2004.10207
Hubble constant tension between CMB lensing and BAO measurements
Wu, Motloch, Hu, Raveri
We apply a tension metric $Q_\textrm{UDM}$, the update difference in mean parameters, to understand the source of the difference in the measured Hubble constant $H_0$ inferred with cosmic microwave background lensing measurements from the Planck satellite ($H_0=67.9^{+1.1}_{-1.3}\, \mathrm{km/s/Mpc}$) and from the South Pole Telescope ($H_0=72.0^{+2.1}_{-2.5}\, \mathrm{km/s/Mpc}$) when both are combined with baryon acoustic oscillation (BAO) measurements with priors on the baryon density (BBN). $Q_\textrm{UDM}$ isolates the relevant parameter directions for tension or concordance where the two data sets are both informative, and aids in the identification of subsets of data that source the observed tension. With $Q_\textrm{UDM}$, we uncover that the difference in $H_0$ is driven by the tension between Planck lensing and BAO+BBN, at probability-to-exceed of 6.6%. Most of this mild tension comes from the galaxy BAO measurements parallel to the line of sight. The redshift dependence of the parallel BAOs pulls both the matter density $\Omega_m$ and $H_0$ high in $\Lambda$CDM, but these parameter anomalies are usually hidden when the BAO measurements are combined with other cosmological data sets with much stronger $\Omega_m$ constraints.
Hubble constant tension between CMB lensing and BAO measurements
Wu, Motloch, Hu, Raveri
We apply a tension metric $Q_\textrm{UDM}$, the update difference in mean parameters, to understand the source of the difference in the measured Hubble constant $H_0$ inferred with cosmic microwave background lensing measurements from the Planck satellite ($H_0=67.9^{+1.1}_{-1.3}\, \mathrm{km/s/Mpc}$) and from the South Pole Telescope ($H_0=72.0^{+2.1}_{-2.5}\, \mathrm{km/s/Mpc}$) when both are combined with baryon acoustic oscillation (BAO) measurements with priors on the baryon density (BBN). $Q_\textrm{UDM}$ isolates the relevant parameter directions for tension or concordance where the two data sets are both informative, and aids in the identification of subsets of data that source the observed tension. With $Q_\textrm{UDM}$, we uncover that the difference in $H_0$ is driven by the tension between Planck lensing and BAO+BBN, at probability-to-exceed of 6.6%. Most of this mild tension comes from the galaxy BAO measurements parallel to the line of sight. The redshift dependence of the parallel BAOs pulls both the matter density $\Omega_m$ and $H_0$ high in $\Lambda$CDM, but these parameter anomalies are usually hidden when the BAO measurements are combined with other cosmological data sets with much stronger $\Omega_m$ constraints.
2004.10213
Measuring star formation histories, distances, and metallicities with pixel color-magnitude diagrams II: applications to nearby elliptical galaxies
Cook, Conroy, van Dokkum
We present spatially-resolved measurements of star formation histories (SFHs), metallicities, and distances in three nearby elliptical galaxies and the bulge of M31 derived using the pixel color-magnitude diagram (pCMD) technique. We compute pCMDs from archival $\textit{HST}$ photometry of M87, M49, NGC 3377 and M31, and fit the data using the new code $\texttt{PCMDPy}$. We measure distances to each system that are accurate to $\sim 10\%$. The recovered non-parametric SFHs place reasonable ($\pm 1$ dex) constraints on the recent (< 2 Gyr) star formation in M31 and NGC 3377, both of which show evidence of inside-out growth. The SFHs in M87 and M49 are constrained only at the oldest ages. The pCMD technique is a promising new avenue for studying the evolutionary history of the nearby universe, and is highly complementary to existing stellar population modeling techniques.
2004.10296
Decrease in the brightness of the cosmic X-ray and soft gamma-ray background toward clusters of galaxies
Grebenev, Sunyaev
We show that Compton scattering by electrons of the hot intergalactic gas in galaxy clusters should lead to peculiar distortions of the cosmic background X-ray and soft gamma-ray radiation - an increase in its brightness at E<60-100 keV and a drop at higher energies. The distortions allow the most important cluster parameters to be measured. The spectral shape of the distortions and its dependence on the gas temperature, optical depth, and surface density distribution law have been studied using Monte Carlo computations and confirmed by analytical estimations. In the cluster frame the maximum of the background decrease due to the recoil effect occurs at ~500-600 keV. The photoionization of H- and He-like iron and nickel ions leads to additional distortions in the background spectrum - a strong absorption line with the threshold at ~9 keV (and also to an absorption jump at ~2 keV for cold clusters). The absorption of intrinsic thermal radiation from the cluster gas by these ions also leads to such lines. In nearby (z<1) clusters the line at ~2 keV is noticeably enhanced by absorption in the colder (~10^6 K) plasma of their peripheral (~3 Mpc) regions; moreover, the absorption line at ~1.3 keV splits off from it. The redshift of distant clusters shifts the absorption lines in the background spectrum (at ~2, ~9, and ~500 keV) to lower energies. Thus, in contrast to the microwave background scattering effect, this effect depends on the cluster redshift z, but in a very peculiar way. When observing clusters at z>1, the effect allows one to determine how the X-ray background evolved and how it was "gathered" with z. To detect the effect, the accuracy of measurements should reach ~0.1%. We consider the most promising clusters for observing the effect and discuss the techniques whereby the influence of the thermal gas radiation hindering the detection of background distortions should be minimal.
Decrease in the brightness of the cosmic X-ray and soft gamma-ray background toward clusters of galaxies
Grebenev, Sunyaev
We show that Compton scattering by electrons of the hot intergalactic gas in galaxy clusters should lead to peculiar distortions of the cosmic background X-ray and soft gamma-ray radiation - an increase in its brightness at E<60-100 keV and a drop at higher energies. The distortions allow the most important cluster parameters to be measured. The spectral shape of the distortions and its dependence on the gas temperature, optical depth, and surface density distribution law have been studied using Monte Carlo computations and confirmed by analytical estimations. In the cluster frame the maximum of the background decrease due to the recoil effect occurs at ~500-600 keV. The photoionization of H- and He-like iron and nickel ions leads to additional distortions in the background spectrum - a strong absorption line with the threshold at ~9 keV (and also to an absorption jump at ~2 keV for cold clusters). The absorption of intrinsic thermal radiation from the cluster gas by these ions also leads to such lines. In nearby (z<1) clusters the line at ~2 keV is noticeably enhanced by absorption in the colder (~10^6 K) plasma of their peripheral (~3 Mpc) regions; moreover, the absorption line at ~1.3 keV splits off from it. The redshift of distant clusters shifts the absorption lines in the background spectrum (at ~2, ~9, and ~500 keV) to lower energies. Thus, in contrast to the microwave background scattering effect, this effect depends on the cluster redshift z, but in a very peculiar way. When observing clusters at z>1, the effect allows one to determine how the X-ray background evolved and how it was "gathered" with z. To detect the effect, the accuracy of measurements should reach ~0.1%. We consider the most promising clusters for observing the effect and discuss the techniques whereby the influence of the thermal gas radiation hindering the detection of background distortions should be minimal.
2004.10771
The ALPINE-ALMA [CII] survey: molecular gas budget in the Early Universe as traced by [CII]
Dessauges-Zavadsky, et al
The molecular gas content of normal galaxies at z>4 is poorly constrained, because the commonly used molecular gas tracers become hard to detect. We use the [CII]158um luminosity, recently proposed as a molecular gas tracer, to estimate the molecular gas content in a large sample of main-sequence star-forming galaxies at z=4.4-5.9, with a median stellar mass of 10^9.7 Msun, drawn from the ALMA Large Program to INvestigate [CII] at Early times (ALPINE) survey. The agreement between molecular gas masses derived from [CII] luminosity, dynamical mass, and rest-frame 850um luminosity, extrapolated from the rest-frame 158um continuum, supports [CII] as a reliable tracer of molecular gas in our sample. We find a continuous decline of the molecular gas depletion timescale from z=0 to z=5.9, which reaches a mean value of (4.6+/-0.8)x10^8 yr at z~5.5, only a factor of 2-3 shorter than in present-day galaxies. This suggests a mild enhancement of star formation efficiency toward high redshifts, unless the molecular gas fraction significantly increases. Our estimates show that the rise in molecular gas fraction as reported previously, flattens off above z~3.7 to achieve a mean value of 63%+/-3 over z=4.4-5.9. This redshift evolution of the gas fraction is in line with the one of the specific star formation rate. We use multi-epoch abundance matching to follow the gas fraction evolution over cosmic time of progenitors of z=0 Milky Way-like galaxies in 10^13 Msun halos and of more massive z=0 galaxies in 10^14 Msun halos. Interestingly, the former progenitors show a monotonic decrease of the gas fraction with cosmic time, while the latter show a constant gas fraction from z=5.9 to z~2 and a decrease at z<2. We discuss three possible effects, namely outflows, halt of gas supplying, and over-efficient star formation, which may jointly contribute to the gas fraction plateau of the latter massive galaxies.
2004.11328
Origin and evolution of the Galactic inventories of interstellar dust and its composition
Gupta, Sahijpal
Interstellar dust is a significant component of matter in the galaxies. The dust owns its origin and reprocessing in a wide range of astrophysical environments. In order to understand the origin and evolution of the distinct types of interstellar dust grains, we have attempted a comprehensive correlated study of the thermodynamics condensation of dust grains in distinct stellar environments with the Galactic chemical evolution of the Milky Way Galaxy. The Galaxy is evolved in terms of elemental evolution resulting from stellar nucleosynthetic contributions of several generations of stars. Based on the elemental composition of the evolving Galaxy, the relative abundances of the major constituents of interstellar dust are assessed. The major aim is to redistribute the various condensable elements at any epoch during the evolution of the Galaxy into various grain constituents and understand their abundance evolution based on a mass-balance formalism. We also performed thermodynamical equilibrium condensation calculations to understand the stellar origin of various grain constituents that could carry the isotopic signatures of the various stellar nucleosynthetic sources. This is perhaps a novel attempt to estimate the bulk dust mass budget in the evolving Galaxy. The normalized mass of the Galactic dust is predicted to decrease with the increase in distance from the Galactic centre. It increases over time. The supernovae SN Ia are predicted as the most prominent sources of Fe-dust mass, the supernovae SN II+Ib/c produces oxides and silicate dust mass, and the AGB stars contributes to carbonaceous dust mass.
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