We present estimates of black hole accretion rates (BHARs) and nuclear, extended, and total star formation rates for a complete sample of Seyfert galaxies. Using data from the Spitzer Space ...Telescope, we measure the active galactic nucleus (AGN) luminosity using the OIV lambda25.89 mum emission line and the star-forming luminosity using the 11.3 mum aromatic feature and extended 24 mum continuum emission. We find that black hole growth is strongly correlated with nuclear (r < 1 kpc) star formation, but only weakly correlated with extended (r > 1 kpc) star formation in the host galaxy. In particular, the nuclear star formation rate (SFR) traced by the 11.3 mum aromatic feature follows a relationship with the BHAR of the form SFR is proportional to M sub(BH) super(0.8), with an observed scatter of 0.5 dex. This SFR-BHAR relationship persists when additional star formation in physically matched r = 1 kpc apertures is included, taking the form SFR is proportional to M sub(BH) super(0.6). However, the relationship becomes almost indiscernible when total SFRs are considered. This suggests a physical connection between the gas on sub-kiloparsec and sub-parsec scales in local Seyfert galaxies that is not related to external processes in the host galaxy. It also suggests that the observed scaling between star formation and black hole growth for samples of AGNs will depend on whether the star formation is dominated by a nuclear or an extended component. We estimate the integrated black hole and bulge growth that occurs in these galaxies and find that an AGN duty cycle of 5%-10% would maintain the ratio between black hole and bulge masses seen in the local universe.
We describe the sample design for the SDSS-IV MaNGA survey and present the final properties of the main samples along with important considerations for using these samples for science. Our target ...selection criteria were developed while simultaneously optimizing the size distribution of the MaNGA integral field units (IFUs), the IFU allocation strategy, and the target density to produce a survey defined in terms of maximizing signal-to-noise ratio, spatial resolution, and sample size. Our selection strategy makes use of redshift limits that only depend on i-band absolute magnitude (Mi), or, for a small subset of our sample, Mi and color (NUV − i). Such a strategy ensures that all galaxies span the same range in angular size irrespective of luminosity and are therefore covered evenly by the adopted range of IFU sizes. We define three samples: the Primary and Secondary samples are selected to have a flat number density with respect to Mi and are targeted to have spectroscopic coverage to 1.5 and 2.5 effective radii (Re), respectively. The Color-Enhanced supplement increases the number of galaxies in the low-density regions of color-magnitude space by extending the redshift limits of the Primary sample in the appropriate color bins. The samples cover the stellar mass range and are sampled at median physical resolutions of 1.37 and 2.5 kpc for the Primary and Secondary samples, respectively. We provide weights that will statistically correct for our luminosity and color-dependent selection function and IFU allocation strategy, thus correcting the observed sample to a volume-limited sample.
Abstract
Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG ...in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced S ii/Hα, N ii/Hα, O ii/Hβ and O i/Hα. The gradients in these line ratios are determined by metallicity gradients and ΣHα. In line ratio diagnostic diagrams, contamination by DIG moves H ii regions towards composite or low-ionization nuclear emission-line region (LI(N)ER)-like regions. A harder ionizing spectrum is needed to explain DIG line ratios. Leaky H ii region models can only shift line ratios slightly relative to H ii region models, and thus fail to explain the composite/LI(N)ER line ratios displayed by DIG. Our result favours ionization by evolved stars as a major ionization source for DIG with LI(N)ER-like emission. DIG can significantly bias the measurement of gas metallicity and metallicity gradients derived using strong-line methods. Metallicities derived using N2O2 are optimal because they exhibit the smallest bias and error. Using O3N2, R
23, N2 = N ii/Hα and N2S2Hα to derive metallicities introduces bias in the derived metallicity gradients as large as the gradient itself. The strong-line method of Blanc et al. (IZI hereafter) cannot be applied to DIG to get an accurate metallicity because it currently contains only H ii region models that fail to describe the DIG.
Abstract
Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated that low ionization emission-line regions (LIERs) in local galaxies result from photoionization by hot evolved ...stars, not active galactic nuclei, hence tracing galactic region hosting old stellar population where, despite the presence of ionized gas, star formation is no longer occurring. LIERs are ubiquitous in both quiescent galaxies and in the central regions of galaxies where star formation takes place at larger radii. We refer to these two classes of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies, respectively. cLIERs are late-type galaxies primarily spread across the green valley, in the transition region between the star formation main sequence and quiescent galaxies. These galaxies display regular disc rotation in both stars and gas, although featuring a higher central stellar velocity dispersion than star-forming galaxies of the same mass. cLIERs are consistent with being slowly quenched inside-out; the transformation is associated with massive bulges, pointing towards the importance of bulge growth via secular evolution. eLIERs are morphologically early types and are indistinguishable from passive galaxies devoid of line emission in terms of their stellar populations, morphology and central stellar velocity dispersion. Ionized gas in eLIERs shows both disturbed and disc-like kinematics. When a large-scale flow/rotation is observed in the gas, it is often misaligned relative to the stellar component. These features indicate that eLIERs are passive galaxies harbouring a residual cold gas component, acquired mostly via external accretion. Importantly, quiescent galaxies devoid of line emission reside in denser environments and have significantly higher satellite fraction than eLIERs. Environmental effects thus represent the likely cause for the existence of line-less galaxies on the red sequence.
Abstract
We investigate galactic winds in the HizEA galaxies, a collection of 46 late-stage galaxy mergers at
z
= 0.4–0.8, with stellar masses of
log
(
M
*
/
M
⊙
)
=
10.4
–
11.5
, star formation ...rates (SFRs) of 20–500
M
⊙
yr
−1
, and ultra-compact (a few 100 pc) central star-forming regions. We measure their gas kinematics using the Mg
ii
λ
λ
2796,2803 absorption lines in optical spectra from MMT, Magellan, and Keck. We find evidence of outflows in 90% of targets, with maximum outflow velocities of 550–3200 km s
−1
. We combine these data with ten samples from the literature to construct scaling relations for outflow velocity versus SFR, star formation surface density (Σ
SFR
),
M
*
, and SFR/
M
*
. The HizEA galaxies extend the dynamic range of the scaling relations by a factor of ∼2–4 in outflow velocity and an order of magnitude in SFR and Σ
SFR
. The ensemble scaling relations exhibit strong correlations between outflow velocity, SFR, SFR/
R
, and Σ
SFR
, and weaker correlations with
M
*
and SFR/
M
*
. The HizEA galaxies are mild outliers on the SFR and
M
*
scaling relations, but they connect smoothly with more typical star-forming galaxies on plots of outflow velocity versus SFR/
R
and Σ
SFR
. These results provide further evidence that the HizEA galaxies’ exceptional outflow velocities are a consequence of their extreme star formation conditions rather than hidden black hole activity, and they strengthen previous claims that Σ
SFR
is one of the most important properties governing the velocities of galactic winds.
Ninety per cent of baryons are located outside galaxies, either in the circumgalactic or intergalactic medium
. Theory points to galactic winds as the primary source of the enriched and massive ...circumgalactic medium
. Winds from compact starbursts have been observed to flow to distances somewhat greater than ten kiloparsecs
, but the circumgalactic medium typically extends beyond a hundred kiloparsecs
. Here we report optical integral field observations of the massive but compact galaxy SDSS J211824.06+001729.4. The oxygen O II lines at wavelengths of 3726 and 3729 angstroms reveal an ionized outflow spanning 80 by 100 square kiloparsecs, depositing metal-enriched gas at 10,000 kelvin through an hourglass-shaped nebula that resembles an evacuated and limb-brightened bipolar bubble. We also observe neutral gas phases at temperatures of less than 10,000 kelvin reaching distances of 20 kiloparsecs and velocities of around 1,500 kilometres per second. This multi-phase outflow is probably driven by bursts of star formation, consistent with theory
.
We present Spitzer measurements of the aromatic (also known as polycyclic aromatic hydrocarbon) features for 35 Seyfert galaxies from the revised Shapley-Ames sample and find that the relative ...strengths of the features differ significantly from those observed in star-forming galaxies. Specifically, the features at 6.2, 7.7, and 8.6 Delta *mm are suppressed relative to the 11.3 Delta *mm feature in Seyferts. Furthermore, we find an anti-correlation between the L(7.7 Delta *mm)/L(11.3 Delta *mm) ratio and the strength of the rotational H2 emission, which traces shocked gas. This suggests that shocks suppress the short-wavelength features by modifying the structure of the aromatic molecules or destroying the smallest grains. Most Seyfert nuclei fall on the relationship between aromatic emission and Ne II emission for star-forming galaxies, indicating that aromatic-based estimates of the star formation rate are generally reasonable in galaxies hosting active galactic nuclei. For the outliers from this relationship, which have small L(7.7 Delta *mm)/L(11.3 Delta *mm) ratios and strong H2 emission, the 11.3 Delta *mm feature still provides a valid measure of the star formation rate.
ABSTRACT We measure the clustering of X-ray, radio, and mid-IR-selected active galactic nuclei (AGNs) at 0.2 < z < 1.2 using multi-wavelength imaging and spectroscopic redshifts from the PRIMUS and ...DEEP2 redshift surveys, covering seven separate fields spanning ∼10 deg 2 . Using the cross-correlation of AGNs with dense galaxy samples, we measure the clustering scale length and slope, as well as the bias, of AGNs selected at different wavelengths. Similar to previous studies, we find that X-ray and radio AGNs are more clustered than mid-IR-selected AGNs. We further compare the clustering of each AGN sample with matched galaxy samples designed to have the same stellar mass, star-formation rate (SFR), and redshift distributions as the AGN host galaxies and find no significant differences between their clustering properties. The observed differences in the clustering of AGNs selected at different wavelengths can therefore be explained by the clustering differences of their host populations, which have different distributions in both stellar mass and SFR. Selection biases inherent in AGN selection therefore determine the clustering of observed AGN samples. We further find no significant difference between the clustering of obscured and unobscured AGNs, using IRAC or Wide-field Infrared Survey Explorer colors or X-ray hardness ratio.
We investigate if and how growing supermassive black holes (SMBH) known as active galactic nuclei (AGN) and gravitational interactions affect the warm molecular gas and dust of galaxies. Our analysis ...focuses on the morphologies and warm ISM properties of 630 galaxies at z < 0.1. We use grizy images from the Pan-STARRS survey to classify the galaxies into mergers, early mergers, and non-mergers. We use MIR spectroscopic measurements of emission from rotational H2 transitions, dust, and polycyclic aromatic hydrocarbon (PAH) features, and silicate emission or absorption lines at 9.7 m to study how gravitational interactions impact the warm ISM in AGN and non-AGN hosts. We find that in AGN-hosts, the ISM is warmer, the ratios of H2 to PAHs are larger, the PAH emission-line ratios and silicate strengths have a wider range of values than in non-AGN hosts. We find some statistical differences between the H2 emission of mergers and non-mergers, but those differences are less statistically significant than those between AGN and non-AGN hosts. Our results do not establish a relation between the rate of BH growth and the warm ISM but point to highly statistically significant differences between AGN hosts and non-AGN hosts, differences that are not present with the same statistical significance between mergers and non-mergers. We speculate that the combination of triggering mechanisms, AGN orientations, and evolutionary stages that allow AGN to be classified as such in the MIR indicate that those AGN are energetically coupled on kiloparsec scales to their host galaxies's warm ISM. Future optical and IR, spatially resolved spectroscopic studies are best suited to characterize this connection.
ABSTRACT The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for ...10,000 nearby galaxies at a spectral resolution of R ∼ 2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (Re) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5Re (Primary sample), and one-third of the sample is covered to 2.5Re (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specifically the point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ∼70 per 1.4 Å pixel for spectra stacked between 1Re and 1.5Re. Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals.
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