Autor: Mehta, A. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Oscillatory fluid flow and heat transfer through porous medium between parallel plates with inclined magnetic field, radiative heat flux and heat source
Autorzy:: Mehta, T.
Mehta, R.
Mehta, A
Tematy:: pole magnetyczne
ciało porowate
promieniowanie
źródło ciepła
oscillatory
inclined magnetic field
porous medium
radiation
heat source
skin-friction coefficient and Nusselt number; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/265399.pdf Link otwiera się w nowym oknie
Opis:: The aim of the paper is to investigate an oscillatory fluid flow and heat transfer through a porous medium between parallel plates in the presence of an inclined magnetic field, radiative heat flux and heat source. It is assumed that electrical conductivity of the fluid is small and the electromagnetic force produced is very small. The governing coupled equations of motion and energy are solved analytically. Numerical results for the velocity and temperature profiles, local skin friction coefficient and local Nusselt number for various values of physical parameters are discussed numerically and presented graphically.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Emission Spectra of Triple Activated SrS Phosphors
Autorzy:: Rao, A. P.
Sinha, O. P.
Machwe, V. G.
Mehta, A. S.
Tematy:: 33.50.-j; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1945381.pdf Link otwiera się w nowym oknie
Opis:: Fluorescence spectra of strontium sulphide phosphors activated by three activators viz. Mn, Cu, and Gd individually and in different combinations have been discussed at length. X-ray is used as excitation source. Probable inferences are drawn regarding energy transfer phenomenon. The two channels for transfer of energy are concluded in present phosphor series. A model is also proposed.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: Very-high-energy γ-ray emission from young massive star clusters in the Large Magellanic Cloud
Autorzy:: Schutte, H. M.
Rowell, G.
Montanari, A.
Marx, R.
Kundu, A.
Glicenstein, J. F.
Żywucka, N.
Jamrozy, Marek
Pühlhofer, G.
Martins, V. Barbosa
Benkhali, F. Ait
Ostrowski, Michał
Brown, A.
Böttcher, M.
Le Stum, S.
Leuschner, F.
Chibueze, O.
Ren, H.
Sushch, I.
Aschersleben, J.
White, R.
de Bony de Lavergne, M.
Mackey, J.
Kluźniak, W.
Renaud, M.
Mitchell, A.
Reimer, A.
Reville, B.
Vecchi, M.
de Naurois, M.
Lenain, J.-P.
Cristofari, P.
Ravikularaman, S.
Chandra, S.
Reimer, O.
Funk, S.
Horns, D.
Filipovic, M.
Sahakian, V.
Lang, R. G.
Egberts, K.
Casanova, S.
Moghadam, M. O.
Brose, R.
Hofmann, W.
Lemoine-Goumard, M.
Feijen, K.
Tsirou, M.
Schüssler, F.
Batzofin, R.
Ruiz-Velasco, E.
Mehta, A.
Borowska, J.
Wagner, S. J.
Bernlöhr, K.
Kosack, K.
Rudak, B.
Santangelo, A.
Spencer, S.
Zdziarski, A. A.
Jankowsky, F.
Bruno, B.
Cotter, G.
Khatoon, R.
Celic, J.
Jung-Richardt, I.
Katarzyński, K.
Brun, F.
Einecke, S.
Dmytriiev, A.
Devin, J.
Panny, S.
Chibueze, J.
Steppa, C.
Hinton, J. A.
Rieger, F.
Ashkar, H.
Heß, B.
Cerruti, M.
Lemière, A.
Sasaki, M.
Chand, T.
Stawarz, Łukasz
Niemiec, J.
Bolmont, J.
de Ona Wilhelmi, E.
Backes, M.
Berge, D.
Venter, C.
Pensec, U.
Aharonian, F.
Terrier, R.
Tsuji, N.
Khélifi, B.
Moderski, R.
Taylor, A. M.
Chen, A.
Becherini, Y.
Regeard, M.
Haerer, L.
Huang, Zhiqiu
Zacharias, M.
Marandon, V.
Peron, G.
Burger-Scheidlin, C.
Holch, T. L.
Sabri, K.
Gabici, S.
Vink, J.
Kostunin, D.
Djuvsland, J.
Grolleron, G.
Wierzcholska, A.
Djannati-Ataï, A.
Moulin, E.
Steinmassl, S.
van Eldik, C.
Martí-Devesa, G.
Ohm, S.
Olivera-Nieto, L.
Kasai, E.
Streil, K.
Zech, A.
Gallant, Y. A.
Komin, Nu.
Salzmann, H.
Schäfer, J.
Fontaine, G.
Mohrmann, L.
Quirrenbach, A.
Glombitza, J.
Sol, H.
Opis:: The Tarantula Nebula in the Large Magellanic Cloud is known for its high star formation activity. At its center lies the young massive star cluster R136, providing a significant amount of the energy that makes the nebula shine so brightly at many wavelengths. Recently, young massive star clusters have been suggested to also efficiently produce very high-energy cosmic rays, potentially beyond PeV energies. Here, we report the detection of very-high-energy γ-ray emission from the direction of R136 with the High Energy Stereoscopic System, achieved through a multicomponent, likelihood-based modeling of the data. This supports the hypothesis that R136 is indeed a very powerful cosmic-ray accelerator. Moreover, from the same analysis, we provide an updated measurement of the γ-ray emission from 30 Dor C, the only superbubble detected at TeV energies presently. The γ-ray luminosity above 0.5 TeV of both sources is (2–3) × 10$^{35}$ erg s$^{−1}$. This exceeds by more than a factor of 2 the luminosity of HESS J1646−458, which is associated with the most massive young star cluster in the Milky Way, Westerlund 1. Furthermore, the γ-ray emission from each source is extended with a significance of >3σ and a Gaussian width of about 30 pc. For 30 Dor C, a connection between the γ-ray emission and the nonthermal X-ray emission appears likely. Different interpretations of the γ-ray signal from R136 are discussed.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 4.

Tytuł:: TeV flaring activity of the AGN PKS 0625–354 in November 2018
Autorzy:: Schüssler, F.
Holch, T. L.
Batzofin, R.
Mehta, A.
Holler, M.
Niemiec, J.
Barnard, J.
Fontaine, G.
Wierzcholska, A.
Lenain, J.-P.
Aharonian, F.
Kostunin, D.
Lang, R. G.
de Ona Wilhelmi, E.
Ren, H.
Streil, K.
Giavitto, G.
Caroff, S.
Ohm, S.
Glawion, D.
O’Brien, P.
Khatoon, R.
Kasai, E.
Sanchez, D. A.
Takahashi, T.
Sasaki, M.
Leitl, F.
Spencer, S.
Barbosa Martins, V.
Ait Benkhali, F.
Punch, M.
Brose, R.
Reimer, O.
Boisson, C.
Casanova, S.
Bradascio, F.
Katarzyński, K.
Venter, C.
Chibueze, O.
Kluźniak, W.
Bernlöhr, K.
Bulik, T.
Böttcher, M.
Brun, F.
Panny, S.
Cerruti, M.
Veh, J.
van Eldik, C.
Borowska, J.
Schutte, H. M.
Stawarz, Łukasz
Hinton, J. A.
Salzmann, H.
Bylund, T.
Rudak, B.
Bolmont, J.
Reimer, A.
Joshi, V.
Bi, B.
de Naurois, M.
Suzuki, H.
Moulin, E.
Kosack, K.
Wagner, S. J.
Zargaryan, D.
Chand, T.
Mitchell, A.
Gabici, S.
Funk, S.
Chen, A.
Baktash, A.
Steinmassl, S.
Olivera-Nieto, L.
Breuhaus, M.
Dmytriiev, A.
Chandra, S.
Davids, I. D.
Ernenwein, J.-P.
Ostrowski, Michał
Doroshenko, V.
Khélifi, B.
Le Stum, S.
Jamrozy, Marek
Shapopi, J. N. S.
Cotter, G.
Mackey, J.
Moderski, R.
Leuschner, F.
Ghafourizadeh, S.
Einecke, S.
Becherini, Y.
Quirrenbach, A.
Cecil, R.
Aschersleben, J.
Specovius, A.
Tanaka, T.
Damascene Mbarubucyeye, J.
Meyer, M.
Jung-Richardt, I.
Chibueze, J.
Bruno, B.
Haerer, L.
Backes, M.
Prokhorov, D. A.
Djuvsland, J.
Vecchi, M.
Żywucka, N.
Horns, D.
Grolleron, G.
Marx, R.
Glicenstein, J. F.
Reichherzer, P.
Zouari, S.
Goswami, P.
Rieger, F.
Berge, D.
Lemière, A.
Parsons, R. D.
Pühlhofer, G.
Celic, J.
Brown, A.
Ashkar, H.
de Bony de Lavergne, M.
Luashvili, A.
Egberts, K.
Sol, H.
Montanari, A.
Sushch, I.
Jankowsky, F.
Burger-Scheidlin, C.
Glombitza, J.
Füßling, M.
Pita, S.
Sahakian, V.
Zdziarski, A. A.
Zech, A.
Steenkamp, R.
Zacharias, M.
Komin, Nu.
Opis:: Most γ-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of the object PKS 0625−354, its γ-ray flux and spectral variability and its broad-band spectral emission with observations from H.E.S.S., Fermi-LAT, Swift-XRT, and UVOT taken in November 2018. The H.E.S.S. light curve above 200 GeV shows an outburst in the first night of observations followed by a declining flux with a halving time scale of 5.9 h. The γγ-opacity constrains the upper limit of the angle between the jet and the line of sight to ∼10°. The broad-band spectral energy distribution shows two humps and can be well fitted with a single-zone synchrotron self Compton emission model. We conclude that PKS 0625−354, as an object showing clear features of both blazars and radio galaxies, can be classified as an intermediate active galactic nuclei. Multi-wavelength studies of such intermediate objects exhibiting features of both blazars and radio galaxies are sparse but crucial for the understanding of the broad-band emission of γ-ray detected active galactic nuclei in general.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 5.

Tytuł:: Curvature in the very-high energy gamma-ray spectrum of M 87
Autorzy:: Schutte, H. M.
Montanari, A.
Marx, R.
Kundu, A.
Glicenstein, J. F.
Żywucka, N.
Jamrozy, Marek
Pühlhofer, G.
Meyer, M.
Damascene Mbarubucyeye, J.
Pita, S.
Zilberman, P.
Joshi, V.
Le Stum, S.
Böttcher, M.
Chibueze, O.
Ren, H.
Aschersleben, J.
Bradascio, F.
de Bony de Lavergne, M.
Mackey, J.
Kluźniak, W.
Fegan, S.
Mitchell, A.
Reimer, A.
Reville, B.
de Naurois, M.
Lenain, J.-P.
Chandra, S.
Reimer, O.
Funk, S.
Bulik, T.
Horns, D.
Sahakian, V.
Lang, R. G.
Egberts, K.
Casanova, S.
Moghadam, M. O.
Holler, M.
Brose, R.
Hofmann, W.
Tanaka, T.
Ait Benkhali, F.
Lemoine-Goumard, M.
Tsirou, M.
Takahashi, T.
Schüssler, F.
Batzofin, R.
Ruiz-Velasco, E.
Collins, T.
Mehta, A.
Wagner, S. J.
Bernlöhr, K.
Kosack, K.
Rudak, B.
Santangelo, A.
Spencer, S.
Zdziarski, A. A.
Boisson, C.
Jankowsky, F.
Shapopi, J. N. S.
Bruno, B.
Luashvili, A.
Cotter, G.
Khatoon, R.
Celic, J.
Leitl, F.
Jung-Richardt, I.
Katarzyński, K.
Brun, F.
Einecke, S.
Dmytriiev, A.
Panny, S.
Chibueze, J.
Steppa, C.
Rieger, F.
Ashkar, H.
Cerruti, M.
Barbosa Martins, V.
Lemière, A.
Sasaki, M.
Chand, T.
Stawarz, Łukasz
Niemiec, J.
Bolmont, J.
de Ona Wilhelmi, E.
Backes, M.
Berge, D.
Venter, C.
Pensec, U.
Aharonian, F.
Terrier, R.
Malyshev, D.
Khélifi, B.
Steenkamp, R.
Moderski, R.
Taylor, A. M.
Chen, A.
Becherini, Y.
Parsons, R. D.
Haerer, L.
Regeard, M.
Zacharias, M.
Burger-Scheidlin, C.
Holch, T. L.
Gabici, S.
Vink, J.
Kostunin, D.
Djuvsland, J.
Grolleron, G.
Wierzcholska, A.
Lypova, I.
Djannati-Ataï, A.
Moulin, E.
Steinmassl, S.
van Eldik, C.
Martí-Devesa, G.
Ohm, S.
Olivera-Nieto, L.
Bylund, T.
Kasai, E.
Streil, K.
Wach, T.
Cecil, R.
Zech, A.
Komin, Nu.
Salzmann, H.
Murach, T.
Punch, M.
Fontaine, G.
Mohrmann, L.
Quirrenbach, A.
Glombitza, J.
Sol, H.
Panter, M.
Opis:: The radio galaxy M 87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares, which were reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is not yet fully understood. In this study, we investigate the VHE gamma-ray spectrum of M 87 during states of high gamma-ray activity, utilizing 20.2 h of H.E.S.S. observations. Our findings indicate a preference for a curved spectrum, characterized by a log-parabola model with extra-galactic background light (EBL) model above 0.3 TeV at the 4σ level, compared to a power-law spectrum with EBL. We investigate the degeneracy between the absorption feature and the EBL normalization and derive upper limits on EBL models that are mainly sensitive in the wavelength range of 12.4 μm–40 μm.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 6.

Tytuł:: H.E.S.S. programme searching for VHE gamma rays associated with FRBs
Autorzy:: Schüssler, F.
Batzofin, R.
Mehta, A.
Holler, M.
Niemiec, J.
Fontaine, G.
Santangelo, A.
Lenain, J.-P.
Aharonian, F.
Kostunin, D.
Ren, H.
de Ona Wilhelmi, E.
Regeard, M.
Khatoon, R.
Kasai, E.
Wierzcholska, Alicja
Takahashi, T.
Sasaki, M.
Spencer, S.
Steppa, C.
Schäfer, J.
Barbosa Martins, V.
Sharma, A.
Punch, M.
Brose, R.
Reimer, O.
Boisson, C.
Casanova, S.
Huang, Zhiqiu
Wach, T.
Bradascio, F.
Katarzyński, K.
Venter, C.
Chibueze, O.
Kluźniak, W.
Bernlöhr, K.
Böttcher, M.
Brun, F.
Panny, S.
Cerruti, M.
Marandon, V.
van Eldik, C.
Borowska, J.
Sabri, K.
Stawarz, Łukasz
Salzmann, H.
Rudak, B.
Bolmont, J.
Kerszberg, D.
Schutte, H.M.
Parsons, R.D.
Escañuela Nieves, C.
Jaitly, A.
de Naurois, M.
Moulin, E.
Kosack, K.
Żywucka-Hejzner, Natalia
Chand, T.
Mitchell, A.
Archaryya, A.
Lang, R.G.
Gabici, S.
Funk, S.
Ravikularaman, S.
Chen, A.
Steinmassl, S.
Olivera-Nieto, L.
Tsirou, M.
Dmytriiev, A.
Heß, B.
Chandra, S.
Ernenwein, J.-P.
Ostrowski, Michał
Moghadam, M.O.
Djannati-Ataï, A.
Kundu, A.
Khélifi, B.
Le Stum, S.
Jamrozy, Marek
Mackey, J.
Moderski, R.
Einecke, S.
O'Brien, P.
Becherini, Y.
Quirrenbach, A.
Aschersleben, J.
Tanaka, T.
Rowell, G.
Damascene Mbarubucyeye, J.
Meyer, M.
Jung-Richardt, I.
Chibueze, J.
Bruno, B.
Lemoine-Goumard, M.
Pensec, U.
Backes, M.
Djuvsland, J.
Vecchi, M.
Filipovic, M.
Horns, D.
Malyshev, D.
Zdziarski, A.A.
Grolleron, G.
Glicenstein, J.F.
Marx, R.
Rieger, F.
Berge, D.
Lemière, A.
de Assis Scarpin, J.
Pühlhofer, G.
Celic, J.
Brown, A.
Ashkar, H.
de Bony de Lavergne, M.
Hofmann, W.
Luashvili, A.
Egberts, K.
Wagner, S.J.
Shapopi, J.N.S.
Panter, M.
Jankowsky, F.
Burger-Scheidlin, C.
Glombitza, J.
Holch, T.L.
Pita, S.
Sahakian, V.
Reville, B.
Zech, A.
Steenkamp, R.
Komin, Nu.
Opis:: Fast Radio Bursts (FRBs) are highly energetic, extremely short-lived bursts of radio flashes. Despite extensive research, the exact cause of these outbursts remains speculative. The high luminosity, short duration, and high dispersion measure of these events suggest they result from extreme, high-energy extragalactic sources, such as highly magnetized and rapidly spinning neutron stars known as magnetars. The number of detected FRBs, including repeating ones, has grown rapidly in recent years. Except for FRB 20200428D, and FRB-like radio burst that is associated to Galactic magnetar SGR 1935+2154, no multi-wavelength counterpart to any FRB has been detected yet. The High Energy Stereoscopic System (H.E.S.S.) telescope has developed a program to follow up FRBs searching for their gamma-ray counterparts, helping to uncover the nature of FRBs and FRB sources. This paper provides an overview of the searches for FRB sources conducted by H.E.S.S., including follow-up observations and simultaneous multi-wavelength campaigns with radio and X-ray observatories. Among the FRB sources observed by H.E.S.S., nine are localized with redshifts ranging between 0.11 and 0.492 from 2015 to 2022. No significant very high energy (VHE) emission was detected during these observations. We report constraints on the VHE luminosity ranging from 10$^{44}$ erg s$^{-1}$ and 10$^{48}$ erg s$^{-1}$, placing limits on the FRB's region persistent VHE emission and potential FRB afterglow emission across timescales from hours to years.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 7.

Tytuł:: The H.E.S.S. extragalactic sky survey with the first decade of observations
Autorzy:: Rowell, G.
Montanari, A.
Marx, R.
Kundu, A.
Glicenstein, J. F.
Goswami, P.
Sanchez, D. A.
Völk, H. J.
Jamrozy, Marek
Pühlhofer, G.
Suzuki, H.
Ostrowski, Michał
Brown, A.
Böttcher, M.
Le Stum, S.
Leuschner, F.
Chibueze, O.
Ren, H.
Aschersleben, J.
Bradascio, F.
de Bony de Lavergne, M.
Mackey, J.
Fegan, S.
Mitchell, A.
Reimer, A.
Reville, B.
Vecchi, M.
de Naurois, M.
Lenain, J.-P.
Cristofari, P.
Ravikularaman, S.
Chandra, S.
Reimer, O.
O’Brien, P.
Funk, S.
Bulik, T.
Horns, D.
Sahakian, V.
Lang, R. G.
Egberts, K.
Casanova, S.
Żywucka-Hejzner, Natalia
Holler, M.
Brose, R.
Hofmann, W.
Tanaka, T.
Ait Benkhali, F.
Lemoine-Goumard, M.
Tsirou, M.
Takahashi, T.
Schüssler, F.
Batzofin, R.
Ruiz-Velasco, E.
Mehta, A.
Sharma, A.
Borowska, J.
Wagner, S. J.
Bernlöhr, K.
Kosack, K.
Rudak, B.
Santangelo, A.
Spencer, S.
Zdziarski, A. A.
Boisson, C.
Jankowsky, F.
Shapopi, J. N. S.
Bruno, B.
Davids, I. D.
Luashvili, A.
Cotter, G.
Khatoon, R.
Celic, J.
Katarzyński, K.
Brun, F.
Einecke, S.
Dmytriiev, A.
Mbarubucyeye, J. D.
Devin, J.
Panny, S.
Chibueze, J.
Steppa, C.
Hinton, J. A.
Rieger, F.
Ashkar, H.
Heß, B.
Wierzcholska, Alicja
Cerruti, M.
Barbosa Martins, V.
Lemière, A.
Sasaki, M.
Chand, T.
Jardin-Blicq, A.
Stawarz, Łukasz
Niemiec, J.
Bolmont, J.
de Ona Wilhelmi, E.
Backes, M.
Berge, D.
Venter, C.
Pensec, U.
Aharonian, F.
Terrier, R.
Thakur, A.
Malyshev, D.
Khélifi, B.
Steenkamp, R.
Moderski, R.
Taylor, A. M.
Chen, A.
Becherini, Y.
Regeard, M.
Haerer, L.
Huang, Zhiqiu
Zacharias, M.
Marandon, V.
Bouyahiaoui, M.
Burger-Scheidlin, C.
Holch, T. L.
Gabici, S.
Vink, J.
Kostunin, D.
Djuvsland, J.
Grolleron, G.
Steinmassl, S.
van Eldik, C.
Martí-Devesa, G.
Olivera-Nieto, L.
Bylund, T.
Kasai, E.
Wach, T.
Zech, A.
Komin, Nu.
Salzmann, H.
Reis, I.
Schäfer, J.
Punch, M.
Fontaine, G.
Mohrmann, L.
Quirrenbach, A.
Glombitza, J.
Sol, H.
Panter, M.
Opis:: The results of the first extragalactic gamma-ray survey by the High Energy Stereoscopic System (H.E.S.S.) are presented. The survey comprises 2720 hours of very high-energy gamma-ray observations of the extragalactic sky, recorded with H.E.S.S. from 2004 up to the end of 2012. These data have been re-analysed using a common consistent set of up-to-date data calibration and analysis tools. From this analysis, a list of 23 detected objects, predominantly blazars, was obtained. This catalogue was assessed in terms of the source class populations that it contains. The level of source parameter bias for the blazar sources, probed by this observational dataset, was evaluated using Monte-Carlo simulations. Spectral results obtained with the H.E.S.S. data were compared with the Fermi-LAT catalogues to present the full gamma-ray picture of the detected objects. Lastly, this unique dataset was used to assess the contribution of BL Lacertae objects and flat-spectrum radio quasars to the extragalactic gamma-ray background light at several hundreds of gigaelectronvolts. These results are accompanied by the release of the high-level data to the astrophysical community.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 8.

Tytuł:: H.E.S.S. observations of the 2021 periastron passage of PSR B1259-63/LS 2883
Autorzy:: Holler, M.
Funk, S.
Komin, Nu.
Bulik, T.
Ruiz-Velasco, E.
Cerruti, M.
Gallant, Y. A.
Pensec, U.
Reimer, A.
Egberts, K.
Meintjes, P. J.
Fontaine, G.
Chen, A.
Steenkamp, R.
Mehta, A.
Gabici, S.
Kluźniak, W.
Kostunin, D.
Montanari, A.
Żywucka, N.
Khangulyan, D.
Venter, C.
Lenain, J.-P.
Lemoine-Goumard, M.
Moulin, E.
de Naurois, M.
Leuschner, F.
Wach, T.
Aschersleben, J.
Sushch, I.
Malyshev, D.
Zech, A.
Schäfer, J.
Steinmassl, S.
Goswami, P.
Böttcher, M.
Chand, T.
Einecke, S.
de Ona Wilhelmi, E.
Joshi, V.
Barbosa Martins, V.
Khélifi, B.
Wierzcholska, A.
Batzofin, R.
Damascene Mbarubucyeye, J.
Moderski, R.
Santangelo, A.
Brose, R.
Bouyahiaoui, M.
Jamrozy, Marek
Murach, T.
Devin, J.
Thorpe-Morgan, C.
Ohm, S.
Bernlöhr, K.
van Soelen, B.
Huang, Zhiqiu
Werner, F.
Becherini, Y.
Heß, B.
Leitl, F.
Regeard, M.
Chibueze, O.
Chandra, S.
Le Stum, S.
Reis, I.
Kosack, K.
Spencer, S.
Holch, T. L.
Takahashi, T.
Berge, D.
Wagner, S. J.
Ren, H.
Marx, R.
Borowska, J.
Ashkar, H.
Peron, G.
Parsons, R. D.
Punch, M.
Boisson, C.
Kundu, A.
Zacharias, M.
Niemiec, J.
Mitchell, A.
Panter, M.
Salzmann, H.
Kasai, E.
Rudak, B.
Stawarz, Łukasz
Glawion, D.
Hofmann, W.
Panny, S.
Brun, F.
Cotter, G.
Mackey, J.
de Bony de Lavergne, M.
Tanaka, T.
Brown, A.
Katarzyński, K.
Dmytriiev, A.
Shapopi, J. N. S.
Aharonian, F.
van Eldik, C.
Chibueze, J.
Burger-Scheidlin, C.
Glicenstein, J. F.
Terrier, R.
Bolmont, J.
Sasaki, M.
Lang, R. G.
Reimer, O.
Steppa, C.
Lemière, A.
Unbehaun, T.
Bruno, B.
Ait Benkhali, F.
Sahakian, V.
Streil, K.
Ernenwein, J.-P.
Ostrowski, Michał
Taylor, A. M.
Vecchi, M.
Casanova, S.
Jung-Richardt, I.
Pühlhofer, G.
Quirrenbach, A.
Prokhorov, D. A.
Backes, M.
Schüssler, F.
Schutte, H. M.
Zdziarski, A. A.
Tluczykont, M.
Grolleron, G.
Jankowsky, F.
Celic, J.
Vink, J.
Caroff, S.
Martí-Devesa, G.
Rieger, F.
Haerer, L.
Djuvsland, J.
Mohrmann, L.
Khatoon, R.
Opis:: PSR B1259–63/LS 2883 is a gamma-ray binary system that hosts a pulsar in an eccentric orbit, with a 3.4 yr period, around an O9.5Ve star (LS 2883). At orbital phases close to periastron passages, the system radiates bright and variable non-thermal emission, for which the temporal and spectral properties of this emission are, for now, poorly understood. In this regard, very high-energy (VHE) emission is especially useful to study and constrain radiation processes and particle acceleration in the system. We report on an extensive VHE observation campaign conducted with the High Energy Stereoscopic System, comprised of approximately 100 h of data taken over five months, from t$_{p}$ − 24 days to t$_{p}$ + 127 days around the system’s 2021 periastron passage (where t$_{p}$ is the time of periastron). We also present the timing and spectral analyses of the source. The VHE light curve in 2021 is consistent overall with the stacked light curve of all previous observations. Within the light curve, we report a VHE maximum at times coincident with the third X-ray peak first detected in the 2021 X-ray light curve. In the light curve – although sparsely sampled in this time period – we see no VHE enhancement during the second disc crossing. In addition, we see no correspondence to the 2021 GeV flare in the VHE light curve. The VHE spectrum obtained from the analysis of the 2021 dataset is best described by a power law of spectral index Γ = 2.65 ± 0.04$_{stat}$ ± 0.04$_{sys}$, a value consistent with the spectral index obtained from the analysis of data collected with H.E.S.S. during the previous observations of the source. We report spectral variability with a difference of ΔΓ = 0.56 ± 0.18$_{stat}$ ± 0.10$_{sys}$ at 95% confidence intervals, between sub-periods of the 2021 dataset. We also detail our investigation into X-ray/TeV and GeV/TeV flux correlations in the 2021 periastron passage. We find a linear correlation between contemporaneous flux values of X-ray and TeV datasets, detected mainly after t$_{p}$ + 25 days, suggesting a change in the available energy for non-thermal radiation processes. We detect no significant correlation between GeV and TeV flux points, within the uncertainties of the measurements, from ∼t$_{p}$ − 23 days to ∼t$_{p}$ + 126 days. This suggests that the GeV and TeV emission originate from different electron populations.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 9.

Tytuł:: Unveiling extended gamma-ray emission around HESS J1813-178
Autorzy:: Holler, M.
Funk, S.
Renaud, M.
Cecil, R.
Reville, B.
Barnard, J.
Zargaryan, D.
Komin, Nu.
Bulik, T.
Cerruti, M.
Gallant, Y. A.
Noel, Angel
Reimer, A.
Fontaine, G.
Chen, A.
Steenkamp, R.
Mehta, A.
Gabici, S.
Kluźniak, W.
Kostunin, D.
Montanari, A.
Żywucka, N.
Venter, C.
Bi, B.
Lenain, J.-P.
Lemoine-Goumard, M.
Moulin, E.
de Naurois, M.
Leuschner, F.
Wach, T.
Aschersleben, J.
Sushch, I.
Malyshev, D.
Veh, J.
Steinmassl, S.
Suzuki, H.
Goswami, P.
Böttcher, M.
Chand, T.
Giavitto, G.
Einecke, S.
de Ona Wilhelmi, E.
Joshi, V.
Barbosa Martins, V.
Khélifi, B.
Wierzcholska, A.
Ghafourizadeh, S.
Batzofin, R.
Damascene Mbarubucyeye, J.
Moderski, R.
O’Brien, P.
Brose, R.
Bouyahiaoui, M.
Baktash, A.
Jamrozy, Marek
Murach, T.
Specovius, A.
Tsuji, N.
Ohm, S.
Bernlöhr, K.
Becherini, Y.
Leitl, F.
Regeard, M.
Doroshenko, V.
Chibueze, O.
Le Stum, S.
Kosack, K.
Spencer, S.
Holch, T. L.
Takahashi, T.
Berge, D.
Wagner, S. J.
Ren, H.
Marx, R.
Borowska, J.
Ashkar, H.
Parsons, R. D.
Punch, M.
Boisson, C.
Kundu, A.
Roellinghoff, G.
Zacharias, M.
Djannati-Ataï, A.
Niemiec, J.
Mitchell, A.
Panter, M.
Salzmann, H.
Olivera-Nieto, L.
Rudak, B.
Glawion, D.
Hofmann, W.
Marinos, P.
Panny, S.
Füßling, M.
Brun, F.
Cotter, G.
Filipovic, M.
Marandon, V.
Chambery, P.
Breuhaus, M.
Mackey, J.
de Bony de Lavergne, M.
Tanaka, T.
Katarzyński, K.
Zouari, S.
Dmytriiev, A.
Shapopi, J. N. S.
Aharonian, F.
van Eldik, C.
Chibueze, J.
Burger-Scheidlin, C.
Glicenstein, J. F.
Terrier, R.
Feijen, K.
Bolmont, J.
Sasaki, M.
Lang, R. G.
Reimer, O.
Steppa, C.
Lemière, A.
Unbehaun, T.
Reichherzer, P.
Bruno, B.
Ait Benkhali, F.
Sahakian, V.
Ernenwein, J.-P.
Hinton, J. A.
Grondin, M.-H.
Ostrowski, Michał
Vecchi, M.
Casanova, S.
Jung-Richardt, I.
Pühlhofer, G.
Quirrenbach, A.
Prokhorov, D. A.
Backes, M.
Schüssler, F.
Schutte, H. M.
Zdziarski, A. A.
Tluczykont, M.
Grolleron, G.
Jankowsky, F.
Celic, J.
Vink, J.
Klepser, S.
Caroff, S.
Martí-Devesa, G.
Rieger, F.
Mohrmann, L.
Khatoon, R.
Opis:: Context. HESS J1813–178 is a very-high-energy γ-ray source spatially coincident with the young and energetic pulsar PSR J1813–1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813–178 region, taking advantage of improved analysis methods and an extended dataset. Aims. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the γ-ray emission in the region with a consistent model, to provide insights into its origin. Methods. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 yr of Fermi-LAT data and we fitted a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed γ-ray emission in the region. Results. In addition to the compact very-high-energy γ-ray emission centred on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. Conclusions. This study suggests that HESS J1813–178 is associated with a γ-ray PWN powered by PSR J1813–1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Skocz do pozycji: 10.

Tytuł:: Detection of very high-energy gamma-ray emission from Eta Carinae during its 2020 periastron passage
Autorzy:: Schüssler, F.
Holch, T. L.
Batzofin, R.
Mehta, A.
Holler, M.
Niemiec, J.
Fontaine, G.
Ruiz-Velasco, E.
Santangelo, A.
Lenain, J.-P.
Aharonian, F.
Kostunin, D.
Lang, R. G.
de Ona Wilhelmi, E.
Ren, H.
Streil, K.
Regeard, M.
Ohm, S.
Marcowith, A.
Khatoon, R.
Wierzcholska, Alicja
Sasaki, M.
Spencer, S.
Steppa, C.
Schäfer, J.
Barbosa Martins, V.
Ait Benkhali, F.
Brose, R.
Reimer, O.
Boisson, C.
Casanova, S.
Moghadam, M. O.
Werner, F.
Wach, T.
Bradascio, F.
Katarzyński, K.
Collins, T.
Mohrmann, L.
Venter, C.
Chibueze, O.
Kluźniak, W.
Bernlöhr, K.
Huang, Z.
Böttcher, M.
Brun, F.
Panny, S.
Tluczykont, M.
Cerruti, M.
Marandon, V.
van Eldik, C.
Schutte, H. M.
Sabri, K.
Stawarz, Łukasz
Hinton, J. A.
Salzmann, H.
Martí-Devesa, G.
Rudak, B.
Bolmont, J.
Reimer, A.
Escañuela Nieves, C.
de Naurois, M.
Moulin, E.
Kosack, K.
Żywucka-Hejzner, Natalia
Wagner, S. J.
Feijen, K.
Chand, T.
Mitchell, A.
Gabici, S.
Funk, S.
Ravikularaman, S.
Grondin, M.-H.
Chen, A.
Steinmassl, S.
Olivera-Nieto, L.
Tsirou, M.
Dmytriiev, A.
Heß, B.
Chandra, S.
Ernenwein, J.-P.
Ostrowski, Michał
Jardin-Blicq, A.
Djannati-Ataï, A.
Khélifi, B.
Le Stum, S.
Jamrozy, Marek
Shapopi, J. N. S.
Cotter, G.
Mackey, J.
Moderski, R.
Remy, Q.
Einecke, S.
Becherini, Y.
Quirrenbach, A.
Aschersleben, J.
Tanaka, T.
White, R.
Rowell, G.
Damascene Mbarubucyeye, J.
Jung-Richardt, I.
Chibueze, J.
Bruno, B.
Lemoine-Goumard, M.
Haerer, L.
Pensec, U.
Djuvsland, J.
Vecchi, M.
Filipovic, M.
Horns, D.
Malyshev, D.
Grolleron, G.
Marx, R.
Glicenstein, J. F.
Rieger, F.
Berge, D.
Lemière, A.
Terrier, R.
de Assis Scarpin, J.
Parsons, R. D.
Pühlhofer, G.
Celic, J.
Brown, A.
Ashkar, H.
de Bony de Lavergne, M.
Hofmann, W.
Luashvili, A.
Tsuji, N.
Egberts, K.
Panter, M.
Jankowsky, F.
Burger-Scheidlin, C.
Devin, J.
Sahakian, V.
Zdziarski, A. A.
Reville, B.
Zech, A.
Steenkamp, R.
Zacharias, M.
Komin, Nu.
Opis:: The colliding-wind binary system η Carinae has been identified as a source of high-energy (HE, below ∼100 GeV) and very high-energy (VHE, above ∼100 GeV) gamma rays in the last decade, making it unique among these systems. With its eccentric 5.5-year-long orbit, the periastron passage, during which the stars are separated by only 1–2 au, is an intriguing time interval to probe particle acceleration processes within the system. In this work, we report on an extensive VHE observation campaign that for the first time covers the full periastron passage carried out with the High Energy Stereoscopic System (H.E.S.S.) in its 5-telescope configuration with upgraded cameras. The VHE gamma-ray emission from η Carinae was detected during the periastron passage with a steep spectrum with the spectral index Γ = 3.3 ± 0.2stat ± 0.1syst. Together with previous and follow-up observations, we derive a long-term light curve sampling one full orbit, showing hints of an increase in the VHE flux towards periastron, but no hint of variability during the passage itself. An analysis of contemporaneous Fermi-LAT data shows that the VHE spectrum represents a smooth continuation of the HE spectrum. From modelling the combined spectrum, we conclude that the gamma-ray emission region is located at distances of ∼10–20 au from the centre of mass of the system and that protons are accelerated up to energies of at least several tera-electronvolts inside the system in this phase.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

Artykuł

na półce

Informacja

Wyszukujesz frazę "Mehta, A." wg kryterium: Autor