We present new observations, carried out with IRAM NOEMA, of the atomic neutral carbon transitions C
I
(
3
P
1
–
3
P
0
) at 492 GHz and C
I
(
3
P
2
–
3
P
1
) at 809 GHz of GN20, a well-studied ...star-bursting galaxy at
z
= 4.05. The high luminosity line ratio C
I
(
3
P
2
–
3
P
1
) /C
I
(
3
P
1
–
3
P
0
) implies an excitation temperature of 48
+14
−9
K, which is significantly higher than the apparent dust temperature of
T
d
= 33 ± 2 K (
β
= 1.9) derived under the common assumption of an optically thin far-infrared dust emission, but fully consistent with
T
d
= 52 ± 5 K of a general opacity model where the optical depth (
τ
) reaches unity at a wavelength of
λ
0
= 170 ± 23
μ
m. Moreover, the general opacity solution returns a factor of ∼2× lower dust mass and, hence, a lower molecular gas mass for a fixed gas-to-dust ratio, than with the optically thin dust model. The derived properties of GN20 thus provide an appealing solution to the puzzling discovery of starbursts appearing colder than main-sequence galaxies above
z
> 2.5, in addition to a lower dust-to-stellar mass ratio that approaches the physical value predicted for starburst galaxies.
Full text
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FMFMET, NUK, UL, UM, UPUK
We have used two catalogues, a Herschel catalogue selected at 500 μm (HerMES) and an IRAS catalogue selected at 60 μm (RIFSCz), to contrast the sky at these two wavelengths. Both surveys demonstrate ...the existence of “extreme” starbursts, with star-formation rates (SFRs) > 5000 M⊙ yr−1. The maximum intrinsic star-formation rate appears to be ~30 000 M⊙ yr−1. The sources with apparent SFR estimates higher than this are in all cases either lensed systems, blazars, or erroneous photometric redshifts. At redshifts between three and five, the time-scale for the Herschel galaxies to make their current mass of stars at their present rate of star formation is ~108 yr, so these galaxies are making a significant fraction of their stars in the current star-formation episode. Using dust mass as a proxy for gas mass, the Herschel galaxies at redshift three to five have gas masses comparable to their mass in stars. Of the 38 extreme starbursts in our Herschel survey for which we have more complete spectral energy distribution (SED) information, 50% show evidence for QSO-like optical emission, or exhibit AGN dust tori in the mid-infrared SEDs. In all cases however the infrared luminosity is dominated by a starburst component. We derive a mean covering factor for AGN dust as a function of redshift and derive black hole masses and black hole accretion rates. There is a universal ratio of black-hole mass to stellar mass in these high redshift systems of ~10−3, driven by the strong period of star-formation and black-hole growth at z = 1−5.
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Available for:
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Abstract
We report new observations toward the hyperluminous dusty starbursting major merger ADFS-27 (
z
= 5.655), using the Australia Telescope Compact Array (ATCA) and the Atacama Large ...Millimeter/submillimeter Array (ALMA). We detect CO (
J
= 2 → 1), CO (
J
= 8 → 7), CO (
J
= 9 → 8), CO (
J
= 10 → 9), and H
2
O (3
12
→ 2
21
) emission, and a P Cygni−shaped OH
+
(1
1
→ 0
1
) absorption/emission feature. We also tentatively detect H
2
O (3
21
→ 3
12
) and OH
+
(1
2
→ 0
1
) emission and CH
+
(
J
= 1 → 0) absorption. We find a total cold molecular mass of
M
gas
= (2.1 ± 0.2) × 10
11
(
α
CO
/1.0)
M
⊙
. We also find that the excitation of the star-forming gas is overall moderate for a
z
> 5 dusty starburst, which is consistent with its moderate dust temperature. A high-density, high kinetic temperature gas component embedded in the gas reservoir is required to fully explain the CO line ladder. This component is likely associated with the “maximum starburst” nuclei in the two merging galaxies, which are separated by only 140 ± 13 km s
−1
along the line of sight and 9.0 kpc in projection. The kinematic structure of both components is consistent with galaxy disks, but this interpretation remains limited by the spatial resolution of the current data. The OH
+
features are only detected toward the northern component, which is also the one that is more enshrouded in dust and thus remains undetected up to 1.6
μ
m even in our sensitive new Hubble Space Telescope Wide Field Camera 3 imaging. The absorption component of the OH
+
line is blueshifted and peaks near the CO and continuum emission peak, while the emission is redshifted and peaks offset by 1.7 kpc from the CO and continuum emission peak, suggesting that the gas is associated with a massive molecular outflow from the intensely star-forming nucleus that supplies 125
M
⊙
yr
−1
of enriched gas to its halo.
[C i](1–0) and [C i](2–1) in Resolved Local Galaxies Crocker, Alison F.; Pellegrini, Eric; Smith, J.-D. T. ...
Astrophysical journal/The Astrophysical journal,
12/2019, Volume:
887, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
We present resolved C
i
line intensities of 18 nearby galaxies observed with the SPIRE FTS spectrometer on the
Herschel Space Observatory
. We use these data along with resolved CO line ...intensities from
J
up
= 1 to 7 to interpret what phase of the interstellar medium the C
i
lines trace within typical local galaxies. A tight, linear relation is found between the intensities of the CO(4–3) and C
i
(2–1) lines; we hypothesize this is due to the similar upper level temperature of these two lines. We modeled the C
i
and CO line emission using large-velocity gradient models combined with an empirical template. According to this modeling, the C
i
(1–0) line is clearly dominated by the low-excitation component. We determine C
i
to molecular mass conversion factors for both the C
i
(1–0) and C
i
(2–1) lines, with mean values of
α
C
i
(1−0)
= 7.3
M
⊙
K
−1
km
−1
s pc
−2
and
α
C
i
(2−1)
= 34
M
⊙
K
−1
km
−1
s pc
−2
with logarithmic root-mean-square spreads of 0.20 and 0.32 dex, respectively. The similar spread of
to
(derived using the CO(2–1) line) suggests that C
i
(1–0) may be just as good a tracer of cold molecular gas as CO(2–1) in galaxies of this type. On the other hand, the wider spread of
α
C
i
(2−1)
and the tight relation found between C
i
(2–1) and CO(4–3) suggest that much of the C
i
(2–1) emission may originate in warmer molecular gas.
We investigate the relation between star formation rates (
$\dot{{M}}_s$
) and AGN properties in optically selected type 1 quasars at 2 < z < 3 using data from Herschel and the SDSS. We find that
...$\dot{{M}}_s$
remains approximately constant with redshift, at 300 ± 100 M⊙ yr−1. Conversely,
$\dot{{M}}_s$
increases with AGN luminosity, up to a maximum of ∼ 600 M⊙ yr−1, and with C iv FWHM. In context with previous results, this is consistent with a relation between
$\dot{{M}}_s$
and black hole accretion rate (
$\dot{{M}}_{{\rm bh}}$
) existing in only parts of the
$z-\dot{{M}}_{s}-\dot{{M}}_{{\rm bh}}$
plane, dependent on the free gas fraction, the trigger for activity, and the processes that may quench star formation. The relations between
$\dot{{M}}_s$
and both AGN luminosity and C iv FWHM are consistent with star formation rates in quasars scaling with black hole mass, though we cannot rule out a separate relation with black hole accretion rate. Star formation rates are observed to decline with increasing C iv equivalent width. This decline can be partially explained via the Baldwin effect, but may have an additional contribution from one or more of three factors; M
i
is not a linear tracer of L
2500, the Baldwin effect changes form at high AGN luminosities, and high C iv EW values signpost a change in the relation between
$\dot{{M}}_s$
and
$\dot{{M}}_{{\rm bh}}$
. Finally, there is no strong relation between
$\dot{{M}}_s$
and Eddington ratio, or the asymmetry of the C iv line. The former suggests that star formation rates do not scale with how efficiently the black hole is accreting, while the latter is consistent with C iv asymmetries arising from orientation effects.
ABSTRACT We present the Herschel SPIRE Fourier Transform Spectroscopy (FTS) atlas for a complete flux-limited sample of local ultraluminous infrared galaxies (ULIRGs) as part of the HERschel Ultra ...Luminous InfraRed Galaxy Survey (HERUS). The data reduction is described in detail and was optimized for faint FTS sources ,with particular care being taken for the subtraction of the background, which dominates the continuum shape of the spectra. To improve the final spectra, special treatment in the data reduction has been given to any observation suffering from artifacts in the data caused by anomalous instrumental effects. Complete spectra are shown covering 200-671 m, with photometry in the SPIRE bands at 250, 350, and 500 m. The spectra include near complete CO ladders for over half of our sample, as well as fine structure lines from C i 370 m, C i 609 m, and N ii 205 m. We also detect H2O lines in several objects. We construct CO spectral line energy distributions (SLEDs) for the sample, and compare their slopes with the far-infrared (FIR) colors and luminosities. We show that the CO SLEDs of ULIRGs can be broadly grouped into three classes based on their excitation. We find that the mid-J (5 < J < 8) lines are better correlated with the total FIR luminosity, suggesting that the warm gas component is closely linked to recent star formation. The higher J transitions do not linearly correlate with the FIR luminosity, consistent with them originating in hotter, denser gas that is unconnected to the current star formation. We conclude that in most cases more than one temperature component is required to model the CO SLEDs.
Abstract
We report the detection of a massive neutral gas outflow in the
z
= 2.09 gravitationally lensed dusty star-forming galaxy HATLAS J085358.9+015537 (G09v1.40), seen in absorption with the OH
+
...(1
1
−1
0
) transition using spatially resolved (0.″5 × 0.″4) Atacama Large Millimeter/submillimeter Array (ALMA) observations. The blueshifted OH
+
line is observed simultaneously with the CO(9−8) emission line and underlying dust continuum. These data are complemented by high-angular-resolution (0.″17 × 0.″13) ALMA observations of CH
+
(1−0) and underlying dust continuum, and Keck 2.2
μ
m imaging tracing the stellar emission. The neutral outflow, dust, dense molecular gas, and stars all show spatial offsets from each other. The total atomic gas mass of the observed outflow is 6.7 × 10
9
M
⊙
, >25% as massive as the gas mass of the galaxy. We find that a conical outflow geometry best describes the OH
+
kinematics and morphology and derive deprojected outflow properties as functions of possible inclination (0.°38–64°). The neutral gas mass outflow rate is between 83 and 25,400
M
⊙
yr
−1
, exceeding the star formation rate (788 ± 300
M
⊙
yr
−1
) if the inclination is >3.°6 (mass-loading factor = 0.3–4.7). Kinetic energy and momentum fluxes span (4.4–290) × 10
9
L
⊙
and (0.1–3.7) × 10
37
dyne, respectively (energy-loading factor = 0.013–16), indicating that the feedback mechanisms required to drive the outflow depend on the inclination assumed. We derive a gas depletion time between 29 and 1 Myr, but find that the neutral outflow is likely to remain bound to the galaxy unless the inclination is small and may be reaccreted if additional feedback processes do not occur.
Submillimeter galaxies (SMGs) at are luminous in the far-infrared, and have star formation rates, SFR, of hundreds to thousands of solar masses per year. However, it is unclear whether they are true ...analogs of local ULIRGs or whether the mode of their star formation is more similar to that in local disk galaxies. We target these questions by using Herschel-PACS to examine the conditions in the interstellar medium (ISM) in far-infrared luminous SMGs at -4. We present 70-160 m photometry and spectroscopy of the O iv26 m, Fe ii26 m, S iii33 m, Si ii34 m, O iii52 m, N iii57 m, and O i63 m fine-structure lines and the S(0) and S(1) hydrogen rotational lines in 13 lensed SMGs identified by their brightness in early Herschel data. Most of the 13 targets are not individually spectroscopically detected; we instead focus on stacking these spectra with observations of an additional 32 SMGs from the Herschel archive-representing a complete compilation of PACS spectroscopy of SMGs. We detect O i63 m, Si ii34 m, and N iii57 m at in the stacked spectra, determining that the average strengths of these lines relative to the far-IR continuum are , , and , respectively. Using the O iii52 m/N iii57 m emission line ratio, we show that SMGs have average gas-phase metallicities . By using PDR modeling and combining the new spectral measurements with integrated far-infrared fluxes and existing C ii158 m data, we show that SMGs have average gas densities, n, of and FUV field strengths, (in Habing units: ), consistent with both local ULIRGs and lower luminosity star-forming galaxies.
Abstract
In this paper we present our imaging observations on the CO (7−6) line and its underlying continuum emission of the young submillimeter galaxy LESS 073 at redshift 4.755, using the Atacama ...Large Millimeter/submillimeter Array. At the achieved resolution of ∼
(8 × 6 kpc
2
), the CO (7−6) emission is largely unresolved (with a deconvolved size of
), and the continuum emission is totally unresolved. The CO (7−6) line emission has an integrated flux of 0.86 ± 0.08 Jy km s
−1
, and a line width of 343 ± 40 km s
−1
. The continuum emission has a flux density of 0.51 mJy. By fitting the observed far-infrared spectral energy distribution (SED) of LESS 073 with a single-temperature modified blackbody function, we obtained a dust temperature
K, 60–100
μ
m flux density ratio
, and total infrared luminosity
. The SED-fit-based
is consistent with those estimated from various line ratios as advocated by our earlier work, indicating that the proposed line-ratio-based method can be used to practically derive
for high-
z
sources. The total molecular gas mass of LESS 073 is
, and the inferred gas depletion time is about 43 Myr.
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