MIGHTEE-H i: H i galaxy properties in the large scale structure environment at z ∼ 0.37 from a stacking experiment

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2024)

Authors:

Francesco Sinigaglia, Giulia Rodighiero, Ed Elson, Alessandro Bianchetti, Mattia Vaccari, Natasha Maddox, Anastasia A Ponomareva, Bradley S Frank, Matt J Jarvis, Barbara Catinella, Luca Cortese, Sambit Roychowdhury, Maarten Baes, Jordan D Collier, Olivier Ilbert, Ali A Khostovan, Sushma Kurapati, Hengxing Pan, Isabella Prandoni, Sambatriniaina HA Rajohnson, Mara Salvato, Srikrishna Sekhar, Gauri Sharma

Abstract:

<jats:title>Abstract</jats:title> <jats:p>We present the first measurement of HI mass of star-forming galaxies in different large scale structure environments from a blind survey at z ∼ 0.37. In particular, we carry out a spectral line stacking analysis considering 2875 spectra of colour-selected star-forming galaxies undetected in HI at 0.23 &amp;lt; z &amp;lt; 0.49 in the COSMOS field, extracted from the MIGHTEE-HI Early Science datacubes, acquired with the MeerKAT radio telescope. We stack galaxies belonging to different subsamples depending on three different definitions of large scale structure environment: local galaxy overdensity, position inside the host dark matter halo (central, satellite, or isolated), and cosmic web type (field, filament, or knot). We first stack the full star-forming galaxy sample and find a robust HI detection yielding an average galaxy HI mass of MHI = (8.12 ± 0.75) × 109 M⊙ at ∼11.8σ. Next, we investigate the different subsamples finding a negligible difference in MHI as a function of the galaxy overdensity. We report an HI excess compared to the full sample in satellite galaxies (MHI = (11.31 ± 1.22) × 109, at ∼10.2σ) and in filaments (MHI = (11.62 ± 0.90) × 109. Conversely, we report non-detections for the central and knot galaxies subsamples, which appear to be HI-deficient. We find the same qualitative results also when stacking in units of HI fraction (fHI). We conclude that the HI amount in star-forming galaxies at the studied redshifts correlates with the large scale structure environment.</jats:p>

The Thousand-Pulsar-Array programme on MeerKAT – XII. Discovery of long-term pulse profile evolution in 7 young pulsars

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2024) stae483

Authors:

A Basu, P Weltevrede, MJ Keith, S Johnston, A Karastergiou, LS Oswald, B Posselt, X Song, AD Cameron

A new method for short-duration transient detection in radio images: searching for transient sources in MeerKAT data of NGC 5068

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 528:4 (2024) 6985-6996

Authors:

S Fijma, A Rowlinson, RAMJ Wijers, I de Ruiter, WJG de Blok, S Chastain, AJ van der Horst, ZS Meyers, K van der Meulen, R Fender, PA Woudt, A Andersson, A Zijlstra, J Healy, FM Maccagni

Heavy-element production in a compact object merger observed by JWST.

Nature 626:8000 (2024) 737-741

Authors:

Andrew J Levan, Benjamin P Gompertz, Om Sharan Salafia, Mattia Bulla, Eric Burns, Kenta Hotokezaka, Luca Izzo, Gavin P Lamb, Daniele B Malesani, Samantha R Oates, Maria Edvige Ravasio, Alicia Rouco Escorial, Benjamin Schneider, Nikhil Sarin, Steve Schulze, Nial R Tanvir, Kendall Ackley, Gemma Anderson, Gabriel B Brammer, Lise Christensen, Vikram S Dhillon, Phil A Evans, Michael Fausnaugh, Wen-Fai Fong, Andrew S Fruchter, Chris Fryer, Johan PU Fynbo, Nicola Gaspari, Kasper E Heintz, Jens Hjorth, Jamie A Kennea, Mark R Kennedy, Tanmoy Laskar, Giorgos Leloudas, Ilya Mandel, Antonio Martin-Carrillo, Brian D Metzger, Matt Nicholl, Anya Nugent, Jesse T Palmerio, Giovanna Pugliese, Jillian Rastinejad, Lauren Rhodes, Andrea Rossi, Andrea Saccardi, Stephen J Smartt, Heloise F Stevance, Aaron Tohuvavohu, Alexander van der Horst, Susanna D Vergani, Darach Watson, Thomas Barclay, Kornpob Bhirombhakdi, Elmé Breedt, Alice A Breeveld, Alexander J Brown, Sergio Campana, Ashley A Chrimes, Paolo D'Avanzo, Valerio D'Elia, Massimiliano De Pasquale, Martin J Dyer, Duncan K Galloway, James A Garbutt, Matthew J Green, Dieter H Hartmann, Páll Jakobsson, Paul Kerry, Chryssa Kouveliotou, Danial Langeroodi, Emeric Le Floc'h, James K Leung, Stuart P Littlefair, James Munday, Paul O'Brien, Steven G Parsons, Ingrid Pelisoli, David I Sahman, Ruben Salvaterra, Boris Sbarufatti, Danny Steeghs, Gianpiero Tagliaferri, Christina C Thöne, Antonio de Ugarte Postigo, David Alexander Kann

Abstract:

The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs)1, sources of high-frequency gravitational waves (GWs)2 and likely production sites for heavy-element nucleosynthesis by means of rapid neutron capture (the r-process)3. Here we present observations of the exceptionally bright GRB 230307A. We show that GRB 230307A belongs to the class of long-duration GRBs associated with compact object mergers4-6 and contains a kilonova similar to AT2017gfo, associated with the GW merger GW170817 (refs. 7-12). We obtained James Webb Space Telescope (JWST) mid-infrared imaging and spectroscopy 29 and 61 days after the burst. The spectroscopy shows an emission line at 2.15 microns, which we interpret as tellurium (atomic mass A = 130) and a very red source, emitting most of its light in the mid-infrared owing to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy-element nucleosynthesis across the Universe.

Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

Science American Association for the Advancement of Science 383:6681 (2024) 402-406

Abstract:

SS 433 is a microquasar, a stellar binary system that launches collimated relativistic jets. We observed SS 433 in gamma rays using the High Energy Stereoscopic System (H.E.S.S.) and found an energy-dependent shift in the apparent position of the gamma-ray emission from the parsec-scale jets. These observations trace the energetic electron population and indicate that inverse Compton scattering is the emission mechanism of the gamma rays. Our modeling of the energy-dependent gamma-ray morphology constrains the location of particle acceleration and requires an abrupt deceleration of the jet flow. We infer the presence of shocks on either side of the binary system, at distances of 25 to 30 parsecs, and that self-collimation of the precessing jets forms the shocks, which then efficiently accelerate electrons.