Abstracts of Interest
Selected by:
Olaf Koenig
Abstract: 2203.13268
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Observing the inner parsec-scale region of candidate neutrino-emitting blazars
Download PDFAbstract: Context. Many questions on the nature of astrophysical counterparts of high-energy neutrinos remain unanswered. There is increasing evidence of a connection between blazar jets and neutrino events, with the flare of the gamma-ray blazar TXS0506+056 in spatial and temporal proximity of IC170922A representing one of the most outstanding associations of high-energy neutrinos with astrophysical sources reported so far. Aims. With the purpose of characterising potential blazar counterparts to high-energy neutrinos, we analysed the parsec-scale regions of gamma-ray blazars in spatial coincidence with neutrinos detected by IceCube. Specifically, we intended to investigate peculiar radio properties of the candidate counterparts related to neutrino production, as radio flares coincident to the neutrino detection or features in jets morphology (limb brightening, transverse structures). Methods. We collected multi-frequency VLBI follow-up observations of candidate counterparts of four high-energy neutrino events detected by IceCube between January 2019 and November 2020. We analysed their radio characteristics soon after the neutrino arrival in comparison with archival VLBI observations and low-frequency radio observations. We discussed our results with respect to previous statistical works and studies on the case of TXS 0506+056. Results. We identified and analysed in detail five potential neutrino emitting blazars. Our results suggest an enhanced state of radio activity for one source, PKS1725+123. However, the lack of adequate monitoring prior to the neutrino events was a limitation in tracing radio activity and morphological changes in all the sources. Conclusions. We suggest that PKS1725+123 is a promising neutrino source candidate. For the other four sources, our results alone do not allow us to reveal a strong connection between the radio activity state at neutrino arrival.
Abstract: 2203.13276
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:The Fundamental Plane Relation for Gamma-Ray Pulsars Implied by 4FGL
Download PDFAbstract: We explore the validity of the recently reported fundamental plane (FP) relation of gamma-ray pulsars using 190 pulsars included in the latest 4FGL-DR3 catalog. This sample number is more than twice as large as that of the original study. The FP relation incorporates 4 parameters, i.e., the spin-down power, $\dot{\mathcal{E}}$, the surface magnetic field, $B_{\star}$, the total gamma-ray luminosity, $L_{\gamma}$, and a spectral cutoff energy, $\epsilon_{\rm cut}$. The derivation of $\epsilon_{\rm cut}$ is the most intriguing one because $\epsilon_{\rm cut}$ depends on the proper interpretation of the available phase-averaged spectra. We construct synthetic phase-averaged spectra, guided by the few existing phase-resolved ones, to find that the best fit cutoff energy, $\epsilon_{\rm c1}$, corresponding to a purely exponential cutoff (plus a power law) spectral form, is the parameter that optimally probes the maximum cutoff energy of the emission that originates from the core of the dissipative region, i.e., the equatorial current sheet. Computing this parameter for the 190 4FGL pulsars, we find that the resulting FP relation, i.e. the gamma-ray luminosity in terms of the other observables, reads $L_{\gamma}=10^{14.3\pm 1.3}(\epsilon_{\rm c1}/{\rm MeV})^{1.39\pm0.17}(B_{\star}/{\rm G})^{0.12\pm 0.03}(\dot{\mathcal{E}}/{\rm erg\;s^{-1}})^{0.35\pm 0.05}{\rm ~erg\;s^{-1}}$; this is in good agreement with both the empirical relation reported by Kalapotharakos et al. (2019) and the theoretically predicted relation for curvature radiation. Finally, we revisit the radiation reaction limited condition, to find it is a sufficient but not necessary condition for the theoretical derivation of the FP relation. However, the assumption of the radiation reaction limited acceleration reveals the underlying accelerating electric field component and its scaling with $\dot{\mathcal{E}}$.
Abstract: 2203.13827
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:PeV Tau Neutrinos to Unveil Ultra-High-Energy Sources
Download PDFAbstract: The observation of ultra-high-energy EeV-energy cosmogenic neutrinos provides a direct path to identifying the sources of the highest energy cosmic rays; searches have so far resulted in only upper limits on their flux. However, with the realization of cubic-kilometer detectors such as IceCube and, in the near future, KM3NeT, GVD-Baikal, and similar instruments, we anticipate the observation of PeV-energy cosmic neutrinos with high statistics. In this context, we draw attention to the opportunity to identify EeV tau neutrinos at PeV energy using Earth-traversing tau neutrinos. We show that Cherenkov detectors can improve their sensitivity to transient point sources by more than an order of magnitude by indirectly observing EeV tau neutrinos with initial energies that are nominally beyond their reach. This new technique also improves their sensitivity to the ultra-high-energy diffuse neutrino flux by up to a factor of two. Our work exemplifies how observing tau neutrinos at PeV energies provides an unprecedented reach to EeV fluxes.
Abstract: 2203.14198
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Fast Radio Bursts
Download PDFAbstract: The era of fast radio bursts (FRBs) was open in 2007, when a very bright radio pulse of unknown origin was discovered occasionally in the archival data of Parkes Telescope. Over the past fifteen years, this mysterious phenomenon have caught substantial attention among the scientific community and become one of the hottest topic in high-energy astrophysics. The total number of events has a dramatic increase to a few hundred recently, benefiting from new dedicated surveys and improved observational techniques. Our understanding of these bursts has been undergoing a revolutionary growth with observational breakthroughs announced consistently. In this chapter, we will give a comprehensive introduction of FRBs, including the latest progress. Starting from the basics, we will go through population study, inherent physical mechanism, and all the way to the application in cosmology. Plenty of open questions exist right now and there is more surprise to come in this active young field.
Abstract: 2203.14247
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Neutrino Masses and Mass Hierarchy: Evidence for the Normal Hierarchy
Download PDFAbstract: The latest cosmological constraints on the sum of neutrino masses, in combination with the latest laboratory measurements on oscillations, provide a "decisive" Bayesian evidence for the normal neutrino mass hierarchy. We show that this result is robust to the choice of prior by exploring two extremes on the range of prior choices. For Majorana neutrinos this has important implications for the upper limit of the neutrino-less double beta decay half life and thus for the technology and resources needed for future double beta decay experiments.
Abstract: 2203.14300
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Overview of the LAMOST survey in the first decade
Download PDFAbstract: The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), also known as the Guoshoujing Telescope, is a major national scientific facility for astronomical research located in Xinglong, China. Beginning with a pilot survey in 2011, LAMOST has been surveying the night sky for more than 10 years. The LAMOST survey covers various objects in the Universe, from normal stars to peculiar ones, from the Milky Way to other galaxies, and from stellar black holes and their companions to quasars that ignite ancient galaxies. Until the latest data release 8, the LAMOST survey has released spectra for more than 10 million stars, ~220,000 galaxies, and ~71,000 quasars. With this largest celestial spectra database ever constructed, LAMOST has helped astronomers to deepen their understanding of the Universe, especially for our Milky Way galaxy and the millions of stars within it. In this article, we briefly review the characteristics, observations, and scientific achievements of LAMOST. In particular, we show how astrophysical knowledge about the Milky Way has been improved by LAMOST data.
Abstract: 2203.14979
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Current and future neutrino limits on the abundance of primordial black holes
Download PDFAbstract: Primordial black holes (PBHs) formed in the early Universe are sources of neutrinos emitted via Hawking radiation. Such astrophysical neutrinos could be detected at Earth and constraints on the abundance of comet-mass PBHs could be derived from the null observation of this neutrino flux. Here, we consider non-rotating PBHs and improve constraints using Super-Kamiokande neutrino data, as well as we perform forecasts for next-generation neutrino (Hyper-Kamiokande, JUNO, DUNE) and dark matter (DARWIN, ARGO) detectors, which we compare. For PBHs less massive than $\sim \textrm{few} \times 10^{14}$ g, PBHs would have already evaporated by now, whereas more massive PBHs would still be present and would constitute a fraction of the dark matter of the Universe. We consider monochromatic and extended (log-normal) mass distributions, and a PBH mass range spanning from $10^{12}$ g to $\sim 10^{16}$ g. Finally, we also compare our results with previous ones in the literature.
Abstract: 2203.15169
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Efficiency of Nonthermal Particle Acceleration in Magnetic Reconnection
Download PDFAbstract: The nonthermal particle acceleration during magnetic reconnection remains a fundamental topic in several astrophysical phenomena, such as solar flares, pulsar wind, magnetars, etc, for more than half a century, and one of the unresolved questions is its efficiency. Recently, nonthermal particle acceleration mechanisms during reconnection have been extensively studied by particle-in-cell simulations, yet it is an intriguing enigma as to how the magnetic field energy is divided into thermally heated plasmas and nonthermal particles. Here we study both non-relativistic and relativistic magnetic reconnections using large-scale particle-in-cell simulation for a pair plasma, and indicate that the production of the nonthermal particle becomes efficient with increasing the plasma temperature. In the relativistic hot plasma case, we determine that the heated plasmas by reconnection can be approximated by a kappa distribution function with the kappa index of approximately 3 or less (equivalent to 2 or less for the power-law index), and the nonthermal energy density of reconnection is approximately over 95% of the total internal energy in the downstream exhaust.
Abstract: 2203.15181
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:EstrellaNueva: an open-source software to study the interactions and detection of neutrinos emitted by supernovae
Download PDFAbstract: Supernovae emit large fluxes of neutrinos which can be detected by detectors on Earth. Future tonne-scale detectors will be sensitive to several neutrino interaction channels, with thousands of events expected if a supernova emerges in the galaxy neighborhood. There is a limited number of tools to study the interaction rates of supernova neutrinos, although a plethora of available supernova models exists. EstrellaNueva is an open-source software to calculate expected rates of supernova neutrinos in detectors using target materials with typical compositions, and additional compositions can be easily added. This software considers the flavor transformation of neutrinos in the supernova through the adiabatic Mikheyev--Smirnov--Wolfenstein effect, and their interaction in detectors through several channels. Most of the interaction cross sections have been analytically implemented, such as neutrino-electron and neutrino-proton elastic scattering, inverse beta decay, and coherent elastic neutrino-nucleus scattering. This software provides a link between supernova simulations and the expected events in detectors by calculating fluences and event rates to ease any comparison between theory and observation. It provides a simple and standalone tool to explore many physics scenarios offering an option to add analytical cross sections and define any target material.
Abstract: 2203.15538
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Optical and X-ray GRB Fundamental Planes as Cosmological Distance Indicators
Download PDFAbstract: Gamma-Ray Bursts (GRBs), observed up to $z=9.4$, can be employed as standardized candles, extending the distance ladder beyond Supernovae Type Ia (SNe Ia, $z=2.26$). We standardize GRBs using the 3D fundamental plane relation among the rest-frame end time of the X-ray plateau emission, its corresponding luminosity, and the peak prompt luminosity. Combining SNe Ia and GRBs, we constrain the matter content $\Omega_{\text{M}}= 0.299 \pm 0.009$ assuming a flat $\Lambda$CDM cosmology with and without correcting for selection biases and redshift evolution. Using a similar 3D correlation in optical, we find that our optical GRB sample is as efficacious in the determination of $\Omega_{\text{M}}$ as the X-ray sample. We trimmed our GRB samples to achieve tighter planes to be used to simulate additional GRBs. We determined how many GRBs are needed to be used as standalone probes to achieve a comparable precision on $\Omega_{\text{M}}$ to the one obtained by SNe Ia only. {\bf We achieve the error measurements derived using SNe Ia in (Conley et al. 2011) with 142 GRBs in optical considering the errorbars on the variables halved and in Betoule et al. (2014) with 284 optical GRBs, by considering that the error bars on the variables halved. Using a doubled sample (obtained by future machine learning approaches that allow both a lightcurve reconstruction and the estimates of GRBs for which the GRB is unknown) compared to our current one, with errorbars halved we will reach the same precision of (Scolnic et al. 2018) with 390 GRBs which will be uses as efficient standalone probes as SNe Ia by 2054.
Abstract: 2203.15540
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Pushchino multibeam pulsar search: I. Targeted search of weak pulsars
Download PDFAbstract: The search for pulsars in a sample of pulsar candidates found based on a multi-year survey conducted with low (6 channels; sampling 0.1s) time-frequency resolution on declinations -9^o < \delta < +42^o was carried out. A Large Phased Array (LPA) transit telescope operating at 111 MHz in the 2.5 MHz band was used. Search, analysis and evidence of pulsar detection were carried out using a visualization program of summed up power spectra obtained from the survey data with high 32 channels; sampling 12.5ms) time-frequency resolution. 11 new pulsars with periods P0 = 0.41-3.75 s and dispersion measure DM=15-154 pc/cm^3 have been discovered. In total, in the survey with a low time-frequency resolution for the period 2016-2021 in a blind search, 208 pulsars were found, of them 42 new and 166 known pulsars. It is shown that in the search on the data with high time-frequency resolution accumulated over a time interval of 7 years, pulsars with a flux density of 0.1 - 0.2 mJy at the frequency of 111 MHz can be detected. When searching for pulsars with regular (periodic) emission at declinations +21^o < \delta < +42^o, all pulsars located outside the galactic plane, having P0 \ge 0.5 s, DM \le 100 pc/cm^3 and the flux density S \ge 0.5 mJy, can be detected
Abstract: 2203.15621
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Impact of COVID-19 on Astronomy: Two Years In
Download PDFAbstract: We study the impact of the COVID-19 pandemic on astronomy using public records of astronomical publications. We show that COVID-19 has had both positive and negative impacts on research in astronomy. We find that the overall output of the field, measured by the yearly paper count, has increased. This is mainly driven by boosted individual productivity seen across most countries, possibly the result of cultural and technological changes in the scientific community during COVID. However, a decreasing number of incoming new researchers is seen in most of the countries we studied, indicating larger barriers for new researchers to enter the field or for junior researchers to complete their first project during COVID. Unfortunately, the overall improvement in productivity seen in the field is not equally shared by female astronomers. By fraction, fewer papers are written by women and fewer women are among incoming new researchers in most countries. Even though female astronomers also became more productive during COVID, the level of improvement is smaller than for men. Pre-COVID, female astronomers in the Netherlands, Australia, Switzerland were equally as or even more productive than their male colleagues. During COVID, no single country's female astronomers were able to be more productive than their male colleagues on average.
Abstract: 2203.15624
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Microphysics of diffusive shock acceleration: impact on the spectrum of accelerated particles
Download PDFAbstract: Diffusive shock acceleration at collisionless shocks remains the most likely process for accelerating particles in a variety of astrophysical sources. While the standard prediction for strong shocks is that the spectrum of accelerated particles is universal, $f(p)\propto p^{-4}$, numerous phenomena affect this simple conclusion. In general, the non-linear dynamical reaction of accelerated particles leads to a concave spectrum, steeper than $p^{-4}$ at momenta below a few tens of GeV/c and harder than the standard prediction at high energies. However, the non-linear effects become important in the presence of magnetic field amplification, which in turn leads to higher values of the maximum momentum $p_{max}$. It was recently discovered that the self-generated perturbations that enhance particle scattering, when advected downstream, move in the same direction as the background plasma, so that the effective compression factor at the shock decreases and the spectrum becomes steeper. We investigate the implications of the excitation of the non-resonant streaming instability on these spectral deformations, the dependence of the spectral steepening on the shock velocity and the role played by the injection momentum.
Abstract: 2203.15759
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Galactic diffuse gamma rays meet the PeV frontier
Download PDFAbstract: The Tibet AS$\gamma$ and LHAASO collaborations recently reported the observation of a $\gamma$-ray diffuse emission with energy up to the PeV from the Galactic plane.} {We discuss the relevance of non-uniform cosmic-ray transport scenarios and the implications of these results for cosmic-ray physics.} {We use the {\tt DRAGON} and {\tt HERMES} codes to build high-resolution maps and spectral distributions of that emission for several representative models under the condition that they reproduce a wide set of local cosmic-ray data up to 100 PeV.} {We show that the energy spectra measured by Tibet AS$\gamma$, LHAASO, ARGO-YBJ and Fermi-LAT in several regions of interest in the sky can all be consistently described in terms of the emission arising by the Galactic cosmic-ray "sea". We also show that all our models are compatible with IceTop $\gamma$-ray upper limits.} {Our results favor transport models characterized by spatial-dependent diffusion although some degeneracy remains between the choice of the transport scenario and that of the cosmic-ray spectral shape above 10 TeV. We discuss the role of forthcoming measurements in resolving that ambiguity.
Abstract: 2203.16404
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Gamma-Ray Emission from Nova Shocks Expanding in the Red Giant Wind: Interpretation of the 2021 Outburst of the Recurrent Nova RS Ophiuchi
Download PDFAbstract: Nova outbursts take place in binary star systems comprising a white dwarf (WD) and either a low-mass Sun-like star (classical novae) or, as in the case of the symbiotic nova, a red giant. GeV gamma-ray emission has been detected from a dozen of classical novae and from one symbiotic nova (V407 Cyg) by Fermi-LAT. For classical novae, gamma-ray emission is generally thought to be related to internal shocks formed as fast outflow collides with the slow outflow. However, for the symbiotic nova V407 Cyg, the origin of the gamma-ray emission has been debated, as both internal shock and external shock, resulted from the collision between the nova ejecta and the ambient wind of the giant companion, were suggested to explain the gamma-ray data. Recently, bright GeV and TeV gamma-ray emission has been detected from a symbiotic Nova, RS Ophiuchi, during its 2021 outburst, which shows a remarkably smooth powerlaw decay in time up to about one month after the outburst. We show that this temporal decay behavior can be interpreted as arising from an external shock, which is in the self-similar deceleration phase. In this interpretation, the gamma-rays are produced by shock-accelerated protons interacting with the dense wind through the hadronic process. Our interpretation thus indicates that the nova shock is able to accelerate cosmic ray protons up to TeV energies even when it has been significantly decelerated.
Abstract: 2203.16443
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:100 years of mathematical cosmology: Models, theories, and problems
Download PDFAbstract: An elementary survey of mathematical cosmology is presented. We cover certain key ideas and developments in a qualitative way, from the time of the Einstein static universe in 1917 until today. We divide our presentation into four main parts, the first part containing important cosmologies discovered until 1960. The second period (1960-80) contains discussions of geometric extensions of the standard cosmology, singularities, chaotic behaviour, and the initial input of particle physics ideas into cosmology. Our survey for the third period (1980-2000) continues with brief descriptions of the main ideas of inflation, the multiverse, quantum, Kaluza-Klein, and string cosmologies, wormholes and baby universes, cosmological stability, and modified gravity. The last period which ends today includes various more advanced topics such as M-theoretic cosmology, braneworlds, the landscape, topological issues, the measure problem, genericity, dynamical singularities, and dark energy. We emphasize certain threads that run throughout the whole period of development of theoretical cosmology and underline their importance in the overall structure of the field. We end this outline with an inclusion of the abstracts of all papers contributed to the Philosophical Transactions of the Royal Society A, Theme Issue `The Future of Mathematical Cosmology'.
Abstract: 2203.16559
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Fast Neutrino Conversion in Hydrodynamic Simulations of Neutrino-Cooled Accretion Disks
Download PDFAbstract: The outflows from neutrino-cooled black-hole (BH) accretion disks formed in neutron-star mergers or cores of collapsing stars are expected to be neutron-rich enough to explain a large fraction of elements created by the rapid neutron-capture (r-) process, but their precise chemical composition remains elusive. Here, we investigate the role of fast neutrino flavor conversion, motivated by the findings of our post-processing analysis that shows evidence of electron-neutrino lepton-number (ELN) crossings deep inside the disk, hence suggesting possibly non-trivial effects due to neutrino flavor mixing. We implement a parametric, dynamically self-consistent treatment of fast conversion in time-dependent simulations and examine the impact on the disk and its outflows. By activating the, otherwise inefficient, emission of heavy-lepton neutrinos, fast conversions enhance the disk cooling rates and reduce the absorption rates of electron-type neutrinos, causing a reduction of the electron fraction in the disk by 0.03-0.06 and in the ejected material by 0.01-0.03. The r-process yields are enhanced by typically no more than a factor of two, rendering the overall impact of fast conversions modest. The kilonova is prolonged as a net result of increased lanthanide opacities and enhanced radioactive heating rates. We observe only mild sensitivity to the disk mass, the condition for the onset of flavor conversion, and to the considered cases of flavor mixing. Remarkably, parametric models of flavor mixing that conserve the lepton numbers per family result in an overall smaller impact than models invoking three-flavor equipartition, often assumed in previous works.
Abstract: 2203.16648
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Predicting Winners of the Reality TV Dating Show $\textit{The Bachelor}$ Using Machine Learning Algorithms
Download PDFAbstract: $\textit{The Bachelor}$ is a reality TV dating show in which a single bachelor selects his wife from a pool of approximately 30 female contestants over eight weeks of filming (American Broadcasting Company 2002). We collected the following data on all 422 contestants that participated in seasons 11 through 25: their Age, Hometown, Career, Race, Week they got their first 1-on-1 date, whether they got the first impression rose, and what "place" they ended up getting. We then trained three machine learning models to predict the ideal characteristics of a successful contestant on $\textit{The Bachelor}$. The three algorithms that we tested were: random forest classification, neural networks, and linear regression. We found consistency across all three models, although the neural network performed the best overall. Our models found that a woman has the highest probability of progressing far on $\textit{The Bachelor}$ if she is: 26 years old, white, from the Northwest, works as an dancer, received a 1-on-1 in week 6, and did not receive the First Impression Rose. Our methodology is broadly applicable to all romantic reality television, and our results will inform future $\textit{The Bachelor}$ production and contestant strategies. While our models were relatively successful, we still encountered high misclassification rates. This may be because: (1) Our training dataset had fewer than 400 points or (2) Our models were too simple to parameterize the complex romantic connections contestants forge over the course of a season.
Abstract: 2203.16740
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Searching for neutrino emissions from multi-frequency sources
Download PDFAbstract: Pinpointing the neutrino sources is crucial to unveil the mystery of high-energy cosmic rays. The search for neutrino-source candidates from coincident neutrino-photon signatures and electromagnetic objects with peculiar flaring behaviors have the potential to increase our chances of finding neutrino emitters. In this paper, we first study the temporal correlations of astrophysical flares with neutrinos, considering a few hundreds of multi-frequency sources from ALMA, WISE, Swift, and Fermi in the containment regions of IceCube high-energy alerts. Furthermore, the spatial correlations between blazars and neutrinos are investigated using the subset of 10-year IceCube track-like neutrinos with around 250 thousand events. In the second test, we account for 2700 blazars with different types of flaring phases in addition to sole position. No significant neutrino emissions were found from our analyses. Our results indicate an interesting trend showing the infrared flaring stages of WISE blazars might be correlated with arrival times of the neutrino alerts. Possible overflow of neutrinos associated with two of our blazar sub-samples are also illustrated. One is characterized by a significant flaring lag in infrared with respect to gamma-rays, like seen for TXS0506+056, and the other is characterized by highly simultaneous infrared and gamma-ray flares. These phenomena suggest the need to improve current multi-frequency light-curve catalogs to pair with the advent of more sensitive neutrino observatories.
Abstract: 2203.17135
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Neutrino follow-up with the Zwicky Transient Facility: Results from the first 24 campaigns
Download PDFAbstract: The Zwicky Transient Transient Facility (ZTF) performs a systematic neutrino follow-up program, searching for optical counterparts to high-energy neutrinos with dedicated Target-of-Opportunity (ToO) observations. Since first light in March 2018, ZTF has taken prompt observations for 24 high-quality neutrino alerts from the IceCube Neutrino Observatory, with a median latency of 12.2 hours from initial neutrino detection. From two of these campaigns, we have already reported tidal disruption event (TDE) AT2019dsg and likely TDE AT2019fdr as probable counterparts, suggesting that TDEs contribute >7.8% of the astrophysical neutrino flux. We here present the full results of our program through to December 2021. No additional candidate neutrino sources were identified by our program, allowing us to place the first constraints on the underlying optical luminosity function of astrophysical neutrino sources. Transients with optical absolutes magnitudes brighter that -21 can contribute no more than 87% of the total, while transients brighter than -22 can contribute no more than 58% of the total, neglecting the effect of extinction. These are the the first observational constraints on the neutrino emission of bright populations such as superluminous supernovae. None of the neutrinos were coincident with bright optical AGN flares comparable to that observed for TXS 0506+056/IC170922A, suggesting that most astrophysical neutrinos are not produced during such optical flares. We highlight the outlook for electromagnetic neutrino follow-up programs, including the expected potential for the Rubin Observatory.
Abstract: 2203.17223
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Cosmological Neutrinos
Download PDFAbstract: Within the context of hot big-bang cosmology, a cosmic background of presently low energy neutrinos is predicted to exist in concert with the photons of the cosmic background radiation. The number density of the cosmological neutrinos is of the same order as that of the photons of the cosmic background radiation. That makes neutrinos the second most abundant particle species in the universe. In the early universe, when these neutrinos were highly relativistic, their effects in determining the ultimate structure and evolution of the universe were significant.
This page created: Mon Apr 4 14:58:55 ACST 2022 by Olaf Koenig
For a printable title listing click here
For details on generating this page see the instructions. If there are problems with this page (and I expect there will be from time to time) contact Jose.
For previous lists of abstracts of interest click Previous abstracts of interest