Review of Particle Physics

Progress of Theoretical and Experimental Physics Oxford University Press (OUP) 2020 (2020)

PA Zyla, RM Barnett, J Beringer, O Dahl, DA Dwyer, DE Groom, C-J Lin, KS Lugovsky, E Pianori, DJ Robinson, CG Wohl, W-M Yao, K Agashe, G Aielli, BC Allanach, C Amsler, M Antonelli, EC Aschenauer, DM Asner, H Baer, S Banerjee, L Baudis, CW Bauer, JJ Beatty, VI Belousov, S Bethke, A Bettini, O Biebel, KM Black, E Blucher, O Buchmuller, V Burkert, MA Bychkov, RN Cahn, M Carena, A Ceccucci, A Cerri, D Chakraborty, RS Chivukula, G Cowan, G D'Ambrosio, T Damour, D de Florian, A de Gouvêa, T DeGrand, P de Jong, G Dissertori, BA Dobrescu, M D'Onofrio, M Doser, M Drees, HK Dreiner, P Eerola, U Egede, S Eidelman, J Ellis, J Erler, VV Ezhela, W Fetscher, BD Fields, B Foster, A Freitas, H Gallagher, L Garren, H-J Gerber, G Gerbier, T Gershon, Y Gershtein, T Gherghetta, AA Godizov, MC Gonzalez-Garcia, M Goodman, C Grab, AV Gritsan, C Grojean, M Grünewald, A Gurtu, T Gutsche, HE Haber, C Hanhart, S Hashimoto, Y Hayato, A Hebecker, S Heinemeyer, B Heltsley, JJ Hernández-Rey, K Hikasa, J Hisano, A Höcker, J Holder, A Holtkamp, J Huston, T Hyodo, KF Johnson, M Kado, M Karliner, UF Katz, M Kenzie, VA Khoze, SR Klein, E Klempt, RV Kowalewski, F Krauss, M Kreps, B Krusche, Y Kwon, O Lahav, J Laiho, LP Lellouch, J Lesgourgues, AR Liddle, Z Ligeti, C Lippmann, TM Liss, L Littenberg, C Lourengo, SB Lugovsky, A Lusiani, Y Makida, F Maltoni, T Mannel, AV Manohar, WJ Marciano, A Masoni, J Matthews, U-G Meißner, M Mikhasenko, DJ Miller, D Milstead, RE Mitchell, K Mönig, P Molaro, F Moortgat, M Moskovic, K Nakamura, M Narain, P Nason, S Navas, M Neubert, P Nevski, Y Nir, KA Olive, C Patrignani, JA Peacock, ST Petcov, VA Petrov, A Pich, A Piepke, A Pomarol, S Profumo, A Quadt, K Rabbertz, J Rademacker, G Raffelt, H Ramani, M Ramsey-Musolf, BN Ratcliff, P Richardson, A Ringwald, S Roesler, S Rolli, A Romaniouk, LJ Rosenberg, JL Rosner, G Rybka, M Ryskin, RA Ryutin, Y Sakai, GP Salam, S Sarkar, F Sauli, O Schneider, K Scholberg, AJ Schwartz, J Schwiening, D Scott, V Sharma, SR Sharpe, T Shutt, M Silari, T Sjöstrand, P Skands, T Skwarnicki, GF Smoot, A Soffer, MS Sozzi, S Spanier, C Spiering, A Stahl, SL Stone, Y Sumino, T Sumiyoshi, MJ Syphers, F Takahashi, M Tanabashi, J Tanaka, M Taševský, K Terashi, J Terning, U Thoma, RS Thorne, L Tiator, M Titov, NP Tkachenko, DR Tovey, K Trabelsi, P Urquijo, G Valencia, R Van de Water, N Varelas, G Venanzoni, L Verde, MG Vincter, P Vogel, W Vogelsang, A Vogt, V Vorobyev, SP Wakely, W Walkowiak, CW Walter, D Wands, MO Wascko, DH Weinberg, EJ Weinberg, M White, LR Wiencke, S Willocq, CL Woody, RL Workman, M Yokoyama, R Yoshida, G Zanderighi, GP Zeller, OV Zenin, R-Y Zhu, S-L Zhu, F Zimmermann, J Anderson, T Basaglia, VS Lugovsky, P Schaffner, W Zheng

<jats:title>Abstract</jats:title> <jats:p>The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,324 new measurements from 878 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on High Energy Soft QCD and Diffraction and one on the Determination of CKM Angles from B Hadrons.</jats:p> <jats:p>The Review is divided into two volumes. Volume 1 includes the Summary Tables and 98 review articles. Volume 2 consists of the Particle Listings and contains also 22 reviews that address specific aspects of the data presented in the Listings.</jats:p> <jats:p>The complete Review (both volumes) is published online on the website of the Particle Data Group ( and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print and as a web version optimized for use on phones as well as an Android app.</jats:p>

In-situ calibration of the single-photoelectron charge response of the IceCube photomultiplier tubes

Journal of Instrumentation IOP Publishing (2020)

TI Collaboration

We describe an improved in-situ calibration of the single-photoelectron charge distributions for each of the in-ice Hamamatsu Photonics R7081-02[MOD] photomultiplier tubes in the IceCube Neutrino Observatory. The characterization of the individual PMT charge distributions is important for PMT calibration, data and Monte Carlo simulation agreement, and understanding the effect of hardware differences within the detector. We discuss the single photoelectron identification procedure and how we extract the single-photoelectron charge distribution using a deconvolution of the multiple-photoelectron charge distribution.

ANTARES and IceCube Combined Search for Neutrino Point-like and Extended Sources in the Southern Sky

The Astrophysical Journal: an international review of astronomy and astronomical physics American Astronomical Society (2020)

ANTARES Collaboration, A Albert, M André, M Anghinolfi, G Anton, M Ardid, J-J Aubert, J Aublin, B Baret, S Basa, B Belhorma, V Bertin, S Biagi, M Bissinger, J Boumaaza, S Bourret, M Bouta, MC Bouwhuis, H Brânzaş, R Bruijn, J Brunner, J Busto, A Capone, L Caramete, M Chabab, S SARKAR, I Collaboration

A search for point-like and extended sources of cosmic neutrinos using data collected by the ANTARES and IceCube neutrino telescopes is presented. The data set consists of all the track-like and shower-like events pointing in the direction of the Southern Sky included in the nine-year ANTARES point-source analysis, combined with the through-going track-like events used in the seven-year IceCube point-source search. The advantageous field of view of ANTARES and the large size of IceCube are exploited to improve the sensitivity in the Southern Sky by a factor $\sim$2 compared to both individual analyses. In this work, the Southern Sky is scanned for possible excesses of spatial clustering, and the positions of preselected candidate sources are investigated. In addition, special focus is given to the region around the Galactic Centre, whereby a dedicated search at the location of SgrA* is performed, and to the location of the supernova remnant RXJ 1713.7-3946. No significant evidence for cosmic neutrino sources is found and upper limits on the flux from the various searches are presented.

Transport of high-energy charged particles through spatially-intermittent turbulent magnetic fields

Astrophysical Journal American Astronomical Society 892 (2020) 114

LE Chen, AFA Bott, P Tzeferacos, A Rigby, A Bell, R Bingham, C Graziani, J Katz, R Petrasso, G Gregori, F Miniati

Identifying the sources of the highest energy cosmic rays requires understanding how they are deflected by the stochastic, spatially intermittent intergalactic magnetic field. Here we report measurements of energetic charged-particle propagation through a laser-produced magnetized plasma with these properties. We characterize the diffusive transport of the particles experimentally. The results show that the transport is diffusive and that, for the regime of interest for the highest-energy cosmic rays, the diffusion coefficient is unaffected by the spatial intermittency of the magnetic field.

A Search for MeV to TeV Neutrinos from Fast Radio Bursts with IceCube

The Astrophysical Journal: an international review of astronomy and astronomical physics American Astronomical Society (2020)

GW Sullivan, T Stürwald, K Tollefson, T Stuttard, L Tomankova, A Terliuk, F Tenholt, I Taboada, S Tilav, M Tselengidou, S Toscano, CF Turley, A Turcati, R Turcotte, C Tönnis, A Trettin, CF Tung, D Tosi, J Vandenbroucke, MAU Elorrieta, NV Eijndhoven, WV Driessche, S Vanheule, E Unger, M Usner

We present two searches for IceCube neutrino events coincident with 28 fast radio bursts (FRBs) and one repeating FRB. The first improves upon a previous IceCube analysis -- searching for spatial and temporal correlation of events with FRBs at energies greater than roughly 50 GeV -- by increasing the effective area by an order of magnitude. The second is a search for temporal correlation of MeV neutrino events with FRBs. No significant correlation is found in either search, therefore, we set upper limits on the time-integrated neutrino flux emitted by FRBs for a range of emission timescales less than one day. These are the first limits on FRB neutrino emission at the MeV scale, and the limits set at higher energies are an order-of-magnitude improvement over those set by any neutrino telescope.

When galaxies align: intrinsic alignments of the progenitors of elliptical galaxies in the Horizon-AGN simulation

Monthly Notices of the Royal Astronomical Society Oxford University Press 491 (2019) 4057-4068

J Bate, NE Chisari, S Codis, G Martin, Y Dubois, J Devriendt, C Pichon, A Slyz

Elliptical galaxies today appear aligned with the large-scale structure of the Universe, but it is still an open question when they acquire this alignment. Observational data is currently insufficient to provide constraints on the time evolution of intrinsic alignments, and hence existing models range from assuming that galaxies gain some primordial alignment at formation, to suggesting that they react instantaneously to tidal interactions with the large-scale structure. Using the cosmological hydrodynamical simulation Horizon-AGN, we measure the relative alignments between the major axes of galaxies and eigenvectors of the tidal field as a function of redshift. We focus on constraining the time evolution of the alignment of the main progenitors of massive $z=0$ elliptical galaxies, the main weak lensing contaminant at low redshift. We show that this population, which at $z=0$ has a stellar mass above $10^{10.4}$ M$_\odot$, transitions from having no alignment with the tidal field at $z=3$, to a significant alignment by $z=1$. From $z=0.5$ they preserve their alignment at an approximately constant level until $z=0$. We find a mass-dependence of the alignment signal of elliptical progenitors, whereby ellipticals that are less massive today ($10^{10.4}&lt;M/{\rm M}_\odot&lt;10^{10.7}$) do not become aligned till later redshifts ($z&lt;2$), compared to more massive counterparts. We also present an extended study of progenitor alignments in the parameter space of stellar mass and galaxy dynamics, the impact of shape definition and tidal field smoothing.

A Search for Neutrino Point-Source Populations in 7 Years of IceCube Data with Neutrino-count Statistics

The Astrophysical Journal: an international review of astronomy and astronomical physics American Astronomical Society (2020)

B Eberhardt, T Ehrhardt, P Eller, R Engel, A Fritz, TK Gaisser, J Gallagher, E Ganster, S Garrappa, L Gerhardt, K Ghorbani, T Glauch, T Glüsenkamp, A Goldschmidt, JG Gonzalez, D Grant, S Griswold, F Huang, M Huber, T Huber, K Hultqvist, GS Japaridze, M Jeong, K Jero, BJP Jones

The presence of a population of point sources in a dataset modifies the underlying neutrino-count statistics from the Poisson distribution. This deviation can be exactly quantified using the non-Poissonian template fitting technique, and in this work we present the first application this approach to the IceCube high-energy neutrino dataset. Using this method, we search in 7 years of IceCube data for point-source populations correlated with the disk of the Milky Way, the Fermi bubbles, the Schlegel, Finkbeiner, and Davis dust map, or with the isotropic extragalactic sky. No evidence for such a population is found in the data using this technique, and in the absence of a signal we establish constraints on population models with source count distribution functions that can be described by a power-law with a single break. The derived limits can be interpreted in the context of many possible source classes. In order to enhance the flexibility of the results, we publish the full posterior from our analysis, which can be used to establish limits on specific population models that would contribute to the observed IceCube neutrino flux.

Time-integrated Neutrino Source Searches with 10 years of IceCube Data

Physical Review Letters American Physical Society (2020)

S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, D Rysewyk, I Safa, SES Herrera, A Sandrock, J Sandroos, M Santander, SUBIR Sarkar, S SARKAR, K Satalecka, M Schaufel, H Schieler, P Schlunder, T Schmidt, A Schneider, J Schneider, FG Schröder, L Schumacher, S Sclafani, D Seckel, S Seunarine

This paper presents the results from point-like neutrino source searches using ten years of IceCube data collected between Apr.~6, 2008 and Jul.~10, 2018. We evaluate the significance of an astrophysical signal from a point-like source looking for an excess of clustered neutrino events with energies typically above $\sim1\,$TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the Northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of $2.9\,\sigma$ after accounting for statistical trials. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the Northern catalog are inconsistent with background at 3.3$\,\sigma$ significance. These results, all based on searches for a cumulative neutrino signal integrated over the ten years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

Development of an analysis to probe the neutrino mass ordering with atmospheric neutrinos using three years of IceCube DeepCore data: IceCube Collaboration

European Physical Journal C 80 (2020)

MG Aartsen, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, C Alispach, K Andeen, T Anderson, I Ansseau, G Anton, C Argüelles, J Auffenberg, S Axani, P Backes, H Bagherpour, X Bai, A Barbano, SW Barwick, V Baum, R Bay, JJ Beatty, KH Becker, JB Tjus, S BenZvi, D Berley, E Bernardini, DZ Besson, G Binder, D Bindig, E Blaufuss, S Blot, C Bohm, M Börner, S Böser, O Botner, E Bourbeau, J Bourbeau, F Bradascio, J Braun, HP Bretz, S Bron, J Brostean-Kaiser, A Burgman, RS Busse, T Carver, C Chen, E Cheung, D Chirkin, K Clark, L Classen, GH Collin, JM Conrad, P Coppin, P Correa, DF Cowen, R Cross, P Dave, JPAM de André, C De Clercq, JJ DeLaunay, H Dembinski, K Deoskar, S De Ridder, P Desiati, KD de Vries, G de Wasseige, M de With, T DeYoung, A Diaz, JC Díaz-Vélez, H Dujmovic, M Dunkman, E Dvorak, B Eberhardt, T Ehrhardt, B Eichmann, P Eller, JJ Evans, PA Evenson, S Fahey, AR Fazely, J Felde, K Filimonov, C Finley, A Franckowiak, E Friedman, A Fritz, TK Gaisser, J Gallagher, E Ganster, S Garrappa, L Gerhardt, K Ghorbani, T Glauch, T Glüsenkamp, A Goldschmidt, JG Gonzalez, D Grant, Z Griffith

© 2020, The Author(s). The Neutrino Mass Ordering (NMO) remains one of the outstanding questions in the field of neutrino physics. One strategy to measure the NMO is to observe matter effects in the oscillation pattern of atmospheric neutrinos above ∼1GeV, as proposed for several next-generation neutrino experiments. Moreover, the existing IceCube DeepCore detector can already explore this type of measurement. We present the development and application of two independent analyses to search for the signature of the NMO with three years of DeepCore data. These analyses include a full treatment of systematic uncertainties and a statistically-rigorous method to determine the significance for the NMO from a fit to the data. Both analyses show that the dataset is fully compatible with both mass orderings. For the more sensitive analysis, we observe a preference for normal ordering with a p-value of pIO= 15.3 % and CL s= 53.3 % for the inverted ordering hypothesis, while the experimental results from both analyses are consistent within their uncertainties. Since the result is independent of the value of δCP and obtained from energies Eν≳5GeV, it is complementary to recent results from long-baseline experiments. These analyses set the groundwork for the future of this measurement with more capable detectors, such as the IceCube Upgrade and the proposed PINGU detector.

Design and Performance of the first IceAct Demonstrator at the South Pole

Journal of Instrumentation IOP Publishing (2020)

GW Sullivan, I Taboada, A Taketa, S Ter-Antonyan, HKM Tanaka, F Tenholt, A Terliuk, S Tilav, K Tollefson, L Tomankova, C Tönnis, S Toscano, D Tosi, M Tselengidou, A Turcati, A Trettin, CF Tung, R Turcotte, CF Turley, MAU Elorrieta, B Ty, E Unger, J Vandenbroucke, M Usner, WV Driessche

In this paper we describe the first results of a compact imaging air-Cherenkov telescope, IceAct, operating in coincidence with the IceCube Neutrino Observatory (IceCube) at the geographic South Pole. An array of IceAct telescopes (referred to as the IceAct project) is under consideration as part of the IceCube-Gen2 extension to IceCube. Surface detectors in general will be a powerful tool in IceCube-Gen2 for distinguishing astrophysical neutrinos from the dominant backgrounds of cosmic-ray induced atmospheric muons and neutrinos: the IceTop array is already in place as part of IceCube, but has a high energy threshold. Although the duty cycle will be lower for the IceAct telescopes than the present IceTop tanks, the IceAct telescopes may prove to be more effective at lowering the detection threshold for air showers. Additionally, small imaging air-Cherenkov telescopes in combination with IceTop, the deep IceCube detector or other future detector systems might improve measurements of the composition of the cosmic ray energy spectrum. In this paper we present measurements of a first 7-pixel imaging air Cherenkov telescope demonstrator, proving the capability of this technology to measure air showers at the South Pole in coincidence with IceTop and the deep IceCube detector.

Computational Techniques for the Analysis of Small Signals in High-Statistics Neutrino Oscillation Experiments

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment Elsevier (2020)

D Altmann, K Andeen, T Anderson, R Cross, P Dave, M Day, JPAMD André, GD Wasseige, Z Griffith, C Haack, A Hallgren, F Halzen, K Hanson, N Iovine, A Ishihara, D Kang, A Kappes, D Kappesser, T Karg, J Kiryluk, T Kittler, Klein, R Koirala, H Kolanoski, DJ Koskinen

The current and upcoming generation of Very Large Volume Neutrino Telescopes - collecting unprecedented quantities of neutrino events - can be used to explore subtle effects in oscillation physics, such as (but not restricted to) the neutrino mass ordering. The sensitivity of an experiment to these effects can be estimated from Monte Carlo simulations. With the very high number of events that will be collected, there is a trade-off between the computational expense of running such simulations and the inherent statistical uncertainty in the determined values. In such a scenario, it becomes impractical to produce and use adequately-sized sets of simulated events to use with traditional methods, such as Monte Carlo weighting. In this work we present a staged approach to the generation of binned event distributions in order to overcome these challenges. By combining multiple integration and smoothing techniques which address limited statistics from simulation it arrives at reliable analysis results using modest computational resources.

Search for PeV Gamma-Ray Emission from the Southern Hemisphere with 5 Years of Data from the IceCube Observatory

The Astrophysical Journal: an international review of astronomy and astronomical physics American Astronomical Society (2020)

H Bagherpour, C Argüelles, J Auffenberg, T Anderson, I Ansseau, P Backes, G Anton, S Axani, X Bai, E Bernardini, DZ Besson, E Blaufuss, D Bindig, S BenZvi, D Berley, JB Tjus, G Binder, S Blot, J Brostean-Kaiser, RS Busse, D Chirkin, A Burgman, J Buscher, T Carver, E Cheung

The measurement of diffuse PeV gamma-ray emission from the Galactic plane would provide information about the energy spectrum and propagation of Galactic cosmic rays, and the detection of a point-like source of PeV gamma rays would be strong evidence for a Galactic source capable of accelerating cosmic rays up to at least a few PeV. This paper presents several un-binned maximum likelihood searches for PeV gamma rays in the Southern Hemisphere using 5 years of data from the IceTop air shower surface detector and the in-ice array of the IceCube Observatory. The combination of both detectors takes advantage of the low muon content and deep shower maximum of gamma-ray air showers, and provides excellent sensitivity to gamma rays between $\sim$0.6 PeV and 100 PeV. Our measurements of point-like and diffuse Galactic emission of PeV gamma rays are consistent with background, so we constrain the angle-integrated diffuse gamma-ray flux from the Galactic Plane at 2 PeV to $2.61 \times 10^{-19}$ cm$^{-2}$ s$^{-1}$ TeV$^{-1}$ at 90% confidence, assuming an E$^{-3}$ spectrum, and we estimate 90% upper limits on point-like emission at 2 PeV between 10$^{-21}$ - 10$^{-20}$ cm$^{-2}$ s$^{-1}$ TeV$^{-1}$ for an E$^{-2}$ spectrum, depending on declination. Furthermore, we exclude unbroken power-law emission up to 2 PeV for several TeV gamma-ray sources observed by H.E.S.S., and calculate upper limits on the energy cutoffs of these sources at 90% confidence. We also find no PeV gamma rays correlated with neutrinos from IceCube's high-energy starting event sample. These are currently the strongest constraints on PeV gamma-ray emission.

The impact of the connectivity of the cosmic web on the physical properties of galaxies at its nodes

Monthly Notices of the Royal Astronomical Society Oxford University Press 491 (2019) 4294–4309-

K Kraljic, C Pichon, S Codis, C Laigle, R Davé, Y Dubois, HS Hwang, D Pogosyan, S Arnouts, J Devriendt, M Musso, S Peirani, A Slyz, M Treyer

We investigate the impact of the number of filaments connected to the nodes of the cosmic web on the physical properties of their galaxies using the Sloan Digital Sky Survey. We compare these measurements to the cosmological hydrodynamical simulations Horizon-(no)AGN and Simba. We find that more massive galaxies are more connected, in qualitative agreement with theoretical predictions and measurements in dark matter only simulation. The star formation activity and morphology of observed galaxies both display some dependence on the connectivity of the cosmic web at fixed stellar mass: less star forming and less rotation supported galaxies also tend to have higher connectivity. These results qualitatively hold both for observed and virtual galaxies, and can be understood given that the cosmic web is the main source of fuel for galaxy growth. The simulations show the same trends at fixed halo mass, suggesting that the geometry of filamentary infall impacts galaxy properties beyond the depth of the local potential well. Based on simulations, it is also found that AGN feedback is key in reversing the relationship between stellar mass and connectivity at fixed halo mass. Technically, connectivity is a practical observational proxy for past and present accretion (minor mergers or diffuse infall).

IceCube Search for Neutrinos Coincident with Compact Binary Mergers from LIGO-Virgo's First Gravitational-Wave Transient Catalog

The Astrophysical Journal: an international review of astronomy and astronomical physics American Astronomical Society (2020)

MG Aartsen, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, C Alispach, K Andeen, T Anderson, I Ansseau, G Anton, C Argüelles, J Auffenberg, S Axani, H Bagherpour, X Bai, AB V, A Barbano, I Bartos, SW Barwick, B Bastian, V Baum, S Baur, R Bay, JJ Beatty, K-H Becker, JB Tjus, S BenZvi, D Berley, E Bernardini, DZ Besson, G Binder, D Bindig, E Blaufuss, S Blot, C Bohm, S Böser, O Botner, J Böttcher, E Bourbeau, J Bourbeau, F Bradascio, J Braun, S Bron, J Brostean-Kaiser, A Burgman, J Buscher, RS Busse, T Carver, C Chen, E Cheung, D Chirkin, S Choi, BA Clark, K Clark, L Classen, A Coleman, GH Collin, JM Conrad, P Coppin, KR Corley, P Correa, S Countryman, DF Cowen, R Cross, P Dave, CD Clercq, JJ DeLaunay, H Dembinski, K Deoskar, SD Ridder, P Desiati, KDD Vries, GD Wasseige, MD With, T DeYoung, S Dharani, A Diaz, JC Díaz-Vélez, H Dujmovic, M Dunkman, E Dvorak, B Eberhardt, T Ehrhardt, P Eller, R Engel, PA Evenson, S Fahey, AR Fazely, J Felde, K Filimonov, C Finley, D Fox, A Franckowiak, E Friedman, A Fritz, TK Gaisser, J Gallagher, E Ganster, S Garrappa, L Gerhardt, K Ghorbani, T Glauch, T Glüsenkamp, A Goldschmidt, JG Gonzalez, D Grant, T Grégoire, Z Griffith, S Griswold, M Günder, M Gündüz, C Haack, A Hallgren, R Halliday, L Halve, F Halzen, K Hanson, A Haungs, S Hauser, D Hebecker, D Heereman, P Heix, K Helbing, R Hellauer, F Henningsen, S Hickford, J Hignight, GC Hill, KD Hoffman, R Hoffmann, T Hoinka, B Hokanson-Fasig, K Hoshina, F Huang, M Huber, T Huber, K Hultqvist, M Hünnefeld, R Hussain, S In, N Iovine, A Ishihara, M Jansson, GS Japaridze, M Jeong, K Jero, BJP Jones, F Jonske, R Joppe, D Kang, W Kang, A Kappes, D Kappesser, T Karg, M Karl, A Karle, U Katz, M Kauer, A Keivani, M Kellermann, JL Kelley, A Kheirandish, J Kim, T Kintscher, J Kiryluk, T Kittler, SR Klein, R Koirala, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, P Koundal, M Kowalski, K Krings, G Krückl, N Kulacz, N Kurahashi, A Kyriacou, JL Lanfranchi, MJ Larson, F Lauber, JP Lazar, K Leonard, A Leszczynska, Y Li, QR Liu, E Lohfink, CJL Mariscal, L Lu, F Lucarelli, A Ludwig, J Lünemann, W Luszczak, Y Lyu, WY Ma, J Madsen, G Maggi, KBM Mahn, Y Makino, P Mallik, K Mallot, S Mancina, IC Mariş, S Marka, Z Marka, R Maruyama, K Mase, R Maunu, F McNally, K Meagher, M Medici, A Medina, M Meier, S Meighen-Berger, G Merino, J Merz, T Meures, J Micallef, D Mockler, G Momenté, T Montaruli, RW Moore, R Morse, M Moulai, P Muth, R Nagai, U Naumann, G Neer, LV Nguyen, H Niederhausen, MU Nisa, SC Nowicki, DR Nygren, AO Pollmann, M Oehler, A Olivas, A O'Murchadha, E O'Sullivan, T Palczewski, H Pandya, DV Pankova, N Park, P Peiffer, CPDL Heros, S Philippen, D Pieloth, S Pieper, E Pinat, A Pizzuto, M Plum, Y Popovych, A Porcelli, PB Price, GT Przybylski, C Raab, A Raissi, M Rameez, L Rauch, K Rawlins, IC Rea, A Rehman, R Reimann, B Relethford, M Renschler, G Renzi, E Resconi, W Rhode, M Richman, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, DR Cantu, I Safa, SES Herrera, A Sandrock, J Sandroos, M Santander, S Sarkar, S Sarkar, K Satalecka, M Scharf, M Schaufel, H Schieler, P Schlunder, T Schmidt, A Schneider, J Schneider, FG Schröder, L Schumacher, S Sclafani, D Seckel, S Seunarine, S Shefali, M Silva, R Snihur, J Soedingrekso, D Soldin, M Song, GM Spiczak, C Spiering, J Stachurska, M Stamatikos, T Stanev, R Stein, J Stettner, A Steuer, T Stezelberger, RG Stokstad, A Stössl, NL Strotjohann, T Stürwald, T Stuttard, GW Sullivan, I Taboada, F Tenholt, S Ter-Antonyan, A Terliuk, S Tilav, K Tollefson, L Tomankova, C Tönnis, S Toscano, D Tosi, A Trettin, M Tselengidou, CF Tung, A Turcati, R Turcotte, CF Turley, B Ty, E Unger, MAU Elorrieta, M Usner, J Vandenbroucke, WV Driessche, DV Eijk, NV Eijndhoven, JV Santen, S Verpoest, D Veske, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, TB Watson, C Weaver, A Weindl, MJ Weiss, J Weldert, C Wendt, J Werthebach, BJ Whelan, N Whitehorn, K Wiebe, CH Wiebusch, L Wille, DR Williams, L Wills, M Wolf, J Wood, TR Wood, K Woschnagg, G Wrede, J Wulff, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, T Yuan, M Zöcklein

Using the IceCube Neutrino Observatory, we search for high-energy neutrino emission coincident with compact binary mergers observed by the LIGO and Virgo gravitational wave (GW) detectors during their first and second observing runs. We present results from two searches targeting emission coincident with the sky localization of each gravitational wave event within a 1000 second time window centered around the reported merger time. One search uses a model-independent unbinned maximum likelihood analysis, which uses neutrino data from IceCube to search for point-like neutrino sources consistent with the sky localization of GW events. The other uses the Low-Latency Algorithm for Multi-messenger Astrophysics, which incorporates astrophysical priors through a Bayesian framework and includes LIGO-Virgo detector characteristics to determine the association between the GW source and the neutrinos. No significant neutrino coincidence is seen by either search during the first two observing runs of the LIGO-Virgo detectors. We set upper limits on the time-integrated neutrino emission within the 1000 second window for each of the 11 GW events. These limits range from 0.02-0.7 $\mathrm{GeV~cm^{-2}}$. We also set limits on the total isotropic equivalent energy, $E_{\mathrm{iso}}$, emitted in high-energy neutrinos by each GW event. These limits range from 1.7 $\times$ 10$^{51}$ - 1.8 $\times$ 10$^{55}$ erg. We conclude with an outlook for LIGO-Virgo observing run O3, during which both analyses are running in real time.

Kinematic unrest of low mass galaxy groups

Astronomy and Astrophysics EDP Sciences 635 (2020) A36

J Devriendt, G Gozaliasl, A Finoguenov, HG Khosroshahi, C Laigle, CC Kirkpatrick, K Kiiveri, Y Dubois, J Ahoranta

In an effort to better understand the formation of galaxy groups, we examine the kinematics of a large sample of spectroscopically confirmed X-ray galaxy groups in the Cosmic Evolution Survey (COSMOS) with a high sampling of galaxy group members up to $z=1$. We compare our results with predictions from the cosmological hydrodynamical simulation of {\sc Horizon-AGN}. Using a phase-space analysis of dynamics of groups with halo masses of $M_{\mathrm{200c}}\sim 10^{12.6}-10^{14.50}M_\odot$, we show that the brightest group galaxies (BGG) in low mass galaxy groups ($M_{\mathrm{200c}}&lt;2 \times 10^{13} M_\odot$) have larger proper motions relative to the group velocity dispersion than high mass groups. The dispersion in the ratio of the BGG proper velocity to the velocity dispersion of the group, $\sigma_{\mathrm{BGG}}/\sigma_{group}$, is on average $1.48 \pm 0.13$ for low mass groups and $1.01 \pm 0.09$ for high mass groups. A comparative analysis of the {\sc Horizon-AGN} simulation reveals a similar increase in the spread of peculiar velocities of BGGs with decreasing group mass, though consistency in the amplitude, shape, and mode of the BGG peculiar velocity distribution is only achieved for high mass groups. The groups hosting a BGG with a large peculiar velocity are more likely to be offset from the $L_x-\sigma_{v}$ relation; this is probably because the peculiar motion of the BGG is influenced by the accretion of new members.

Reionization history constraints from neural network based predictions of high-redshift quasar continua

Monthly Notices of the Royal Astronomical Society Oxford University Press 493 (2020) 4256–4275-

D Ďurovčíková, H Katz, SEI Bosman, FB Davies, J Devriendt, A Slyz

Observations of the early Universe suggest that reionization was complete by z ∼ 6, however, the exact history of this process is still unknown. One method for measuring the evolution of the neutral fraction throughout this epoch is via observing the Lyα damping wings of high-redshift quasars. In order to constrain the neutral fraction from quasar observations, one needs an accurate model of the quasar spectrum around Lyα, after the spectrum has been processed by its host galaxy but before it is altered by absorption and damping in the intervening IGM. In this paper, we present a novel machine learning approach, using artificial neural networks, to reconstruct quasar continua around Lyα. Our QSANNDRA algorithm improves the error in this reconstruction compared to the state-of-the-art PCA-based model in the literature by 14.2% on average, and provides an improvement of 6.1% on average when compared to an extension thereof. In comparison with the extended PCA model, QSANNDRA further achieves an improvement of 22.1% and 16.8% when evaluated on low-redshift quasars most similar to the two high-redshift quasars under consideration, ULAS J1120+0641 at z = 7.0851 and ULAS J1342+0928 at z = 7.5413, respectively. Using our more accurate reconstructions of these two z > 7 quasars, we estimate the neutral fraction of the IGM using a homogeneous reionization model and find x¯H1=0.25+0.05−0.05 at z = 7.0851 and x¯H1=0.60+0.11−0.11 at z = 7.5413. Our results are consistent with the literature and favour a rapid end to reionization.

A few StePS forward in unveiling the complexity of galaxy evolution: light-weighted stellar ages of intermediate-redshift galaxies with WEAVE

Astronomy and Astrophysics EDP Sciences 632 (2019) A9

L Costantin, A Iovino, S Zibetti, M Longhetti, A Gallazzi, A Mercurio, I Lonoce, M Balcells, M Bolzonella, G Busarello, G Dalton, A Ferre-Mateu, R Garcia-Benito, S Jin, F La Barbera, P Merluzzi, DNA Murphy, PDAL de Arriba, P Sanchez-Blazquez, M Talia, C Tortora, SC Trager, A Vazdekis, D Vergani, B Vulcani

<br><strong><i>Context. </strong></i>The upcoming new generation of optical spectrographs on four-meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide invaluable information for reconstructing the history of star formation in individual galaxies up to redshifts of about 0.7.</br> <br><strong><i>Aims. </strong></i>We aim at defining simple but robust and meaningful physical parameters that can be used to trace the coexistence of widely diverse stellar components: younger stellar populations superimposed on the bulk of older ones.</br> <br><strong><i>Methods. </strong></i>We produced spectra of galaxies closely mimicking data from the forthcoming Stellar Populations at intermediate redshifts Survey (StePS), a survey that uses the WEAVE spectrograph on the William Herschel Telescope. First, we assessed our ability to reliably measure both ultraviolet and optical spectral indices in galaxies of different spectral types for typically expected signal-to-noise ratios. We then analyzed such mock spectra with a Bayesian approach, deriving the probability density function of r- and u-band light-weighted ages as well as of their difference.</br> <br><strong><i>Results. </strong></i>We find that the ultraviolet indices significantly narrow the uncertainties in estimating the r- and u-band light-weighted ages and their difference in individual galaxies. These diagnostics, robustly retrievable for large galaxy samples even when observed at moderate signal-to-noise ratios, allow us to identify secondary episodes of star formation up to an age of ∼0.1 Gyr for stellar populations older than ∼1.5 Gyr, pushing up to an age of ∼1 Gyr for stellar populations older than ∼5 Gyr.</br> <br><strong><i>Conclusions. </strong></i>The difference between r-band and u-band light-weighted ages is shown to be a powerful diagnostic to characterize and constrain extended star-formation histories and the presence of young stellar populations on top of older ones. This parameter can be used to explore the interplay between different galaxy star-formation histories and physical parameters such as galaxy mass, size, morphology, and environment.</br>

Evidence for anisotropy of cosmic acceleration

Astronomy and Astrophysics: a European journal EDP Sciences (2019)

J Colin, R Mohayaee, M Rameez, S Sarkar

Observations reveal a `bulk flow' in the local Universe which is faster and extends to much larger scales than is expected around a typical observer in the standard $\Lambda$CDM cosmology. This is expected to result in a scale-dependent dipolar modulation of the acceleration of the expansion rate inferred from observations of objects within the bulk flow. From a maximum-likelihood analysis of the Joint Lightcurve Analysis (JLA) catalogue of Type Ia supernovae we find that the deceleration parameter, in addition to a small monopole, indeed has a much bigger dipole component aligned with the CMB dipole which falls exponentially with redshift $z$: $q_0 = q_\mathrm{m} + \vec{q}_\mathrm{d}.\hat{n}\exp(-z/S)$. The best fit to data yields $q_\mathrm{d} = -8.03$ and $S = 0.0262~(\Rightarrow d \sim 100~\mathrm{Mpc})$, rejecting isotropy ($q_\mathrm{d} = 0$) with $3.9\sigma$ statistical significance, while $q_\mathrm{m} = -0.157$ and consistent with no acceleration ($q_\mathrm{m} = 0$) at $1.4\sigma$. Thus the cosmic acceleration deduced from supernovae may be an artefact of our being non-Copernican observers, rather than evidence for a dominant component of `dark energy' in the Universe.

Simulating MOS science on the ELT: Ly alpha forest tomography

Astronomy and Astrophysics EDP Sciences 632 (2019) A94

J Japelj, C Laigle, M Puech, C Pichon, H Rahmani, Y Dubois, J Devriendt, P Petitjean, F Hammer, E Gendron, L Kaper, S Morris, N Pirzkal, R Sanchez-Janssen, A Slyz, SD Vergani, Y Yang

Mapping of the large-scale structure through cosmic time has numerous applications in the studies of cosmology and galaxy evolution. At $z &gt; 2$, the structure can be traced by the neutral intergalactic medium (IGM) by way of observing the Ly$\alpha$, forest towards densely-sampled lines-of-sight of bright background sources, such as quasars and star forming galaxies. We investigate the scientific potential of MOSAIC, a planned multi-object spectrograph on the European Extremely Large Telescope (ELT), for the 3D mapping of the IGM at $z \gtrsim 3$. We simulate a survey of $3 \lesssim z \lesssim 4$ galaxies down to a limiting magnitude of $m_{r}\sim 25.5$ mag in an area of 1 degree$^2$ in the sky. Galaxies and their spectra (including the line-of-sight Ly$\alpha$ absorption) are taken from the lightcone extracted from the Horizon-AGN cosmological hydrodynamical simulation. The quality of the reconstruction of the original density field is studied for different spectral resolutions and signal-to-noise ratios of the spectra. We demonstrate that the minimum $S/N$ (per resolution element) of the faintest galaxies that such survey has to reach is $S/N = 4$. We show that a survey with such sensitivity enables a robust extraction of cosmic filaments and the detection of the theoretically-predicted galaxy stellar mass and star-formation rate gradients towards filaments. By simulating the realistic performance of MOSAIC we obtain $S/N(T_{\rm obs}, R, m_{r})$ scaling relations. We estimate that $\lesssim 35~(65)$ nights of observation time are required to carry out the survey with the instrument's high multiplex mode and with the spectral resolution of $R=1000~(2000)$. A survey with a MOSAIC-concept instrument on the ELT is found to enable the mapping of the IGM at $z &gt; 3$ on Mpc scales, and as such will be complementary to and competitive with other planned IGM tomography surveys. [abridged]

A response to Rubin &amp; Heitlauf: "Is the expansion of the universe accelerating? All signs \emph{still} point to yes"

arXiv (2019)

J Colin, R Mohayaee, M Rameez, SUBIR Sarkar

We have shown (Colin et al. 2019) that the acceleration of the Hubble expansion rate inferred from Type Ia supernovae is essentially a dipole with 3.9$\sigma$ significance, approximately aligned with the CMB dipole, while its monopole component which may be interpreted as due to a Cosmological Constant (or more generally dark energy) is consistent with zero at 1.4$\sigma$. This is challenged by Rubin &amp; Heitlauf (2019) who assert that we incorrectly assumed the supernova light-curve parameters to be independent of redshift, and erred further in considering their measured redshifts (in the heliocentric frame) rather than transforming them to the CMB frame (in which the universe supposedly looks isotropic). We emphasize that our procedure is justified and that their criticism serves only to highlight the rather "arbitrary corrections" that are made to the data in order to infer isotropic cosmic acceleration. This is a vivid illustration of the 'Cosmological Fitting Problem' faced by observers who live in an inhomogeneous universe but still use the maximally symmetric FLRW cosmolgy to interpret observations.