Pulsars, transients and relativistic astrophysics

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Very high energy $\gamma$-ray emission from two blazars of unknown redshift and upper limits on their distance

(2020)

Authors:

HESS Collaboration, H Abdalla, R Adam, F Aharonian, F Ait Benkhali, EO Angüner, M Arakawa, C Arcaro, C Armand, T Armstrong, H Ashkar, M Backes, V Baghmanyan, V Barbosa Martins, A Barnacka, M Barnard, Y Becherini, D Berge, K Bernlöhr, M Böttcher, C Boisson, J Bolmont, S Bonnefoy, J Bregeon, M Breuhaus, F Brun, P Brun, M Bryan, M Büchele, T Bulik, T Bylund, S Caroff, A Carosi, S Casanova, T Chand, S Chandra, A Chen, G Cotter, M Curyło, ID Davids, J Davies, C Deil, J Devin, P deWilt, L Dirson, A Djannati-Ataï, A Dmytriiev, A Donath, V Doroshenko, J Dyks, K Egberts, F Eichhorn, G Emery, J-P Ernenwein, K Feijen, S Fegan, A Fiasson, G Fontaine, S Funk, M Füßling, S Gabici, YA Gallant, G Giavitto, L Giunti, D Glawion, JF Glicenstein, D Gottschall, M-H Grondin, J Hahn, M Haupt, G Hermann, JA Hinton, W Hofmann, C Hoischen, TL Holch, M Holler, M H{\"}orbe, D Horns, D Huber, H Iwasaki, M Jamrozy, D Jankowsky, F Jankowsky, A Jardin-Blicq, V Joshi, I Jung-Richardt, MA Kastendieck, K Katarzynski, M Katsuragawa, U Katz, D Khangulyan, B Khélifi, S Klepser, W Kluzniak, Nu Komin, R Konno, K Kosack, D Kostunin, M Kreter, G Lamanna, A Lemière, M Lemoine-Goumard, J-P Lenain, E Leser, C Levy, T Lohse, I Lypova, J Mackey, J Majumdar, D Malyshev, D Malyshev, V Marandon, P Marchegiani, A Marcowith, A Mares, G Martí-Devesa, R Marx, G Maurin, PJ Meintjes, R Moderski, M Mohamed, L Mohrmann, C Moore, P Morris, E Moulin, J Muller, T Murach, S Nakashima, K Nakashima, M de Naurois, H Ndiyavala, F Niederwanger, J Niemiec, L Oakes, P O'Brien, H Odaka, S Ohm, E de Ona Wilhelmi, M Ostrowski, M Panter, RD Parsons, B Peyaud, Q Piel, S Pita, V Poireau, A Priyana Noel, DA Prokhorov, H Prokoph, G Pühlhofer, M Punch, A Quirrenbach, S Raab, R Rauth, A Reimer, O Reimer, Q Remy, M Renaud, F Rieger, L Rinchiuso, C Romoli, G Rowell, B Rudak, E Ruiz-Velasco, V Sahakian, S Sailer, S Saito, DA Sanchez, A Santangelo, M Sasaki, M Scalici, F Schüssler, HM Schutte, U Schwanke, S Schwemmer, M Seglar-Arroyo, M Senniappan, AS Seyffert, N Shafi, K Shiningayamwe, R Simoni, A Sinha, H Sol, A Specovius, S Spencer, M Spir-Jacob, Ł Stawarz, R Steenkamp, C Stegmann, C Steppa, T Takahashi, T Tavernier, AM Taylor, R Terrier, D Tiziani, M Tluczykont, L Tomankova, C Trichard, M Tsirou, N Tsuji, R Tuffs, Y Uchiyama, DJ van der Walt, C van Eldik, C van Rensburg, B van Soelen, G Vasileiadis, J Veh, C Venter, P Vincent, J Vink, HJ Völk, T Vuillaume, Z Wadiasingh, SJ Wagner, J Watson, F Werner, R White, A Wierzcholska, R Yang, H Yoneda, M Zacharias, R Zanin, D Zargaryan, AA Zdziarski, A Zech, SJ Zhu, J Zorn, N Żywucka, M Cerruti
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Intermediate-mass Black Holes' Effects on Compact Object Binaries

ASTROPHYSICAL JOURNAL American Astronomical Society 892:2 (2020) ARTN 130

Authors:

Barnabas Deme, Yohai Meiron, Bence Kocsis

Abstract:

Although their existence is not yet confirmed observationally, intermediate mass black holes (IMBHs) may play a key role in the dynamics of galactic nuclei. In this paper, we neglect the effect of the nuclear star cluster itself and investigate only how a small reservoir of IMBHs influences the secular dynamics of stellar-mass black hole binaries, using N-body simulations. We show that our simplifications are valid and that the IMBHs significantly enhance binary evaporation by pushing the binaries into the Hill-unstable region of parameter space, where they are separated by the SMBH's tidal field. For binaries in the S-cluster region of the Milky Way, IMBHs drive the binaries to merge in up to 1-6% of cases, assuming five IMBHs within 5 pc of mass 10,000 solar masses each. Observations of binaries in the Galactic center may strongly constrain the population of IMBHs therein.
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LOFAR 144-MHz follow-up observations of GW170817

(2020)

Authors:

JW Broderick, TW Shimwell, K Gourdji, A Rowlinson, S Nissanke, K Hotokezaka, PG Jonker, C Tasse, MJ Hardcastle, JBR Oonk, RP Fender, RAMJ Wijers, A Shulevski, AJ Stewart, S ter Veen, VA Moss, MHD van der Wiel, DA Nichols, A Piette, ME Bell, D Carbone, S Corbel, J Eislöffel, J-M Grießmeier, EF Keane, CJ Law, T Muñoz-Darias, M Pietka, M Serylak, AJ van der Horst, J van Leeuwen, R Wijnands, P Zarka, JM Anderson, MJ Bentum, R Blaauw, WN Brouw, M Brüggen, B Ciardi, M de Vos, S Duscha, RA Fallows, TMO Franzen, MA Garrett, AW Gunst, M Hoeft, JR Hörandel, M Iacobelli, E Jütte, LVE Koopmans, A Krankowski, P Maat, G Mann, H Mulder, A Nelles, H Paas, M Pandey-Pommier, R Pekal, W Reich, HJA Röttgering, DJ Schwarz, O Smirnov, M Soida, MC Toribio, MP van Haarlem, RJ van Weeren, C Vocks, O Wucknitz, P Zucca
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Radio Afterglows of Very High Energy Gamma-Ray Bursts 190829A and 180720B

(2020)

Authors:

L Rhodes, AJ van der Horst, R Fender, I Monageng, GE Anderson, J Antoniadis, MF Bietenholz, M Bottcher, JS Bright, C Kouveliotou, M Kramer, SE Motta, DRA Williams, PA Woudt, .
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Effective spin distribution of black hole mergers in triples

Monthly Notices of the Royal Astronomical Society 493:3 (2020) 3920-3931

Authors:

G Fragione, B Kocsis

Abstract:

© 2020 The Author(s). Many astrophysical scenarios have been proposed to explain the several black hole (BH) and neutron star binary mergers observed via gravitational waves (GWs) by the LIGO-Virgo collaboration. Contributions from various channels can be statistically disentangled by mass, spin, eccentricity, and redshift distributions of merging binaries. In this paper,we investigate the signatures of BH-BH binary mergers induced by a third companion through the Lidov-Kozai mechanism in triple systems. We adopt different prescriptions for the supernovae natal kicks and consider different progenitor metallicities and initial orbital parameters. We show that the typical eccentricity in the LIGO band is 0.01-0.1 and that the merger rate is in the range 0.008-9Gpc-3 yr-1, depending on the natal kick prescriptions and progenitor metallicity. Furthermore, we find that the typical distribution of effective projected spin is peaked at Xeff ~ 0 with significant tails. We show that the triple scenario could reproduce the distribution of Xeff. We find that the triple channel may be strongly constrained by the misalignment angle between the binary component spins in future detections with spin precession.
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