We trace the assembly history of red galaxies since z = 1 by measuring their evolving space density with the B-band luminosity function. Our sample of 39,599 red galaxies, selected from 6.96 deg ...super(2) of imaging from the NOAO Deep Wide-Field Survey and the Spitzer IRAC Shallow Survey, is an order of magnitude larger, in size and volume, than comparable samples in the literature. We measure a higher space density of z 6 0.9 red galaxies than some of the recent literature, in part because we account for the faint yet significant galaxy flux that falls outside of our photometric aperture. The B-band luminosity density of red galaxies, which effectively measures the evolution of 6L* galaxies, increases by only 36% c 13% from z = 0 to z = 1. If red galaxy stellar populations have faded by 1.24 B-band magnitudes since z = 1, the stellar mass contained within the red galaxy population has roughly doubled over the past 8 Gyr. This is consistent with star-forming galaxies being transformed into L* red galaxies after a decline in their star formation rates. In contrast, the evolution of 4L* red galaxies differs only slightly from a model with negligible z<1 star formation and no galaxy mergers. If this model approximates the luminosity evolution of red galaxy stellar populations, then 80% of the stellar mass contained within today's 4L* red galaxies was already in place at z = 0.7. While red galaxy mergers have been observed, such mergers do not produce rapid growth of 4L* red galaxy stellar masses between z = 1 and the present day.
Mid-Infrared Selection of Active Galaxies Stern, Daniel; Eisenhardt, Peter; Gorjian, Varoujan ...
The Astrophysical journal,
09/2005, Letnik:
631, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Mid-infrared photometry provides a robust technique for identifying active galaxies. While the ultraviolet to mid-infrared (l < 5 km) continuum of stellar populations is dominated by the composite ...blackbody curve and peaks at approximately 1.6 km, the ultraviolet to mid-infrared continuum of active galactic nuclei (AGNs) is dominated by a power law. Consequently, with a sufficient wavelength baseline, one can easily distinguish AGNs from stellar populations. Mirroring the tendency of AGNs to be bluer than galaxies in the ultraviolet, where galaxies (and stars) sample the blue, rising portion of stellar spectra, AGNs tend to be redder than galaxies in the mid-infrared, where galaxies sample the red, falling portion of the stellar spectra. We report on Spitzer Space Telescope mid-infrared colors, derived from the IRAC Shallow Survey, of nearly 10,000 spectroscopically identified sources from the AGN and Galaxy Evolution Survey. On the basis of this spectroscopic sample, we find that simple mid-infrared color criteria provide remarkably robust separation of active galaxies from normal galaxies and Galactic stars, with over 80% completeness and less than 20% contamination. Considering only broad-lined AGNs, these mid-infrared color criteria identify over 90% of spectroscopically identified quasars and Seyfert 1 galaxies. Applying these color criteria to the full imaging data set, we discuss the implied surface density of AGNs and find evidence for a large population of optically obscured active galaxies.
Abstract
James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) images of the luminous infrared (IR) galaxy VV 114 are presented. This redshift ∼0.020 merger has a western component (VV ...114W) rich in optical star clusters and an eastern component (VV 114E) hosting a luminous mid-IR nucleus hidden at UV and optical wavelengths by dust lanes. With MIRI, the VV 114E nucleus resolves primarily into bright NE and SW cores separated by 630 pc. This nucleus comprises 45% of the 15
μ
m light of VV 114, with the NE and SW cores having IR luminosities,
L
IR
(8 − 1000
μ
m) ∼ 8 ± 0.8 × 10
10
L
⊙
and ∼ 5 ± 0.5 × 10
10
L
⊙
, respectively, and IR densities, Σ
IR
≳ 2 ± 0.2 × 10
13
L
⊙
kpc
−2
and ≳ 7 ± 0.7 × 10
12
L
⊙
kpc
−2
, respectively—in the range of Σ
IR
for the Orion star-forming core and the nuclei of Arp 220. The NE core, previously speculated to have an active galactic nucleus (AGN), has starburst-like mid-IR colors. In contrast, the VV 114E SW core has AGN-like colors. Approximately 40 star-forming knots with
L
IR
∼ 0.02–5 × 10
10
L
⊙
are identified, 28% of which have no optical counterpart. Finally, diffuse emission accounts for 40%–60% of the mid-IR emission. Mostly notably, filamentary polycyclic aromatic hydrocarbon (PAH) emission stochastically excited by UV and optical photons accounts for half of the 7.7
μ
m light of VV 114. This study illustrates the ability of JWST to detect obscured compact activity and distributed PAH emission in the most extreme starburst galaxies in the local universe.
ABSTRACT
We use the overlap between multiband photometry of the Kilo-Degree Survey (KiDS) and spectroscopic data based on the Sloan Digital Sky Survey and Galaxy And Mass Assembly to infer the ...colour–magnitude relation of red-sequence galaxies. We then use this inferred relation to select luminous red galaxies (LRGs) in the redshift range of 0.1 < z < 0.7 over the entire KiDS Data Release 3 footprint. We construct two samples of galaxies with different constant comoving densities and different luminosity thresholds. The selected red galaxies have photometric redshifts with typical photo-z errors of σz ∼ 0.014(1 + z) that are nearly uniform with respect to observational systematics. This makes them an ideal set of galaxies for lensing and clustering studies. As an example, we use the KiDS-450 cosmic shear catalogue to measure the mean tangential shear signal around the selected LRGs. We detect a significant weak lensing signal for lenses out to z ∼ 0.7.
Abstract
The nearby, luminous infrared galaxy NGC 7469 hosts a Seyfert nucleus with a circumnuclear star-forming ring and is thus the ideal local laboratory for investigating the starburst–AGN ...(active galactic nucleus) connection in detail. We present integral-field observations of the central 1.3 kpc region in NGC 7469 obtained with the JWST Mid-InfraRed Instrument. Molecular and ionized gas distributions and kinematics at a resolution of ∼100 pc over the 4.9–7.6
μ
m region are examined to study the gas dynamics influenced by the central AGN. The low-ionization Fe
ii
λ
5.34
μ
m and Ar
ii
λ
6.99
μ
m lines are bright on the nucleus and in the starburst ring, as opposed to H
2
S(5)
λ
6.91
μ
m, which is strongly peaked at the center and surrounding ISM. The high-ionization Mg
v
line is resolved and shows a broad, blueshifted component associated with the outflow. It has a nearly face-on geometry that is strongly peaked on the nucleus, where it reaches a maximum velocity of −650 km s
−1
, and extends about 400 pc to the east. Regions of enhanced velocity dispersion in H
2
and Fe
ii
∼ 180 pc from the AGN that also show high
L
(H
2
)/
L
(PAH) and
L
(Fe
ii
)/
L
(Pf
α
) ratios to the W and N of the nucleus pinpoint regions where the ionized outflow is depositing energy, via shocks, into the dense interstellar medium between the nucleus and the starburst ring. These resolved mid-infrared observations of the nuclear gas dynamics demonstrate the power of JWST and its high-sensitivity integral-field spectroscopic capability to resolve feedback processes around supermassive black holes in the dusty cores of nearby luminous infrared galaxies.
Abstract
We present mid-infrared spectroscopic observations of the nucleus of the nearby Seyfert galaxy NGC 7469 taken with the MIRI instrument on the James Webb Space Telescope (JWST) as part of ...Directors Discretionary Time Early Release Science program 1328. The high-resolution nuclear spectrum contains 19 emission lines covering a wide range of ionization. The high-ionization lines show broad, blueshifted emission reaching velocities up to 1700 km s
−1
and FWHM ranging from ∼500 to 1100 km s
−1
. The width of the broad emission and the broad-to-narrow line flux ratios correlate with ionization potential. The results suggest a decelerating, stratified, AGN-driven outflow emerging from the nucleus. The estimated mass outflow rate is 1–2 orders of magnitude larger than the current black hole accretion rate needed to power the AGN. Eight pure rotational H
2
emission lines are detected with intrinsic widths ranging from FWHM ∼125 to 330 km s
−1
. We estimate a total mass of warm H
2
gas of ∼1.2 × 10
7
M
⊙
in the central 100 pc. The PAH features are extremely weak in the nuclear spectrum, but a 6.2
μ
m PAH feature with an equivalent width of ∼0.07
μ
m and a flux of 2.7 × 10
−17
W m
−2
is detected. The spectrum is steeply rising in the mid-infrared, with a silicate strength of ∼0.02, significantly smaller than seen in most PG QSOs but comparable to other Seyfert 1s. These early MIRI mid-infrared IFU data highlight the power of JWST to probe the multiphase interstellar media surrounding actively accreting supermassive black holes.
We present the surface density of luminous active galactic nuclei (AGNs) associated with a uniformly selected galaxy cluster sample identified in the 8.5 deg2 Bootes field of the NOAO Deep Wide-Field ...Survey. The clusters are distributed over a large range of redshift (0 < z < 1.5), and we identify AGN using three different selection criteria: mid-IR color, radio luminosity, and X-ray luminosity. Relative to the field, we note a clear overdensity of the number of AGNs within 0.5 Mpc of the cluster centers at z > 0.5. The amplitude of this AGN overdensity increases with redshift. Although there are significant differences between the AGN populations probed by each selection technique, the rise in cluster AGN surface density generally increases more steeply than that of field quasars. In particular, X-ray-selected AGNs are at least 3 times more prevalent in clusters at 1 < z < 1.5 compared to clusters at 0.5 < z < 1. This effect is stronger than can be explained by the evolving median richness of our cluster sample. We thus confirm the existence of a Butcher-Oemler-type effect for AGN in galaxy clusters, with the number of AGNs in clusters increasing with redshift.
Abstract
We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first spatially resolved, mid-infrared images of
IIZw096
, a merging luminous infrared ...galaxy (LIRG) at
z
= 0.036. Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity (
L
IR
) of the system originated from a small region outside of the two merging nuclei. New observations with JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is responsible for the bulk of the IR emission. We estimate that 40%–70% of the IR bolometric luminosity, or 3–5 × 10
11
L
⊙
, arises from a source no larger than 175 pc in radius, suggesting a luminosity density of at least 3–5 × 10
12
L
⊙
kpc
−2
. In addition, we detect 11 other star-forming sources, five of which were previously unknown. The MIRI F1500W/F560W colors of most of these sources, including the source responsible for the bulk of the far-IR emission, are much redder than the nuclei of local LIRGs. These observations reveal the power of JWST to disentangle the complex regions at the hearts of merging, dusty galaxies.
We present the first detailed integral field spectroscopy study of nine central void galaxies with M⋆ > 1010 M⊙ using the Wide Field Spectrograph to determine how a range of assembly histories ...manifest themselves in the current day Universe. While the majority of these galaxies are evolving secularly, we find a range of morphologies, merger histories and stellar population distributions, though similarly low Hα-derived star formation rates (<1 M⊙ yr−1). Two of our nine galaxies host active galactic nuclei, and two have kinematic disruptions to their gas that are not seen in their stellar component. Most massive void galaxies are red and discy, which we attribute to a lack of major mergers. Some have disturbed morphologies and may be in the process of evolving to early-type thanks to ongoing minor mergers at present times, likely fed by tendrils leading off filaments. The diversity in our small galaxy sample, despite being of similar mass and environment means that these galaxies are still assembling at present day, with minor mergers playing an important role in their evolution. We compare our sample to a mass and magnitude-matched sample of field galaxies, using data from the Sydney-AAO Multi-object Integral field spectrograph galaxy survey. We find that despite environmental differences, galaxies of mass M⋆ > 1010 M⊙ have similarly low star formation rates (<3 M⊙ yr−1). The lack of distinction between the star formation rates of the void and field environments points to quenching of massive galaxies being a largely mass-related effect.
Abstract
In galaxy clusters, efficiently accreting active galactic nuclei (AGNs) are preferentially located in the infall regions of the cluster projected phase-space, and are rarely found in the ...cluster core. This has been attributed to both an increase in triggering opportunities for infalling galaxies, and a reduction of those mechanisms in the hot, virialized, cluster core. Exploiting the depth and completeness (98 per cent at r < 19.8 mag) of the Galaxy And Mass Assembly survey (GAMA), we probe down the group halo mass function to assess whether AGNs are found in the same regions in groups as they are in clusters. We select 451 optical AGNs from 7498 galaxies with log10(M*/M⊙) > 9.9 in 695 groups with 11.53 ≤ log10(M200/M⊙) ≤ 14.56 at z < 0.15. By analysing the projected phase-space positions of these galaxies, we demonstrate that when split both radially, and into physically derived infalling and core populations, AGN position within group projected phase-space is dependent on halo mass. For groups with log10(M200/M⊙) > 13.5, AGNs are preferentially found in the infalling galaxy population with 3.6σ confidence. At lower halo masses, we observe no difference in AGN fraction between core and infalling galaxies. These observations support a model where a reduced number of low-speed interactions, ram pressure stripping and intra-group/cluster medium temperature, the dominance of which increase with halo mass, work to inhibit AGN in the cores of groups and clusters with log10(M200/M⊙) > 13.5, but do not significantly affect nuclear activity in cores of less massive structures.
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