ORCID Profile
0000-0002-0087-0693
Current Organisation
University of Wisconsin-Madison IceCube Particle Astrophysics Center
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: American Physical Society (APS)
Date: 15-02-2019
Publisher: American Astronomical Society
Date: 05-10-2018
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Galactic PeV cosmic-ray accelerators (PeVatrons) are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact hadronically with nearby ambient gas or the interstellar medium, resulting in γ -rays and neutrinos. Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12 γ -ray sources with emissions above 100 TeV, making them candidates for PeVatrons. While at these high energies the Klein–Nishina effect exponentially suppresses leptonic emission from Galactic sources, evidence for neutrino emission would unequivocally confirm hadronic acceleration. Here, we present the results of a search for neutrinos from these γ -ray sources and stacking searches testing for excess neutrino emission from all 12 sources as well as their subcatalogs of supernova remnants and pulsar wind nebulae with 11 yr of track events from the IceCube Neutrino Observatory. No significant emissions were found. Based on the resulting limits, we place constraints on the fraction of γ -ray flux originating from the hadronic processes in the Crab Nebula and LHAASO J2226+6057.
Publisher: Springer Science and Business Media LLC
Date: 2020
DOI: 10.1140/EPJC/S10052-019-7555-0
Abstract: The Neutrino Mass Ordering (NMO) remains one of the outstanding questions in the field of neutrino physics. One strategy to measure the NMO is to observe matter effects in the oscillation pattern of atmospheric neutrinos above $$\\sim 1\\,\\mathrm {GeV}$$ ∼ 1 GeV , as proposed for several next-generation neutrino experiments. Moreover, the existing IceCube DeepCore detector can already explore this type of measurement. We present the development and application of two independent analyses to search for the signature of the NMO with three years of DeepCore data. These analyses include a full treatment of systematic uncertainties and a statistically-rigorous method to determine the significance for the NMO from a fit to the data. Both analyses show that the dataset is fully compatible with both mass orderings. For the more sensitive analysis, we observe a preference for normal ordering with a p -value of $$p_\\mathrm {IO} = 15.3\\%$$ p IO = 15.3 % and $$\\mathrm {CL}_\\mathrm {s}=53.3\\%$$ CL s = 53.3 % for the inverted ordering hypothesis, while the experimental results from both analyses are consistent within their uncertainties. Since the result is independent of the value of $$\\delta _\\mathrm {CP}$$ δ CP and obtained from energies $$E_\\nu \\gtrsim 5\\,\\mathrm {GeV}$$ E ν ≳ 5 GeV , it is complementary to recent results from long-baseline experiments. These analyses set the groundwork for the future of this measurement with more capable detectors, such as the IceCube Upgrade and the proposed PINGU detector.
Publisher: American Physical Society (APS)
Date: 21-02-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 11-07-2018
Abstract: Previous detections of in idual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera-electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength c aign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray-emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.
Publisher: American Astronomical Society
Date: 09-2029
Abstract: The understanding of novae, the thermonuclear eruptions on the surfaces of white dwarf stars in binaries, has recently undergone a major paradigm shift. Though the bolometric luminosity of novae was long thought to arise directly from photons supplied by the thermonuclear runaway, recent gigaelectronvolt (GeV) gamma-ray observations have supported the notion that a significant portion of the luminosity could come from radiative shocks. More recently, observations of novae have lent evidence that these shocks are acceleration sites for hadrons for at least some types of novae. In this scenario, a flux of neutrinos may accompany the observed gamma rays. As the gamma rays from most novae have only been observed up to a few GeV, novae have previously not been considered as targets for neutrino telescopes, which are most sensitive at and above teraelectronvolt (TeV) energies. Here, we present the first search for neutrinos from novae with energies between a few GeV and 10 TeV using IceCube-DeepCore, a densely instrumented region of the IceCube Neutrino Observatory with a reduced energy threshold. We search both for a correlation between gamma-ray and neutrino emission as well as between optical and neutrino emission from novae. We find no evidence for neutrino emission from the novae considered in this analysis and set upper limits for all gamma-ray detected novae.
Publisher: American Astronomical Society
Date: 27-03-2020
Publisher: American Astronomical Society
Date: 13-11-2019
Publisher: IOP Publishing
Date: 21-10-2019
Publisher: American Astronomical Society
Date: 27-02-2020
Publisher: American Physical Society (APS)
Date: 23-10-2019
Publisher: American Physical Society (APS)
Date: 17-09-2023
Publisher: IOP Publishing
Date: 08-04-2019
Publisher: Elsevier BV
Date: 2002
Publisher: American Astronomical Society
Date: 03-2023
Abstract: We present the results of dark matter (DM) searches in a s le of 31 dwarf irregular (dIrr) galaxies within the field of view of the HAWC Observatory. dIrr galaxies are DM-dominated objects in which astrophysical gamma-ray emission is estimated to be negligible with respect to the secondary gamma-ray flux expected by annihilation or decay of weakly interacting massive particles (WIMPs). While we do not see any statistically significant DM signal in dIrr galaxies, we present the exclusion limits (95% C.L.) for annihilation cross section and decay lifetime for WIMP candidates with masses between 1 and 100 TeV. Exclusion limits from dIrr galaxies are relevant and complementary to benchmark dwarf Spheroidal (dSph) galaxies. In fact, dIrr galaxies are targets kinematically different from benchmark dSph, preserving the footprints of different evolution histories. We compare the limits from dIrr galaxies to those from ultrafaint and classical dSph galaxies previously observed with HAWC. We find that the constraints are comparable to the limits from classical dSph galaxies and ∼2 orders of magnitude weaker than the ultrafaint dSph limits.
Publisher: IOP Publishing
Date: 12-02-2021
Publisher: IOP Publishing
Date: 16-07-2020
Publisher: American Astronomical Society
Date: 06-07-2020
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Physical Society (APS)
Date: 08-02-2020
Publisher: American Astronomical Society
Date: 16-06-2017
Publisher: Springer Science and Business Media LLC
Date: 09-2020
DOI: 10.1140/EPJC/S10052-020-8069-5
Abstract: Adopting the Standard Halo Model (SHM) of an isotropic Maxwellian velocity distribution for dark matter (DM) particles in the Galaxy, the most stringent current constraints on their spin-dependent scattering cross-section with nucleons come from the IceCube neutrino observatory and the PICO-60 $$\\hbox {C}_3\\hbox {F}_8$$ C 3 F 8 superheated bubble chamber experiments. The former is sensitive to high energy neutrinos from the self-annihilation of DM particles captured in the Sun, while the latter looks for nuclear recoil events from DM scattering off nucleons. Although slower DM particles are more likely to be captured by the Sun, the faster ones are more likely to be detected by PICO. Recent N-body simulations suggest significant deviations from the SHM for the smooth halo component of the DM, while observations hint at a dominant fraction of the local DM being in substructures. We use the method of Ferrer et al. (JCAP 1509: 052, 2015) to exploit the complementarity between the two approaches and derive conservative constraints on DM-nucleon scattering. Our results constrain $$\\sigma _{\\mathrm{SD}} \\lesssim 3 \\times 10^{-39} \\mathrm {cm}^2$$ σ SD ≲ 3 × 10 - 39 cm 2 ( $$6 \\times 10^{-38} \\mathrm {cm}^2$$ 6 × 10 - 38 cm 2 ) at $$\\gtrsim 90\\%$$ ≳ 90 % C.L. for a DM particle of mass 1 TeV annihilating into $$\\tau ^+ \\tau ^-$$ τ + τ - ( $$b\\bar{b}$$ b b ¯ ) with a local density of $$\\rho _{\\mathrm{DM}} = 0.3~\\mathrm {GeV/cm}^3$$ ρ DM = 0.3 GeV / cm 3 . The constraints scale inversely with $$\\rho _{\\mathrm{DM}}$$ ρ DM and are independent of the DM velocity distribution.
Publisher: IOP Publishing
Date: 04-02-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-11-2013
Abstract: Neutrinos are thought to be produced in astrophysical sources outside our solar system but, up until recently, they had only been observed from one supernova in 1987. Aartsen et al. ( 10.1126/science.1242856 see the cover) report data obtained between 2010 and 2012 with the IceCube neutrino detector that reveal the presence of a high-energy neutrino flux containing the most energetic neutrinos ever observed, including 28 events at energies between 30 and 1200 TeV. Although the origin of this flux is unknown, the findings are consistent with expectations for a neutrino population with origins outside the solar system.
Publisher: American Astronomical Society
Date: 18-02-2020
Publisher: American Astronomical Society
Date: 05-2023
Abstract: Core-collapse supernovae are a promising potential high-energy neutrino source class. We test for correlation between seven years of IceCube neutrino data and a catalog containing more than 1000 core-collapse supernovae of types IIn and IIP and a s le of stripped-envelope supernovae. We search both for neutrino emission from in idual supernovae as well as for combined emission from the whole supernova s le, through a stacking analysis. No significant spatial or temporal correlation of neutrinos with the cataloged supernovae was found. All scenarios were tested against the background expectation and together yield an overall p -value of 93% therefore, they show consistency with the background only. The derived upper limits on the total energy emitted in neutrinos are 1.7 × 10 48 erg for stripped-envelope supernovae, 2.8 × 10 48 erg for type IIP, and 1.3 × 10 49 erg for type IIn SNe, the latter disfavoring models with optimistic assumptions for neutrino production in interacting supernovae. We conclude that stripped-envelope supernovae and supernovae of type IIn do not contribute more than 14.6% and 33.9%, respectively, to the diffuse neutrino flux in the energy range of about [ 10 3 –10 5 ] GeV, assuming that the neutrino energy spectrum follows a power-law with an index of −2.5. Under the same assumption, we can only constrain the contribution of type IIP SNe to no more than 59.9%. Thus, core-collapse supernovae of types IIn and stripped-envelope supernovae can both be ruled out as the dominant source of the diffuse neutrino flux under the given assumptions.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: Galaxy clusters have the potential to accelerate cosmic rays (CRs) to ultrahigh energies via accretion shocks or embedded CR acceleration sites. The CRs with energies below the Hillas condition will be confined within the cluster and eventually interact with the intracluster medium gas to produce secondary neutrinos and gamma rays. Using 9.5 yr of muon neutrino track events from the IceCube Neutrino Observatory, we report the results of a stacking analysis of 1094 galaxy clusters with masses ≳10 14 M ⊙ and redshifts between 0.01 and ∼1 detected by the Planck mission via the Sunyaev–Zel’dovich effect. We find no evidence for significant neutrino emission and report upper limits on the cumulative unresolved neutrino flux from massive galaxy clusters after accounting for the completeness of the catalog up to a redshift of 2, assuming three different weighting scenarios for the stacking and three different power-law spectra. Weighting the sources according to mass and distance, we set upper limits at a 90% confidence level that constrain the flux of neutrinos from massive galaxy clusters (≳10 14 M ⊙ ) to be no more than 4.6% of the diffuse IceCube observations at 100 TeV, assuming an unbroken E −2.5 power-law spectrum.
Publisher: EDP Sciences
Date: 06-2019
DOI: 10.1051/0004-6361/201935171
Abstract: In order to identify the sources of the observed diffuse high-energy neutrino flux, it is crucial to discover their electromagnetic counterparts. To increase the sensitivity of detecting counterparts of transient or variable sources by telescopes with a limited field of view, IceCube began releasing alerts for single high-energy ( E ν 60 TeV) neutrino detections with sky localisation regions of order 1° radius in 2016. We used Pan-STARRS1 to follow-up five of these alerts during 2016–2017 to search for any optical transients that may be related to the neutrinos. Typically 10–20 faint ( m i P1 ≲ 22.5 mag) extragalactic transients are found within the Pan-STARRS1 footprints and are generally consistent with being unrelated field supernovae (SNe) and AGN. We looked for unusual properties of the detected transients, such as temporal coincidence of explosion epoch with the IceCube timest , or other peculiar light curve and physical properties. We found only one transient that had properties worthy of a specific follow-up. In the Pan-STARRS1 imaging for IceCube-160427A (probability to be of astrophysical origin of ∼50%), we found a SN PS16cgx, located at 10.0′ from the nominal IceCube direction. Spectroscopic observations of PS16cgx showed that it was an H-poor SN at redshift z = 0.2895 ± 0.0001. The spectra and light curve resemble some high-energy Type Ic SNe, raising the possibility of a jet driven SN with an explosion epoch temporally coincident with the neutrino detection. However, distinguishing Type Ia and Type Ic SNe at this redshift is notoriously difficult. Based on all available data we conclude that the transient is more likely to be a Type Ia with relatively weak Si II absorption and a fairly normal rest-frame r -band light curve. If, as predicted, there is no high-energy neutrino emission from Type Ia SNe, then PS16cgx must be a random coincidence, and unrelated to the IceCube-160427A. We find no other plausible optical transient for any of the five IceCube events observed down to a 5 σ limiting magnitude of m i P1 ≈ 22 mag, between 1 day and 25 days after detection.
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We present a measurement of the high-energy astrophysical muon–neutrino flux with the IceCube Neutrino Observatory. The measurement uses a high-purity selection of 650k neutrino-induced muon tracks from the northern celestial hemisphere, corresponding to 9.5 yr of experimental data. With respect to previous publications, the measurement is improved by the increased size of the event s le and the extended model testing beyond simple power-law hypotheses. An updated treatment of systematic uncertainties and atmospheric background fluxes has been implemented based on recent models. The best-fit single power-law parameterization for the astrophysical energy spectrum results in a normalization of ϕ @ 100 TeV ν μ + ν ¯ μ = 1.44 − 0.26 + 0.25 × 10 − 18 GeV − 1 cm − 2 s − 1 sr − 1 and a spectral index γ SPL = 2.37 − 0.09 + 0.09 , constrained in the energy range from 15 TeV to 5 PeV. The model tests include a single power law with a spectral cutoff at high energies, a log-parabola model, several source-class-specific flux predictions from the literature, and a model-independent spectral unfolding. The data are consistent with a single power-law hypothesis, however, spectra with softening above one PeV are statistically more favorable at a two-sigma level.
Publisher: American Astronomical Society
Date: 11-2022
Abstract: Gamma-ray bursts (GRBs) are considered as promising sources of ultra-high-energy cosmic rays (UHECRs) due to their large power output. Observing a neutrino flux from GRBs would offer evidence that GRBs are hadronic accelerators of UHECRs. Previous IceCube analyses, which primarily focused on neutrinos arriving in temporal coincidence with the prompt gamma-rays, found no significant neutrino excess. The four analyses presented in this paper extend the region of interest to 14 days before and after the prompt phase, including generic extended time windows and targeted precursor searches. GRBs were selected between 2011 May and 2018 October to align with the data set of candidate muon-neutrino events observed by IceCube. No evidence of correlation between neutrino events and GRBs was found in these analyses. Limits are set to constrain the contribution of the cosmic GRB population to the diffuse astrophysical neutrino flux observed by IceCube. Prompt neutrino emission from GRBs is limited to ≲1% of the observed diffuse neutrino flux, and emission on timescales up to 10 4 s is constrained to 24% of the total diffuse flux.
Publisher: American Astronomical Society
Date: 10-2022
Abstract: The majority of astrophysical neutrinos have undetermined origins. The IceCube Neutrino Observatory has observed astrophysical neutrinos but has not yet identified their sources. Blazars are promising source candidates, but previous searches for neutrino emission from populations of blazars detected in ≳GeV gamma rays have not observed any significant neutrino excess. Recent findings in multimessenger astronomy indicate that high-energy photons, coproduced with high-energy neutrinos, are likely to be absorbed and reemitted at lower energies. Thus, lower-energy photons may be better indicators of TeV–PeV neutrino production. This paper presents the first time-integrated stacking search for astrophysical neutrino emission from MeV-detected blazars in the first Fermi Large Area Telescope low energy (1FLE) catalog using ten years of IceCube muon–neutrino data. The results of this analysis are found to be consistent with a background-only hypothesis. Assuming an E −2 neutrino spectrum and proportionality between the blazars MeV gamma-ray fluxes and TeV–PeV neutrino flux, the upper limit on the 1FLE blazar energy-scaled neutrino flux is determined to be 1.64 × 10 −12 TeV cm −2 s −1 at 90% confidence level. This upper limit is approximately 1% of IceCube’s diffuse muon–neutrino flux measurement.
Publisher: American Physical Society (APS)
Date: 15-01-2020
Publisher: American Astronomical Society
Date: 04-2020
Publisher: IOP Publishing
Date: 12-04-2016
Publisher: American Astronomical Society
Date: 04-2023
Abstract: This paper presents the results of a search for neutrinos that are spatially and temporally coincident with 22 unique, nonrepeating fast radio bursts (FRBs) and one repeating FRB (FRB 121102). FRBs are a rapidly growing class of Galactic and extragalactic astrophysical objects that are considered a potential source of high-energy neutrinos. The IceCube Neutrino Observatory’s previous FRB analyses have solely used track events. This search utilizes seven years of IceCube cascade events which are statistically independent of track events. This event selection allows probing of a longer range of extended timescales due to the low background rate. No statistically significant clustering of neutrinos was observed. Upper limits are set on the time-integrated neutrino flux emitted by FRBs for a range of extended time windows.
Publisher: American Astronomical Society
Date: 03-2023
Abstract: Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. While no correlations have yet been detected between high-energy neutrinos and GRBs, the recent observation of GRB 221009A—the brightest GRB observed by Fermi-GBM to date and the first one to be observed above an energy of 10 TeV—provides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A. We find no significant deviation from background expectation across event s les ranging from MeV to PeV energies, placing stringent upper limits on the neutrino emission from this source.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 17-11-2017
Abstract: Several cosmic-ray detectors have found more positrons arriving at Earth than expected. Some researchers interpret this as a signature of exotic physics, such as the annihilation of dark matter particles. Others prefer a more mundane explanation that involves positron generation at pulsars followed by diffusion to Earth. Abeysekara et al. detected extended emission of gamma rays around two nearby pulsars, generated by high-energy electrons and positrons. The size of the extended emission was used to calculate how far positrons generated by the pulsars diffuse through space—which turns out to be insufficient to reach Earth. The excess positrons detected on Earth must therefore have a more exotic origin than nearby pulsars. Science , this issue p. 911
Publisher: American Astronomical Society
Date: 20-04-2020
Publisher: American Astronomical Society
Date: 05-2022
Abstract: We present the first comprehensive search for high-energy neutrino emission from high- and low-mass X-ray binaries conducted by IceCube. Galactic X-ray binaries are long-standing candidates for the source of Galactic hadronic cosmic rays and neutrinos. The compact object in these systems can be the site of cosmic-ray acceleration, and neutrinos can be produced by interactions of cosmic rays with radiation or gas, in the jet of a microquasar, in the stellar wind, or in the atmosphere of the companion star. We study X-ray binaries using 7.5 yr of IceCube data with three separate analyses. In the first, we search for periodic neutrino emission from 55 binaries in the Northern Sky with known orbital periods. In the second, the X-ray light curves of 102 binaries across the entire sky are used as templates to search for time-dependent neutrino emission. Finally, we search for time-integrated emission of neutrinos for a list of 4 notable binaries identified as microquasars. In the absence of a significant excess, we place upper limits on the neutrino flux for each hypothesis and compare our results with theoretical predictions for several binaries. In addition, we evaluate the sensitivity of the next generation neutrino telescope at the South Pole, IceCube-Gen2, and demonstrate its power to identify potential neutrino emission from these binary sources in the Galaxy.
Publisher: American Astronomical Society
Date: 07-2023
Abstract: Beginning in 2016, the IceCube Neutrino Observatory has sent out alerts in real time containing the information of high-energy ( E ≳ 100 TeV) neutrino candidate events with moderate to high (≳30%) probability of astrophysical origin. In this work, we use a recent catalog of such alert events, which, in addition to events announced in real time, includes events that were identified retroactively and covers the time period of 2011–2020. We also search for additional, lower-energy neutrinos from the arrival directions of these IceCube alerts. We show how performing such an analysis can constrain the contribution of rare populations of cosmic neutrino sources to the diffuse astrophysical neutrino flux. After searching for neutrino emission coincident with these alert events on various timescales, we find no significant evidence of either minute-scale or day-scale transient neutrino emission or of steady neutrino emission in the direction of these alert events. This study also shows how numerous a population of neutrino sources has to be to account for the complete astrophysical neutrino flux. Assuming that sources have the same luminosity, an E −2.5 neutrino spectrum, and number densities that follow star formation rates, the population of sources has to be more numerous than 7 × 10 −9 Mpc −3 . This number changes to 3 × 10 −7 Mpc −3 if number densities instead have no cosmic evolution.
Location: United States of America
No related grants have been discovered for Juan Carlos Díaz Vélez.