Pub Date : 2025-02-20DOI: 10.1088/1475-7516/2025/02/048
Amanda MacInnis and Neelima Sehgal
We show for the first time that high-resolution CMB lensing observations can probe structure on sub-galactic scales. In particular, a CMB-HD experiment can probe out to k ∼ 55 h/Mpc, corresponding to halo masses of about 108 M⊙. Over the range 0.005 h/Mpc
{"title":"CMB-HD as a probe of dark matter on sub-galactic scales","authors":"Amanda MacInnis and Neelima Sehgal","doi":"10.1088/1475-7516/2025/02/048","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/048","url":null,"abstract":"We show for the first time that high-resolution CMB lensing observations can probe structure on sub-galactic scales. In particular, a CMB-HD experiment can probe out to k ∼ 55 h/Mpc, corresponding to halo masses of about 108 M⊙. Over the range 0.005 h/Mpc <k < 55 h/Mpc, spanning four orders of magnitude, the total lensing signal-to-noise ratio (SNR) from the temperature, polarization, and lensing power spectra is greater than 1900. CMB-HD gains most of the lensing SNR at small scales from the temperature power spectrum, as opposed to the lensing spectrum. These lensing measurements allow CMB-HD to distinguish between cold dark matter (CDM) and non-CDM models that change the matter power spectrum on sub-galactic scales. We also find that CMB-HD can distinguish between baryonic feedback effects and non-CDM models due to the different way each impacts the lensing signal. The kinetic Sunyaev-Zel'dovich (kSZ) power spectrum further constrains non-CDM models that deviate from CDM on the smallest scales CMB-HD measures. For example, CMB-HD can detect 1 keV warm dark matter (WDM) at 30σ, or rule out about 7 keV WDM at 95% CL, in a ΛWDM+Neff+ ∑ mν + mWDM + log10TAGN + AkSZ + nkSZ model; here TAGN characterizes the strength of the feedback, and AkSZ and nkSZ allow freedom in the amplitude and slope of the kinetic Sunyaev-Zel'dovich power spectrum. This work provides an initial exploration of what can be achieved with reasonable assumptions about systematic effects. We make the CMB-HD Fisher code used here publicly available, and note that it can be modified to use any non-CDM model that changes the matter power spectrum.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"51 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/044
Yusuke Mikura and Yuichiro Tada
Towards a classification of UV completable Higgs inflation in the framework of parity-even metric-affine gravity, we investigate the particle spectrum of a deformed theory in the large-N limit. In a simple Higgs inflation model in metric-affine gravity, it is known that its UV cutoff is much smaller than the Planck scale. While it calls for UV completion, a concrete example has not yet been found, even with the large-N limit known as a successful technique to complete an original Higgs inflation defined on the Riemannian geometry. This motivates us to study how small deformation of the simple Higgs inflation affects the emergence and properties of dynamical fields particularly in the large-N limit. As a UV theory has to be free of ghosts or tachyons at least around Minkowski space, we perform the parameter search and find the healthy parameter region where a new heavy particle can propagate without these pathologies.
{"title":"Towards a classification of UV completable Higgs inflation in metric-affine gravity","authors":"Yusuke Mikura and Yuichiro Tada","doi":"10.1088/1475-7516/2025/02/044","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/044","url":null,"abstract":"Towards a classification of UV completable Higgs inflation in the framework of parity-even metric-affine gravity, we investigate the particle spectrum of a deformed theory in the large-N limit. In a simple Higgs inflation model in metric-affine gravity, it is known that its UV cutoff is much smaller than the Planck scale. While it calls for UV completion, a concrete example has not yet been found, even with the large-N limit known as a successful technique to complete an original Higgs inflation defined on the Riemannian geometry. This motivates us to study how small deformation of the simple Higgs inflation affects the emergence and properties of dynamical fields particularly in the large-N limit. As a UV theory has to be free of ghosts or tachyons at least around Minkowski space, we perform the parameter search and find the healthy parameter region where a new heavy particle can propagate without these pathologies.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"209 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/042
Ryoto Inui, Hayato Motohashi, Shi Pi, Yuichiro Tada and Shuichiro Yokoyama
The curvature perturbation in a model of constant-roll (CR) inflation is interpreted in view of the logarithmic duality discovered in ref. [1] according to the δN formalism. We confirm that the critical value β:=φ̈/(Hφ̇)= -3/2 determining whether the CR condition is stable or not is understood as the point at which the dual solutions, i.e., the attractor and non-attractor solutions of the field equation, are interchanged. For the attractor-solution domination, the curvature perturbation in the CR model is given by a simple logarithmic mapping of a Gaussian random field, which can realise both the exponential tail (i.e., the single exponential decay) and the Gumbel-distribution-like tail (i.e., the double exponential decay) of the probability density function, depending on the value of β. Such a tail behaviour is important for, e.g., the estimation of the primordial black hole (PBH) abundance.
{"title":"Constant roll and non-Gaussian tail in light of logarithmic duality","authors":"Ryoto Inui, Hayato Motohashi, Shi Pi, Yuichiro Tada and Shuichiro Yokoyama","doi":"10.1088/1475-7516/2025/02/042","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/042","url":null,"abstract":"The curvature perturbation in a model of constant-roll (CR) inflation is interpreted in view of the logarithmic duality discovered in ref. [1] according to the δN formalism. We confirm that the critical value β:=φ̈/(Hφ̇)= -3/2 determining whether the CR condition is stable or not is understood as the point at which the dual solutions, i.e., the attractor and non-attractor solutions of the field equation, are interchanged. For the attractor-solution domination, the curvature perturbation in the CR model is given by a simple logarithmic mapping of a Gaussian random field, which can realise both the exponential tail (i.e., the single exponential decay) and the Gumbel-distribution-like tail (i.e., the double exponential decay) of the probability density function, depending on the value of β. Such a tail behaviour is important for, e.g., the estimation of the primordial black hole (PBH) abundance.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/041
Yiheng Jiang and Teruaki Suyama
We study the generation of high-frequency gravitational waves (GWs) through graviton bremsstrahlung during the decay of inflaton in the post-inflationary universe, focusing on scenarios with a polynomial inflaton potential. Two main reheating channels are considered: decays into bosons (spin 0) and fermions (spin 1/2). We compute the resulting GW spectra from three-body decays, where the inflaton decays into a pair of daughter particles and a graviton. We numerically compute the GW spectra for various polynomial exponents by employing two distinct approaches: one treating the inflaton as a collection of rest particles and the other treating it as a coherently oscillating classical field. In the former approach, only gravitons with energies below half the inflaton mass are produced, while the latter allows for the production of gravitons with arbitrarily high energies when the potential exponent is 4 or greater. This difference arises because the inflaton's oscillations are no longer described by a single harmonic mode but instead consist of infinitely many harmonic modes with different frequencies. As a result, the GW spectrum exhibits multiple peaks, with these peaks being less pronounced for higher powers of the potential. We also examine the dependence of the GW spectrum on the coupling constant between the inflaton and daughter particles. Our findings suggest that future GW detectors targeting GWs in the GHz band, such as resonant cavities, may have the capability to detect these signals, offering potential insights into the reheating phase of the early universe.
{"title":"Spectrum of high-frequency gravitational waves from graviton bremsstrahlung by the decay of inflaton: case with polynomial potential","authors":"Yiheng Jiang and Teruaki Suyama","doi":"10.1088/1475-7516/2025/02/041","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/041","url":null,"abstract":"We study the generation of high-frequency gravitational waves (GWs) through graviton bremsstrahlung during the decay of inflaton in the post-inflationary universe, focusing on scenarios with a polynomial inflaton potential. Two main reheating channels are considered: decays into bosons (spin 0) and fermions (spin 1/2). We compute the resulting GW spectra from three-body decays, where the inflaton decays into a pair of daughter particles and a graviton. We numerically compute the GW spectra for various polynomial exponents by employing two distinct approaches: one treating the inflaton as a collection of rest particles and the other treating it as a coherently oscillating classical field. In the former approach, only gravitons with energies below half the inflaton mass are produced, while the latter allows for the production of gravitons with arbitrarily high energies when the potential exponent is 4 or greater. This difference arises because the inflaton's oscillations are no longer described by a single harmonic mode but instead consist of infinitely many harmonic modes with different frequencies. As a result, the GW spectrum exhibits multiple peaks, with these peaks being less pronounced for higher powers of the potential. We also examine the dependence of the GW spectrum on the coupling constant between the inflaton and daughter particles. Our findings suggest that future GW detectors targeting GWs in the GHz band, such as resonant cavities, may have the capability to detect these signals, offering potential insights into the reheating phase of the early universe.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"51 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/047
C. Alispach, A. Araudo, M. Balbo, V. Beshley, A. Biland, J. Blažek, J. Borkowski, T. Bulik, F. Cadoux, S. Casanova, A. Christov, J. Chudoba, L. Chytka, P. Dědič, D. della Volpe, Y. Favre, M. Garczarczyk, L. Gibaud, T. Gieras, P. Hamal, M. Heller, M. Hrabovský, P. Janeček, M. Jelínek, V. Jílek, J. Juryšek, V. Karas, B. Lacave, E. Lyard, E. Mach, D. Mandát, W. Marek, S. Michal, J. Michałowski, R. Moderski, T. Montaruli, A. Muraczewski, S. Muthyala, A.L. Müller, A. Nagai, K. Nalewajski, D. Neise, J. Niemiec, M. Nikołajuk, V. Novotný, M. Ostrowski, M. Palatka, M. Pech, M. Prouza, P. Rajda, P. Schovanek, K. Seweryn, V. Sliusar, Ł. Stawarz, R. Sternberger, M. Stodulska, J. Świerblewski, P. Świerk, J. Štrobl, T. Tavernier, P. Trávníček, I. Troyano Pujadas, J. Vícha, M. Vacula, R. Walter and K. Ziȩtara
The SST-1M (webpage: https://sst-1m.space) is a Small-Sized Telescope (SST) designed to provide a cost-effective and high-performance solution for gamma-ray astrophysics, particularly for energies beyond a few TeV. The goal is to integrate this telescope into an array of similar instruments, leveraging its lightweight design, earthquake resistance, and established Davies-Cotton configuration. Additionally, its optical system is designed to function without a protective dome, allowing it to withstand the harsh atmospheric conditions typical of mountain environments above 2000 m a.s.l. The SST-1M utilizes a fully digitizing camera system based on silicon photomultipliers (SiPMs). This camera is capable of digitizing all signals from the UV-optical light detectors, allowing for the implementation of various triggers and data analysis methods. We detail the process of designing, prototyping, and validating this system, ensuring that it meets the stringent requirements for gamma-ray detection and performance. An SST-1M stereo system is currently operational and collecting data at the Ondřejov observatory in the Czech Republic, situated at 500 m a.s.l. Preliminary results from this system are promising. A forthcoming paper will provide a comprehensive analysis of the telescope's performance in detecting gamma rays and operating under real-world conditions.
{"title":"The SST-1M imaging atmospheric Cherenkov telescope for gamma-ray astrophysics","authors":"C. Alispach, A. Araudo, M. Balbo, V. Beshley, A. Biland, J. Blažek, J. Borkowski, T. Bulik, F. Cadoux, S. Casanova, A. Christov, J. Chudoba, L. Chytka, P. Dědič, D. della Volpe, Y. Favre, M. Garczarczyk, L. Gibaud, T. Gieras, P. Hamal, M. Heller, M. Hrabovský, P. Janeček, M. Jelínek, V. Jílek, J. Juryšek, V. Karas, B. Lacave, E. Lyard, E. Mach, D. Mandát, W. Marek, S. Michal, J. Michałowski, R. Moderski, T. Montaruli, A. Muraczewski, S. Muthyala, A.L. Müller, A. Nagai, K. Nalewajski, D. Neise, J. Niemiec, M. Nikołajuk, V. Novotný, M. Ostrowski, M. Palatka, M. Pech, M. Prouza, P. Rajda, P. Schovanek, K. Seweryn, V. Sliusar, Ł. Stawarz, R. Sternberger, M. Stodulska, J. Świerblewski, P. Świerk, J. Štrobl, T. Tavernier, P. Trávníček, I. Troyano Pujadas, J. Vícha, M. Vacula, R. Walter and K. Ziȩtara","doi":"10.1088/1475-7516/2025/02/047","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/047","url":null,"abstract":"The SST-1M (webpage: https://sst-1m.space) is a Small-Sized Telescope (SST) designed to provide a cost-effective and high-performance solution for gamma-ray astrophysics, particularly for energies beyond a few TeV. The goal is to integrate this telescope into an array of similar instruments, leveraging its lightweight design, earthquake resistance, and established Davies-Cotton configuration. Additionally, its optical system is designed to function without a protective dome, allowing it to withstand the harsh atmospheric conditions typical of mountain environments above 2000 m a.s.l. The SST-1M utilizes a fully digitizing camera system based on silicon photomultipliers (SiPMs). This camera is capable of digitizing all signals from the UV-optical light detectors, allowing for the implementation of various triggers and data analysis methods. We detail the process of designing, prototyping, and validating this system, ensuring that it meets the stringent requirements for gamma-ray detection and performance. An SST-1M stereo system is currently operational and collecting data at the Ondřejov observatory in the Czech Republic, situated at 500 m a.s.l. Preliminary results from this system are promising. A forthcoming paper will provide a comprehensive analysis of the telescope's performance in detecting gamma rays and operating under real-world conditions.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/045
Tanveer Karim, Sukhdeep Singh, Mehdi Rezaie, Daniel Eisenstein, Boryana Hadzhiyska, Joshua S. Speagle, Jessica Nicole Aguilar, Steven Ahlen, David Brooks, Todd Claybaugh, Axel de la Macorra, Simone Ferraro, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A. Gontcho, Gaston Gutierrez, Julien Guy, Klaus Honscheid, Stephanie Juneau, David Kirkby, Alex Krolewski, Andrew Lambert, Martin Landriau, Michael Levi, Aaron Meisner, Ramon Miquel, John Moustakas, Andrea Muñoz-Gutiérrez, Adam Myers, Gustavo Niz, Nathalie Palanque-Delabrouille, Will Percival, Francisco Prada, Graziano Rossi, Eusebio Sanchez, Edward Schlafly, David Schlegel, Michael Schubnell, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver and Hu Zou
Measuring the growth of structure is a powerful probe for studying the dark sector, especially in light of the σ8 tension between primary CMB anisotropy and low-redshift surveys. This paper provides a new measurement of the amplitude of the matter power spectrum, σ8, using galaxy-galaxy and galaxy-CMB lensing power spectra of Dark Energy Spectroscopic Instrument Legacy Imaging Surveys Emission-Line Galaxies and the Planck 2018 CMB lensing map. We create an ELG catalog composed of 24 million galaxies and with a purity of 85%, covering a redshift range 0 < z < 3, with zmean = 1.09. We implement several novel systematic corrections, such as jointly modeling the contribution of imaging systematics and photometric redshift uncertainties to the covariance matrix. We also study the impacts of various dust maps on cosmological parameter inference. We measure the cross-power spectra over fsky = 0.25 with a signal-to-background ratio of up to 30σ. We find that the choice of dust maps to account for imaging systematics in estimating the ELG overdensity field has a significant impact on the final estimated values of σ8 and ΩM, with far-infrared emission-based dust maps preferring σ8 to be as low as 0.702 ± 0.030, and stellar-reddening-based dust maps preferring as high as 0.719 ± 0.030. The highest preferred value is at ∼ 3 σ tension with the Planck primary anisotropy results. These findings indicate a need for tomographic analyses at high redshifts and joint modeling of systematics.
{"title":"Measuring σ 8 using DESI Legacy Imaging Surveys Emission-Line galaxies and Planck CMB lensing, and the impact of dust on parameter inference","authors":"Tanveer Karim, Sukhdeep Singh, Mehdi Rezaie, Daniel Eisenstein, Boryana Hadzhiyska, Joshua S. Speagle, Jessica Nicole Aguilar, Steven Ahlen, David Brooks, Todd Claybaugh, Axel de la Macorra, Simone Ferraro, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A. Gontcho, Gaston Gutierrez, Julien Guy, Klaus Honscheid, Stephanie Juneau, David Kirkby, Alex Krolewski, Andrew Lambert, Martin Landriau, Michael Levi, Aaron Meisner, Ramon Miquel, John Moustakas, Andrea Muñoz-Gutiérrez, Adam Myers, Gustavo Niz, Nathalie Palanque-Delabrouille, Will Percival, Francisco Prada, Graziano Rossi, Eusebio Sanchez, Edward Schlafly, David Schlegel, Michael Schubnell, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver and Hu Zou","doi":"10.1088/1475-7516/2025/02/045","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/045","url":null,"abstract":"Measuring the growth of structure is a powerful probe for studying the dark sector, especially in light of the σ8 tension between primary CMB anisotropy and low-redshift surveys. This paper provides a new measurement of the amplitude of the matter power spectrum, σ8, using galaxy-galaxy and galaxy-CMB lensing power spectra of Dark Energy Spectroscopic Instrument Legacy Imaging Surveys Emission-Line Galaxies and the Planck 2018 CMB lensing map. We create an ELG catalog composed of 24 million galaxies and with a purity of 85%, covering a redshift range 0 < z < 3, with zmean = 1.09. We implement several novel systematic corrections, such as jointly modeling the contribution of imaging systematics and photometric redshift uncertainties to the covariance matrix. We also study the impacts of various dust maps on cosmological parameter inference. We measure the cross-power spectra over fsky = 0.25 with a signal-to-background ratio of up to 30σ. We find that the choice of dust maps to account for imaging systematics in estimating the ELG overdensity field has a significant impact on the final estimated values of σ8 and ΩM, with far-infrared emission-based dust maps preferring σ8 to be as low as 0.702 ± 0.030, and stellar-reddening-based dust maps preferring as high as 0.719 ± 0.030. The highest preferred value is at ∼ 3 σ tension with the Planck primary anisotropy results. These findings indicate a need for tomographic analyses at high redshifts and joint modeling of systematics.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/043
Colton R. Feathers, Mihir Kulkarni and Eli Visbal
A key obstacle to accurate models of the first stars and galaxies is the vast range of distance scales that must be considered. While star formation occurs on sub-parsec scales within dark matter (DM) minihalos, it is influenced by large-scale baryon-dark matter streaming velocities (vbc) and Lyman-Werner (LW) radiative feedback which vary significantly on scales of ∼100 Mpc. We present a novel approach to this issue in which we utilize artificial neural networks (NNs) to emulate the Population III (PopIII) and Population II (PopII) star formation histories of many small-scale cells given by a more complex semi-analytic framework based on DM halo merger trees. Within each simulation cell, the NN takes a set of input parameters that depend on the surrounding large-scale environment, such as the cosmic overdensity, δ(x⃗), and vbc of the cell, then outputs the resulting star formation far more efficiently than is possible with the semi-analytic model. This rapid emulation allows us to self-consistently determine the LW background intensity on ∼100 Mpc scales, while simultaneously including the detailed merger histories (and corresponding star formation histories) of the low-mass minihalos that host the first stars. Comparing with the full semi-analytic framework utilizing DM halo merger trees, our NN emulators yield star formation histories with redshift-averaged errors of ∼7.3% and ∼5.2% for PopII and PopIII, respectively. When compared to a simpler sub-grid star formation prescription reliant on halo mass function integration, we find that the diversity of halo merger histories in our simulation leads to enhanced spatial fluctuations, an earlier transition from PopIII to PopII dominated star formation, and more scatter in star formation histories overall.
{"title":"From dark matter minihalos to large-scale radiative feedback: a self-consistent 3D simulation of the first stars and galaxies using neural networks","authors":"Colton R. Feathers, Mihir Kulkarni and Eli Visbal","doi":"10.1088/1475-7516/2025/02/043","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/043","url":null,"abstract":"A key obstacle to accurate models of the first stars and galaxies is the vast range of distance scales that must be considered. While star formation occurs on sub-parsec scales within dark matter (DM) minihalos, it is influenced by large-scale baryon-dark matter streaming velocities (vbc) and Lyman-Werner (LW) radiative feedback which vary significantly on scales of ∼100 Mpc. We present a novel approach to this issue in which we utilize artificial neural networks (NNs) to emulate the Population III (PopIII) and Population II (PopII) star formation histories of many small-scale cells given by a more complex semi-analytic framework based on DM halo merger trees. Within each simulation cell, the NN takes a set of input parameters that depend on the surrounding large-scale environment, such as the cosmic overdensity, δ(x⃗), and vbc of the cell, then outputs the resulting star formation far more efficiently than is possible with the semi-analytic model. This rapid emulation allows us to self-consistently determine the LW background intensity on ∼100 Mpc scales, while simultaneously including the detailed merger histories (and corresponding star formation histories) of the low-mass minihalos that host the first stars. Comparing with the full semi-analytic framework utilizing DM halo merger trees, our NN emulators yield star formation histories with redshift-averaged errors of ∼7.3% and ∼5.2% for PopII and PopIII, respectively. When compared to a simpler sub-grid star formation prescription reliant on halo mass function integration, we find that the diversity of halo merger histories in our simulation leads to enhanced spatial fluctuations, an earlier transition from PopIII to PopII dominated star formation, and more scatter in star formation histories overall.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"13 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-19DOI: 10.1088/1475-7516/2025/02/046
Pradeep Kumar Kumawat, Subhajit Barman and Bibhas Ranjan Majhi
We study the prospect of the equivalence principle at the quantum regime by investigating the transition probabilities of a two-level atomic detector in different scenarios. In particular, two specific set-ups are considered. (i) Without a boundary: In one scenario the atom is in uniform acceleration and interacting with Minkowski field modes. While in the other the atom is static and in interaction with Rindler field modes. (ii) With a reflecting boundary: In one scenario the atom is uniformly accelerated and the mirror is static, and in the other scenario the atom is static and the mirror is in uniform acceleration. In these cases, the atom interacts with the field modes, defined in the mirror's frame. For both the set-ups, the focus is on the excitation and de-excitation probabilities in (1+1) and (3+1) spacetime dimensions. Our observations affirm that in (1+1) dimensions, for both set-ups the transition probabilities from different scenarios become the same when the atomic and the field frequencies are equal. In contrast, in (3+1) dimensions this equivalence is not observed in general, inspiring us to look for a deeper physical interpretation. Our findings suggest that when the equivalence between different scenarios is concerned, the excitation to de-excitation ratio provides a more consistent measure even in (3+1) dimensions. We discuss the physical interpretation and implications of our findings.
{"title":"Equivalence in virtual transitions between uniformly accelerated and static atoms: from a bird's eye","authors":"Pradeep Kumar Kumawat, Subhajit Barman and Bibhas Ranjan Majhi","doi":"10.1088/1475-7516/2025/02/046","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/046","url":null,"abstract":"We study the prospect of the equivalence principle at the quantum regime by investigating the transition probabilities of a two-level atomic detector in different scenarios. In particular, two specific set-ups are considered. (i) Without a boundary: In one scenario the atom is in uniform acceleration and interacting with Minkowski field modes. While in the other the atom is static and in interaction with Rindler field modes. (ii) With a reflecting boundary: In one scenario the atom is uniformly accelerated and the mirror is static, and in the other scenario the atom is static and the mirror is in uniform acceleration. In these cases, the atom interacts with the field modes, defined in the mirror's frame. For both the set-ups, the focus is on the excitation and de-excitation probabilities in (1+1) and (3+1) spacetime dimensions. Our observations affirm that in (1+1) dimensions, for both set-ups the transition probabilities from different scenarios become the same when the atomic and the field frequencies are equal. In contrast, in (3+1) dimensions this equivalence is not observed in general, inspiring us to look for a deeper physical interpretation. Our findings suggest that when the equivalence between different scenarios is concerned, the excitation to de-excitation ratio provides a more consistent measure even in (3+1) dimensions. We discuss the physical interpretation and implications of our findings.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"49 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1088/1475-7516/2025/02/038
Yang Li, Yongtao Jia and Ligong Bian
We numerically study the domain walls (DWs) dynamic through 3D lattice simulation, and show that DWs formed by the breaking of a discrete symmetry in the early Universe can be dissipated by a later cosmic first-order phase transition (PT), even if the DWs have entered the scaling regime. The decay speed of the DWs is characterized by the bubble nucleation rate of the first-order PT. The produced gravitational wave (GW) spectrum can be dominated by the first-order PT and is of a different shape in comparison to that of the DWs. The mechanism can be probed by the current and upcoming GW detectors.
{"title":"Numerical simulation of domain wall and first-order phase transition in an expanding universe","authors":"Yang Li, Yongtao Jia and Ligong Bian","doi":"10.1088/1475-7516/2025/02/038","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/038","url":null,"abstract":"We numerically study the domain walls (DWs) dynamic through 3D lattice simulation, and show that DWs formed by the breaking of a discrete symmetry in the early Universe can be dissipated by a later cosmic first-order phase transition (PT), even if the DWs have entered the scaling regime. The decay speed of the DWs is characterized by the bubble nucleation rate of the first-order PT. The produced gravitational wave (GW) spectrum can be dominated by the first-order PT and is of a different shape in comparison to that of the DWs. The mechanism can be probed by the current and upcoming GW detectors.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"88 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1088/1475-7516/2025/02/039
P. Conzinu, G. Fanizza, M. Gasperini, E. Pavone, L. Tedesco and G. Veneziano
We discuss a recently proposed fit of the 15-year data set obtained from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) in terms of a relic stochastic background of primordial gravitons, produced in the context of the string cosmology pre-big bang scenario. We show that such interpretation cannot be reconciled with a phenomenologically viable minimal version of such scenario, while it can be allowed if one considers an equally viable but generalised, non-minimal version of pre-big bang evolution. Maintaining the S-duality symmetry throughout the high-curvature string phase is possible although somewhat disfavoured. The implications of this non-minimal scenario for the power spectrum of curvature perturbations are also briefly discussed.
{"title":"Constraints on the Pre-Big Bang scenario from a cosmological interpretation of the NANOGrav data","authors":"P. Conzinu, G. Fanizza, M. Gasperini, E. Pavone, L. Tedesco and G. Veneziano","doi":"10.1088/1475-7516/2025/02/039","DOIUrl":"https://doi.org/10.1088/1475-7516/2025/02/039","url":null,"abstract":"We discuss a recently proposed fit of the 15-year data set obtained from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) in terms of a relic stochastic background of primordial gravitons, produced in the context of the string cosmology pre-big bang scenario. We show that such interpretation cannot be reconciled with a phenomenologically viable minimal version of such scenario, while it can be allowed if one considers an equally viable but generalised, non-minimal version of pre-big bang evolution. Maintaining the S-duality symmetry throughout the high-curvature string phase is possible although somewhat disfavoured. The implications of this non-minimal scenario for the power spectrum of curvature perturbations are also briefly discussed.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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