Abstract
We present emission-line measurements and physical interpretations for a sample of 117 O
iii
emitting galaxies at
z
= 5.33–6.93, using the first deep JWST/NIRCam wide-field slitless ...spectroscopic observations. Our 9.7 hr integration is centered upon the
z
= 6.3 quasar J0100+2802—the first of six fields targeted by the EIGER survey—and covers
λ
= 3–4
μ
m. We detect 133 O
iii
doublets, but close pairs motivated by their small scale clustering excess. The galaxies are characterized by a UV luminosity
M
UV
∼ −19.6 (−17.7 to −22.3), stellar mass ∼10
8
(10
6.8−10.1
)
M
⊙
, H
β
and O
iii
4960+5008
EWs ≈ 850 Å (up to 3000 Å), young ages, a highly excited interstellar medium, and low dust attenuations. These high EWs are very rare in the local universe, but we show they are ubiquitous at
z
∼ 6 based on the measured number densities. The stacked spectrum reveals H
γ
and O
iii
4364
, which shows that the galaxies are typically dust- and metal-poor (E (
B
−
V
) = 0.1,
12
+
log
(
O
/
H
)
=
7.4
) with a high electron temperature (2 × 10
4
K) and a production efficiency of ionizing photons (
ξ
ion
= 10
25.3
Hz erg
−1
). We further show the existence of a strong mass–metallicity relation. The properties of the stars and gas in
z
∼ 6 galaxies conspire to maximize the O
iii
output from galaxies, yielding an O
iii
luminosity density at
z
≈ 6 that is significantly higher than that at
z
≈ 2. Thus, O
iii
emission-line surveys with JWST prove a highly efficient method to trace the galaxy density in the Epoch of Reionization.
We analyze the physical conditions of the cool, photoionized (T similar to 10 super(4) K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos ...within 160 kpc of L ~ L super(*) galaxies at z similar to 0.2. These data are well described by simple photoionization models, with the gas highly ionized (n sub(HII)/n sub(H) gap 99%) by the extragalactic ultraviolet background. Scaling by estimates for the virial radius, R sub(vir), we show that the ionization state (tracked by the dimensionless ionization parameter, U) increases with distance from the host galaxy. The ionization parameters imply a decreasing volume density profile n sub(H) = (10 super(-4+ or -0.25))(R/R sub(vir)) super(-0+ or -0.3). Our derived gas volume densities are several orders of magnitude lower than predictions from standard two-phase models with a cool medium in pressure equilibrium with a hot, coronal medium expected in virialized halos at this mass scale. Applying the ionization corrections to the HI column densities, we estimate a lower limit to the cool gas mass M super(cool) sub(CGM) > 6.5 x 10 super(10) Mmiddot in circle for the volume within R < R sub(vir). Allowing for an additional warm-hot, O VI-traced phase, the CGM accounts for at least half of the baryons purported to be missing from dark matter halos at the 10 super(12) Mmiddot in circle scale.
ABSTRACT We report new observations from a systematic, spectroscopic, ultraviolet absorption-line survey that maps the spatial and kinematic properties of the high velocity gas in the Galactic Center ...(GC) region. We examine the hypothesis that this gas traces the biconical nuclear outflow. We use an ultraviolet spectra of 47 background QSOs and halo stars projected inside and outside the northern Fermi Bubble from the Hubble Space Telescope to study the incidence of high velocity absorption around it. We use five lines of sight inside the northern Fermi Bubble to constrain the velocity and column densities of outflowing gas traced by O i, Al ii, C ii, C iv, Si ii, Si iii, Si iv, and other species. We find that all five lines of sight inside the northern Fermi Bubble exhibit blueshifted high velocity absorption components, whereas only 9 out of the 42 lines of sight outside the northern Fermi Bubble exhibit blueshifted high velocity absorption components. The observed outflow velocity profile decreases with Galactic latitude and radial distance (R) from the GC. The observed blueshifted velocities change from at R 2.3 kpc to at R 6.5 kpc. We derive the metallicity of the entrained gas along the 1H1613-097 sightline, one that passes through the center of the northern Fermi Bubble, finding O/H −0.54 0.15. A simple kinematic model, tuned to match the observed absorption component velocities along the five lines of sight inside the Bubble, constrains the outflow velocities to 1000-1300 , and the age of the outflow to be ∼6-9 Myr. We estimate a minimum mass outflow rate for the nuclear outflow to be . Combining the age and mass outflow rates, we determine a minimum mass of total UV-absorbing cool gas entrained in the Fermi Bubbles to be .
We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z < or =, slant 0.1 galaxies using background QSOs ...observed with the Cosmic Origins Spectrograph. From the projected one-dimensional and two-dimensional distribution of C IV absorption, we find that C IV is detected out to approximately 100 kpc (corresponding roughly to approximately 0.5 R sub(vir)) of the host galaxies. The C IV absorption strength falls off radially as a power law, and beyond approximately 0.5 R sub(vir) no C IV absorption is detected above our sensitivity limit of approximately 50-100 mA. We find a tentative correlation between detected C IV absorption strength and star formation, paralleling the strong correlation seen in highly ionized oxygen for L ~ L* galaxies by the COS-Halos survey. The data imply a large carbon reservoir in the circumgalactic medium (CGM) of these galaxies, corresponding to a minimum carbon mass of gap1.2 x 10 super(6) M sub(middot in circle) out to ~110 kpc. This mass is comparable to the carbon mass in the interstellar medium and exceeds the carbon mass currently in the stars of these galaxies. The C IV absorption seen around these sub-L* galaxies can account for almost two-thirds of all W sub(r) > or =, slanted 100 mA C IV absorption detected at low z. Comparing the C IV covering fraction with hydrodynamical simulations, we find that an energy-driven wind model is consistent with the observations whereas a wind model of constant velocity fails to reproduce the CGM or the galaxy properties.
Abstract
The Galactic Center (GC) is surrounded by plasma lobes that extend up to ∼14 kpc above and below the plane. Until now, UV absorption studies of these lobes have only focused on high-velocity ...components (∣
v
LSR
∣ > 100 km s
−1
) because low- and intermediate-velocity (LIV) components (∣
v
LSR
∣ < 100 km s
−1
) are blended with foreground interstellar medium. To overcome this difficulty, we present a differential experiment to compare the LIV absorption between different structures within the GC region, including the Fermi Bubbles (FBs; seen in gamma rays), the eROSITA Bubbles (eBs; seen in X-rays), and the Loop I North Polar Spur (LNPS) association, an X-ray and radio feature within the northern eB. We use far-UV spectra from Hubble Space Telescope to measure LIV Si
iv
absorption in 61 active galactic nuclei sight lines, of which 21 pass through the FBs, 53 pass through the eBs, and 18 pass through the LNPS. We also compare our measurements to those in the literature from sight lines covering the disk–halo interface and circumgalactic medium (CGM). We find that the FBs and eBs have enhancements in measured columns of 0.22–0.29 dex in log. We also remove the contribution of a modeled disk and CGM component from the measured Si
iv
columns and find that the northern eB still retains a Si
iv
enhancement of 0.62 dex in log. A similar enhancement is not seen in the southern eB. Since a notable difference between the northern and southern eBs is the presence of the LNPS association in the nothern bubble, the northern eB enhancement may be caused by the LNPS.
Abstract
We present the first rest-frame optical spectrum of a high-redshift quasar observed with JWST/NIRCam in Wide Field Slitless mode. The observed quasar, J0100+2802, is the most luminous quasar ...known at
z
> 6. We measure the mass of the central supermassive black hole (SMBH) by means of the rest-frame optical H
β
emission line, and find consistent mass measurements of the quasar’s SMBH of
M
•
≈ 10
10
M
☉
when compared to the estimates based on the properties of rest-frame UV emission lines C
iv
and Mg
ii
, which are accessible from ground-based observatories. To this end, we also present a newly reduced rest-frame UV spectrum of the quasar observed with X-Shooter/Very Large Telescope (VLT) and FIRE/Magellan for a total of 16.8 hr. We readdress the question whether this ultraluminous quasar could be effected by strong gravitational lensing making use of the diffraction limited NIRCam images in three different wide band filters (F115W, F200W, F356W), which improves the achieved spatial resolution compared to previous images taken with the Hubble Space Telescope by a factor of 2. We do not find any evidence for a foreground deflecting galaxy, nor for multiple images of the quasar, and determine the probability for magnification due to strong gravitational lensing with image separations below the diffraction limit of Δ
θ
≲ 0.″05 to be ≲2.2 × 10
−3
. Our observations therefore confirm that this quasar hosts a 10 billion solar mass black hole less than 1 Gyr after the Big Bang, which is challenging to explain with current black hole formation models.
Abstract Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and ...determining their role in cosmic reionization. We perform a spectroscopic search for broad H α emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 H α lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s −1 , contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼10 7–8 M ⊙ . In the UV luminosity range M UV,AGN+host = −21 to −18, we measure number densities of ≈10 −5 cMpc −3 . This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad H α LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex H α profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization.
Abstract
Project AMIGA (Absorption Maps In the Gas of Andromeda) is a survey of the circumgalactic medium (CGM) of Andromeda (M31,
≃ 300 kpc) along 43 QSO sightlines at impact parameters 25 ≤
R
... ≤ 569 kpc (25 at
R
≲
). We use ultraviolet absorption measurements of Si
ii
, Si
iii
, Si
iv
, C
ii
, and C
iv
from the Hubble Space Telescope/Cosmic Origins Spectrograph and O
vi
from the Far Ultraviolet Spectroscopic Explorer to provide an unparalleled look at how the physical conditions and metals are distributed in the CGM of M31. We find that Si
iii
and O
vi
have a covering factor near unity for
R
≲ 1.2
and ≲1.9
, respectively, demonstrating that M31 has a very extended ∼10
4
–10
5.5
K ionized CGM. The metal and baryon masses of the 10
4
–10
5.5
K CGM gas within
are ≳10
8
and ≳4 × 10
10
(
Z
/0.3
Z
⊙
)
−1
M
⊙
, respectively. There is not much azimuthal variation in the column densities or kinematics, but there is with
R
. The CGM gas at
R
≲ 0.5
is more dynamic and has more complicated, multiphase structures than at larger radii, perhaps a result of more direct impact of galactic feedback in the inner regions of the CGM. Several absorbers are projected spatially and kinematically close to M31 dwarf satellites, but we show that those are unlikely to give rise to the observed absorption. Cosmological zoom simulations of ∼
L
* galaxies have O
vi
extending well beyond
as observed for M31 but do not reproduce well the radial column density profiles of the lower ions. However, some similar trends are also observed, such as the lower ions showing a larger dispersion in column density and stronger dependence on
R
than higher ions. Based on our findings, it is likely that the Milky Way has a ∼10
4
–10
5.5
K CGM as extended as for M31 and their CGM (especially the warm–hot gas probed by O
vi
) are overlapping.
We analyse the low-redshift (z ≈ 0.2) circumgalactic medium (CGM) by comparing absorption-line data from the COS-Halos survey to absorption around a matched galaxy sample from two cosmological ...hydrodynamic simulations. The models include different prescriptions for galactic outflows, namely hybrid energy/momentum driven wind (ezw), and constant winds (cw). We compare equivalent widths, covering factors, ion ratios, and kinematics. Both wind models show generally ≲ 1σ agreement with these observations for H i and certain low-ionization metal lines, but poorer agreement with higher ionization metal lines including Si iii and O vi that are well observed by COS-Halos. This suggests that both models predict too much cool, metal-enriched gas and not enough hot gas, and / or that metals are not sufficiently mixed. This may reflect our model assumption of ejecting outflows as cool and unmixing gas. Our ezw simulation includes a heuristic prescription to quench massive galaxies by superheating interstellar medium gas. This produces low-ionization absorption broadly consistent with observations, but substantial O vi absorption inconsistent with data, suggesting that gas around quenched galaxies in the real Universe does not cool. At impact parameters of ≲ 50 kpc, recycling winds dominate the absorption of low ions and even H i, while O vi generally arises from metals ejected ≳ 1 Gyr ago. The similarity between the wind models is surprising, since they differ substantially in the amount and phase distribution of halo gas. We show that this similarity owes mainly to our comparison at fixed stellar (not halo) mass, suggesting that CGM properties are more closely tied to galaxy's stellar (versus halo) mass.
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