Measuring the baryonic Tully–Fisher relation below the detection threshold

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 508:2 (2021) 1897-1907

Authors:

Hengxing Pan, Matt J Jarvis, Anastasia A Ponomareva, Mario G Santos, James R Allison, Natasha Maddox, Bradley S Frank

Abstract:

ABSTRACT We present a novel 2D flux density model for observed H i emission lines combined with a Bayesian stacking technique to measure the baryonic Tully–Fisher relation below the nominal detection threshold. We simulate a galaxy catalogue, which includes H i lines described with either Gaussian or busy function profiles, and H i data cubes with a range of noise and survey areas similar to the MeerKAT International Giga-Hertz Tiered Extragalactic Exploration (MIGHTEE) survey. With prior knowledge of redshifts, stellar masses, and inclinations of spiral galaxies, we find that our model can reconstruct the input baryonic Tully–Fisher parameters (slope and zero-point) most accurately in a relatively broad redshift range from the local Universe to z = 0.3 for all the considered levels of noise and survey areas and up to z = 0.55 for a nominal noise of 90 $\mu$Jy/channel over 5 deg2. Our model can also determine the $M_{\rm H\, \small {I}} - M_{\star }$ relation for spiral galaxies beyond the local Universe and account for the detailed shape of the H i emission line, which is crucial for understanding the dynamics of spiral galaxies. Thus, we have developed a Bayesian stacking technique for measuring the baryonic Tully–Fisher relation for galaxies at low stellar and/or H i masses and/or those at high redshift, where the direct detection of H i requires prohibitive exposure times.

MIGHTEE-H i: the baryonic Tully–Fisher relation over the last billion years

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 508:1 (2021) 1195-1205

Authors:

Anastasia A Ponomareva, Wanga Mulaudzi, Natasha Maddox, Bradley S Frank, Matt J Jarvis, Enrico M Di Teodoro, Marcin Glowacki, Renée C Kraan-Korteweg, Tom A Oosterloo, Elizabeth AK Adams, Hengxing Pan, Isabella Prandoni, Sambatriniaina HA Rajohnson, Francesco Sinigaglia, Nathan J Adams, Ian Heywood, Rebecca AA Bowler, Peter W Hatfield, Jordan D Collier, Srikrishna Sekhar

Abstract:

ABSTRACT Using a sample of 67 galaxies from the MeerKAT International GigaHertz Tiered Extragalactic Exploration Survey Early Science data, we study the H i-based baryonic Tully–Fisher relation (bTFr), covering a period of ∼1 billion years (0 ≤ z ≤ 0.081). We consider the bTFr based on two different rotational velocity measures: the width of the global H i profile and Vout, measured as the outermost rotational velocity from the resolved H i rotation curves. Both relations exhibit very low intrinsic scatter orthogonal to the best-fitting relation (σ⊥ = 0.07 ± 0.01), comparable to the SPARC sample at z ≃ 0. The slopes of the relations are similar and consistent with the z ≃ 0 studies ($3.66^{+0.35}_{-0.29}$ for W50 and $3.47^{+0.37}_{-0.30}$ for Vout). We find no evidence that the bTFr has evolved over the last billion years, and all galaxies in our sample are consistent with the same relation independent of redshift and the rotational velocity measure. Our results set-up a reference for all future studies of the H i-based bTFr as a function of redshift that will be conducted with the ongoing deep SKA pathfinders surveys.

Search for Dark Matter Annihilation Signals from Unidentified Fermi-LAT Objects with HESS

ASTROPHYSICAL JOURNAL 918:1 (2021) ARTN 17

Authors:

H Abdalla, F Aharonian, F Ait Benkhali, EO Anguner, C Arcaro, C Armand, T Armstrong, H Ashkar, M Backes, V Baghmanyan, V Barbosa-Martins, A Barnacka, M Barnard, Y Becherini, D Berge, K Bernloehr, B Bi, M Bottcher, C Boisson, J Bolmont, M de Bony de Lavergne, M Breuhaus, R Brose, F Brun, T Bulik, T Bylund, F Cangemi, S Caroff, S Casanova, P Chambery, J Catalano, T Chand, A Chen, G Cotter, M Curylo, H Dalgleish, J Damascene Mbarubucyeye, ID Davids, J Davies, J Devin, A Djannati-Atai, A Dmytriiev, A Donath, V Doroshenko, L Dreyer, L du Plessis, C Duffy, K Egberts, S Einecke, G Emery, J-P Ernenwein, K Feijen, S Fegan, A Fiasson, G Fichet de Clairfontaine, G Fontaine, S Funk, M Fuessling, S Gabici, YA Gallant, S Ghafourizade, G Giavitto, L Giunti, D Glawion, JF Glicenstein, M-H Grondin, S Hattingh, M Haupt, G Hermann, JA Hinton, W Hofmann, C Hoischen, TL Holch, M Holler, M Horbe, D Horns, Z Huang, D Huber, M Jamrozy, D Jankowsky, F Jankowsky, V Joshi, I Jung-Richardt, E Kasai, K Katarzynski, U Katz, D Khangulyan, B Khelifi, S Klepser, W Kluzniak, Nu Komin, R Konno, K Kosack, D Kostunin, M Kreter, G Kukec Mezek, A Kundu, G Lamanna, S Le Stum, A Lemiere, M Lemoine-Goumard, J-P Lenain, F Leuschner, C Levy, A Luashvili, T Lohse, I Lypova, J Mackey, J Majumdar, D Malyshev, D Malyshev, V Marandon, P Marchegiani, A Marcowith, A Mares, G Marti-Devesa, R Marx, G Maurin, PJ Meintjes, M Meyer, A Mitchell, R Moderski, L Mohrmann, A Montanari, C Moore, P Morris, E Moulin, J Muller, T Murach, K Nakashima, A Nayerhoda, M de Naurois, H Ndiyavala, J Niemiec, A Noel, L Oberholzer, P O'Brien, S Ohm, L Olivera-Nieto, E de Ona Wilhelmi, M Ostrowski, M Panter, S Panny, RD Parsons, G Peron, S Pita, V Poireau, DA Prokhorov, H Prokoph, G Puhlhoefer, M Punch, A Quirrenbach, P Reichherzer, A Reimer, O Reimer, Q Remy, M Renaud, F Rieger, C Romoli, G Rowell, B Rudak, H Rueda Ricarte, E Ruiz-Velasco, V Sahakian, S Sailer, H Salzmann, DA Sanchez, A Santangelo, M Sasaki, J Schaefer, F Schussler, HM Schutte, U Schwanke, M Senniappan, AS Seyffert, JNS Shapopi, K Shiningayamwe, R Simoni, A Sinha, H Spackman, H Sol, A Specovius, S Spencer, M Spir-Jacob, L Stawarz, L Sun, R Steenkamp, C Stegmann, S Steinmassl, C Steppa, T Takahashi, T Tanaka, T Tavernier, AM Taylor, R Terrier, C Thorpe-Morgan, JHE Thiersen, M Tluczykont, L Tomankova, M Tsirou, M 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, A Viana, J Vink, HJ Voelk, SJ Wagner, F Werner, R White, A Wierzcholska, Yu Wun Wong, H Yassin, A Yusafzai, M Zacharias, R Zanin, D Zargaryan, AA Zdziarski, A Zech, SJ Zhu, A Zmija, J Zorn, S Zouari, N Zywucka, HESS Collaboration

Radio spectral properties of star-forming galaxies in the MIGHTEE-COSMOS field and their impact on the far-infrared-radio correlation

Monthly Notices of the Royal Astronomical Society Oxford University Press 507:256 (2021) 2643-2658

Authors:

Fangxia An, M Vaccari, Ian Smail, Mj Jarvis, Ih Whittam, Cl Hale, S Jin, Jd Collier, E Daddi, J Delhaize, B Frank, Ej Murphy, M Prescott, S Sekhar, Ar Taylor, Y Ao, K Knowles, L Marchetti, Sm Randriamampandry, Z Randriamanakoto

Abstract:

We study the radio spectral properties of 2094 star-forming galaxies (SFGs) by combining our early science data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey with VLA, GMRT radio data, and rich ancillary data in the COSMOS field. These SFGs are selected at VLA 3 GHz, and their flux densities from MeerKAT 1.3 GHz and GMRT 325 MHz imaging data are extracted using the ‘superdeblending’ technique. The median radio spectral index is α3GHz1.3GHz=−0.80±0.01 without significant variation across the rest-frame frequencies ∼1.3–10 GHz, indicating radio spectra dominated by synchrotron radiation. On average, the radio spectrum at observer-frame 1.3–3 GHz slightly steepens with increasing stellar mass with a linear fitted slope of β = −0.08 ± 0.01, which could be explained by age-related synchrotron losses. Due to the sensitivity of GMRT 325 MHz data, we apply a further flux density cut at 3 GHz (⁠S3GHz≥50μJy) and obtain a sample of 166 SFGs with measured flux densities at 325 MHz, 1.3 GHz, and 3 GHz. On average, the radio spectrum of SFGs flattens at low frequency with the median spectral indices of α1.3GHz325MHz=−0.59+0.02−0.03 and α3.0GHz1.3GHz=−0.74+0.01−0.02⁠. At low frequency, our stacking analyses show that the radio spectrum also slightly steepens with increasing stellar mass. By comparing the far-infrared-radio correlations of SFGs based on different radio spectral indices, we find that adopting α3GHz1.3GHz for k-corrections will significantly underestimate the infrared-to-radio luminosity ratio (qIR) for >17 per cent of the SFGs with measured flux density at the three radio frequencies in our sample, because their radio spectra are significantly flatter at low frequency (0.33–1.3 GHz).

TeV emission of galactic plane sources with HAWC and H.E.S.S.

Astrophysical Journal IOP Publishing 917:1 (2021) 6

Authors:

H Abdalla, F Aharonian, F Ait Benkhali, Thomas Armstrong, G Cotter, J Davies

Abstract:

The High Altitude Water Cherenkov (HAWC) observatory and the High Energy Stereoscopic System (H.E.S.S.) are two leading instruments in the ground-based very-high-energy γ-ray domain. HAWC employs the water Cherenkov detection (WCD) technique, while H.E.S.S. is an array of Imaging Atmospheric Cherenkov Telescopes (IACTs). The two facilities therefore differ in multiple aspects, including their observation strategy, the size of their field of view, and their angular resolution, leading to different analysis approaches. Until now, it has been unclear if the results of observations by both types of instruments are consistent: several of the recently discovered HAWC sources have been followed up by IACTs, resulting in a confirmed detection only in a minority of cases. With this paper, we go further and try to resolve the tensions between previous results by performing a new analysis of the H.E.S.S. Galactic plane survey data, applying an analysis technique comparable between H.E.S.S. and HAWC. Events above 1 TeV are selected for both data sets, the point-spread function of H.E.S.S. is broadened to approach that of HAWC, and a similar background estimation method is used. This is the first detailed comparison of the Galactic plane observed by both instruments. H.E.S.S. can confirm the γ-ray emission of four HAWC sources among seven previously undetected by IACTs, while the three others have measured fluxes below the sensitivity of the H.E.S.S. data set. Remaining differences in the overall γ-ray flux can be explained by the systematic uncertainties. Therefore, we confirm a consistent view of the γ-ray sky between WCD and IACT techniques.