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MIGHTEE: the nature of the radio-loud AGN population

Monthly Notices of the Royal Astronomical Society Oxford University Press 516:1 (2022) 245-263

Authors:

Ih Whittam, Mj Jarvis, Cl Hale, M Prescott, Lk Morabito, I Heywood, Nj Adams, J Afonso, Fangxia An, Y Ao, Raa Bowler, Jd Collier, Rp Deane, J Delhaize, B Frank, M Glowacki, Pw Hatfield, N Maddox, L Marchetti, Am Matthews, I Prandoni, S Randriamampandry, Z Randriamanakoto, Djb Smith, Ar Taylor, Nl Thomas, M Vaccari

Abstract:

We study the nature of the faint radio source population detected in the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Early Science data in the COSMOS field, focusing on the properties of the radio-loud active galactic nuclei (AGNs). Using the extensive multiwavelength data available in the field, we are able to classify 88 per cent of the 5223 radio sources in the field with host galaxy identifications as AGNs (35 per cent) or star-forming galaxies (54 per cent). We select a sample of radio-loud AGNs with redshifts out to z ∼ 6 and radio luminosities 1020 < L1.4 GHz/W Hz−1 < 1027 and classify them as high-excitation and low-excitation radio galaxies (HERGs and LERGs). The classification catalogue is released with this work. We find no significant difference in the host galaxy properties of the HERGs and LERGs in our sample. In contrast to previous work, we find that the HERGs and LERGs have very similar Eddington-scaled accretion rates; in particular we identify a population of very slowly accreting AGNs that are formally classified as HERGs at these low radio luminosities, where separating into HERGs and LERGs possibly becomes redundant. We investigate how black hole mass affects jet power, and find that a black hole mass ≳ 107.8 M⊙ is required to power a jet with mechanical power greater than the radiative luminosity of the AGN (Lmech/Lbol > 1). We discuss that both a high black hole mass and black hole spin may be necessary to launch and sustain a dominant radio jet.

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Euclid preparation

Astronomy & Astrophysics EDP Sciences 664 (2022) a196

Authors:

R Saglia, S De Nicola, M Fabricius, V Guglielmo, J Snigula, R Zöller, R Bender, J Heidt, D Masters, D Stern, S Paltani, A Amara, N Auricchio, M Baldi, C Bodendorf, D Bonino, E Branchini, M Brescia, J Brinchmann, S Camera, V Capobianco, C Carbone, J Carretero, M Castellano, S Cavuoti, R Cledassou, G Congedo, CJ Conselice, L Conversi, Y Copin, L Corcione, F Courbin, M Cropper, A Da Silva, H Degaudenzi, M Douspis, F Dubath, CAJ Duncan, X Dupac, S Dusini, S Farrens, M Frailis, E Franceschi, S Galeotta, B Garilli, W Gillard, B Gillis, C Giocoli, A Grazian, F Grupp, SVH Haugan, H Hoekstra, W Holmes, F Hormuth, A Hornstrup, K Jahnke, M Kümmel, S Kermiche, A Kiessling, M Kunz, H Kurki-Suonio, R Laureijs, S Ligori, PB Lilje, I Lloro, E Maiorano, O Marggraf, K Markovic, F Marulli, R Massey, HJ McCracken, M Melchior, G Meylan, M Moresco, L Moscardini, E Munari, SM Niemi, C Padilla, F Pasian, K Pedersen, WJ Percival, V Pettorino, S Pires, M Poncet, L Popa, L Pozzetti, F Raison, A Renzi, J Rhodes, G Riccio, E Romelli, E Rossetti, D Sapone, B Sartoris, P Schneider, A Secroun, G Seidel, C Sirignano, G Sirri, L Stanco, P Tallada-Crespí, D Tavagnacco, AN Taylor, I Tereno, R Toledo-Moreo, F Torradeflot, I Tutusaus, EA Valentijn, L Valenziano, T Vassallo, Y Wang, A Zacchei, G Zamorani, J Zoubian, S Andreon, S Bardelli, J Graciá-Carpio, D Maino, N Mauri, A Tramacere, E Zucca, A Alvarez Ayllon, H Aussel, C Baccigalupi, A Balaguera-Antolínez, M Ballardini, A Biviano, M Bolzonella, E Bozzo, C Burigana, R Cabanac, A Cappi, CS Carvalho, S Casas, G Castignani, A Cooray, J Coupon, HM Courtois, S Davini, G Desprez, H Dole, JA Escartin, S Escoffier, M Farina, S Fotopoulou, K Ganga, J Garcia-Bellido, K George, F Giacomini, G Gozaliasl, H Hildebrandt, I Hook, O Ilbert, V Kansal, A Kashlinsky, E Keihanen, CC Kirkpatrick, A Loureiro, J Macías-Pérez, M Magliocchetti, G Mainetti, R Maoli, M Martinelli, N Martinet, RB Metcalf, G Morgante, S Nadathur, AA Nucita, L Patrizii, V Popa, C Porciani, D Potter, A Pourtsidou, P Reimberg, AG Sánchez, Z Sakr, M Schirmer, E Sefusatti, M Sereno, J Stadel, R Teyssier, C Valieri, J Valiviita, A Veropalumbo, M Viel
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MIGHTEE: the nature of the radio-loud AGN population

ArXiv 2207.12379 (2022)

Authors:

IH Whittam, MJ Jarvis, CL Hale, M Prescott, LK Morabito, I Heywood, NJ Adams, J Afonso, Fangxia An, Y Ao, RA Bowler, JD Collier, RP Deane, J Delhaize, B Frank, M Glowacki, PW Hatfield, N Maddox, L Marchetti, AM Matthews, I Prandoni, S Randriamampandry, Z Randriamanakoto, DJB Smith, AR Taylor, NL Thomas, M Vaccari
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Constraining a late time transition of Geff using low-z galaxy survey data

Phys. Rev. D 106, 023526

Authors:

G. Alestas, L. Perivolaropoulos, K. Tanidis

Abstract:

It has recently been pointed out that a gravitational transition taking place at a recent redshift zt, reducing the effective gravitational constant Geff by about 10% for z>zt, has the potential to lead to a resolution of the Hubble tension if zt≲0.01. Since H(z)2∼Geff, such a transition would also lead to sharp change of the slope of the Hubble diagram at z=zt and a sharp decrease in the number of galaxies per redshift bin at zt. Here we attempt to impose constraints on such a transition by using two robust low-z redshift survey datasets (z<0.01), taken from the Six-degree Field Galaxy Survey (6dFGS) as well as the 2MASS Redshift Survey (2MRS). In both surveys, we bin the data in redshift bins and focus on the number of galaxies in each bin (ΔN(zi)). We observe a peak in the distribution of galaxies near a distance of approximately 20 Mpc in both datasets. This feature could be attributed to galactic density fluctuations, to coherent peculiar velocities of galaxies or to an ultra late-time gravitational transition in the same era. In the context of the later scenario we show that this feature could have been induced by a sharp change of Geff by ΔGeff/Geff≃0.6 at zt≃0.005. Thus, in a conservative approach, this method can be used to impose constraints on a possible abrupt change of the gravitational constant taking place at very low redshifts.
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On cosmological bias due to the magnification of shear and position samples in modern weak lensing analyses

Monthly Notices of the Royal Astronomical Society Oxford University Press 515:1 (2022) 1130-1145

Abstract:

The magnification of galaxies in modern galaxy surveys induces additional correlations in the cosmic shear, galaxy-galaxy lensing and clustering observables used in modern lensing “3x2pt” analyses, due to sample selection. In this paper, we emulate the magnification contribution to all three observables utilising the SLICS simulations suite, and test the sensitivity of the cosmological model, galaxy bias and redshift distribution calibration to un-modelled magnification in a Stage-IV-like survey using Monte-Carlo sampling. We find that magnification cannot be ignored in any single or combined observable, with magnification inducing > 1σ biases in the w0 − σ8 plane, including for cosmic shear and 3x2pt analyses. Significant cosmological biases exist in the 3x2pt and cosmic shear from magnification of the shear sample alone. We show that magnification induces significant biases in the mean of the redshift distribution where a position sample is analysed, which may potentially be used to identify contamination by magnification.
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