We present a systematic study of the intensity mapping (IM) technique using updated models for the different emission lines from galaxies. We identify which ones are more promising for cosmological ...studies of the post-reionization epoch. We consider the emission of Lya, Ha, H beta , optical and infrared oxygen lines, nitrogen lines, C II and the CO rotational lines. We show that Lya, Ha, O II, C II and the lowest rotational CO lines are the best candidates to be used as IM probes. These lines form a complementary set of probes of the galaxies' emission spectra. We then use reasonable experimental setups from current, planned or proposed experiments to assess the detectability of the power spectrum of each emission line. IM of Lya emission from z = 2 to 3 will be possible in the near future with Hobby-Eberly Telescope Dark Energy Experiment, while far-infrared lines require new dedicated experiments. We also show that the proposed SPHEREx satellite can use O II and Ha IM to study the large-scale distribution of matter in intermediate redshifts of 1-4. We find that submillimetre experiments with bolometers can have similar performances at intermediate redshifts using C II and CO(3-2).
We calculate the absolute intensity and anisotropies of the Ly alpha radiation field present during the epoch of reionization. We consider emission from both galaxies and the intergalactic medium ...(IGM) and take into account the main contributions to the production of Ly alpha photons: recombinations, collisions, continuum emission from galaxies, and scattering of Lyn photons in the IGM. We find that the emission from individual galaxies dominates over the IGM with a total Ly alpha intensity (times frequency) of about (1.43-3.57) x 10 super(-8) erg s super(-1) cm super(-2) sr super(-1) at a redshift of 7. This intensity level is low, so it is unlikely that the Ly alpha background during reionization can be established by an experiment aiming at an absolute background light measurement. Instead, we consider Ly alpha intensity mapping with the aim of measuring the anisotropy power spectrum that has rms fluctuations at the level of 1 x 10 super(-16) erg s super(-1) cm super(-2) sr super(-1) super(2) at a few Mpc scales. These anisotropies could be measured with a spectrometer at near-IR wavelengths from 0.9 to 1.4 mu m with fields in the order of 0.5 to 1 deg super(2). We recommend that existing ground-based programs using narrowband filters also pursue intensity fluctuations to study statistics on the spatial distribution of faint Ly alpha emitters. We also discuss the cross-correlation signal with 21 cm experiments that probe H I in the IGM during reionization. A dedicated sub-orbital or space-based Ly alpha intensity mapping experiment could provide a viable complimentary approach to probe reionization, when compared to 21 cm experiments, and is likely within experimental reach.
Intensity Mapping of Hα, Hβ, , and Lines at z < 5 Gong, Yan; Cooray, Asantha; Silva, Marta B. ...
Astrophysical journal/The Astrophysical journal,
02/2017, Letnik:
835, Številka:
2
Journal Article
Recenzirano
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Abstract
Intensity mapping is becoming a useful tool to study the large-scale structure of the universe through spatial variations in the integrated emission from galaxies and the intergalactic ...medium. We study intensity mapping of the
, O
iii
5007 Å, O
ii
3727 Å, and
lines at
. The mean intensities of these four emission lines are estimated using the observed luminosity functions (LFs), cosmological simulations, and the star formation rate density (SFRD) derived from observations at
. We calculate the intensity power spectra and consider the foreground contamination of other lines at lower redshifts. We use the proposed NASA small explorer SPHEREx (the Spectro-Photometer for the History of the universe, Epoch of Reionization, and Ices Explorer) as a case study for the detectability of the intensity power spectra of the four emission lines. We also investigate the cross-correlation with the 21 cm line probed by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), Tianlai experiment and the Square Kilometer Array (SKA) at
. We find both the auto and cross power spectra can be well measured for the H
α
, O
iii
and O
ii
lines at
, while it is more challenging for the H
β
line. Finally, we estimate the constraint on the SFRD from intensity mapping, and find we can reach an accuracy higher than 7% at
, which is better than with the usual method of measurements using the LFs of galaxies.
Abstract
Large-scale filaments, with lengths that can reach tens of Mpc, are the most prominent features in the cosmic web. These filaments have only been observed indirectly through the positions of ...galaxies in large galaxy surveys or through absorption features in the spectra of high-redshift sources. In this study, we propose to go one step further and directly detect intergalactic medium filaments through their emission in the H i 21 cm line. We make use of high-resolution cosmological simulations to estimate the intensity of this emission in low-redshift filaments and use it to make predictions for the direct detectability of specific filaments previously inferred from galaxy surveys, in particular the Sloan Digital Sky Survey. Given the expected signal of these filaments, our study shows that H i emission from large filaments can be observed by current and next-generation radio telescopes. We estimate that gas in filaments of length l ≳ 15 h
−1 Mpc with relatively small inclinations to the line of sight (≲ 10°) can be observed in ∼40–100 h with telescopes such as Giant Metrewave Radio Telescope or Expanded Very Large Array, potentially providing large improvements over our knowledge of the astrophysical properties of these filaments. Due to their large field of view and sufficiently long integration times, upcoming H i surveys with the Apertif and Australian Square Kilometre Array Pathfinder instruments will be able to detect large filaments independently of their orientation and curvature. Furthermore, our estimates indicate that a more powerful future radio telescope like Square Kilometre Array can be used to map most of these filaments, which will allow them to be used as a strong cosmological probe.
COMAP Early Science. I. Overview Cleary, Kieran A.; Borowska, Jowita; Breysse, Patrick C. ...
Astrophysical journal/The Astrophysical journal,
07/2022, Letnik:
933, Številka:
2
Journal Article
Recenzirano
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Abstract
The CO Mapping Array Project (COMAP) aims to use line-intensity mapping of carbon monoxide (CO) to trace the distribution and global properties of galaxies over cosmic time, back to the ...Epoch of Reionization (EoR). To validate the technologies and techniques needed for this goal, a Pathfinder instrument has been constructed and fielded. Sensitive to CO(1–0) emission from
z
= 2.4–3.4 and a fainter contribution from CO(2–1) at
z
= 6–8, the Pathfinder is surveying 12 deg
2
in a 5 yr observing campaign to detect the CO signal from
z
∼ 3. Using data from the first 13 months of observing, we estimate
P
CO
(
k
) = −2.7 ± 1.7 × 10
4
μ
K
2
Mpc
3
on scales
k
= 0.051 −0.62 Mpc
−1
, the first direct three-dimensional constraint on the clustering component of the CO(1–0) power spectrum. Based on these observations alone, we obtain a constraint on the amplitude of the clustering component (the squared mean CO line temperature bias product) of
Tb
2
<
49
μ
K
2
, nearly an order-of-magnitude improvement on the previous best measurement. These constraints allow us to rule out two models from the literature. We forecast a detection of the power spectrum after 5 yr with signal-to-noise ratio (S/N) 9–17. Cross-correlation with an overlapping galaxy survey will yield a detection of the CO–galaxy power spectrum with S/N of 19. We are also conducting a 30 GHz survey of the Galactic plane and present a preliminary map. Looking to the future of COMAP, we examine the prospects for future phases of the experiment to detect and characterize the CO signal from the EoR.
Detecting the neutral IGM in filaments with the SKA Kooistra, Robin; Silva, Marta B; Zaroubi, Saleem ...
Monthly notices of the Royal Astronomical Society,
11/2019, Letnik:
490, Številka:
1
Journal Article
Recenzirano
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ABSTRACT
The intergalactic medium (IGM) plays an important role in the formation and evolution of galaxies. Recent developments in upcoming radio telescopes are starting to open up the possibility of ...making a first direct detection of the 21 cm signal of neutral hydrogen (H i) from the warm gas of the IGM in large-scale filaments. The cosmological hydrodynamical EAGLE simulation is used to estimate the typical IGM filament signal. Assuming the same average signal for all filaments, a prediction is made for the detectability of such a signal with the upcoming mid-frequency array of the Square Kilometer Array (SKA1-mid) or the future upgrade to SKA2. The signal to noise (S/N) then only depends on the size and orientation of each filament. With filament spines inferred from existing galaxy surveys as a proxy for typical real filaments, we find hundreds of filaments in the region of the sky accessible to the SKA that can be detected. Once the various phases of the SKA telescope become operational, their own surveys will be able to find the galaxies required to infer the position of even more filaments within the survey area. We find that in 120 h, SKA1-mid/SKA2 will detect H i emission from the strongest filaments in the field with an S/N of the order of 10 to ∼150 for the most pessimistic model considered here. Some of the brighter filaments can be detected with an integration time of a few minutes with SKA1-mid and a few seconds with SKA2. Therefore, SKA2 will be capable of not only detecting but also mapping a large part of the IGM in these filaments.
Abstract
We introduce COMAP-
EoR
, the next generation of the Carbon Monoxide Mapping Array Project aimed at extending CO intensity mapping to the Epoch of Reionization. COMAP-
EoR
supplements the ...existing 30 GHz COMAP Pathfinder with two additional 30 GHz instruments and a new 16 GHz receiver. This combination of frequencies will be able to simultaneously map CO(1–0) and CO(2–1) at reionization redshifts (
z
∼ 5–8) in addition to providing a significant boost to the
z
∼ 3 sensitivity of the Pathfinder. We examine a set of existing models of the EoR CO signal, and find power spectra spanning several orders of magnitude, highlighting our extreme ignorance about this period of cosmic history and the value of the COMAP-
EoR
measurement. We carry out the most detailed forecast to date of an intensity mapping cross correlation, and find that five out of the six models we consider yield signal to noise ratios (S/Ns) ≳ 20 for COMAP-
EoR
, with the brightest reaching a S/N above 400. We show that, for these models, COMAP-
EoR
can make a detailed measurement of the cosmic molecular gas history from
z
∼ 2–8, as well as probe the population of faint, star-forming galaxies predicted by these models to be undetectable by traditional surveys. We show that, for the single model that does not predict numerous faint emitters, a COMAP-
EoR
-type measurement is required to rule out their existence. We briefly explore prospects for a third-generation Expanded Reionization Array (COMAP-
ERA
) capable of detecting the faintest models and characterizing the brightest signals in extreme detail.
We propose observations of the molecular gas distribution during the era of reionization. At z~ 6-8, the 12CO(J = 1-0) line intensity results in a mean brightness temperature of about 0.5 Delta *mK ...with an rms fluctuation of 0.1 Delta *mK at 1-10 Mpc spatial scales, corresponding to 30 arcminute angular scales. This intensity fluctuations can be mapped with an interferometer, similar to existing and planned 21 cm background experiments, but operating at ~12-17 GHz. We discuss the feasibility of detecting the cross-correlation between H I and CO molecular gas since such a cross-correlation has the advantage that it will be independent of systematics and most foregrounds in each of the 21 cm and CO(1-0) line experiments. Additional instruments tuned to higher-order transitions of the CO molecule or an instrument operating with high spectral resolution at millimeter wavelengths targeting 158 Delta *mm C II could further improve the reionization studies with molecular gas. The combined 21 cm and CO line observations has the potential to establish the relative distribution of gas in the intergalactic medium and molecular gas that are clumped in individual first-light galaxies that are closely connected to the formation of massive stars in these galaxies.
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