Publications


Disentangling magnification in combined shear-clustering analyses

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 491 (2020) 1746-1758

L Thiele, CAJ Duncan, D Alonso

<jats:title>ABSTRACT</jats:title> <jats:p>We investigate the sensitivity to the effects of lensing magnification on large-scale structure analyses combining photometric cosmic shear and galaxy clustering data (i.e. the now commonly called ‘3 × 2-point’ analysis). Using a Fisher matrix bias formalism, we disentangle the contribution to the bias on cosmological parameters caused by ignoring the effects of magnification in a theory fit from individual elements in the data vector, for Stage-III and Stage-IV surveys. We show that the removal of elements of the data vectors that are dominated by magnification does not guarantee a reduction in the cosmological bias due to the magnification signal, but can instead increase the sensitivity to magnification. We find that the most sensitive elements of the data vector come from the shear-clustering cross-correlations, particularly between the highest redshift shear bin and any lower redshift lens sample, and that the parameters ΩM, $S_8=\sigma _8\sqrt{\Omega _\mathrm{ M}/0.3}$, and w0 show the most significant biases for both survey models. Our forecasts predict that current analyses are not significantly biased by magnification, but this bias will become highly significant with the continued increase of statistical power in the near future. We therefore conclude that future surveys should measure and model the magnification as part of their flagship ‘3 × 2-point’ analysis.</jats:p>


Group connectivity in COSMOS: a tracer of mass assembly history

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 489 (2019) 5695-5708

ED Ford, C Laigle, G Gozaliasl, C Pichon, J Devriendt, A Slyz, S Arnouts, Y Dubois, A Finoguenov, R Griffiths, K Kraljic, H Pan, S Peirani, F Sarron


The C-Band All-Sky Survey (C-BASS): Simulated parametric fitting in single pixels in total intensity and polarization.

Monthly notices of the Royal Astronomical Society 490 (2019) 2958-2975

L Jew, AC Taylor, ME Jones, A Barr, HC Chiang, C Dickinson, RDP Grumitt, SE Harper, HM Heilgendorff, J Hill-Valler, JL Jonas, JP Leahy, J Leech, TJ Pearson, MW Peel, ACS Readhead, J Sievers

The cosmic microwave background (CMB) B-mode signal is potentially weaker than the diffuse Galactic foregrounds over most of the sky at any frequency. A common method of separating the CMB from these foregrounds is via pixel-based parametric-model fitting. There are not currently enough all-sky maps to fit anything more than the most simple models of the sky. By simulating the emission in seven representative pixels, we demonstrate that the inclusion of a 5 GHz data point allows for more complex models of low-frequency foregrounds to be fitted than at present. It is shown that the inclusion of the C-BASS data will significantly reduce the uncertainties in a number of key parameters in the modelling of both the galactic foregrounds and the CMB. The extra data allow estimates of the synchrotron spectral index to be constrained much more strongly than is presently possible, with corresponding improvements in the accuracy of the recovery of the CMB amplitude. However, we show that to place good limits on models of the synchrotron spectral curvature will require additional low-frequency data.


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.


Cosmic ray spectrum and composition from PeV to EeV using 3 years of data from IceTop and IceCube

PHYSICAL REVIEW D 100 (2019) ARTN 082002

MG Aartsen, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, C Alispach, K Andeen, T Anderson, I Ansseau, G Anton, C Arguelles, J Auffenberg, S Axani, P Backes, H Bagherpour, X Bai, A Barbano, SW Barwick, 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, M Boerner, S Boeser, O Botner, J Boettcher, E Bourbeau, J Bourbeau, F Bradascio, J Braun, H-P Bretz, S Bron, J Brostean-Kaiser, A Burgman, J Buscher, 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 Andre, 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 Diaz-Velez, H Dujmovic, M Dunkman, E Dvorak, B Eberhardt, T Ehrhardt, P Eller, PA Evenson, S Fahey, AR Fazely, J Felde, T Feusels, 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 Gluesenkamp, A Goldschmidt, JG Gonzalez, D Grant, Z Griffith, M Guender, M Guenduez, C Haack, A Hallgren, L Halve, F Halzen, K Hanson, 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, K Hultqvist, M Huennefeld, R Hussain, S In, N Iovine, A Ishihara, E Jacobi, GS Japaridze, M Jeong, K Jero, BJP Jones, F Jonske, R Joppe, W Kang, A Kappes, D Kappesser, T Karg, M Karl, A Karle, U Katz, M Kauer, JL Kelley, A Kheirandish, J Kim, T Kintscher, J Kiryluk, T Kittler, SR Klein, R Koirala, H Kolanoski, L Koepke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, K Krings, G Krueckl, N Kulacz, S Kunwar, N Kurahashi, A Kyriacou, M Labare, JL Lanfranchi, MJ Larson, F Lauber, JP Lazar, K Leonard, M Leuermann, QR Liu, E Lohfink, CJL Mariscal, L Lu, F Lucarelli, J Lunemann, W Luszczak, J Madsen, G Maggi, KBM Mahn, Y Makino, P Mallik, K Mallot, S Mancina, IC Mari, R Maruyama, K Mase, R Maunu, K Meagher, M Medici, A Medina, M Meier, S Meighen-Berger, T Menne, G Merino, T Meures, S Miarecki, J Micallef, G Momente, T Montaruli, RW Moore, R Morse, M Moulai, P Muth, R Nagai, R Nahnhauer, P Nakarmi, U Naumann, G Neer, H Niederhausen, SC Nowicki, DR Nygren, AO Pollmann, A Olivas, A O'Murchadha, E O'Sullivan, T Palczewski, H Pandya, DV Pankova, N Park, P Peiffer, CP de los Heros, S Philippen, D Pieloth, E Pinat, A Pizzuto, M Plum, A Porcelli, PB Price, GT Przybylski, C Raab, A Raissi, M Rameez, L Rauch, K Rawlins, IC Rea, R Reimann, B Relethford, G Renzi, E Resconi, W Rhode, M Richman, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, D Rysewyk, I Safa, SES Herrera, A Sandrock, J Sandroos, M Santander, S Sarkar, K Satalecka, M Schaufel, P Schlunder, T Schmidt, A Schneider, J Schneider, 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, A Stasik, R Stein, J Stettner, A Steuer, T Stezelberger, RG Stokstad, A Stossl, NL Strotjohann, T Stuerwald, T Stuttard, GW Sullivan, M Sutherland, I Taboada, F Tenholt, S Ter-Antonyan, A Terliuk, S Tilav, L Tomankova, C Tonnis, S Toscano, D Tosi, M Tselengidou, CF Tung, A Turcati, R Turcotte, CF Turley, B Ty, E Unger, MAU Elorrieta, M Usner, J Vandenbroucke, W Van Driessche, D van Eijk, N van Eijndhoven, S Vanheule, J van Santen, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, TB Watson, C Weaver, MJ Weiss, J Weldert, C Wendt, J Werthebach, S Westerhoff, BJ Whelan, N Whitehorn, K Wiebe, CH Wiebusch, L Wille, DR Williams, L Wills, M Wolf, J Wood, TR Wood, K Woschnagg, G Wrede, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, T Yuan, M Zoecklein, I Collaboration


Efficient propagation of systematic uncertainties from calibration to analysis with the SnowStorm method in IceCube

Journal of Cosmology and Astroparticle Physics IOP Publishing 2019 (2019) 048-048

MG Aartsen, M Ackermann, J Adams, JA Aguilar, M Ahlers, C Alispach, BA Atoum, K Andeen, T Anderson, I Ansseau, G Anton, C Argüelles, J Auffenberg, S Axani, P Backes, H Bagherpour, X Bai, AB V., A Barbano, 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, M Börner, 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, K Clark, L Classen, A Coleman, GH Collin, JM Conrad, P Coppin, P Correa, DF Cowen, R Cross, P Dave, CD Clercq, JJ DeLaunay, H Dembinski, K Deoskar, SD 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, P Eller, R Engel, 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, S Griswold, M Günder, M Gündüz, C Haack, A Hallgren, L Halve, F Halzen, K Hanson, A Haungs, 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, 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, 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, M Kowalski, K Krings, G Krückl, N Kulacz, N Kurahashi, A Kyriacou, M Labare, JL Lanfranchi, MJ Larson, F Lauber, JP Lazar, K Leonard, A Leszczyńska, M Leuermann, QR Liu, E Lohfink, CJL Mariscal, L Lu, F Lucarelli, J Lünemann, W Luszczak, Y Lyu, WY Ma, J Madsen, G Maggi, KBM Mahn, Y Makino, P Mallik, K Mallot, S Mancina, IC Mariş, R Maruyama, K Mase, R Maunu, F McNally, K Meagher, M Medici, A Medina, M Meier, S Meighen-Berger, T Menne, G Merino, T Meures, J Micallef, D Mockler, G Momenté, T Montaruli, RW Moore, R Morse, M Moulai, P Muth, R Nagai, U Naumann, G Neer, H Niederhausen, 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, C Pérez de los Heros, S Philippen, D Pieloth, E Pinat, A Pizzuto, M Plum, A Porcelli, PB Price, GT Przybylski, C Raab, A Raissi, M Rameez, L Rauch, K Rawlins, IC Rea, R Reimann, B Relethford, M Renschler, G Renzi, E Resconi, W Rhode, M Richman, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, D Rysewyk, I Safa, SES Herrera, A Sandrock, J Sandroos, M Santander, S 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, S Shefali, M Silva, R Snihur, J Soedingrekso, D Soldin, M Song, GM Spiczak, C Spiering, J Stachurska, M Stamatikos, T Stanev, R Stein, P Steinmüller, 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, S Vanheule, JV Santen, 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, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, T Yuan, M Zöcklein


Observation of inverse Compton emission from a long γ-ray burst.

Nature 575 (2019) 459-463

MAGIC Collaboration, P Veres, PN Bhat, MS Briggs, WH Cleveland, R Hamburg, CM Hui, B Mailyan, RD Preece, OJ Roberts, A von Kienlin, CA Wilson-Hodge, D Kocevski, M Arimoto, D Tak, K Asano, M Axelsson, G Barbiellini, E Bissaldi, FF Dirirsa, R Gill, J Granot, J McEnery, N Omodei, S Razzaque, F Piron, JL Racusin, DJ Thompson, S Campana, MG Bernardini, NPM Kuin, MH Siegel, SB Cenko, P O'Brien, M Capalbi, A Daì, M De Pasquale, J Gropp, N Klingler, JP Osborne, M Perri, RLC Starling, G Tagliaferri, A Tohuvavohu, A Ursi, M Tavani, M Cardillo, C Casentini, G Piano, Y Evangelista, F Verrecchia, C Pittori, F Lucarelli, A Bulgarelli, N Parmiggiani, GE Anderson, JP Anderson, G Bernardi, J Bolmer, MD Caballero-García, IM Carrasco, A Castellón, NC Segura, AJ Castro-Tirado, SV Cherukuri, AM Cockeram, P D'Avanzo, A Di Dato, R Diretse, RP Fender, E Fernández-García, JPU Fynbo, AS Fruchter, J Greiner, M Gromadzki, KE Heintz, I Heywood, AJ van der Horst, Y-D Hu, C Inserra, L Izzo, V Jaiswal, P Jakobsson, J Japelj, E Kankare, DA Kann, C Kouveliotou, S Klose, AJ Levan, XY Li, S Lotti, K Maguire, DB Malesani, I Manulis, M Marongiu, S Martin, A Melandri, MJ Michałowski, JCA Miller-Jones, K Misra, A Moin, KP Mooley, S Nasri, M Nicholl, A Noschese, G Novara, SB Pandey, E Peretti, CJP Del Pulgar, MA Pérez-Torres, DA Perley, L Piro, F Ragosta, L Resmi, R Ricci, A Rossi, R Sánchez-Ramírez, J Selsing, S Schulze, SJ Smartt, IA Smith, VV Sokolov, J Stevens, NR Tanvir, CC Thöne, A Tiengo, E Tremou, E Troja, A de Ugarte Postigo, AF Valeev, SD Vergani, M Wieringa, PA Woudt, D Xu, O Yaron, DR Young

Long-duration γ-ray bursts (GRBs) originate from ultra-relativistic jets launched from the collapsing cores of dying massive stars. They are characterized by an initial phase of bright and highly variable radiation in the kiloelectronvolt-to-megaelectronvolt band, which is probably produced within the jet and lasts from milliseconds to minutes, known as the prompt emission1,2. Subsequently, the interaction of the jet with the surrounding medium generates shock waves that are responsible for the afterglow emission, which lasts from days to months and occurs over a broad energy range from the radio to the gigaelectronvolt bands1-6. The afterglow emission is generally well explained as synchrotron radiation emitted by electrons accelerated by the external shock7-9. Recently, intense long-lasting emission between 0.2 and 1 teraelectronvolts was observed from GRB 190114C10,11. Here we report multi-frequency observations of GRB 190114C, and study the evolution in time of the GRB emission across 17 orders of magnitude in energy, from 5 × 10-6 to 1012 electronvolts. We find that the broadband spectral energy distribution is double-peaked, with the teraelectronvolt emission constituting a distinct spectral component with power comparable to the synchrotron component. This component is associated with the afterglow and is satisfactorily explained by inverse Compton up-scattering of synchrotron photons by high-energy electrons. We find that the conditions required to account for the observed teraelectronvolt component are typical for GRBs, supporting the possibility that inverse Compton emission is commonly produced in GRBs.


HORIZON-AGN virtual observatory-2. Template-free estimates of galaxy properties from colours

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 489 (2019) 4817-4835

I Davidzon, C Laigle, PL Capak, O Ilbert, DC Masters, S Hemmati, N Apostolakos, J Coupon, S de la Torre, J Devriendt, Y Dubois, D Kashino, S Paltani, C Pichon


Testing self-interacting dark matter with galaxy warps

PHYSICAL REVIEW D 100 (2019) ARTN 123006

K Pardo, H Desmond, PG Ferreira


Massive spheroids can form in single minor mergers

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 489 (2019) 4679-4689

RA Jackson, G Martin, S Kaviraj, C Laigle, JEG Devriendt, Y Dubois, C Pichon


Comparing galaxy clustering in Horizon-AGN simulated light-cone mocks and VIDEO observations

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 490 (2019) 5043-5056

PW Hatfield, C Laigle, MJ Jarvis, J Devriendt, I Davidzon, O Ilbert, C Pichon, Y Dubois


Gain Stabilization for Radio Intensity Mapping using a Continuous-Wave Reference Signal

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (0)

AW Pollak, CM Holler, ME Jones, AC Taylor

Stabilizing the gain of a radio astronomy receiver is of great importance for sensitive radio intensity mapping. In this paper we discuss a stabilization method using a continuous-wave reference signal injected into the signal chain and tracked in a single channel of the spectrometer to correct for the gain variations of the receiver. This method depends on the fact that gain fluctuations of the receiver are strongly correlated across the frequency band, which we can show is the case for our experimental setup. This method is especially suited for receivers with a digital back-end with high spectral resolution and moderate dynamic range. The sensitivity of the receiver is unaltered except for one lost frequency channel. We present experimental results using a new 4-8.5 GHz receiver with a digital back-end that shows substantial reduction of the 1/ f noise and the 1/ f knee frequency.


SIGNALS: I. Survey description

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 489 (2019) 5530-5546

L Rousseau-Nepton, RP Martin, C Robert, L Drissen, P Amram, S Prunet, T Martin, I Moumen, A Adamo, A Alarie, P Barmby, A Boselli, F Bresolin, M Bureau, L Chemin, RC Fernandes, F Combes, C Crowder, L Della Bruna, S Duarte Puertas, F Egusa, B Epinat, VF Ksoll, M Girard, V Gómez Llanos, D Gouliermis, K Grasha, C Higgs, J Hlavacek-Larrondo, I-T Ho, J Iglesias-Páramo, G Joncas, ZS Kam, P Karera, RC Kennicutt, RS Klessen, S Lianou, L Liu, Q Liu, AL de Amorim, JD Lyman, H Martel, B Mazzilli-Ciraulo, AF McLeod, A-L Melchior, I Millan, M Mollá, R Momose, C Morisset, H-A Pan, AK Pati, A Pellerin, E Pellegrini, I Pérez, A Petric, H Plana, D Rahner, T Ruiz Lara, L Sánchez-Menguiano, K Spekkens, G Stasińska, M Takamiya, N Vale Asari, JM Vílchez

<jats:title>ABSTRACT</jats:title> <jats:p>SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing programme designed to investigate massive star formation and H ii regions in a sample of local extended galaxies. The programme will use the imaging Fourier transform spectrograph SITELLE at the Canada–France–Hawaii Telescope. Over 355 h (54.7 nights) have been allocated beginning in fall 2018 for eight consecutive semesters. Once completed, SIGNALS will provide a statistically reliable laboratory to investigate massive star formation, including over 50 000 resolved H ii regions: the largest, most complete, and homogeneous data base of spectroscopically and spatially resolved extragalactic H ii regions ever assembled. For each field observed, three datacubes covering the spectral bands of the filters SN1 (363–386 nm), SN2 (482–513 nm), and SN3 (647–685 nm) are gathered. The spectral resolution selected for each spectral band is 1000, 1000, and 5000, respectively. As defined, the project sample will facilitate the study of small-scale nebular physics and many other phenomena linked to star formation at a mean spatial resolution of ∼20 pc. This survey also has considerable legacy value for additional topics, including planetary nebulae, diffuse ionized gas, and supernova remnants. The purpose of this paper is to present a general outlook of the survey, notably the observing strategy, galaxy sample, and science requirements.</jats:p>


A new sample of southern radio galaxies: host-galaxy masses and star-formation rates

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 489 (2019) 3403-3411

T Marubini, MJ Jarvis, S Fine, T Mauch, K McAlpine, M Prescott


Synchrotron self-absorption and the minimum energy of optically thick radio flares from stellar mass black holes

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 489 (2019) 4836-4846

R Fender, J Bright


Automatic selection of correlated double sampling timing parameters

Journal of Astronomical Telescopes, Instruments, and Systems 5 (2019)

DP Weatherill, I Shipsey, K Arndt, R Plackett, D Wood, K Metodiev, M Mironova, D Bortoletto, N Demetriou

© 2019 Society of Photo-Optical Instrumentation Engineers (SPIE). Correlated double sampling (CDS) is a process used in many charge-coupled device readout systems to cancel the reset noise component that would otherwise dominate. CDS processing typically consists of subtracting the integrated video signal during a "signal" period from that during a "reset" period. The response of this processing depends, therefore, on the shape of the video signal with respect to the integration bounds. In particular, the amount of noise appearing in the final image and the linearity of the pixel value with signal charge are affected by the choice of the CDS timing intervals. We use a digital CDS readout system which highly oversamples the video signal (as compared with the pixel rate) to reconstruct pixel values for different CDS timings using identical raw video signal data. We use this technique to develop insights into optimal strategy for selecting CDS timings both in the digital case (where the raw video signal may be available) and in the general case (where it is not). In particular, we show that the linearity of the CDS operation allows subtraction of the raw video signals of pixels in bias images from those in illuminated images to directly show the effects of CDS processing on the final (subtracted) pixel values.


WISDOM project – V. Resolving molecular gas in Keplerian rotation around the supermassive black hole in NGC 0383

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 490 (2019) 319-330

EV North, TA Davis, M Bureau, M Cappellari, S Iguchi, L Liu, K Onishi, M Sarzi, MD Smith, TG Williams

<jats:title>ABSTRACT</jats:title> <jats:p>As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), we present a measurement of the mass of the supermassive black hole (SMBH) in the nearby early-type galaxy NGC 0383 (radio source 3C 031). This measurement is based on Atacama Large Millimeter/sub-millimeter Array (ALMA) cycle 4 and 5 observations of the 12CO(2–1) emission line with a spatial resolution of 58 × 32 pc2 (0.18 arcsec × 0.1 arcsec). This resolution, combined with a channel width of 10 km s−1, allows us to well resolve the radius of the black hole sphere of influence (measured as RSOI = 316 pc  =  0.98 arcsec), where we detect a clear Keplerian increase of the rotation velocities. NGC 0383 has a kinematically relaxed, smooth nuclear molecular gas disc with weak ring/spiral features. We forward model the ALMA data cube with the Kinematic Molecular Simulation (KinMS) tool and a Bayesian Markov Chain Monte Carlo method to measure an SMBH mass of (4.2 ± 0.7) × 109 M⊙, a F160W-band stellar mass-to-light ratio that varies from 2.8 ± 0.6 M⊙/L$_{\odot ,\, \mathrm{F160W}}$ in the centre to 2.4 ± 0.3 M⊙$/\rm L_{\odot ,\, \mathrm{F160W}}$ at the outer edge of the disc and a molecular gas velocity dispersion of 8.3 ± 2.1 km s−1(all 3σ uncertainties). We also detect unresolved continuum emission across the full bandwidth, consistent with synchrotron emission from an active galactic nucleus. This work demonstrates that low-J CO emission can resolve gas very close to the SMBH ($\approx 140\, 000$ Schwarzschild radii) and hence that the molecular gas method is highly complimentary to megamaser observations, as it can probe the same emitting material.</jats:p>


Disk-Jet Coupling in the 2017/2018 Outburst of the Galactic Black Hole Candidate X-Ray Binary MAXI J1535-571

ASTROPHYSICAL JOURNAL 883 (2019) ARTN 198

TD Russell, AJ Tetarenko, JCA Miller-Jones, GR Sivakoff, AS Parikh, S Rapisarda, R Wijnands, S Corbel, E Tremou, D Altamirano, MC Baglio, C Ceccobello, N Degenaar, J van den Eijnden, R Fender, I Heywood, HA Krimm, M Lucchini, S Markoff, DM Russell, R Soria, PA Woudt


A compact air cooling system for testing silicon detectors based on a vortex chiller

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 940 (2019) 405-409

K Metodiev, L Vigani, R Plackett, K Arndt, D Wood, DP Weatherill, M Mironova, D Bortoletto, I Shipsey


Towards the analysis of JWST exoplanet spectra: the effective temperature in the context of direct imaging

Monthly Notices of the Royal Astronomical Society Oxford University Press 490 (2019) 2086-2090

R Garland, J-L Baudino, J Taylor, P Irwin

The current sparse wavelength range coverage of exoplanet direct imaging observations, and the fact that models are defined using a finite wavelength range, lead both to uncertainties on effective temperature determination. We study these effects using blackbodies and atmospheric models and we detail how to infer this parameter. Through highlighting the key wavelength coverage that allows for a more accurate representation of the effective temperature, our analysis can be used to mitigate or manage extra uncertainties being added in the analysis from the models. We find that the wavelength range coverage will soon no longer be a problem. An effective temperature computed by integrating the spectroscopic observations of the James Webb Space Telescope will give uncertainties similar to, or better than, the current state–of–the–art, which is to fit models to data. Accurately calculating the effective temperature will help to improve current modelling approaches. Obtaining an independent and precise estimation of this crucial parameter will help the benchmarking process to identify the best practice to model exoplanet atmospheres.

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