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您选择的条件: Yu Gao
  • Diagnosing deceivingly cold dusty galaxies at 3.5

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Using NOEMA and ALMA 3mm line scans, we measure spectroscopic redshifts of six new dusty galaxies at 3.56, based on template IR spectrum energy distribution (SED) from known submillimeter galaxies at z=4--6. Dust SED analyses explain the photo-z overestimate from seemingly cold dust temperatures (Td) and steep Rayleigh-Jeans (RJ) slopes, providing additional examples of cold dusty galaxies impacted by the Cosmic Microwave Background (CMB) as found in Jin et al. (2019). We thus study the general properties of the enlarged sample of 10 ``cold" dusty galaxies over 3.5~4, together with the severe impact of the CMB on their RJ observables, paving the way for the diagnostics of optically thick dust in the early universe. Conventional gas mass estimates based on RJ dust continuum luminosities implicitly assume an optically thin case, overestimating gas masses by a factor of 2--3 on average in compact dusty star-forming galaxies.

  • Broadband Dark Matter Axion Detection using a Cylindrical Capacitor

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The cosmological axions/axion-like particles can compose a significant part of dark matter, however the uncertainty of their mass is large. Here we propose to search the axions using a cylindrical capacitor, in which the static electric field converts dark matter axions into an oscillating magnetic field. Using a static electric field can greatly reduce the magnetic field background compared to using the $\vec B$ field in which the small fluctuations could be hard to annihilate. A cylindrical setup shields the electric field to the laboratory as well as encompasses the axion induced magnetic field within the capacitor, and results in an increased magnetic field strength. The induced oscillating magnetic field then can be picked up by a very sensitive magnetometer. In addition, adding a superconductor ring-coil system into the induced magnetic field region can further boost the sensitivity and maintain the axion dark matter inherent bandwidth. This proposed setup is capable of a wide mass range search.

  • Non-detection of Broad Hydrogen Radio Recombination Lines in Circinus Galaxy

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The line widths of broad line regions (BLRs) of AGNs are key parameters for understanding the central super massive black holes (SMBHs). However, due to obscuration from dusty torus, optical recombination lines from BLRs in type II AGNs can not be directly detected. Radio recombination lines (RRLs), with low extinction, can be ideal tracers to probe emission from BLRs in type II AGNs. We performed RRL observations for H35$\alpha$ and H36$\alpha$ toward the center of Circinus galaxy with ALMA. Narrow components of H35$\alpha$ and H36$\alpha$, which are thought to be mainly from star forming regions around the nuclear region, are detected. However, only upper limits are obtained for broad H35$\alpha$ and H36$\alpha$. Since Circinus galaxy is one of the nearest AGN, non-detection of broad RRLs in Circinus galaxy at this band tells us that it is hopeless to detect broad RRL emission in local AGNs with current facilities. Submillimetre RRLs, with flux densities that are dozens of times higher than those at the millimetre level, could be the tools to directly detect BLRs in type II AGNs with ALMA, once its backend frequency coverage has been upgraded to several times better than its current capabilities.

  • The Minimal UV-induced Effective QCD Axion Theory

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The characteristic axion couplings could be generated via effective couplings between the Standard Model (SM) fermions to a pseudo-Goldstone from a high-scale $U(1)$ Peccei-Quinn (PQ) symmetry breaking. Assuming that the UV-induced effective operators generate necessary couplings before the PQ symmetry breaking, and any low-scale couplings to the SM are restricted to the Yukawa sector, three minimal natural scenarios can be formulated, which provides a connection between the QCD-axions and mediators at the GUT/string scales. We find that the PQ symmetry breaking scale could be about $10^{15}$ GeV, higher than the classical QCD dark matter axion window but possible if the anthropic window is considered. We also propose an experiment to probe such scenarios. If the dark matter axion is discovered, they might suggest that we live in an atypical Hubble volume.

  • 21-cm constraints on spinning primordial black holes

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Hawking radiation from primordial black holes (PBH) can ionize and heat up neutral gas during the cosmic dark ages, leaving imprints on the global 21-cm signal of neutral hydrogen. We use the global 21-cm signal to constrain the abundance of spinning PBHs in mass range of $[2 \times 10^{13}, 10^{18}]$ grams. We consider several extended PBH distribution models. Our results show that 21-cm can set the most stringent PBH bounds in our mass window. Compared with constraints set by {\it Planck} cosmic microwave background (CMB) data, 21-cm limits are more stringent by about two orders of magnitudes. PBHs with higher spin are typically more strongly constrained. Our 21-cm constraints for the monochromatic mass distribution rule out spinless PBHs with initial mass below $1.5 \times 10^{17}\ \r{g}$, whereas extreme Kerr PBHs with reduced initial spin of $a_0=0.999$ are excluded as the dominant dark matter component for masses below $6 \times 10^{17}\ \r{g}$. We also derived limits for the log-normal, power-law and critical collapse PBH mass distributions.

  • Resonant Electric Probe to Axionic Dark Matter

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The oscillating light axion field is known as wave dark matter. We propose an LC-resonance enhanced detection of the narrow band electric signals induced by the axion dark matter using a solenoid magnet facility. We provide full 3D electromagnetic simulation results for the signal electric field. The electric signal is enhanced by the high $Q$-factor of a resonant LC circuit and then amplified and detected by the state-of-the-art cryogenic electrical transport measurement technique. The amplifier noise is the leading noise in the setup. We demonstrate that the setup has promising sensitivity for axionic dark matter with mass $m_a$ below $10^{-6}$ eV. The projected sensitivities increase with the size of the magnetic field, and the electric signal measurement can be potentially sensitive to the QCD axion with $g_{a\gamma} \sim 10^{-16}$ GeV$^{-1}$ with a multi-meter scale magnetized region.

  • Constraining primordial black holes with relativistic degrees of freedom

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Scalar perturbations in the early Universe create over-dense regions that can collapse into primordial black holes (PBH). This process emits scalar-induced gravitational waves (SIGW) that behaves like an extra radiation component and contributes to the relativistic degrees of freedom ($N_{\rm{eff}}$). We show that $N_{\rm{eff}}$ limits from cosmic microwave background (CMB) give promising sensitivities on both the abundance of PBHs and the primordial curvature perturbation ($\mathcal{P}_{\mathcal{R}}(k)$) at small scales. We show that {\it Planck} and ACTPol data can exclude supermassive PBHs with peak mass $M_{\bullet} \in [3 \times 10^{5}, 5 \times 10^{10}] {\rm{M}}_{\odot}$ as the major component of dark matter, depending on the shape of the PBHs mass distribution. Future CMB-S4 mission is capable of broadening this limit to a vast PBH mass window of $M_{\bullet} \in [8 \times 10^{-5}, 5 \times 10^{10}] {\rm{M}}_{\odot}$, covering sub-stellar masses. These limits correspond to the enhanced sensitivity of $\mathcal{P}_{\mathcal{R}}(k)$ on scales of $k \in [10^1, 10^{22}]\ \rm{Mpc^{-1}}$, which is much smaller than those scales probed by direct perturbation power spectra (CMB and large-scale structure).

  • Resonant Electric Probe to Axionic Dark Matter

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The oscillating light axion field is known as wave dark matter. We propose an LC-resonance enhanced detection of the narrow band electric signals induced by the axion dark matter using a solenoid magnet facility. We provide full 3D electromagnetic simulation results for the signal electric field. The electric signal is enhanced by the high $Q$-factor of a resonant LC circuit and then amplified and detected by the state-of-the-art cryogenic electrical transport measurement technique. The amplifier noise is the leading noise in the setup. We demonstrate that the setup has promising sensitivity for axionic dark matter with mass $m_a$ below $10^{-6}$ eV. The projected sensitivities increase with the size of the magnetic field, and the electric signal measurement can be potentially sensitive to the QCD axion with $g_{a\gamma} \sim 10^{-16}$ GeV$^{-1}$ with a multi-meter scale magnetized region.

  • A scaling relation in [C II]-detected galaxies and its likely application in cosmology

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We identify and investigate a possible correlation between the $\rm{[CII]} 158{\mu}m$ luminosity and linewidth in the $\rm{[CII]}$-detected galaxies. Observationally, the strength of the $\rm{[CII]} 158{\mu}m$ emission line is usually stronger than that of the CO emission line and this $\rm{[CII]}$ line has been used as another tracer of the galactic characteristics. Moreover, many $\rm{[CII]}$-detected galaxies are identified in $z > 4$. Motivated by previous studies of the CO luminosity - FWHM correlation relation (LFR) and the available new $\rm{[CII]}$ measurements, we compile samples of the $\rm{[CII]}$-detected galaxies in the literature and perform the linear regression analysis. The $\rm{[CII]}$ LFR is confirmed at a robust level. We also demonstrate the possible application of the $\rm{[CII]}$ LFR by utilizing it on the distance measurement of the high-$z$ galaxy. As a result, we extend the cosmic spatial scale beyond the redshift $z$ of $7$. With the outcome of the distance measurement, we constrain the cosmology parameters in the Chevallier-Polarski-Linder model, which considers the evolution of dark energy. Consequently, the uncertainties of the $\textit{w}_{0}$ and $\textit{w}_{a}$ are reduced significantly when the measured distance data of the $\rm{[CII]}$-detected galaxies are included in the cosmological parameter constraint, exemplifying the potential of using the $\rm{[CII]}$-detected galaxies as a tracer to constrain the cosmological parameters.

  • Quantum dual-path interferometry scheme for axion dark matter searches

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We propose a dual-path interferometry amplification configuration in the cavity axion dark matter searches. We show quantum-mechanically that, in a low temperature cavity permeated by a magnetic field, the single axion-photon conversion rate is enhanced by the cavity quality factor $Q$, and quantitatively larger than the classical result by a factor $\pi/2$. Under modern cryogenic conditions, thermal photons in the cavity are negligible, thus the axion cavity can be considered as a quantum device emitting single-photons with temporal separations. This differs from the classical picture in which axions transition in batches and the converted energy accumulates in the electromagnetic field inside the cavity. It reveals a possibility for the axion cavity experiment to handle the signal sensitivity at the quantum level, e.g. cross-power and second order correlation measurements. The correlation of photon field quadratures in the amplification chain, within current technology, enhances the signal-to-noise ratio up to two orders of magnitude or one order of magnitude compared with single-path amplification scheme based on high electronic mobility transistor amplifier or Josephson Parametric Amplifiers (JPA), respectively. Especially, it is useful to combine the dual-path interferometry scheme with other techniques, e.g. JPAs, to overcome the inevitable microwave signals insertion loss (normally it is $\sim-3\,$dB) in the channels between the cavity and the quantum-limited amplifiers. This enhancement would greatly reduce the signal scanning time and improve the sensitivity of the axion-photon coupling. In addition, the second order correlation function measurement in the due path scheme can provide an additional verification that if the candidate signals are axion converted or other noises.

  • NOEMA Observations of CO Emission in Arp 142 and Arp 238

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Previous studies have shown significant differences in the enhancement of the star-formation rate (SFR) and the star-formation efficiency (SFE=SFR/M_mol) between spiral-spiral and spiral-elliptical mergers. In order to shed light on the physical mechanism of these differences, we present NOEMA observations of the molecular gas distribution and kinematics (linear resolutions of ~ 2kpc) in two representative close major-merger star-forming pairs: the spiral-elliptical pair Arp142 and the spiral-spiral pair Arp238. The CO in Arp142 is widely distributed over a highly distorted disk without any nuclear concentration, and an off-centric ring-like structure is discovered in channel maps. The SFE varies significantly within Arp142, with a starburst region (Region 1) near the eastern tip of the distorted disk showing an SFE ~0.3 dex above the mean of the control sample of isolated galaxies, and the SFE of the main disk (Region 4) 0.43 dex lower than the mean of the control sample. In contrast, the CO emission in Arp238 is detected only in two compact sources at the galactic centers. Compared to the control sample, Arp238-E shows an SFE enhancement of more than 1 dex whereas Arp238-W has an enhancement of ~0.7 dex. We suggest that the extended CO distribution and the large SFE variation in Arp142 are due to an expanding large-scale ring triggered by a recent high-speed head-on collision between the spiral galaxy and the elliptical galaxy, and the compact CO sources with high SFEs in Arp238 are associated with nuclear starbursts induced by gravitational tidal torques in a low-speed coplanar interaction.

  • Deep Observations of CO and Free-Free Emission in Ultraluminous Infrared QSO IRAS F07599+6508

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Infrared quasi-stellar objects (IR QSOs) are a rare subpopulation selected from ultraluminous infrared galaxies (ULIRGs) and have been regarded as promising candidates of ULIRG-to-optical QSO transition objects. Here we present NOEMA observations of the CO(1-0) line and 3 mm continuum emission in an IR QSO IRAS F07599+6508 at $z=0.1486$, which has many properties in common with Mrk 231. The CO emission is found to be resolved with a major axis of $\sim$6.1 kpc that is larger than the size of $\sim$4.0 kpc derived for 3 mm continuum. We identify two faint CO features located at a projected distance of $\sim$11.4 and 19.1 kpc from the galaxy nucleus, respectively, both of which are found to have counterparts in the optical and radio bands and may have a merger origin. A systematic velocity gradient is found in the CO main component, suggesting that the bulk of molecular gas is likely rotationally supported. Based on the radio-to-millimeter spectral energy distribution and IR data, we estimate that about 30$\%$ of the flux at 3 mm arises from free-free emission and infer a free-free-derived star formation rate of 77 $M_\odot\ {\rm yr^{-1}}$, close to the IR estimate corrected for the AGN contribution. We find a high-velocity CO emission feature at the velocity range of about -1300 to -2000 km s$^{-1}$. Additional deep CO observations are needed to confirm the presence of a possible very high-velocity CO extension of the OH outflow in this IR QSO.

  • The Carbon-to-H$_2$, CO-to-H$_2$ Conversion Factors and Carbon Abundance on Kiloparsec Scales in Nearby Galaxies

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Using the atomic carbon [CI](1$-$0) and [CI](2$-$1) emission maps observed with the $Herschel\ Space\ Observatory$, and CO(1$-$0), HI, infrared and submm maps from literatures, we estimate the [CI]-to-H$_2$ and CO-to-H$_2$ conversion factors of $\alpha_\mathrm{[CI](1-0)}$, $\alpha_\mathrm{[CI](2-1)}$, and $\alpha_\mathrm{CO}$ at a linear resolution $\sim1\,$kpc scale for six nearby galaxies of M 51, M 83, NGC 3627, NGC 4736, NGC 5055, and NGC 6946. This is perhaps the first effort, to our knowledge, in calibrating both [CI]-to-H$_2$ conversion factors across the spiral disks at spatially resolved $\sim1\,$kpc scale though such studies have been discussed globally in galaxies near and far. In order to derive the conversion factors and achieve these calibrations, we adopt three different dust-to-gas ratio (DGR) assumptions which scale approximately with metallicity taken from precursory results. We find that for all DGR assumptions, the $\alpha_\mathrm{[CI](1-0)}$, $\alpha_\mathrm{[CI](2-1)}$, and $\alpha_\mathrm{CO}$ are mostly flat with galactocentric radii, whereas both $\alpha_\mathrm{[CI](2-1)}$ and $\alpha_\mathrm{CO}$ show decrease in the inner regions of galaxies. And the central $\alpha_\mathrm{CO}$ and $\alpha_\mathrm{[CI](2-1)}$ values are on average $\sim 2.2$ and $1.8$ times lower than its galaxy averages. The obtained carbon abundances from different DGR assumptions show flat profiles with galactocentric radii, and the average carbon abundance of the galaxies is comparable to the usually adopted value of $3 \times 10^{-5}$. We find that both metallicity and infrared luminosity correlate moderately with the $\alpha_\mathrm{CO}$ whereas only weakly with either the $\alpha_\mathrm{[CI](1-0)}$ or carbon abundance, and not at all with the $\alpha_\mathrm{[CI](2-1)}$.

  • Quantum dual-path interferometry scheme for axion dark matter searches

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We propose a dual-path interferometry amplification configuration in the cavity axion dark matter searches. We show quantum-mechanically that, in a low temperature cavity permeated by a magnetic field, the single axion-photon conversion rate is enhanced by the cavity quality factor $Q$, and quantitatively larger than the classical result by a factor $\pi/2$. Under modern cryogenic conditions, thermal photons in the cavity are negligible, thus the axion cavity can be considered as a quantum device emitting single-photons with temporal separations. This differs from the classical picture in which axions transition in batches and the converted energy accumulates in the electromagnetic field inside the cavity. It reveals a possibility for the axion cavity experiment to handle the signal sensitivity at the quantum level, e.g. cross-power and second order correlation measurements. The correlation of photon field quadratures in the amplification chain, within current technology, enhances the signal-to-noise ratio up to two orders of magnitude or one order of magnitude compared with single-path amplification scheme based on high electronic mobility transistor amplifier or Josephson Parametric Amplifiers (JPA), respectively. Especially, it is useful to combine the dual-path interferometry scheme with other techniques, e.g. JPAs, to overcome the inevitable microwave signals insertion loss (normally it is $\sim-3\,$dB) in the channels between the cavity and the quantum-limited amplifiers. This enhancement would greatly reduce the signal scanning time and improve the sensitivity of the axion-photon coupling. In addition, the second order correlation function measurement in the due path scheme can provide an additional verification that if the candidate signals are axion converted or other noises.

  • From haloes to galaxies. III. The gas cycle of local galaxy populations

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: In Dou et al. (2021), we introduced the Fundamental Formation Relation (FFR), a tight relation between specific SFR (sSFR), H$_2$ star formation efficiency (SFE$_{\rm H_2}$), and the ratio of H$_2$ to stellar mass. Here we show that atomic gas HI does not follow a similar FFR as H$_2$. The relation between SFE$_{\rm HI}$ and sSFR shows significant scatter and strong systematic dependence on all of the key galaxy properties that we have explored. The dramatic difference between HI and H$_2$ indicates that different processes (e.g., quenching by different mechanisms) may have very different effects on the HI in different galaxies and hence produce different SFE$_{\rm HI}$-sSFR relations, while the SFE$_{\rm H_2}$-sSFR relation remains unaffected. The facts that SFE$_{\rm H_2}$-sSFR relation is independent of other key galaxy properties, and that sSFR is directly related to the cosmic time and acts as the cosmic clock, make it natural and very simple to study how different galaxy populations (with different properties and undergoing different processes) evolve on the same SFE$_{\rm H_2}$-sSFR $\sim t$ relation. In the gas regulator model (GRM), the evolution of a galaxy on the SFE$_{\rm H_2}$-sSFR($t$) relation is uniquely set by a single mass-loading parameter $\lambda_{\rm net,H_2}$. This simplicity allows us to accurately derive the H$_2$ supply and removal rates of the local galaxy populations with different stellar masses, from star-forming galaxies to the galaxies in the process of being quenched. This combination of FFR and GRM, together with the stellar metallicity requirement, provide a new powerful tool to study galaxy formation and evolution.

  • Non-detection of Broad Hydrogen Radio Recombination Lines in Circinus Galaxy

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: The line widths of broad line regions (BLRs) of AGNs are key parameters for understanding the central super massive black holes (SMBHs). However, due to obscuration from dusty torus, optical recombination lines from BLRs in type II AGNs can not be directly detected. Radio recombination lines (RRLs), with low extinction, can be ideal tracers to probe emission from BLRs in type II AGNs. We performed RRL observations for H35$\alpha$ and H36$\alpha$ toward the center of Circinus galaxy with ALMA. Narrow components of H35$\alpha$ and H36$\alpha$, which are thought to be mainly from star forming regions around the nuclear region, are detected. However, only upper limits are obtained for broad H35$\alpha$ and H36$\alpha$. Since Circinus galaxy is one of the nearest AGN, non-detection of broad RRLs in Circinus galaxy at this band tells us that it is hopeless to detect broad RRL emission in local AGNs with current facilities. Submillimetre RRLs, with flux densities that are dozens of times higher than those at the millimetre level, could be the tools to directly detect BLRs in type II AGNs with ALMA, once its backend frequency coverage has been upgraded to several times better than its current capabilities.

  • Constraining primordial black holes with relativistic degrees of freedom

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Scalar perturbations in the early Universe create over-dense regions that can collapse into primordial black holes (PBH). This process emits scalar-induced gravitational waves (SIGW) that behaves like an extra radiation component and contributes to the relativistic degrees of freedom ($N_{\rm{eff}}$). We show that $N_{\rm{eff}}$ limits from cosmic microwave background (CMB) give promising sensitivities on both the abundance of PBHs and the primordial curvature perturbation ($\mathcal{P}_{\mathcal{R}}(k)$) at small scales. We show that {\it Planck} and ACTPol data can exclude supermassive PBHs with peak mass $M_{\bullet} \in [3 \times 10^{5}, 5 \times 10^{10}] {\rm{M}}_{\odot}$ as the major component of dark matter, depending on the shape of the PBHs mass distribution. Future CMB-S4 mission is capable of broadening this limit to a vast PBH mass window of $M_{\bullet} \in [8 \times 10^{-5}, 5 \times 10^{10}] {\rm{M}}_{\odot}$, covering sub-stellar masses. These limits correspond to the enhanced sensitivity of $\mathcal{P}_{\mathcal{R}}(k)$ on scales of $k \in [10^1, 10^{22}]\ \rm{Mpc^{-1}}$, which is much smaller than those scales probed by direct perturbation power spectra (CMB and large-scale structure).

  • Dense Gas and Star Formation in Nearby Infrared Bright Galaxies: APEX survey of HCN and HCO+ J=2-1

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Both Galactic and extragalactic studies on star formation suggest that stars form directly from dense molecular gas. To trace such high volume density gas, HCN and HCO+ J=1-0 have been widely used for their high dipole moments, relatively high abundances, and often being the strongest lines after CO. However, HCN and HCO+ J=1-0 emission could be arguably dominated by the gas components at low volume densities. HCN J=2-1 and HCO+ J=2-1, with more suitable critical densities and excitation requirements, would trace typical dense gas closely related to star formation. Here we report new observations of HCN J=2-1 and HCO+ J=2-1 towards 17 nearby infrared-bright galaxies with the APEX 12-m telescope. The correlation slopes between luminosities of HCN J=2-1, and HCO+ J=2-1 and total infrared emission are 1.03 +- 0.05 and 1.00 +- 0.05, respectively. The correlations of their surface densities, normalised with the area of radio/sub-millimeter continuum, show even tighter relations (Slopes: 0.99 +- 0.03 and 1.02 +- 0.03). The eight AGN-dominated galaxies show no significant difference from the eleven star-formation dominated galaxies in above relations. The average HCN/HCO+ ratios are 1.15 +- 0.26 and 0.98 +- 0.42 for AGN-dominated and star-formation dominated galaxies, respectively, without obvious dependencies on infrared luminosity, dust temperature, or infrared pumping. The Magellanic Clouds roughly follow the same correlations, expanding to eight orders of magnitude. On the other hand, ultra-luminous infrared galaxies with active galactic nucleus (AGN) systematically lay above the correlations, indicating potential biases introduced by AGNs.

  • A scaling relation in [C II]-detected galaxies and its likely application in cosmology

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We identify and investigate a possible correlation between the $\rm{[CII]} 158{\mu}m$ luminosity and linewidth in the $\rm{[CII]}$-detected galaxies. Observationally, the strength of the $\rm{[CII]} 158{\mu}m$ emission line is usually stronger than that of the CO emission line and this $\rm{[CII]}$ line has been used as another tracer of the galactic characteristics. Moreover, many $\rm{[CII]}$-detected galaxies are identified in $z > 4$. Motivated by previous studies of the CO luminosity - FWHM correlation relation (LFR) and the available new $\rm{[CII]}$ measurements, we compile samples of the $\rm{[CII]}$-detected galaxies in the literature and perform the linear regression analysis. The $\rm{[CII]}$ LFR is confirmed at a robust level. We also demonstrate the possible application of the $\rm{[CII]}$ LFR by utilizing it on the distance measurement of the high-$z$ galaxy. As a result, we extend the cosmic spatial scale beyond the redshift $z$ of $7$. With the outcome of the distance measurement, we constrain the cosmology parameters in the Chevallier-Polarski-Linder model, which considers the evolution of dark energy. Consequently, the uncertainties of the $\textit{w}_{0}$ and $\textit{w}_{a}$ are reduced significantly when the measured distance data of the $\rm{[CII]}$-detected galaxies are included in the cosmological parameter constraint, exemplifying the potential of using the $\rm{[CII]}$-detected galaxies as a tracer to constrain the cosmological parameters.

  • Prospects of Future CMB Anisotropy Probes for Primordial Black Holes

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: Cascade of particles injected as Hawking Radiation from Primordial Black Holes (PBH) can potentially change the cosmic recombination history by ionizing and heating the intergalactic medium, which results in altering the anisotropy spectra of the Cosmic Microwave Background (CMB). In this paper, we study the expected sensitivity of several future CMB experiments in constraining the abundance of PBHs distributed in $10^{15}\sim10^{17}$ g mass window according to four mass functions: the monochromatic, log-normal, power-law and critical collapse models. Our result shows that future experiments, such as CMB-S4 and PICO, can improve current {\it{Planck}} bounds by about two orders of magnitudes. All regions in PBH parameter space that are allowed by current CMB data, including monochromatically distributed PBHs with mass heavier than $4 \times 10^{16}$ grams, can be excluded by upcoming missions with high significance.