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Papers by pooja bhattacharjee
arXiv (Cornell University), Sep 6, 2023
Physical review. D/Physical review. D., Jun 21, 2024
BENTHAM SCIENCE PUBLISHERS eBooks, May 8, 2024
arXiv (Cornell University), 2015
ABSTRACT
Zenodo (CERN European Organization for Nuclear Research), Feb 1, 2023
Proceedings of the Seventh Marcel Grossman Meeting on recent developments in theoretical and experimental general relativity, gravitation, and relativistic field theories, 1996
A low background PICASSO experiment to search for dark matter is in progress at the Sudbury Neutr... more A low background PICASSO experiment to search for dark matter is in progress at the Sudbury Neutrino Observatory (Canada) by using 10 detectors with total target mass of 0.72 kg of 19 F and exposure time of 114 kgd. Recoil energy thresholds are 1.7 keV which allows the sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c 2 . No dark matter signal was found till now. The limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c 2 with a cross section on protons of 0.032 pb (90% C.L.), in the spin independent sector close to the low WIMP mass region of 7 GeV/c 2 with cross section on protons 1.41 · 10 -4 pb (90 % C.L.).
Physical Review Letters, 1996
The self-consistent spatial distribution of particles of Galactic dark matter is derived includin... more The self-consistent spatial distribution of particles of Galactic dark matter is derived including their own gravitational potential, as also of that of the visible matter of the Galaxy. In order to reproduce the observed rotation curve of the Galaxy the value of the dispersion velocity of the dark matter particles, v 2 1/2 DM , should be ∼ 600 km s −1 or larger.
The European Open Science Cloud (EOSC) forms an ecosystem of research data and related services t... more The European Open Science Cloud (EOSC) forms an ecosystem of research data and related services that enable and enhance access and reuse of FAIR research outputs (i.e., data and other digital objects). The test science projects (TSPs) in EOSC Future will serve as examples of how joint projects can address major, if not global, challenges for Europe's societies and how research infrastructures can align to support Horizon Europe's missions within the EOSC. The five Science Clusters ENVRI-FAIR, ESCAPE, EOSC-Life, PANOSC and SSHOC have designed a set of TSPs to drive integration of research infrastructure data and services ("composability") between the science domains and, as they mature and become ready for production, demonstrate how services from EOSC-Core can be incorporated into the routine provisioning of research infrastructure services. As one key output from the science clusters towards EOSC, they will contribute thematic services to the EOSC Ecosystem which will be aggregated at the cluster level, reflect the needs, requirements and considerable digital assets and services of the associated research communities and mobilise the research communities for widespread use of EOSC resources. This paper present Science Project: Dark Matter.
International Cosmic Ray Conference, 2013
International Cosmic Ray Conference, 2013
Physical review, Feb 10, 2023
Brown dwarfs (BDs) are celestial objects representing the link between the least massive mainsequ... more Brown dwarfs (BDs) are celestial objects representing the link between the least massive mainsequence stars and giant gas planets. In the first part of this article, we perform a model-independent search of a gamma-ray signal from the direction of nine nearby BDs in 13 years of Fermi-LAT data. We find no significant excess of gamma rays, and we, therefore, set 95% confidence level upper limits on the gamma-ray flux with a binned-likelihood approach. In the second part of the paper, we interpret these bounds within an exotic mechanism proposed for gamma-ray production in BDs: If the dark matter (DM) of the universe is constituted of particles with non-negligible couplings to the standard model, BDs may efficiently accumulate them through scatterings. DM particles eventually thermalise, and can annihilate into light, long-lived, mediators which later decay into photons outside the BD. Within this framework, we set a stacked upper limits on the DM-nucleon elastic scattering cross section at the level ∼ 10 −38 cm 2 for DM masses below 10 GeV. Our limits are comparable to similar bounds from the capture of DM particles in celestial objects, but have the advantage of covering a larger portion of the parameter space in mediator decay length and DM mass. They also depend only on the local DM abundance, as opposed to the inner Galaxy profile, and are thus more robust.
arXiv (Cornell University), Oct 31, 2011
The radiation mechanism of very high energy γ-ray emission from blazars and crucial parameters li... more The radiation mechanism of very high energy γ-ray emission from blazars and crucial parameters like magnetic field, and size of the emitting region are not well understood yet. To understand the above mentioned properties of blazars, we observed five nearby TeV γ-ray emitting blazars (Mrk421, Mrk501, 1ES2344+514, 1ES1218+304 and 3C454.3) and one radio galaxy (M87) using the High Altitude GAmma Ray (HAGAR) telescope. HAGAR is an array of seven telescopes located at Hanle, India to detect Cherenkov light caused by extensive air showers initiated by γ-rays. Mrk421 was observed to undergo one of its brightest flaring episodes on 2010 February 17, and detected by various experiments in X-rays and γ-rays. HAGAR observations of this source during 2010 February 13-19, in the energies above 250 GeV show an enhancement in the flux level, with a flux of 6-7 Crab units being detected on 2010 February 17. We present the spectral energy distribution of the source during this flaring episode. In addition to this, the analysis procedure to extract γ-ray signal from HAGAR data is discussed and preliminary results on all the AGNs are presented.
Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)
Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)
arXiv (Cornell University), Sep 6, 2023
Physical review. D/Physical review. D., Jun 21, 2024
BENTHAM SCIENCE PUBLISHERS eBooks, May 8, 2024
arXiv (Cornell University), 2015
ABSTRACT
Zenodo (CERN European Organization for Nuclear Research), Feb 1, 2023
Proceedings of the Seventh Marcel Grossman Meeting on recent developments in theoretical and experimental general relativity, gravitation, and relativistic field theories, 1996
A low background PICASSO experiment to search for dark matter is in progress at the Sudbury Neutr... more A low background PICASSO experiment to search for dark matter is in progress at the Sudbury Neutrino Observatory (Canada) by using 10 detectors with total target mass of 0.72 kg of 19 F and exposure time of 114 kgd. Recoil energy thresholds are 1.7 keV which allows the sensitivity to interactions from Weakly Interacting Massive Particles (WIMPs) with masses below 10 GeV/c 2 . No dark matter signal was found till now. The limits in the spin dependent sector were obtained for WIMP masses of 20 GeV/c 2 with a cross section on protons of 0.032 pb (90% C.L.), in the spin independent sector close to the low WIMP mass region of 7 GeV/c 2 with cross section on protons 1.41 · 10 -4 pb (90 % C.L.).
Physical Review Letters, 1996
The self-consistent spatial distribution of particles of Galactic dark matter is derived includin... more The self-consistent spatial distribution of particles of Galactic dark matter is derived including their own gravitational potential, as also of that of the visible matter of the Galaxy. In order to reproduce the observed rotation curve of the Galaxy the value of the dispersion velocity of the dark matter particles, v 2 1/2 DM , should be ∼ 600 km s −1 or larger.
The European Open Science Cloud (EOSC) forms an ecosystem of research data and related services t... more The European Open Science Cloud (EOSC) forms an ecosystem of research data and related services that enable and enhance access and reuse of FAIR research outputs (i.e., data and other digital objects). The test science projects (TSPs) in EOSC Future will serve as examples of how joint projects can address major, if not global, challenges for Europe's societies and how research infrastructures can align to support Horizon Europe's missions within the EOSC. The five Science Clusters ENVRI-FAIR, ESCAPE, EOSC-Life, PANOSC and SSHOC have designed a set of TSPs to drive integration of research infrastructure data and services ("composability") between the science domains and, as they mature and become ready for production, demonstrate how services from EOSC-Core can be incorporated into the routine provisioning of research infrastructure services. As one key output from the science clusters towards EOSC, they will contribute thematic services to the EOSC Ecosystem which will be aggregated at the cluster level, reflect the needs, requirements and considerable digital assets and services of the associated research communities and mobilise the research communities for widespread use of EOSC resources. This paper present Science Project: Dark Matter.
International Cosmic Ray Conference, 2013
International Cosmic Ray Conference, 2013
Physical review, Feb 10, 2023
Brown dwarfs (BDs) are celestial objects representing the link between the least massive mainsequ... more Brown dwarfs (BDs) are celestial objects representing the link between the least massive mainsequence stars and giant gas planets. In the first part of this article, we perform a model-independent search of a gamma-ray signal from the direction of nine nearby BDs in 13 years of Fermi-LAT data. We find no significant excess of gamma rays, and we, therefore, set 95% confidence level upper limits on the gamma-ray flux with a binned-likelihood approach. In the second part of the paper, we interpret these bounds within an exotic mechanism proposed for gamma-ray production in BDs: If the dark matter (DM) of the universe is constituted of particles with non-negligible couplings to the standard model, BDs may efficiently accumulate them through scatterings. DM particles eventually thermalise, and can annihilate into light, long-lived, mediators which later decay into photons outside the BD. Within this framework, we set a stacked upper limits on the DM-nucleon elastic scattering cross section at the level ∼ 10 −38 cm 2 for DM masses below 10 GeV. Our limits are comparable to similar bounds from the capture of DM particles in celestial objects, but have the advantage of covering a larger portion of the parameter space in mediator decay length and DM mass. They also depend only on the local DM abundance, as opposed to the inner Galaxy profile, and are thus more robust.
arXiv (Cornell University), Oct 31, 2011
The radiation mechanism of very high energy γ-ray emission from blazars and crucial parameters li... more The radiation mechanism of very high energy γ-ray emission from blazars and crucial parameters like magnetic field, and size of the emitting region are not well understood yet. To understand the above mentioned properties of blazars, we observed five nearby TeV γ-ray emitting blazars (Mrk421, Mrk501, 1ES2344+514, 1ES1218+304 and 3C454.3) and one radio galaxy (M87) using the High Altitude GAmma Ray (HAGAR) telescope. HAGAR is an array of seven telescopes located at Hanle, India to detect Cherenkov light caused by extensive air showers initiated by γ-rays. Mrk421 was observed to undergo one of its brightest flaring episodes on 2010 February 17, and detected by various experiments in X-rays and γ-rays. HAGAR observations of this source during 2010 February 13-19, in the energies above 250 GeV show an enhancement in the flux level, with a flux of 6-7 Crab units being detected on 2010 February 17. We present the spectral energy distribution of the source during this flaring episode. In addition to this, the analysis procedure to extract γ-ray signal from HAGAR data is discussed and preliminary results on all the AGNs are presented.
Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)
Proceedings of 38th International Cosmic Ray Conference — PoS(ICRC2023)