galactic plane. This flux is expected from cosmic-ray interactions with the interstellar medium or near localized sources. Two methods were developed to test for a spatially extended flux from the entire plane, both of which are maximum likelihood fits but with different signal and background modeling techniques. We consider three templates for Galactic neutrino emission based primarily on gamma-ray observations and models that cover a wide …

Multi-Messenger Observations Of A Binary Neutron Star Merger, Karen Andeen

Physics Faculty Research and Publications

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg² at a luminosity distance of Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to …

Measurement Of The Νμ Energy Spectrum With Icecube-79, Karen Andeen

Physics Faculty Research and Publications

IceCube is a neutrino observatory deployed in the glacial ice at the geographic South Pole. The νμ energy unfolding described in this paper is based on data taken with IceCube in its 79-string configuration. A sample of muon neutrino charged-current interactions with a purity of 99.5% was selected by means of amultivariate classification process based on machine learning. The subsequent unfolding was performed using the software TRUEE. The resulting spectrum covers an E_ν-range of more than four orders of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric neutrino flux model, the energy spectrum shows …

Antihydrogen Accumulation For Fundamental Symmetry Tests, Timothy Tharp, M. Ahmadi, P. Nolan, P. Pusa, B. X. R. Alves, T. Friesen, C. O. Rasmussen, G. Stutter, C. J. Baker, M. Charlton, S. Eriksson, C. A. Isaac, S. A. Jones, N. Madsen, D. Maxwell, M. Sameed, D. P. Van Der Werf, W. Bertsche, M. A. Johnson, E. Butler, A. Capra, R. Collister, M. C. Fujiwara, L. Kurchaninov, J. T. K. Mckenna, J. M. Michan, K. Olchanski, A. Olin, C. Carruth, J. Fajans, J. S. Wurtele, C. L. Cesar, R. L. Sacramento, D. M. Silveira, S. Cohen, A. Evans, C. So, R. I. Thompson, N. Evetts, W. N. Hardy, T. Momose, A. Gutierrez, M. E. Hayden, J. J. Munich, A. Ishida, S. Jonsell, M. Mathers, S. Menary, J. E. Thompson, J.M. Michan, F. Robicheaux, E. Sarid, S. Stracha

Physics Faculty Research and Publications

Antihydrogen, a positron bound to an antiproton, is the simplest anti-atom. Its structure and properties are expected to mirror those of the hydrogen atom. Prospects for precision comparisons of the two, as tests of fundamental symmetries, are driving a vibrant programme of research. In this regard, a limiting factor in most experiments is the availability of large numbers of cold ground state antihydrogen atoms. Here, we describe how an improved synthesis process results in a maximum rate of 10.5 ± 0.6 atoms trapped and detected per cycle, corresponding to more than an order of magnitude improvement over previous work. Additionally, …

Search For Astrophysical Sources Of Neutrinos Using Cascade Events In Icecube, Karen Andeen

Physics Faculty Research and Publications

The IceCube neutrino observatory has established the existence of a flux of high-energy astrophysical neutrinos, which is inconsistent with the expectation from atmospheric backgrounds at a significance greater than 5σ. This flux has been observed in analyses of both track events from muon neutrino interactions and cascade events from interactions of all neutrino flavors. Searches for astrophysical neutrino sources have focused on track events due to the significantly better angular resolution of track reconstructions. To date, no such sources have been confirmed. Here we present the first search for astrophysical neutrino sources using cascades interacting in IceCube with …

Search For Neutrinos From Dark Matter Self-Annihilations In The Center Of The Milky Way With 3 Years Of Icecube/Deepcore, Karen Andeen, Icecube Collaboration

Physics Faculty Research and Publications

We present a search for a neutrino signal from dark matter self-annihilations in the Milky Way using the IceCube Neutrino Observatory (IceCube). In 1005 days of data we found no significant excess of neutrinos over the background of neutrinos produced in atmospheric air showers from cosmic ray interactions. We derive upper limits on the velocity averaged product of the dark matter self-annihilation cross section and the relative velocity of the dark matter particles ⟨ σ A v ⟩

. Upper limits are set for dark matter particle candidate masses ranging from 10 GeV up to 1 TeV while considering annihilation …

Observation Of The Hyperfine Spectrum Of Antihydrogen, M. Ahmadi, B. X. R. Alves, C. J. Baker, W. Bertsche, E. Butler, A. Capra, C. Carruth, C. L. Cesar, M. Charlton, S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, A. Gutierrez, J. S. Hangst, W. N. Hardy, M. E. Hayden, C. A. Isaac, A. Ishida, M. A. Johnson, S. A. Jones, S. Jonsell, L. Kurchaninov, N. Madsen, M. Mathers, D. Maxwell, J. T. K. Mckenna, S. Menary, J. M. Michan, T. Momose, J. J. Munich, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C. O. Rasmussen, F. Robicheaux, R. L. Sacramento, M. Sameed, E. Sarid, D. M. Silveira, S. Stracka, G. Stutter, C. So, Timothy Tharp, J. E. Thompson, R. I. Thompson, D. P. Van Der Werf, J. S. Wurtele

Physics Faculty Research and Publications

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers^1,2,3 and the measurement⁴ of the zero-field ground-state splitting at the level of seven parts in 10¹³ are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron^5,6,7,8, inspired Schwinger’s relativistic theory of quantum electrodynamics^9,10 and gave rise to the hydrogen maser¹¹, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry …

Search For High-Energy Neutrinos From Gravitational Wave Event Gw151226 And Candidate Lvt151012 With Antares And Icecube, Karen Andeen, Antares Collaboration, Icecube Collaboration, Ligo Scientific Collaboration, Virgo Collaboration

Physics Faculty Research and Publications

The Advanced LIGO observatories detected gravitational waves from two binary black hole mergers during their first observation run (O1). We present a high-energy neutrino follow-up search for the second gravitational wave event, GW151226, as well as for gravitational wave candidate LVT151012. We find two and four neutrino candidates detected by IceCube, and one and zero detected by Antares, within ±500  s around the respective gravitational wave signals, consistent with the expected background rate. None of these neutrino candidates are found to be directionally coincident with GW151226 or LVT151012. We use nondetection to constrain isotropic-equivalent high-energy neutrino emission from GW151226, adopting …

Extending The Search For Muon Neutrinos Coincident With Gamma-Ray Bursts In Icecube Data, Karen Andeen

Physics Faculty Research and Publications

We present an all-sky search for muon neutrinos produced during the prompt γ-ray emission of 1172 gamma-ray bursts (GRBs) with the IceCube Neutrino Observatory. The detection of these neutrinos would constitute evidence for ultra-high-energy cosmic-ray (UHECR) production in GRBs, as interactions between accelerated protons and the prompt γ-ray field would yield charged pions, which decay to neutrinos. A previously reported search for muon neutrino tracks from northern hemisphere GRBs has been extended to include three additional years of IceCube data. A search for such tracks from southern hemisphere GRBs in five years of IceCube data has been introduced …

Search For Sterile Neutrino Mixing Using Three Years Of Icecube Deepcore Data, Karen Andeen, The Icecube Collaboration

Physics Faculty Research and Publications

We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10–60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance …

The Icecube Realtime Alert System, Karen Andeen, Icecube Collaboration

Physics Faculty Research and Publications

Although high-energy astrophysical neutrinos were discovered in 2013, their origin is still unknown. Aiming for the identification of an electromagnetic counterpart of a rapidly fading source, we have implemented a realtime analysis framework for the IceCube neutrino observatory. Several analyses selecting neutrinos of astrophysical origin are now operating in realtime at the detector site in Antarctica and are producing alerts for the community to enable rapid follow-up observations. The goal of these observations is to locate the astrophysical objects responsible for these neutrino signals. This paper highlights the infrastructure in place both at the South Pole site and at IceCube …

Astrophysical Neutrinos And Cosmic Rays Observed By Icecube, Karen Andeen, Icecube Collaboration

Physics Faculty Research and Publications

The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of …

Search For Annihilating Dark Matter In The Sun With 3 Years Of Icecube Data, Karen Andeen

Physics Faculty Research and Publications

We present results from an analysis looking for darkmatter annihilation in the Sun with the IceCube neutrino telescope. Gravitationally trapped dark matter in the Sun’s core can annihilate into Standard Model particles making the Sun a source of GeV neutrinos. IceCube is able to detect neutrinos with energies>100GeVwhile its low-energy infill array DeepCore extends this to >10GeV. This analysis uses data gathered in the austral winters between May 2011 and May 2014, corresponding to 532 days of livetime when the Sun, being below the horizon, is a source of up-going neutrino events, easiest to discriminate against the dominant background …

All-Sky Search For Time-Integrated Neutrino Emission From Astrophysical Sources With 7 Yr Of Icecube Data, Karen Andeen

Physics Faculty Research and Publications

Since the recent detection of an astrophysical flux of high-energy neutrinos, the question of its origin has not yet fully been answered. Much of what is known about this flux comes from a small event sample of high neutrino purity, good energy resolution, but large angular uncertainties. In searches for point-like sources, on the other hand, the best performance is given by using large statistics and good angular reconstructions. Track-like muon events produced in neutrino interactions satisfy these requirements. We present here the results of searches for point-like sources with neutrinos using data acquired by the IceCube detector over 7 …

First Search For Dark Matter Annihilations In The Earth With The Icecube Detector, Karen Andeen, Icecube Collaboration

Physics Faculty Research and Publications

We present the results of the first IceCube search for dark matter annihilation in the center of the Earth. Weakly interacting massive particles (WIMPs), candidates for dark matter, can scatter off nuclei inside the Earth and fall below its escape velocity. Over time the captured WIMPs will be accumulated and may eventually self-annihilate. Among the annihilation products only neutrinos can escape from the center of the Earth. Large-scale neutrino telescopes, such as the cubic kilometer IceCube Neutrino Observatory located at the South Pole, can be used to search for such neutrino fluxes. Data from 327 days of detector livetime during …

The Contribution Of Fermi-2lac Blazars To Diffuse Tev-Pev Neutrino Flux, Karen Andeen

Physics Faculty Research and Publications

The recent discovery of a diffuse cosmic neutrino flux extending up to PeV energies raises the question of which astrophysical sources generate this signal. Blazars are one class of extragalactic sources which may produce such high-energy neutrinos. We present a likelihood analysis searching for cumulative neutrino emission from blazars in the 2nd Fermi-LAT AGN catalog (2LAC) using IceCube neutrino data set 2009-12, which was optimized for the detection of individual sources. In contrast to those in previous searches with IceCube, the populations investigated contain up to hundreds of sources, the largest one being the entire blazar sample in the …

The Iron-Type Nitrile Hydratase Activator Protein Is A Gtpase, Natalie Gumataotao, Karunagala Pathiranage Wasantha Lankathilaka, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

The Fe-type nitrile hydratase activator protein from Rhodococcus equi TG328-2 (ReNHase TG328-2) was successfully expressed and purified. Sequence analysis and homology modeling suggest that it is a G3E P-loop guanosine triphosphatase (GTPase) within the COG0523 subfamily. Kinetic studies revealed that the Fe-type activator protein is capable of hydrolyzing GTP to GDP with a k_cat value of 1.2 × 10⁻³s⁻¹ and a K_m value of 40 μM in the presence of 5 mM MgCl₂ in 50 mM 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid at a pH of 8.0. The addition of divalent metal ions, such as Co(II), …

Multiple States Of Nitrile Hydratase From Rhodococcus Equi Tg328-2: Structural And Mechanistic Insights From Electron Paramagnetic Resonance And Density Functional Theory Studies, Natalia Stein, Natalie Gumataotao, Natalia Hajnas, Rui Wu, Karunagala Pathiranage Wasantha Lankathilaka, Uwe Bornscheuer, Dali Liu, Adam T. Fiedler, Richard C. Holz, Brian Bennett

Physics Faculty Research and Publications

Iron-type nitrile hydratases (NHases) contain an Fe(III) ion coordinated in a characteristic “claw setting” by an axial cysteine thiolate, two equatorial peptide nitrogens, the sulfur atoms of equatorial cysteine-sulfenic and cysteine-sulfinic acids, and an axial water/hydroxyl moiety. The cysteine-sulfenic acid is susceptible to oxidation, and the enzyme is traditionally prepared using butyric acid as an oxidative protectant. The as-prepared enzyme exhibits a complex electron paramagnetic resonance (EPR) spectrum due to multiple low-spin (S = ¹/₂) Fe(III) species. Four distinct signals can be assigned to the resting active state, the active state bound to butyric acid, an …

A Cobalt-Containing Eukaryotic Nitrile Hydratase, Salette Martinez, Xinhang Yang, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

Nitrile hydratase (NHase), an industrially important enzyme that catalyzes the hydration of nitriles to their corresponding amides, has only been characterized from prokaryotic microbes. The putative NHase from the eukaryotic unicellular choanoflagellate organism Monosiga brevicollis (MbNHase) was heterologously expressed in Escherichia coli. The resulting enzyme expressed as a single polypeptide with fused α- and β-subunits linked by a seventeen-histidine region. Size-exclusion chromatography indicated that MbNHase exists primarily as an (αβ)₂ homodimer in solution, analogous to the α₂β₂ homotetramer architecture observed for prokaryotic NHases. The NHase enzyme contained its full complement of Co(III) …