15 research outputs found
Young Supernovae fabricating the high energy universe: Diffuse Gamma rays and Neutrinos
No full textMulti-wavelength observations of different core-collapse Supernovae (SNe) have confirmed the presence of dense Circumstellar Material (CSM) around the progenitor star. The CSM is formed as a result of high mass loss of the progenitor star a few years prior to its death. Interaction of this CSM with high energy particles created in supernova explosion can produce secondary particles like high energy neutrinos and gamma rays. We term such SNe as Young Supernova (YSNe) as this interaction generally lasts for about a year after explosion and estimate the spectra of high energy neutrinos and gamma rays emitted by different types (IIn, II-P, Ib/c, and IIb/II-L) of YSNe. The estimate of the diffuse backgrounds of high energy neutrinos and gamma rays from YSNe shows largest contribution to the diffuse background by type IIn, followed by II-P and Ib/c. Interestingly, the corresponding diffuse neutrino background can also explain very well the IceCube’s diffuse flux. However, the dense CSM of these YSNe attenuate a large fraction of the gamma rays resulting in a ``dark’' source in the diffuse flux and doesn’t create any tension with the Fermi-LAT’s Isotropic Gamma Ray Background (IGRB)
New constraints on the gamma-ray and high energy neutrino fluxes from the circumstellar interaction of SN 2023ixf
No full textThe recent supernova, SN 2023ixf, one of the closest observed type II SNe has
revealed the presence of a dense circumstellar material (CSM). Interaction of
the SN ejecta with this dense CSM might create high energy protons of PeV
energies through shock acceleration. These accelerated protons then colliding
with the CSM (inelastic collision) can produce secondaries such as high
energy gamma-rays and neutrinos. However, no gamma-rays and neutrinos have been
detected by Fermi-LAT and IceCube from this event. Fermi-LAT has placed an
upper limit on the gamma-ray flux above ~MeV to be . On the other hand, IceCube's upper limit on
muon neutrino flux is . {\color{black}
Taking these limits into account and using the shock-CSM properties derived
from multi-wavelength observations, we obtain new upper limits on the gamma-ray
() and neutrino ()
fluxes from SN 2023ixf produced via the interaction channel.} While we
found the gamma-ray flux to be consistent with Fermi-LAT's upper limit, the
neutrino flux is found to be about orders of magnitude smaller than the
IceCube's upper limit. We further analyse the detection prospects of such
secondary signals from future SN 2023 like events with upcoming detectors, CTA
and IceCube-Gen2 and found to have great discovery potential, if any similar
event occurs within Mpc.Comment: Accepted for publication in JCAP. A new section added with a new
figur
High energy particles from young supernovae:gamma-ray and neutrino connections
No full textAbstract
Young core-collapse supernovae (YSNe)
are factories of high-energy neutrinos and gamma-rays as the shock accelerated protons efficiently interact with the protons in the
dense circumstellar medium. We explore the detection prospects of secondary particles from YSNe of Type
IIn, II-P, IIb/II-L, and Ib/c.
Type IIn YSNe are found to produce the largest flux of neutrinos and gamma-rays, followed by II-P YSNe.
Fermi-LAT and the Cherenkov Telescope Array (IceCube-Gen2) have the potential to detect Type IIn YSNe up to 10 Mpc (4 Mpc),
with the remaining YSNe Types being detectable closer to Earth.
We also find that YSNe may dominate the diffuse neutrino background, especially between 10 TeV and 103 TeV, while they do not constitute a dominant component to the isotropic gamma-ray background observed by Fermi-LAT. At the same time, the IceCube high-energy starting events and Fermi-LAT data already allow us to exclude a large fraction of the model parameter space of YSNe otherwise inferred from multi-wavelength electromagnetic observations of these transients.</jats:p
A relook at the GZK Neutrino-Photon Connection: Impact of Extra-galactic Radio Background & UHECR properties
No full textUltra-high energy cosmic rays (UHECRs) beyond the Greisen-Zatsepin-Kuzmin
(GZK) cut-off provide us with a unique opportunity to understand the universe
at extreme energies. Secondary GZK photons and GZK neutrinos associated with
the same interaction are indeed interconnected and render access to
multi-messenger analysis of UHECRs. The GZK photon flux is heavily attenuated
due to the interaction with Cosmic Microwave Background (CMB) and the
Extra-galactic Radio Background (ERB). The present estimate of the ERB
comprising of several model uncertainties together with the ARCADE2 radio
results in large propagation uncertainties in the GZK photon flux. On the other
hand, the weakly interacting GZK neutrino flux is unaffected by these
propagation effects. In this work, we make an updated estimate of the GZK
photon and GZK neutrino fluxes considering a wide variation of both the
production and propagation properties of the UHECR like, the spectral index,
the cut-off energy of the primary spectrum, the distribution of sources and the
uncertainties in the ERB estimation. We explore the detection prospects of the
GZK fluxes with various present and upcoming UHECR and UHE neutrino detectors
such as Auger, TA, GRAND, ANITA, ARA, IceCube and IceCube-Gen2. The predicted
fluxes are found to be beyond the reach of the current detectors. In future,
proposed IceCube-Gen2, Auger upgrade and GRAND experiments will have the
sensitivity to the predicted GZK photon and GZK neutrino fluxes. Such detection
can put constraints on the UHECR source properties and the propagation effects
due to the ERB. We also propose an indirect limit on the GZK photon flux using
the neutrino-photon connection for any future detection of GZK neutrinos by the
IceCube-Gen2 detector. We find this limit to be consistent with our GZK flux
predictions.Comment: Accepted for publication in JCA
The Amaterasu particle: constraining the superheavy dark matter origin of UHECRs
No full textAmaterasu, the second most energetic ( EeV) cosmic ray particle has been
recently detected by the Telescope Array (TA) surface detector. The origin of
the TA Amaterasu event is puzzling, as its arrival direction points back to a
void in the local Universe, lacking conventional astrophysical
ultra-high-energy (UHE) cosmic ray (CR) sources. Hence, we explore the
possibility if this TA Amaterasu event could have originated from the decay of
superheavy dark matter (SHDM) in the Milky Way. Such an origin also opens up
multi-messenger detection channels in both UHE gamma-rays and UHE neutrinos. In
this present work, using the TA Amaterasu event and the multi-messenger
limits/sensitivities from various UHE telescopes, we place stringent
constraints on the lifetime and mass of the SHDM. We find that the
non-detection of the corresponding gamma-rays at the Pierre Auger Observatory
(PAO) and the TA is in severe tension with the SHDM parameter space required to
explain the TA Amaterasu event. Additionally, we extend the multi-messenger
analysis to the future UHE gamma-ray and UHE neutrino telescopes such as PAO
upgrade, GRAND 200k and IceCube-Gen2. We find that the bounds from the future
neutrino telescopes will be able to compete with the present UHECR bounds.
However, compared to the existing UHE gamma-ray bounds, the future PAO upgrade
and the GRAND 200k gamma-ray detectors will improve the bounds on SHDM lifetime
by at least one order of magnitude.Comment: 9 pages, 4 figure
Gamma-rays and neutrinos from supernovae of Type Ib/c with late time emission
No full textObservations of some supernovae (SNe), such as SN 2014C, in the X-ray and
radio wavebands revealed a rebrightening over a timescale of about a year since
their detection. Such a discovery hints towards the evolution of a
hydrogen-poor SN of Type Ib/c into a hydrogen-rich SN of Type IIn, the late
time activity being attributed to the interaction of the SN ejecta with a dense
hydrogen-rich circumstellar medium (CSM) far away from the stellar core. We
compute the neutrino and gamma-ray emission from these SNe, considering
interactions between the shock accelerated protons and the non-relativistic CSM
protons. Assuming three CSM models inspired by recent electromagnetic
observations, we explore the dependence of the expected multi-messenger signals
on the CSM characteristics. The detection prospects of existing and upcoming
gamma-ray (Fermi-LAT and Cerenkov Telescope Array) and neutrino (IceCube and
IceCube-Gen2) telescopes are also outlines. Our findings are in agreement with
the non-detection of neutrinos and gamma-rays from past SNe exhibiting late
time emission. Nevertheless, the detection prospects of SNe with late time
emission in gamma-rays and neutrinos with the Cerenkov Telescope Array and
IceCube-Gen2 (Fermi-LAT and IceCube) are promising and could potentially
provide new insight into the CSM properties, if the SN burst should occur
within Mpc ( Mpc).Comment: Accepted for publication in PRD. KM3NeT/ARCA sensitivity is dropped
from Fig. 3 and Fig. 4. Appendix adde
Gamma-Rays and High Energy Neutrinos from Young Supernovae
No full textMultiwavelength observations of Supernovae (SNe) have revealed the presence of dense Circumstellar Material (CSM) around their progenitor stars. This CSM is formed due to heavy mass loss that the progenitor stars suffer a few years prior to their death as SNe. High energy protons accelerated in SN explosion interacting with this CSM can produce secondary particles like high energy neutrinos and gamma-rays. We term such SNe as Young Supernova (YSNe) as this interaction generally lasts for about a year after explosion. In this work, we estimate the fluxes of high energy neutrinos and gamma rays emitted by different types (IIn, II-P, Ib/c, and IIb/II-L) of YSNe. Type IIn produces the largest neutrino and gamma-ray fluxes, followed by Ib/c and II-P. Telescopes like IceCube-Gen2 (neutrino) and Fermi-LAT (gamma-ray) might detect type IIn upto 10 Mpc, while the remaining types are detectable at smaller distances. The different classes of YSNe can also produce diffuse backgrounds of high energy neutrinos and gamma-rays. The contribution to these diffuse backgrounds is found to be dominated by type IIn YSNe, followed by type II-P and Ib/c YSNe. The diffuse neutrino background from YSNe explains very well the IceCube High Energy Starting Events (HESE). Interestingly, the gamma-ray counterpart to diffuse background do not create tension to the resolved Isotropic Gamma-ray Background (IGRB) measured by Fermi-LAT.</p
A New Genre of Recommender Systems Based on Modern Paradigms of Data Filtering
No full textAbstractIn this era of web, we have a huge amount of information overload over internet. To extract useful information, filtering is required. Search engines help to solve this problem to some extent but they do not provide personalization of data. Hence, there is a need of recommendation engine. With the help of recommender software the preferences of user for a particular product can be foreseen. Recommender systems help in pinpointing the required information thereby deescalating unwanted information. Collaborative filtering is the most efficient approach to create recommendations so that the identified choices of a user's group can be used to envisage the preferences for other users which are not yet known to them. Through this paper we endeavor to present a thorough survey of collaborative filtering methods that can help in future for further research in this field and thereby propose a solution to enhance the precision and recall measures of recommendations
An Extended Hybridization of Vigenere and Caesar Cipher Techniques for Secure Communication
No full textAbstractCryptography is one of the most popular fields of study these days as it is necessary to maintain the confidentiality of the data which is sent over the network. There are various cipher techniques available for encrypting the messages such as vernam cipher, mono-alphabetic cipher, poly-alphabetic cipher, etc. One of the most popular cipher techniques is the vigenere cipher. It is a poly-alphabetic cipher technique which uses the vigenere table for the process of encryption of alphabets. This paper extends the vigenere table by including numerical data, so that the numbers can also be encrypted using this technique. It combines the encryption process of vigenere and Caesar cipher for getting the cipher text from the given plaintext and key
