Article
Astronomy & Astrophysics
Tomas Ondro, Rudolf Galis
Summary: The article studied the temperature-density relation of the intergalactic medium in the range 1.6 <= z < 2.0, using Lyman alpha forest decomposition and an iterative fitting procedure to calibrate measurements against mock data. The results showed a decreasing trend in temperature at mean density predicted by various models at lower redshifts, while power-law index values were close to 1.6 as expected in models assuming balance of photoheating with adiabatic cooling after reionization events.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
T-S Kim, B. P. Wakker, F. Nasir, R. F. Carswell, B. D. Savage, J. S. Bolton, A. J. Fox, M. Viel, M. G. Haehnelt, J. C. Charlton, B. E. Rosenwasser
Summary: A uniform analysis of the HI transmitted flux and Hi column density distribution in the low-density IGM as a function of redshift was conducted using spectra from different instruments. The evolution from higher to lower redshifts and the stability at z < 0.5 were observed, with significant variations along different sightlines. The shape of the column density distribution function at lower redshifts can be replicated by rotating a higher redshift distribution slightly, and there is an evolutionary break in absorption line number at z around 1.5. High-N-HI absorbers evolve more rapidly than low-N-HI absorbers, possibly due to stronger clustering at lower redshifts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
T-s Kim, B. P. Wakker, F. Nasir, R. F. Carswell, B. D. Savage, J. S. Bolton, A. J. Fox, M. Viel, M. G. Haehnelt, J. C. Charlton, B. E. Rosenwasser
Summary: A new uniform analysis of the H I transmitted flux and column density distribution in the low-density IGM as a function of redshift was presented. The study confirmed previous conclusions and revealed evolution in flux and column density distribution with decreasing redshift, as well as variations in sightlines. High-NH absorbers were found to evolve more rapidly than low-N(H I ) absorbers, decreasing in number or cross-section over time.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Chenxing Dong, Anthony Gonzalez, Stephen Eikenberry, Sarik Jeram, Manunya Likamonsavad, Jochen Liske, Deno Stelter, Amanda Townsend
Summary: The study presents end-to-end simulations aiming to constrain the rate of change in the expansion history of the Universe through redshift drift of Lyman-alpha forest absorption lines. Results show that using a dedicated facility and designed observing plan, redshift drift can be detected with 3σ significance in 15 years.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Alexander Beckettt, Simon L. Morris, Michele Fumagalli, Nicolas Tejos, Buell Jannuzi, Sebastiano Cantalupo
Summary: We use H i absorption to model potential disc and outflow structures in the circumgalactic medium, and find possible outflows and co-rotating structures, suggesting that geometric cuts are not sufficient to distinguish between discs and outflows in single line-of-sight studies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ka-Hou Leong, Avery Meiksin, Althea Lai, K. H. To
Summary: We compared numerical methods for solving the radiative transfer equation and studied the direct integration and photon packet solutions in the photoionization background of intergalactic hydrogen and helium. The photon packet schemes were found to be more computationally efficient than direct integration. It was shown that a fully time-dependent method is required to capture the gas temperature and ionization structure near a source where the ionization front expands at a speed close to the speed of light, leading to temperature differences as high as 5 x 10(4) K in the Epoch of Reionization (EoR). Variations in temperature and ionization structure far from the source may impact predictions for 21-cm EoR experiments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Solene Chabanier, J. D. Emberson, Zarija Lukic, Jesus Pulido, Salman Habib, Esteban Rangel, Jean Sexton, Nicholas Frontiere, Michael Buehlmann
Summary: The two state-of-the-art numerical codes show good agreement in modelling the intergalactic medium and reproducing Lyman-alpha forest observables.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
James S. Bolton, Prakash Gaikwad, Martin G. Haehnelt, Tae-Sun Kim, Fahad Nasir, Ewald Puchwein, Matteo Viel, Bart P. Wakker
Summary: We compared the column density distribution function (CDDF) and Doppler parameter distribution of the Lyα forest from hydrodynamical simulations and COS observations. The simulations agree with the observed CDDF in a certain column density range, but the simulated lines are narrower than the COS data in terms of Doppler width. AGN feedback and enhanced photoheating rates are not able to explain this discrepancy, indicating the need for a non-canonical source of heating or an unresolved line of sight turbulent velocity component.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Suk Sien Tie, Joseph F. Hennawi, Koki Kakiichi, Sarah E. Bosman
Summary: The distribution and abundance of metals in the diffuse intergalactic medium play a crucial role in galaxy formation and evolution models, and are sensitive to the reionization history of the Universe. A new technique based on clustering analysis allows for the detection of weak absorbers in the intergalactic medium. The two-point correlation function of the C IV forest can be used to probe the metallicity and enrichment topology, providing precise measurements at high redshifts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Runxuan Wang, Rupert A. C. Croft, Patrick Shaw
Summary: In this study, we utilize deep learning techniques to infer the temperature of the intergalactic medium in the high-redshift Ly alpha forest. By training neural networks on simulated spectra, the temperature can be effectively reconstructed from the Doppler broadening effect. The method is especially successful for high-resolution spectra with moderate signal-to-noise ratio. Additionally, this approach allows for the detection and characterization of high-temperature bubbles, and even the generation of tomographic images.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
T. Roy Choudhury, Aseem Paranjape, Sarah E. Bosman
Summary: A computationally efficient method is proposed in this study to simulate Lyman alpha absorption optical depth in the presence of neutral hydrogen "islands" leftover from reionization at redshifts between 5 and 6. By analyzing large-scale fluctuations in optical depth, it is confirmed at greater than or similar to 2 sigma confidence that reionization is not complete before around 5.6, with a possibility of completion as late as around 5.2.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Zhijie Qu, Hsiao-Wen Chen, Gwen C. Rudie, Fakhri S. Zahedy, Sean D. Johnson, Erin Boettcher, Sebastiano Cantalupo, Mandy C. Chen, Kathy L. Cooksey, David DePalma, Claude-Andre Faucher-Giguere, Michael Rauch, Joop Schaye, Robert A. Simcoe
Summary: This paper presents a systematic study of the photoionization and thermodynamic properties of the cool circumgalactic medium (CGM) around galaxies at redshift z less than or similar to 1, providing important insights into the gas density, temperature, and pressure of individual absorbing components and their non-thermal motions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Thomas J. Cooper, Gwen C. Rudie, Hsiao-Wen Chen, Sean D. Johnson, Fakhri S. Zahedy, Mandy C. Chen, Erin Boettcher, Gregory L. Walth, Sebastiano Cantalupo, Kathy L. Cooksey, Claude-Andre Faucher-Giguere, Jenny E. Greene, Sebastian Lopez, John S. Mulchaey, Steven Penton, Patrick Petitjean, Mary E. Putman, Marc Rafelski, Michael Rauch, Joop Schaye, Robert A. Simcoe
Summary: This study investigates two partial Lyman limit systems (pLLSs) discovered in the Cosmic Ultraviolet Baryon Survey (CUBS), providing detailed information on the ionization analysis of multiphase gas in diverse galaxy environments. The data reveal kinematically aligned gas components with varying chemical abundances and densities, stressing the importance of considering the heterogeneous nature of circumgalactic gas in theoretical models. Additionally, survey data point to these systems being located near star-forming galaxies, highlighting the significance of studying the gas surrounding galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Sowgat Muzahid, Joop Schaye, Sebastiano Cantalupo, Raffaella Anna Marino, Nicolas F. Bouche, Sean Johnson, Michael Maseda, Martin Wendt, Lutz Wisotzki, Johannes Zabl
Summary: The first characterization of the circumgalactic medium of Ly alpha emitters (LAEs) reveals distinct features in terms of luminosity and interstellar material absorption, with no strong dependence of absorption on transverse distance, redshift, or Ly alpha emission line properties. However, a correlation is found between increased absorption near LAEs with higher star formation rates, suggesting a link between surrounding interstellar hydrogen and star formation in LAEs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Martin Wendt, Nicolas F. Bouche, Johannes Zabl, Ilane Schroetter, Sowgat Muzahid
Summary: The study investigates the dust content of the circum-galactic medium (CGM) in relation to the position of quasar sightlines with respect to the galaxy major-axis. It finds a positive correlation between the azimuthal angle and [Zn/Fe], indicating that CGM along the minor axis is on average more metal enriched compared to the gas located along the major axis. This anisotropic distribution is consistent with recent results on outflow and accretion in hydro-dynamical simulations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Margherita Molaro, Vid Irsic, James S. Bolton, Laura C. Keating, Ewald Puchwein, Prakash Gaikwad, Martin G. Haehnelt, Girish Kulkarni, Matteo Viel
Summary: Using a hybrid hydrodynamical and radiative transfer simulation, we modeled the effect of inhomogeneous reionization on the Lyman alpha forest transmitted flux power spectrum. We found that inhomogeneous reionization can suppress or enhance the power spectrum, highlighting the importance of considering this effect in future high precision measurements.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Nicole E. Drakos, Bruno Villasenor, Brant E. Robertson, Ryan Hausen, Mark E. Dickinson, Henry C. Ferguson, Steven R. Furlanetto, Jenny E. Greene, Piero Madau, Alice E. Shapley, Daniel P. Stark, Risa H. Wechsler
Summary: In this study, a deep realistic extragalactic model (DREaM) is presented for creating synthetic galaxy catalogs, which will greatly enhance the understanding of galaxy formation during the epoch of reionization. The synthetic catalogs and simulated images are made publicly available to prepare for upcoming data.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Tomas Tamfal, Lucio Mayer, Thomas R. Quinn, Arif Babul, Piero Madau, Pedro R. Capelo, Sijing Shen, Marius Staub
Summary: In this study, a cosmological N-body hydrodynamical simulation with unprecedented resolution was used to investigate the formation process of a Milky Way-sized galaxy halo. The simulated galaxy exhibits early assembly characteristics consistent with extrapolations of star-forming galaxy main sequences to higher redshifts. The results suggest the early presence of a compact, thin rotating stellar disk and a multi-component structure, challenging previous literature reports of upside-down disk growth, with implications for high-redshift galaxy observations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
James S. Bolton, Prakash Gaikwad, Martin G. Haehnelt, Tae-Sun Kim, Fahad Nasir, Ewald Puchwein, Matteo Viel, Bart P. Wakker
Summary: We compared the column density distribution function (CDDF) and Doppler parameter distribution of the Lyα forest from hydrodynamical simulations and COS observations. The simulations agree with the observed CDDF in a certain column density range, but the simulated lines are narrower than the COS data in terms of Doppler width. AGN feedback and enhanced photoheating rates are not able to explain this discrepancy, indicating the need for a non-canonical source of heating or an unresolved line of sight turbulent velocity component.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Astrid Lamberts, Ewald Puchwein, Christoph Pfrommer, Philip Chang, Mohamad Shalaby, Avery Broderick, Paul Tiede, Gwen Rudie
Summary: This study compares different blazar heating models with recent observations of the intergalactic medium (IGM) and finds that the inhomogeneous blazar heating model is in good agreement with the observations at high redshift, but is challenged by the data at lower redshift.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ewald Puchwein, James S. Bolton, Laura C. Keating, Margherita Molaro, Prakash Gaikwad, Girish Kulkarni, Martin G. Haehnelt, Vid Irsic, Tomas Soltinsky, Matteo Viel, Dominique Aubert, George D. Becker, Avery Meiksin
Summary: We introduce the Sherwood-Relics simulations, which are a new set of large cosmological hydrodynamical simulations designed to model the intergalactic medium (IGM) during and after the cosmic reionization of hydrogen. This suite includes over 200 simulations covering a wide range of astrophysical and cosmological parameters, and incorporates a new lightweight hybrid scheme for handling radiative transfer effects. Using this hybrid technique, we investigate the impact of patchy cosmic reionization on the spatial fluctuations in IGM properties, and find that it causes long-lasting temperature fluctuations and increases the Lyman-alpha forest flux power spectrum on large scales.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ryan Hausen, Brant E. E. Robertson, Hanjue Zhu, Nickolay Y. Y. Gnedin, Piero Madau, Evan E. E. Schneider, Bruno Villasenor, Nicole E. E. Drakos
Summary: By using Explainable Boosting Machines (EBMs), a machine-learning method, we have discovered the connections between galaxy stellar mass, star formation rate, and dark matter halo mass in the theory of galaxy formation. The most dominant contribution comes from the peak circular velocity of the galaxy, while environmental properties have a lesser impact on the simulated galaxies.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Margherita Molaro, Vid Irsic, James S. Bolton, Maggie Lieu, Laura C. Keating, Ewald Puchwein, Martin G. Haehnelt, Matteo Viel
Summary: Inhomogeneous reionization increases the power spectrum of the 1D Ly alpha forest at large scales at redshifts z >= 4. This is due to coherent fluctuations in the ionized hydrogen fraction resulting from large-scale variations in post-reionization gas temperature. An analysis of Ly alpha forest power spectrum measurements at 4.0 <= z <= 4.6 suggests a preference for a large-scale enhancement, potentially indicating inhomogeneous reionization. Future power spectrum measurements with lower uncertainties should provide more conclusive evidence for this enhancement.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Piero Madau
Summary: We introduce a mathematical framework for statistical exoplanet population and astrobiology studies, which maps star formation, metal enrichment, and the occurrence of exoplanets and potentially life-harboring worlds over time. Our results show that the formation of exoplanets near the Sun is episodic, with a significant number of habitable Earth-size planets within 100 parsecs. The closest Earth-like planet capable of harboring life is estimated to be less than 20 parsecs away.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Prakash Gaikwad, Martin G. Haehnelt, Fredrick B. Davies, Sarah E. Bosman, Margherita Molaro, Girish Kulkarni, Valentina D'Odorico, George D. Becker, Rebecca L. Davies, Fahad Nasir, James S. Bolton, Laura C. Keating, Vid Irsic, Ewald Puchwein, Yongda Zhu, Shikhar Asthana, Jinyi Yang, Samuel Lai, Anna-Christina Eilers
Summary: In this study, we measured the mean free path, photoionization rate, and neutral fraction of hydrogen at different redshifts using QSO absorption spectra. We compared our results with simulations and found significant evolution of these parameters with increasing redshift.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Bruno Villasenor, Brant Robertson, Piero Madau, Evan Schneider
Summary: The forest of Lyman-a absorption lines detected in distant quasars encodes information on the nature and properties of dark matter and the thermodynamics of diffuse baryonic material. A suite of high-resolution cosmological hydrodynamical simulations is used to study the evolution of the Lyman-a forest under different gas thermal histories and free-streaming lengths. Comparing synthetic data with the observed flux power spectrum, the lower-limit for the WDM particle mass is determined and the amplitude and spectrum of the photoheating and photoionizing background are constrained.
Article
Astronomy & Astrophysics
Sultan Hassan, Christopher C. Lovell, Piero Madau, Marc Huertas-Company, Rachel S. Somerville, Blakesley Burkhart, Keri L. Dixon, Robert Feldmann, Tjitske K. Starkenburg, John F. Wu, Christian Kragh Jespersen, Joseph D. Gelfand, Ankita Bera
Summary: New observational capabilities provide important constraints on models of the epoch of first light in the Universe. Recent JWST observations of the UV radiation background at cosmic dawn have implications for radio experiments detecting the redshifted 21 cm hyperfine transition of neutral hydrogen. The declining UV luminosity density inferred from JWST early galaxy data suggests a possible detection at low frequencies, but uncertainties from cosmic variance and galaxy luminosity function make it difficult to confirm the cosmic 21 cm absorption signal.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
