Browsing Research Articles (Physics) by Author "Santos, Mario G."

Now showing items 1-12 of 12

    • Constraining the reionization history using deep learning from 21-cm tomography with the Square Kilometre Array 

      Mangena, Tumelo; Hassan, Sultan; Santos, Mario G. (Oxford University Press, 2020)
      Upcoming 21-cm surveys with the SKA1-LOW telescope will enable imaging of the neutral hydrogen distribution on cosmological scales in the early Universe. These surveys are expected to generate huge imaging data sets that ...

    • Cosmology on ultralarge scales with intensity mapping of the neutral hydrogen 21 cm emission: limits on primodial non-gaussianity 

      Camera, Stefano; Santos, Mario G.; Ferreira, Pedro G.; Ferramacho, Luis (American Physical Society, 2013)
      The large-scale structure of the Universe supplies crucial information about the physical processes at play at early times. Unresolved maps of the intensity of 21 cm emission from neutral hydrogen HI at redshifts z ~ 1 − ...

    • Einstein's legacy in galaxy surveys 

      Camera, Stefano; Maartens, Roy; Santos, Mario G. (Oxford University Press, 2015)
      Non-Gaussianity in the primordial fluctuations that seeded structure formation produces a signal in the galaxy power spectrum on very large scales. This signal contains vital information about the primordial Universe, but ...

    • H I intensity mapping with MeerKAT: Power spectrum detection in cross-correlation with WiggleZ galaxies 

      Cunnington, Steven; Li, Yichao; Santos, Mario G. (Oxford University Press, 2023)
      We present a detection of correlated clustering between MeerKAT radio intensity maps and galaxies from the WiggleZ Dark Energy Survey. We find a 7.7σ detection of the cross-correlation power spectrum, the amplitude of which ...

    • Hunting down horizon-scale effects with multi-wavelength surveys 

      Fonseca, Jose; Camera, Stefano; Santos, Mario G.; Maartens, Roy (American Astronomical Society, 2015)
      Next-generation cosmological surveys will probe ever larger volumes of the universe, including the largest scales, near and beyond the horizon. On these scales, the galaxy power spectrum carries signatures of local primordial ...

    • Measuring the HI mass function below the detection threshold 

      Pan, Hengxing; Jarvis, Matt J.; Santos, Mario G. (Royal Astronomical Society, 2020)
      We present a Bayesian stacking technique to directly measure the H I mass function (HIMF) and its evolution with redshift using galaxies formally below the nominal detection threshold. We generate galaxy samples over several ...

    • Nonlinear modulation of the HI power spectrum on ultra-large scales. I 

      Umeh, Obinna; Maartens, Roy; Santos, Mario G. (IOP Science, 2015)
      Intensity mapping of the neutral hydrogen brightness temperature promises to provide a three-dimensional view of the universe on very large scales. Nonlinear effects are typically thought to alter only the small-scale ...

    • The optically selected 1.4-GHz quasar luminosity function below 1 mJy 

      Malefahlo, Eliab; Santos, Mario G.; Jarvis, Matt J; White, Sarah V.; Zwart, Jonathan T. L. (Oxford University Press, 2020)
      We present the radio luminosity function (RLF) of optically selected quasars below 1 mJy, constructed by applying a Bayesian-fitting stacking technique to objects well below the nominal radio flux density limit. We test ...

    • Probing reionization with LOFAR (Low Frequency Array) using 21-cm redshift space distortions 

      Jensen, Hannes; Datta, Kanan K.; Santos, Mario G.; Mellema, Garrelt; Chapman, Emma; Abdalla, Filipe B.; Iliev, Ilian T.; Mao, Yi; Shapiro, Paul R.; Zaroubi, Saleem; Bernardi, Gianni; Brentjens, M. A.; de Bruyn, A. G.; Ciardi, B.; Harker, G. J. A.; Jelić, V.; Kazemi, S.; Koopmans, L. V. E.; Labropoulos, P.; Martinez, O.; Offringa, A. R.; Pandey, V. N.; Schaye, J.; Thomas, R. M.; Veligatla, V.; Vedantham, H.; Yatawatta, S. (Oxford University Press, 2013)
      One of the most promising ways to study the epoch of reionization (EoR) is through radio observations of the redshifted 21-cm line emission from neutral hydrogen. These observations are complicated by the fact that the ...

    • Prospects for cosmic magnification measurements using H I intensity mapping 

      Witzemann, Amadeus; Pourtsidou, Alkistis; Santos, Mario G. (Oxford University Press, 2020)
      We investigate the prospects of measuring the cosmic magnification effect by cross-correlating neutral hydrogen intensity mapping (H I IM) maps with background optical galaxies. We forecast the signal-to-noise ratio for ...

    • Synergies between intensity maps of hydrogen lines 

      Fonseca, Jose; Maartens, Roy; Santos, Mario G. (Oxford University Press, 2018)
      We study synergies between Hi 21cm and Hα intensity map observations, focusing on SKA1- like and SPHEREx-like surveys. We forecast how well such a combination can measure features in the angular power spectrum on the ...

    • Validation of the hera phase i epoch of reionization 21 cm power spectrum software pipeline 

      Aguirre, James E.; Murray, Steven G.; Santos, Mario G. (IOP Publishing, 2022)
      We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to validate the software and algorithms used in ...