The analysis of galaxies on the star formation rate-stellar mass (SFR–M∗) plane is a powerful diagnostic for galaxy evolution at different cosmic times. We consider a sample of 24 463 galaxies from ...the CANDELS/GOODS-S survey to conduct a detailed analysis of the SFR–M∗ relation at redshifts \hbox{$0.5\leqslant z<$}0.5 ⩽ z<3 over more than three dex in stellar mass. To obtain SFR estimates, we utilise mid- and far-IR photometry when available, and rest-UV fluxes for all the other galaxies. We perform our analysis in different redshift bins, with two different methods: 1) a linear regression fitting of all star-forming galaxies, defined as those with specific SFRs log 10(sSFR/ yr-1) > −9.8, similarly to what is typically done in the literature; 2) a multi-Gaussian decomposition to identify the galaxy main sequence (MS), the starburst sequence and the quenched galaxy cloud. We find that the MS slope becomes flatter when higher stellar mass cuts are adopted, and that the apparent slope change observed at high masses depends on the SFR estimation method. In addition, the multi-Gaussian decomposition reveals the presence of a starburst population which increases towards low stellar masses and high redshifts. We find that starbursts make up ~ 5% of all galaxies at z = 0.5−1.0, while they account for ~ 16% of galaxies at 2 <z< 3 with log10(M∗/M0) = 8.25–11.25. We conclude that the dissection of the SFR–M∗ in multiple components over a wide range of stellar masses is necessary to understand the importance of the different modes of star formation through cosmic time.
Abstract
We study a large galaxy sample from the Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) to search for sources with enhanced
3.6
μ
m
fluxes indicative of strong H
α
...emission at
z
=
3.9
–
4.9
. We find that the percentage of “H
α
excess” sources reaches 37%–40% for galaxies with stellar masses
log
10
(
M
*
/
M
⊙
)
≈
9
–
10
and decreases to
<
20
%
at
log
10
(
M
*
/
M
⊙
)
∼
10.7
. At higher stellar masses, however, the trend reverses, although this is likely due to active galactic nucleus contamination. We derive star formation rates (SFR) and specific SFR (sSFR) from the inferred H
α
equivalent widths of our “H
α
excess” galaxies. We show, for the first time, that the “H
α
excess” galaxies clearly have a bimodal distribution on the SFR–
M
* plane: they lie on the main sequence of star formation (with
log
10
(
sSFR
/
yr
−
1
)
<
−
8.05
) or in a starburst cloud (with
log
10
(
sSFR
/
yr
−
1
)
>
−
7.60
). The latter contains
∼
15
%
of all the objects in our sample and accounts for
>
50
%
of the cosmic SFR density at
z
=
3.9
–
4.9
, for which we derive a robust lower limit of
0.066
M
⊙
yr
−
1
Mpc
−
3
. Finally, we identify an unusual
>
50
σ
overdensity of
z
=
3.9
–
4.9
galaxies within a
0.20
×
0.20
arcmin
2
region. We conclude that the SMUVS unique combination of area and depth at mid-IR wavelengths provides an unprecedented level of statistics and dynamic range that are fundamental to revealing new aspects of galaxy evolution in the young universe.
Abstract
Mid-infrared (mid-IR) observations are powerful in identifying heavily obscured active galactic nuclei (AGN) that have weak emission in other wavelengths. Data from the Mid-Infrared ...Instrument (MIRI) on board the James Webb Space Telescope provides an excellent opportunity to perform such studies. We take advantage of the MIRI imaging data from the Cosmic Evolution Early Release Science Survey to investigate the AGN population in the distant universe. We estimate the source properties of MIRI-selected objects by utilizing spectral energy distribution (SED) modeling, and classify them into star-forming galaxies (SFs), SF-AGN mixed objects, and AGN. The source numbers of these types are 433, 102, and 25, respectively, from four MIRI pointings covering ∼9 arcmin
2
. The sample spans a redshift range of ≈0–5. We derive the median SEDs for all three source types, respectively, and publicly release them. The median MIRI SED of AGN is similar to the typical SEDs of hot dust-obscured galaxies and Seyfert 2s, for which the mid-IR SEDs are dominated by emission from AGN-heated hot dust. Based on our SED-fit results, we estimate the black hole accretion density (BHAD; i.e., total BH growth rate per comoving volume) as a function of redshift. At
z
< 3, the resulting BHAD agrees with the X-ray measurements in general. At
z
> 3, we identify a total of 27 AGN and SF-AGN mixed objects, leading to that our high-
z
BHAD is substantially higher than the X-ray results (∼0.5 dex at
z
≈ 3–5). This difference indicates MIRI can identify a large population of heavily obscured AGN missed by X-ray surveys at high redshifts.
Aims.
We present a new prediction for the luminosity functions (LFs) of the C
II
line at 158 μm, of the CO lines from
J
= 0 to
J
= 24, and of the molecular gas mass density up to
z
= 10, using ...the Spectro-Photometric Realisations of Infrared-selected Targets at all-
z
(S
PRITZ
) simulation.
Methods.
We update the state-of-the-art phenomenological simulation S
PRITZ
to include both the CO (
J
≤ 24) and the C
II
line luminosities. This has been performed using different empirical and theoretical relations to convert the total infrared luminosity (or star formation rate, SFR) to the C
II
or CO luminosity. The resulting line LFs were compared for validation with a large set of observations available in the literature. We then used the derived CO and C
II
line luminosities to estimate the molecular gas mass density and compare it with available observations.
Results.
The CO and C
II
LFs presented here are in good agreement with all the available observations. In particular, the best results for C
II
are obtained deriving the C
II
luminosity directly from the SFR, but considering a dependence of this relation on the gas metallicity. For all the CO LFs, the estimates favoured by the data are derived considering different relations, depending on the ionisation mechanism dominating each galaxy, namely star formation or active galactic nuclei, and, moreover, by deriving the
J
≥ 4 CO lines directly from the C
II
luminosity. However, further data are necessary to fully distinguish between models. Finally, the best agreements with observations of the molecular gas mass density are derived by converting the C
II
luminosity to H
2
mass, using a C
II
-to-H
2
conversion ∼130
M
⊙
/
L
⊙
. All the line LFs, useful for planning and interpreting future observations, are made publicly available.
Stellar masses in future James Webb Space Telescope (JWST) deep blank fields will be mainly derived by fitting the spectral energy distribution (SED) with theoretical galaxy templates. We investigate ...the uncertainties and biases of the stellar masses derived by using the LePhare code for SED fitting and the Yggdrasil theoretical templates. We consider a sample of mock galaxies at z = 7-10 with mock JWST observations with S/NF150W ≥ 10. Our goal is to provide a list of statistical stellar mass corrections to include on the stellar mass derivation for different output galaxy properties and JWST filter combinations to correct for template degeneracies. Median statistical stellar mass corrections vary from −0.83 to 0.87 dex, while 25% (75%) quartiles range from −0.83 (−0.67) to 0.51 (0.88) dex, depending on filter combinations and galaxy models. The most challenging cases are galaxies with nebular emission lines, especially the ones that are wrongly identified as galaxies without, relative dust-free galaxies, and galaxies with small metallicities (i.e., Z = 1/50 Z ). The stellar mass estimation of galaxies correctly identified without emission lines is generally fine, except at z = 10 when considering only the eight NIRCam bands, which make the MIRI bands very valuable. We have tested our stellar mass corrections using the public JAGUAR galaxy catalog, deriving that the average discrepancy in the recovered stellar mass distribution decreases by 20%-50% at z > 7 after the correction. We found that without the stellar mass corrections, the number of low-mass galaxies (M* < 107 M ) is overestimated, which can potentially lead to systematic errors in the calculation of the galaxy stellar mass function faint-end slope at high z.
Abstract The Cosmic Evolution Early Release Science Survey (CEERS), targeting the Extended Groth Strip extragalactic field, is one of the James Webb Space Telescope Director’s Discretionary Early ...Release Science programs. To date, all observations have been executed and include NIRCam/MIRI imaging and NIRSpec/NIRCam spectroscopic exposures. Here we discuss the MIRI imaging, which includes eight pointings, four of which provide deep imaging with the bluer bands (F560W and F770W) and four of which provide contiguous wavelength coverage in F1000W, F1280W, F1500W, and F1800W, where two of these also include coverage in F770W and F2100W. We present a summary of the data, data quality, and data reduction. The data reduction is based on the jwst calibration pipeline combined with custom modifications and additional steps designed to enhance the output quality, including improvements in astrometry and the removal of detector artifacts. We estimate the image depth of the reduced mosaics and show that these generally agree with expectations from the Exposure Time Calculator. We compare the MIRI F560W and F770W flux densities for bright sources to measurements from Spitzer/IRAC Ch3 (5.8 μ m) and Ch4 (8.0 μ m), and we find that they agree with systematic differences of <0.1 mag. For the redder MIRI bands, we assess their quality by studying the spectral energy distributions (SEDs) of Galactic stars. The SEDs are consistent with the expected Rayleigh–Jeans law with a deviation of ∼0.03 mag, indicating that the MIRI colors are reliable. We also discuss all publicly released data products (images and source catalogs), which are available on the CEERS website ( https://ceers.github.io/ ).
Imaging with the James Webb Space Telescope (JWST) will allow observations of the bulk of distant galaxies at the epoch of reionization. The recovery of their properties, such as age, color excess , ...specific star formation rate (sSFR), and stellar mass, will mostly rely on spectral energy distribution fitting, based on the data provided by JWST's two imager cameras, namely the Near Infrared Camera (NIRCam) and the Mid Infrared Imager (MIRI). In this work we analyze the effect of choosing different combinations of NIRCam and MIRI broadband filters, from 0.6 to 7.7 m, on the recovery of these galaxy properties. We performed our tests on a sample of 1542 simulated galaxies, with known input properties, at z = 7-10. We found that, with only eight NIRCam broadbands, we can recover the galaxy age within 0.1 Gyr and the color excess within 0.06 mag for 70% of the galaxies. Additionally, the stellar masses and sSFR are recovered within 0.2 and 0.3 dex, respectively, at z = 7-9. Instead, at z = 10, no NIRCam band traces purely the λ > 4000 regime and the percentage of outliers in stellar mass (sSFR) increases by >20% (>90%), in comparison to z = 9. The MIRI F560W and F770W bands are crucial to improve the stellar mass and the sSFR estimation at z = 10. When nebular emission lines are present, deriving correct galaxy properties is challenging at any redshift and with any band combination. In particular, the stellar mass is systematically overestimated in up to 0.3 dex on average with NIRCam data alone and including MIRI observations only marginally improves the estimation.
Microwave kinetic inductance detector (MKID) provides a way to build large ground-based sub-mm instruments such as NIKA and A-MKID. For such instruments, therefore, it is important to understand and ...characterize the response to ensure good linearity and calibration over a wide dynamic range. We propose to use the MKID readout frequency response to determine the MKID responsivity to an input optical source power. A signal can be measured in a KID as a change in the phase of the readout signal with respect to the KID resonant circle. Fundamentally, this phase change is due to a shift in the KID resonance frequency, in turn due to a radiation induced change in the quasiparticle number in the superconducting resonator. We show that the shift in resonant frequency can be determined from the phase shift by using KID phase versus frequency dependence using a previously measured resonant frequency. Working in this calculated resonant frequency, we gain near linearity and constant calibration to a constant optical signal applied in a wide range of operating points on the resonance and readout powers. This calibration method has three particular advantages: first, it is fast enough to be used to calibrate large arrays, with pixel counts in the thousands of pixels; second, it is based on data that are already necessary to determine KID positions; third, it can be done without applying any optical source in front of the array.
Although dust in galaxies represents only a few percent of the total baryonic mass, it plays a crucial role in the physical processes occurring in galaxies. Studying the dust content of galaxies, ...particularly at high $z$, is therefore crucial for understanding the link between dust production, obscured star formation, and the build-up of galaxy stellar mass. We study the dust properties (mass and temperature) of the largest Atacama Large Millimeter/submillimeter Array (ALMA)-selected sample of star-forming galaxies available from the archive (A$^3$COSMOS), and we derive the dust mass function and dust mass density of galaxies from $z=0.5\,-\,6$. We fit the spectral energy distribution (SED) with the CIGALE code to constrain the dust mass and temperature of the A$^3$COSMOS galaxy sample based on the UV-to-near-infrared photometric coverage of each galaxy combined with the ALMA (and Herschel when available) coverage of the Rayleigh-Jeans tail of their dust-continuum emission. We then computed and fit the dust mass function by combining the A$^3$COSMOS and the most recent Herschel samples in order to obtain the best estimate of the integrated dust mass density up to $z The dust masses in galaxies in lie between $ 10^8$ and $ $ M$_ odot $. From the SED fitting, we were also able to derive a dust temperature. The distribution of the dust temperature peaks at $ 30-35$K. The dust mass function at $z=0.5\,-\,6$ evolves with an increase in $M^*$ and a decrease in the number density ($ ^*$), and it agrees well with literature estimates. The dust mass density decreases smoothly in its evolution from $z 0.5$ to $z 6$, which is steeper than what is found by models at $z
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