The IceCube detector is an array of optical light detectors embedded deep in the South Pole ice that aims to discover the origins of astrophysical neutrinos. Due to the detector’s location, the ...southern equatorial sky astrophysical neutrino signal lies under a large background of muons generated in cosmic ray interactions in the atmosphere. Therefore, IceCube’s sensitivity to astrophysical neutrino sources has always been stronger in the northern sky, where the main background is atmospheric neutrinos created by cosmic ray air showers. The research presented here focuses on improving IceCube’s sensitivity to southern sky sources by selecting for starting tracks, which are created by muon neutrinos that interact inside of the IceCube detector volume. By selecting for starting tracks, we not only reduce the atmospheric muon background but also the atmospheric neutrino background, allowing for a high purity sample of astrophysical neutrinos in the southern sky. The starting tracks were used to perform four types of searches for astrophysical neutrino sources: a whole sky neutrinosource search, an individual source search with locations from bright gamma ray objects, a stacked source search which looks for a signal from multiple sources of the same type, and a galactic plane template search which looks for neutrinos created in the galactic plane medium. All searches were unable to significantly detect an astrophysical neutrino source, but the starting track selection technique could be used in tandem with other selections to discover galactic sources of neutrinos in the future.
The measurement of a diffuse astrophysical neutrino flux using starting track events marks the first time IceCube has observed and subsequently measured the astrophysical diffuse flux using a dataset ...composed primarily of starting track events. Starting tracks combine an excellent angular and energy resolution. This enables us to take advantage of the self-veto effect in the southern sky reducing the atmospheric neutrino rate allowing us to detect astrophysical neutrinos to energies well below 100 TeV. We measure the astrophysical flux as \(\phi^{per-flavor}_{Astro}=1.68^{+0.19}_{-0.22}\)(at 100 TeV) and \(\gamma_{Astro} = 2.58^{+0.10}_{-0.09}\) assuming a single power law flux. The astrophysical flux 90% sensitive energy range is 3 TeV to 500 TeV, extending IceCube's reach to the low energy astrophysical flux by an order of magnitude. A brief summary of tests performed to search for neutrinos from the galactic plane using this dataset is also provided. With this sample, we did not find statistically significant evidence for emission from the galactic plane. We then tested the impact of these galactic plane neutrinos on the isotropic diffuse flux, with at most 10% effect on the overall normalization and negligible impact to the spectral index.
IceCube real-time alerts allow for rapid follow-up observations of likely astrophysical neutrino events, enabling searches for multi-messenger counterparts. The Enhanced Starting Track Real-time ...Stream (ESTReS) is a real-time extension of the Enhanced Starting Track Event Selection (ESTES), a high astrophysical purity muon-neutrino sample recently used by IceCube to measure the astrophysical diffuse flux. A set of computationally cheap cuts allows us to run a fast filter in seconds. This online filter selects about 100 events per day to be sent to Madison, WI via satellite where the full ESTES event selection is applied within minutes. Events that pass the final set of cuts (ESTReS + ESTES) will be sent out as real-time alerts to the broader astrophysical community. ESTReS's unique contribution to the current real-time alerts will be events in the southern sky in the 5 TeV - 100 TeV range. We expect about 10.3 events per year which average 50% astrophysical purity. In this talk I will report the status of the ESTReS alert stream in the context of the IceCube real-time program.
The IceCube Neutrino Observatory has the invaluable capability of continuously monitoring the whole sky. This has affirmed the role of IceCube as a sentinel, providing real-time alerts to the ...astrophysical community on the detection of high-energy neutrinos and neutrino flares from a variety of astrophysical sources. As a response to the IceCube alerts, different observatories can join forces in the multi-messenger observation of transient events and the characterisation of their astrophysical sources. The 2017 breakthrough identification of blazar TXS 0506+056 as the source of high-energy neutrinos and UHE gamma rays was proof of this strategy. The Gamma-ray Follow-Up (GFU) is the IceCube program for identifying high-energy muon neutrino single events, as well as outstanding neutrino flares from relevant sources and the whole wide universe. While the identification of single high-energy neutrinos is shared on public alert distribution networks, partner Imaging Air Cherenkov Telescopes are sent low-latency alerts following the detection of neutrino flares, for which they have dedicated follow-up programs. I will present an overview of the GFU platform together with new results from the analysis of recorded neutrino flares, after a dozen years of GFU operation and hundreds of alerts being sent.
The IceCube Neutrino Observatory is a cubic kilometer-sized detector designed to detect neutrinos of astrophysical origin. However, muons created by cosmic rays interacting in the atmosphere pose a ...significant background for these astrophysical neutrinos particularly in the southern equatorial sky. Identifying neutrino events that start in the detector allows us to reduce the atmospheric muon component while retaining a high rate of starting neutrino events. The method presented today also rejects atmospheric neutrinos if they are accompanied by muons from the same cosmic ray shower, lowering the 50\(\%\) purity threshold for astrophysical-to-atmospheric neutrinos from 100 TeV to ~10 TeV at declinations less than -25{\deg}. We use 10\(\%\) (burn sample) of 9.5 years IceCube data to demonstrate the status of this dataset. We outline a planned measurement of the diffuse neutrino flux inclusive of theoretical and detector systematic uncertainties. In addition, we discuss searches for neutrino point sources and diffuse galactic plane neutrino emission in the Southern sky and plans to release high astrophysical-purity real-time alerts to the multi-messenger community.
IceCube measures the diffuse neutrino flux across several neutrino flavors and energy ranges. ESTES focuses on the measurement of the diffuse neutrino flux using high purity astrophysical muon ...neutrinos with energies above 1 TeV. We use the Enhanced Starting Track Event Selection dataset which selects for tracks starting within the IceCube fiducial volume. We employ a machine learning algorithm to help differentiate between tracks from atmospheric and astrophysical neutrinos. This produces a high purity diffuse neutrino sample that can provide valuable insight into the properties of the atmospheric and astrophysical diffuse neutrino spectrum. Using simulated neutrinos, we show the sensitivity for this measurement of the diffuse neutrino flux with ESTES.
IceCube analyses which look for an astrophysical neutrino signal in the southern sky face a large background of atmospheric muons and neutrinos created by cosmic ray air showers. By selecting ...starting events in the southern sky, atmospheric muons and neutrinos with accompanying muons are rejected, producing a sample with high astrophysical neutrino purity at lower energies than northern sky samples. Our new selection method looks for muon tracks from a neutrino interaction with a vertex contained inside the detector volume by using the good pointing resolution of the track morphology to create an event specific veto region in the detector to reject entering tracks. This starting track event selection has a high astrophysical neutrino purity above 10 TeV at declinations less than -30\(^{\circ}\) which makes it ideal for use as a southern sky realtime neutrino alert stream. We will discuss neutrino point source searches using this event selection and look at the advantages of the starting track alert stream for multimessenger astrophysics.
Breast cancer is the most common type of cancer in women. Although current treatments can increase patient survival, they are rarely curative when the disease is advanced (metastasis). Therefore, ...there is an urgent need to develop new cytotoxic drugs with a high selectivity toward cancer cells. Since repurposing approved drugs for cancer therapy has been a successful strategy in recent years, in this study, we screened a library of antiviral piperazine-derived compounds as anticancer agents. The compounds included a piperazine ring and aryl urea functions, which are privileged structures present in several anti-breast cancer drugs. The selective cytotoxic activity of a set of thirty-four 4-acyl-2-substituted piperazine urea derivatives against MCF7 breast cancer cells and MCF 10A normal breast cells was determined. Compounds
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showed high selective anticancer activity against breast cancer cells and were also tested against another common type of cancer, non-small cell lung cancer (A549 lung cancer cells versus MRC-5 lung normal cells). Compounds
and
also showed selectivity against lung cancer cells. These results suggest that compounds
and
may be promising hit compounds for the development of new anticancer agents.
