A New Measurement of the Temperature–density Relation of the IGM from Voigt Profile Fitting

Hiss, Hector; Walther, Michael; Hennawi, Joseph F.; Oñorbe, José; O’Meara, John M.; Rorai, Alberto; Lukić, Zarija

doi:10.3847/1538-4357/aada86

Cited by 93 publications

(158 citation statements)

References 72 publications

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“…Convincing evidence of a non-monotonic heating of the plasma of the IGM around z ∼ 3.5 [80][81][82] has been interpreted as evidence of the reionization of HeII. Although the magnitude of this feature varies at the ∼ O(50%) level in recent analyses [82][83][84], a consensus seems strong that the IGM was heated by no more than ∆T 10 4 K 0.8 eV. Since the majority of this heating is surmised to come from the partial ionization of helium atoms, bounds on anomalous heating of the IGM of size ∼ 0.5 eV per baryon in the range 2 ≤ z ≤ 5 were presented in [82].…”

Section: Helium II Reionizationmentioning

confidence: 99%

Cosmological evolution of light dark photon dark matter

McDermott

Witte

2020

Phys. Rev. D

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Light dark photons are subject to various plasma effects, such as Debye screening and resonant oscillations, which can lead to a more complex cosmological evolution than is experienced by conventional cold dark matter candidates. Maintaining a consistent history of dark photon dark matter requires ensuring that the super-thermal abundance present in the early Universe (i) does not deviate significantly after the formation of the CMB, and (ii) does not excessively leak into the Standard Model plasma after BBN. We point out that the role of non-resonant absorption, which has previously been neglected in cosmological studies of this dark matter candidate, produces strong constraints on dark photon dark matter with mass as low as 10 −22 eV. Furthermore, we show that resonant conversion of dark photons after recombination can produce excessive heating of the IGM which is capable of prematurely reionizing hydrogen and helium, leaving a distinct imprint on both the Ly−α forest and the integrated optical depth of the CMB. Our constraints surpass existing cosmological bounds by more than five orders of magnitude across a wide range of dark photon masses.

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Section: Helium II Reionizationmentioning

confidence: 99%

Cosmological evolution of light dark photon dark matter

McDermott

Witte

2020

Phys. Rev. D

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“…the High Resolution Echelle Spectrometer (HIRES) (Vogt et al 1994;Lehner et al 2014;O'Meara et al 2016O'Meara et al , 2017 and Ultraviolet and Visual Echelle Spectrograph (UVES) (Dekker et al 2000;Dall'Aglio et al 2008) dataset in Hiss et al 2018). Further, we add Gaussian random noise to the skewers assuming a fixed signal-to-noise ratio (SNR) of 63 per resolution element for the purpose of choosing a value comparable to the SNR of the dataset in Hiss et al (2018) PDF value Figure 2. Left: A b-NHI distribution illustrated as a cloud of points generated by concatenating the VPFIT output for 6000 skewers from a DM only simulation snapshot at z = 2 with thermal parameters (log T0, γ) = (4.011, 1.333).…”

Section: Forward Modeling Noise and Resolutionmentioning

confidence: 99%

“…We apply the exact same Voigt-profile fitting scheme described in Hiss et al (2018) to the 6000 forward modeled simulated skewers generated for 100 different combinations of T 0 , γ. To summarize, Voigt-profiles were fitted to our simulated data using VPFIT version 10.2 2 (Carswell & Webb 2014).…”

Section: Forward Modeling Noise and Resolutionmentioning

confidence: 99%

“…In addition, narrow metal line absorbers, which are difficult to completely identify and mask, can result in significant contamination around the cutoff, compromising the precision with which the cutoff can be determined, and adding systematics which are difficult to control. Another complication of this method, as shown in Hiss et al (2018) in the context of the comparison with the results by Rorai et al (2018), is that choice of cutoff fitting method (i.e. least-squares or mean-deviation minimization) can lead to significantly different T 0 and γ measurements.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b–N_{H i} Distribution of Absorbers in the Lyα Forest

Hiss

Walther

Oñorbe

2019

ApJ

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We present a new method for determining the thermal state of the intergalactic medium based on Voigt profile decomposition of the Lyα forest. The distribution of Doppler parameter and column density (b-N HI distribution) is sensitive to the temperature density relation T = T 0 (ρ/ρ 0 ) γ−1 , and previous work has inferred T 0 and γ by fitting its low-b cutoff. This approach discards the majority of available data, and is susceptible to systematics related to cutoff determination. We present a method that exploits all information encoded in the b-N HI distribution by modeling its entire shape. We apply kernel density estimation to discrete absorption lines to generate model probability density functions, then use principal component decomposition to create an emulator which can be evaluated anywhere in thermal parameter space. We introduce a Bayesian likelihood based on these models enabling parameter inference via Markov chain Monte Carlo. The method's robustness is tested by applying it to a large grid of thermal history simulations. By conducting 160 mock measurements we establish that our approach delivers unbiased estimates and valid uncertainties for a 2D (T 0 , γ) measurement. Furthermore, we conduct a pilot study applying this methodology to real observational data at z = 2. Using 200 absorbers, equivalent in pathlength to a single Lyα forest spectrum, we measure log T 0 = 4.092 +0.050 −0.055 and γ = 1.49 +0.073 −0.074 in excellent agreement with cutoff fitting determinations using the same data. Our method is far more sensitive than cutoff fitting, enabling measurements of log T 0 and γ with precision on log T 0 (γ) nearly two (three) times higher for current dataset sizes.

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“…The HeII reionization was completed later on at z ∼ 2.8 (e.g. Shull et al 2004;Worseck et al 2011;Becker et al 2011;Hiss et al 2018), and it is thought to have been driven by the hard UV radiation from QSOs (e.g. Kriss et al 2001;Compostella et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Local photoionization feedback effects on galaxies

Obreja

Macciò

Moster

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We implement an optically thin approximation for the effects of the local radiation field from stars and hot gas on the gas heating and cooling in the N-body SPH code GASOLINE2. We resimulate three galaxies from the NIHAO project: one dwarf, one Milky Way-like and one massive spiral, and study what are the local radiation field effects on various galaxy properties. We also study the effects of varying the Ultra Violet Background (UVB) model, by running the same galaxies with two different UVBs. Galaxy properties at z = 0 like stellar mass, stellar effective mass radius, HI mass, and radial extent of the HI disc, show significant changes between the models with and without the local radiation field, and smaller differences between the two UVB models. The intrinsic effect of the local radiation field through cosmic time is to increase the equilibrium temperature at the interface between the galaxies and their circumgalactic media (CGM), moving this boundary inwards, while leaving relatively unchanged the gas inflow rate. Consequently, the temperature of the inflow increases when considering the local radiation sources. This temperature increase is a function of total galaxy mass, with a median CGM temperature difference of one order of magnitude for the massive spiral. The local radiation field suppresses the stellar mass growth by 20 per cent by z = 0 for all three galaxies, while the HI mass is roughly halfed. The differences in the gas phase diagrams, significantly impact the HI column densities, shifting their peaks in the distributions towards lower N HI .

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A New Measurement of the Temperature–density Relation of the IGM from Voigt Profile Fitting

Cited by 93 publications

References 72 publications

Cosmological evolution of light dark photon dark matter

Cosmological evolution of light dark photon dark matter

A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b–N_{H i} Distribution of Absorbers in the Lyα Forest

Local photoionization feedback effects on galaxies

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A New Measurement of the Temperature–density Relation of the IGM from Voigt Profile Fitting

Cited by 93 publications

References 72 publications

Cosmological evolution of light dark photon dark matter

Cosmological evolution of light dark photon dark matter

A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b–NH i Distribution of Absorbers in the Lyα Forest

Local photoionization feedback effects on galaxies

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Product

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A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b–N_{H i} Distribution of Absorbers in the Lyα Forest