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Register a new userThe Thermal Sunyaev-Zeldovich Effect from Massive, Quiescent 0.5 $leq$ z $leq$ 1.5 Galaxies
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We use combined South Pole Telescope (SPT)+Planck temperature maps to analyze the circumgalactic medium (CGM) encompassing 138,235 massive, quiescent 0.5 $leq$ z $leq$ 1.5 galaxies selected from data from the Dark Energy Survey (DES) and Wide-Field Infrared Survey Explorer (WISE). Images centered on these galaxies were cut from the 1.85 arcmin resolution maps with frequency bands at 95, 150, and 220 GHz. The images were stacked, filtered, and fit with a gray-body dust model to isolate the thermal Sunyaev-Zeldovich (tSZ) signal, which is proportional to the total energy contained in the CGM of the galaxies. We separate these $M_{star} = 10^{10.9} M_odot$ - $10^{12} M_odot$ galaxies into 0.1 dex stellar mass bins, detecting tSZ per bin up to $5.6sigma$ and a total signal-to-noise ratio of $10.1sigma$. We also detect dust with an overall signal-to-noise ratio of $9.8sigma$, which overwhelms the tSZ at 150GHz more than in other lower-redshift studies. We correct for the $0.16$ dex uncertainty in the stellar mass measurements by parameter fitting for an unconvolved power-law energy-mass relation, $E_{rm therm} = E_{rm therm,peak} left(M_star/M_{star,{rm peak}} right)^alpha$, with the peak stellar mass distribution of our selected galaxies defined as $M_{star,{rm peak}}= 2.3 times 10^{11} M_odot$. This yields an $E_{rm therm,peak}= 5.98_{-1.00}^{+1.02} times 10^{60}$ erg and $alpha=3.77_{-0.74}^{+0.60}$. These are consistent with $z approx 0$ observations and within the limits of moderate models of active galactic nuclei (AGN) feedback. We also compute the radial profile of our full sample, which is similar to that recently measured at lower-redshift by Schaan et al. (2021).
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We present an investigation of clumpy galaxies in the Hubble Ultra Deep Field at 0.5 $leq z leq$ 1.5 in the rest-frame far-ultraviolet (FUV) using HST WFC3 broadband imaging in F225W, F275W, and F336W. An analysis of 1,404 galaxies yields 209 galaxies that host 403 kpc-scale clumps. These host galaxies appear to be typical star-forming galaxies, with an average of 2 clumps per galaxy and reaching a maximum of 8 clumps. We measure the photometry of the clumps, and determine the mass, age, and star formation rates (SFR) utilizing the SED-fitting code FAST. We find that clumps make an average contribution of 19% to the total rest-frame FUV flux of their host galaxy. Individually, clumps contribute a median of 5% to the host galaxy SFR and an average of $sim$4% to the host galaxy mass, with total clump contributions to the host galaxy stellar mass ranging widely from less than 1% up to 93%. Clumps in the outskirts of galaxies are typically younger, with higher star formation rates, than clumps in the inner regions. The results are consistent with clump migration theories in which clumps form through violent gravitational instabilities in gas-rich turbulent disks, eventually migrate toward the center of the galaxies, and coalesce into the bulge.
Using the CANDELS photometric catalogs for the HST/ACS and WFC3, we identified massive evolved galaxies at $3 < z < 4.5$, employing three different selection methods. We find the comoving number density of these objects to be $sim 2 times 10^{-5}$ and $8 times 10^{-6}Mpc^{-3}$ after correction for completeness for two redshift bins centered at $z=3.4, 4.7$. We quantify a measure of how much confidence we should have for each candidate galaxy from different selections and what are the conservative error estimates propagated into our selection. Then we compare the evolution of the corresponding number densities and their stellar mass density with numerical simulations, semi-analytical models, and previous observational estimates, which shows slight tension at higher redshifts as the models tend to underestimate the number and mass densities. By estimating the average halo masses of the candidates ($M_h approx 4.2, 1.9, 1.3 times 10^{12} M_odot$ for redshift bins centered at $z=3.4, 4.1, 4.7$), we find them to be consistent with halos that were efficient in turning baryons to stars and were relatively immune to the feedback effects and on the verge of transition into hot-mode accretion. This can suggest the relative cosmological starvation of the cold gas followed by an overconsumption phase in which the galaxy consumes the available cold gas rapidly as one of the possible drivers for the quenching of the massive evolved population at high redshift.
In the present universe, magnetic fields exist with various strengths and on various scales. One possible origin of these cosmic magnetic fields is the primordial magnetic fields (PMFs) generated in the early universe. PMFs are considered to contribute to matter density evolution via Lorentz force and the thermal history of intergalactic medium (IGM) gas due to ambipolar diffusion. Therefore, information about PMFs should be included in the temperature anisotropy of the Cosmic Microwave Background through the thermal Sunyaev-Zeldovich (tSZ) effect in IGM. In this article, given an initial power spectrum of PMFs, we show the spatial fluctuation of mass density and temperature of the IGM and tSZ angular power spectrum created by the PMFs. Finally, we find that the tSZ angular power spectrum induced by PMFs becomes significant on small scales, even with PMFs below the observational upper limit. Therefore, we conclude that the measurement of tSZ anisotropy on small scales will provide the most stringent constraint on PMFs.
The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zeldovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as $P(k)propto B_{rm 1Mpc}^2 k^{n_{B}}$, we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton $y$-parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton $y$-parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast just after the recombination epoch. These facts result in making the tSZ angular power spectrum induced by the PMFs more remarkable at $ell >10^4$ than that by galaxy clusters even with $B_{rm 1Mpc}=0.1$ nG and $n_{B}=-1.0$ because the contribution from galaxy clusters decreases with increasing $ell$. The measurement of the tSZ angular power spectrum on high $ell$ modes can provide the stringent constraint on PMFs.
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Prakash Gaikwad
, Raghunathan Srianand
, Martin G. Haehnelt andn Tirthankar Roy Choudhury
2020
We characterise the thermal state of the intergalactic medium (IGM) in ten redshift bins in the redshift range $2 leq z leq 4$ with a sample of 103 high resolution, high S/N Ly$alpha$ forest spectra using four different flux distribution statistics. Our measurements are calibrated with mock spectra from a large suite of hydrodynamical simulations post-processed with our thermal IGM evolution code CITE, finely sampling amplitude and slope of the expected temperature-density relation. The thermal parameters inferred from our measurements of the flux power spectrum, Doppler parameter distribution, as well as wavelet and curvature statistics agree well within their respective errors and all clearly show the peak in temperature and minimum in slope of the temperature density relation expected from HeII reionization. Combining our measurements from the different flux statistics gives $T_0=(14750 pm 1322)$K for the peak temperature at mean density and a corresponding minimum slope $gamma = 1.225 pm 0.120$. The peak in the temperature evolution occurs at $z approx 3$, in agreement with previous measurements that had suggested the presence of such a peak, albeit with a large scatter. Using CITE, we also calculate the thermal state of the IGM predicted by five widely used (spatially homogeneous) UV-background models. The rather rapid thermal evolution inferred by our measurements is well reproduced by two of the models, if we assume (physically well motivated) non-equilibrium evolution with photo-heating rates that are reduced by a moderate factor of $sim 0.7-0.8$. The other three models predict HeII reionization to be more extended with a somewhat earlier as well as higher temperature peak than our measurements suggest.
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