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Register a new userDense and warm neutral gas in BR1202-0725 at z = 4.7 as traced by the [O I] 145 um line
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We report the detection of [O I]145.5um in the BR 1202-0725 system, a compact group at z=4.7 consisting of a quasar (QSO), a submillimeter-bright galaxy (SMG), and three faint Lya emitters. By taking into account the previous detections and upper limits, the [O I]/[C II] line ratios of the now five known high-z galaxies are higher than or on the high-end of the observed values in local galaxies ([O I]/[C II]$gtrsim$0.13). The high [O I]/[C II] ratios and the joint analysis with the previous detection of [N II] lines for both the QSO and the SMG suggest the presence of warm and dense neutral gas in these highly star-forming galaxies. This is further supported by new CO (12-11) line detections and a comparison with cosmological simulations. There is a possible positive correlation between the [NII]122/205 line ratio and the [O I]/[C II] ratio when all local and high-z sources are taken into account, indicating that the denser the ionized gas, the denser and warmer the neutral gas (or vice versa). The detection of the [O I] line in the BR1202-0725 system with a relatively short amount of integration with ALMA demonstrates the great potential of this line as a dense gas tracer for high-z galaxies.
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The radio-quiet quasar BR1202-0725 (z=4.695) is a remarkable source with a bright Northwest (NW) companion detected at submm and radio wavelengths but invisible in the optical. In the absence of amplification by gravitational lensing, BR1202-0725 would be the most luminous binary CO and FIR source in the Universe. In this paper, we report observations with the IRAM Plateau de Bure interferometer of BR1202-0725 in the redshifted emission of the CO(5-4) and (7-6) lines, the [C I](3P2-3P1) line, a high angular resolution (0.3 x 0.8 arcsec) 1.3 mm map of the rest-frame, far-IR dust continuum, and a search for the CO(11-10) line. We compare these results with recent ALMA data in the [C II] line. Both the quasar host galaxy and its NW companion are spatially resolved in the molecular line emission and the dust continuum. The CO profile of the NW companion is very broad with a full width at half maximum of 1000 +/- 130 km/s, compared to 360 +/- 40 km/s for the quasar host galaxy to the Southeast (SE). The difference in linewidths and center velocities, and the absence of any lens candidate or arc-like structure in the field, at any wavelength, show that the obscured NW galaxy and the SE quasar host galaxy cannot be lensed images of the same object. Instead, we find morphological and kinematic evidence for sub-structures in both the NW and SE sources. We interpret these results as strong indications that the BR1202-0725 complex is a group of young, interacting, and highly active starburst galaxies.
We present ~3 resolution imaging of the z=4.7 QSO BR1202-0725 at 900 micron from the Submillimeter Array. The two submillimeter continuum components are clearly resolved from each other, and the positions are consistent with previous lower frequency images. In addition, we detect [CII] line emission from the northern component. The ratio of [CII] to far-infrared luminosity is 0.04% for the northern component, and an upper limit of < 0.03% is obtained for the southern component. These ratios are similar to the low values found in local ultraluminous galaxies, indicating that the excitation conditions are different from those found in local field galaxies. X-ray emission is detected by Chandra from the southern component at L$_{0.5-2keV}=3times10^{45}$~erg~s$^{-1}$, and detected at 99.6% confidence from the northern component at L$_{0.5-2keV}sim3times10^{44}$erg~s$^{-1}$, supporting the idea that BR1202-0725 is a pair of interacting galaxies at z=4.7 that each harbor an active nucleus.
We use sensitive observations of three high redshift sources; [CII] fine structure and CO(2-1) rotational transitions for the z=6.4 Quasar host galaxy (QSO) J1148+5251, and [CII] and CO(5-4) transitions from the QSO BR1202-0725 and its sub-millimeter companion (SMG) galaxy at z=4.7. We use these observations to place constraints on the quantity Dz = z(CO) - z(CII) for each source where z(CO) and z(CII) are the observed redshifts of the CO rotational transition and [CII] fine structure transition respectively, using a combination of approaches; 1) By modelling the emission line profiles using `shapelets to compare both the emission redshifts and the line profiles themselves, in order to make inferences about the intrinsic velocity differences between the molecular and atomic gas, and 2) By performing a marginalisation over all model parameters in order to calculate a non-parametric estimate of Dz. We derive 99% confidence intervals for the marginalised posterior of Dz of (-1.9 pm 1.3) x10^-3, (-3 pm 8) x10^-4 and (-2 pm 4) x10^-3 for J1148+5251, and the BR1202-0725 QSO and SMG respectively. We show the [CII] and CO(2-1) line profiles for J1148+5251 are consistent with each other within the limits of the data, whilst the [CII] and CO(5-4) line profiles from the BR1202-0725 QSO and SMG respectively have 65 and >99.9% probabilities of being inconsistent, with the CO(5-4) lines ~ 30% wider than the [CII] lines. Therefore whilst the observed values of Dz can correspond to variations in the quantity Delta F/F with cosmic time, where F=alpha^2/mu, with alpha the fine structure constant, and mu the proton-to-electron mass ratio, of both (-3.3 pm 2.3) x10^-4 for a look back time of 12.9 Gyr and of (-5 pm 15) x10^-5 for a look back time of 12.4 Gyr we propose that they are the result of the two species of gas being spatially separated as indicated by the inconsistencies in their line profiles.
Aims. We aim to investigate the I([CII]) versus I([NII]) integrated intensity behavior in the AF region in order to assess the [CII] emission contribution from the H II region, which is traced by [NII] line observations, and PDR components in the high-metallicity environment of the GC. Methods. We used [CII] 158 um and [NII] 205 um fine-structure line observations of the AF in the literature to compare their observational integrated intensity distribution to semi-theoretical predictions for the contribution of H II regions and adjacent PDRs to the observed [CII] emission. We explored variations in the [C/N] elemental abundance ratio to explain the overall behavior of the observed relationship. Based on our models, the H II region and PDR contributions to the observed [CII] emission is calculated for a few positions within and near to the AF. Estimates for the [C/N] abundance ratio and [N/H] nitrogen elemental abundance in the AF can then be derived. Results. The behavior of the I([CII]) versus I([NII]) relationship in the AF can be explained by model results satisfying 0.84 < [C/N]_AF < 1.41, with model metallicities ranging from 1 Z to 2 Z, hydrogen volume density log n(H) = 3.5, and ionization parameters log U from -1 to -2. A least-squares fit to the model data points yields log I([CII]) = 1.068log I([NII]) + 0.645 to predict the [CII] emission arising from the H II regions in the AF. The fraction of the total observed [CII] emission arising from within PDRs varies between ~ 0.20 and ~ 0.75. Our results yield average values for the carbon-to-nitrogen ratio and nitrogen elemental abundances of [C/N]_AF = 1.13 +/- 0.09 and [N/H]_AF = 6.21x10^4 for the AF, respectively. They are a factor of ~ 0.4 smaller and ~ 7.5 larger than their corresponding Galactic disk values.
We present initial results from the textit{COS and Gemini Mapping the Circumgalactic Medium} (mbox{CGMCGM} $equiv$ CGM$^{2}$) survey. The CGM$^{2}$ survey consists of 1689 galaxies, all with high-quality Gemini GMOS spectra, within 1 Mpc of twenty-two $z lesssim 1$ quasars, all with S/N$sim$10 {emph{HST/COS}} G130M$+$G160M spectra. For 572 of these galaxies having stellar masses $10^{7} M_{odot} < M_{star} < 10^{11} M_{odot}$ and $z lesssim 0.5$, we show that the ion{H}{1} covering fraction above a threshold of NHI$>10^{14} $cm$^{-2}$ is $gtrsim 0.5$ within 1.5 virial radii ($R_{rm vir} sim R_{200m}$). We examine the ion{H}{1} kinematics and find that the majority of absorption lies within $pm$ 250 km s$^{-1}$ of the galaxy systemic velocity. We examine ion{H}{1} covering fractions over a range of impact parameters to infer a characteristic size of the CGM, $R^{14}_{rm CGM}$, as a function of galaxy mass. $R^{14}_{rm CGM}$ is the impact parameter at which the probability of observing an absorber with NHI $>$ 10$^{14}$ cm$^{-2}$ is $>$ 50%. In this framework, the radial extent of the CGM of $M_{star} > 10^{9.9} M_{odot}$ galaxies is $R^{14}_{rm CGM} = 346^{+57}_{-53}$ kpc or $R^{14}_{rm CGM} simeq 1.2R_{rm vir}$. Intermediate-mass galaxies with $10^{9.2} < M_{star}/M_{odot} < 10^{9.9}$ have an extent of $R^{14}_{rm CGM} = 353^{+64}_{-50}$ kpc or $R^{14}_{rm CGM} simeq 2.4R_{rm vir}$. Low-mass galaxies, $M_{star} < 10^{9.2} M_{odot}$, show a smaller physical scale $R^{14}_{rm CGM} = 177_{-65}^{+70}$ kpc and extend to $R^{14}_{rm CGM} simeq 1.6R_{rm vir}$. Our analysis suggests that using $R_{rm vir}$ as a proxy for the characteristic radius of the CGM likely underestimates its extent.
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