Abstract
We investigate the stellar and ionized gas kinematics, and stellar populations of NGC 3182 galaxy using integral field spectrograph data from the Calar Alto Legacy Integral Field Area ...survey. We try to clarify the nature of the ring structure in NGC 3182. We find a negative stellar age gradient out to the ring, while
α
/Fe considerably enhanced in the ring. The stellar metallicity shows a smooth negative gradient. From the line-ratio diagnostic diagrams, we confirm that NGC 3182 is a Seyfert galaxy from emission-line flux ratio, while the gas in the inner ring is ionized mostly by young stars. However, any obvious feature of outflows is not found in its gas kinematics. In the ring, star formation seems to have recently occurred and the gas metallicity is slightly enhanced compared to the center. From our results, we conclude that star formation has occurred in the circumnuclear region within a short period and this may result from a positive feedback by active galactic nucleus radiation pressure.
Abstract
We investigate the stellar population properties of bulges and disks separately for 34 S0s using integral-field spectroscopy from the Calar Alto Legacy Integral Field Area survey. The ...spatially resolved stellar age and metallicity of bulge and disk components are simultaneously estimated using the penalized pixel fitting method with photometrically defined weights for the two components. We find a tight correlation between age and metallicity for bulges, while the relation for disks has a larger scatter than that for bulges. This implies that the star formation histories of disks are more complicated than those of bulges. The bulges of high-mass S0s are mostly comparable in terms of metallicity, while bulges appear to be systematically more metal-rich than disks for low-mass S0s. The ages of bulges and disks in high-mass S0s appear to increase with local density. The bulge ages of low-mass S0s also increase with local density, but such a trend is not clear in the disk ages of low-mass S0s. In addition, the age difference between bulge and disk components (ΔAge) tends to increase with local density, for both high-mass and low-mass S0s. High-mass S0s have systematically greater ΔAge than low-mass S0s at a given local density. Our results indicate that the stellar mass significantly influences the evolution of S0 galaxies, but the environment also plays an important role in determining the evolution of bulges and disks at a given stellar mass.
Abstract
We present near-infrared spectra of three low-luminosity protostars and one background star in the Perseus molecular cloud, acquired using the infrared camera on board the AKARI space ...telescope. For the comparison with different star-forming environments, we also present spectra of the massive protostar AFGL 7009S, where the protostellar envelope is heated significantly, and the low-mass protostar RNO 91, which is suspected to be undergoing an episodic burst. We detected ice absorption features of H
2
O, CO
2
, and CO in all spectra around the wavelengths of 3.05, 4.27, and 4.67
μ
m, respectively. For at least two low-luminosity protostars, we also detected the XCN ice feature at 4.62
μ
m. The presence of the crystalline H
2
O ice and XCN ice components indicates that the low-luminosity protostars experienced a hot phase via accretion bursts during the past mass accretion process. We compared the ice abundances of the low-luminosity protostars with those of embedded low-mass protostars and the dense molecular clouds and cores, suggesting that their ice abundances reflect the strength of prior bursts and the timescale after the last burst.
Abstract
We investigate the variation in the mid-infrared spectral energy distributions of 373 low-redshift (
z
< 0.4) star-forming galaxies, which reflects a variety of polycyclic aromatic ...hydrocarbon (PAH) emission features. The relative strength of PAH emission is parameterized as
q
PAH
, which is defined as the mass fraction of PAH particles in the total dust mass. With the aid of continuous mid-infrared photometric data points covering 7–24
μ
m and far-infrared flux densities,
q
PAH
values are derived through spectral energy distribution fitting. The correlation between
q
PAH
and other physical properties of galaxies, i.e., gas-phase metallicity (
12
+
log
(
O
/
H
)
), stellar mass, and specific star-formation rate (sSFR) are explored. As in previous studies,
q
PAH
values of galaxies with high metallicity are found to be higher than those with low metallicity. The strength of PAH emission is also positively correlated with the stellar mass and negatively correlated with the sSFR. The correlation between
q
PAH
and each parameter still exists even after the other two parameters are fixed. In addition to the PAH strength, the application of metallicity-dependent gas-to-dust mass ratio appears to work well to estimate gas mass that matches the observed relationship between molecular gas and physical parameters. The result obtained will be used to calibrate the observed PAH luminosity-total infrared luminosity relation, based on the variation of MIR-FIR SED, which is used in the estimation of hidden star formation.
Abstract
While many Ly
α
blobs (LABs) are found in and around several well-known protoclusters at high redshift, how they trace the underlying large-scale structure is still poorly understood. In ...this work, we utilize 5352 Ly
α
emitters (LAEs) and 129 LABs at
z
= 3.1 identified over a ∼9.5 deg
2
area in early data from the ongoing One-hundred-deg
2
DECam Imaging in Narrowbands (ODIN) survey to investigate this question. Using LAEs as tracers of the underlying matter distribution, we identify overdense structures as galaxy groups, protoclusters, and filaments of the cosmic web. We find that LABs preferentially reside in regions of higher-than-average density and are located in closer proximity to overdense structures, which represent the sites of protoclusters and their substructures. Moreover, protoclusters hosting one or more LABs tend to have a higher descendant mass than those which do not. Blobs are also strongly associated with filaments of the cosmic web, with ∼70% of the population being within a projected distance of ∼2.4 pMpc from a filament. We show that the proximity of LABs to protoclusters is naturally explained by their association with filaments as large cosmic structures are where many filaments converge. The contiguous wide-field coverage of the ODIN survey allows us to establish firmly a connection between LABs as a population and filaments of the cosmic web for the first time.
Abstract We search for quasi-stellar objects (QSOs) in a wide area of the south ecliptic pole (SEP) field, which has been and will continue to be intensively explored through various space missions. ...For this purpose, we obtain deep broadband optical images of the SEP field covering an area of ∼14.5 × 14.5 deg 2 with the Korea Microlensing Telescope Network (KMTNet). The 5 σ detection limits for point sources in the BVRI bands are estimated to be ∼22.59, 22.60, 22.98, and 21.85 mag, respectively. Utilizing data from the Wide-field Infrared Survey Explorer, unobscured QSO candidates are selected among the optically pointlike sources using mid-infrared (MIR) and optical–MIR colors. To refine our selection further and eliminate any contamination not adequately removed by the color-based selection, we perform spectral energy distribution fitting with archival photometric data ranging from optical to MIR. As a result, we identify a total of 2383 unobscured QSO candidates in the SEP field. We also apply a similar method to the north ecliptic pole field using Pan-STARRS data and obtain a similar result of identifying 2427 candidates. The differential number count per area of our QSO candidates is in good agreement with those measured from spectroscopically confirmed ones in other fields. Finally, we compare the results with the literature and discuss how this work will impact future studies, especially upcoming space missions.
ABSTRACT
In order to understand the interaction between the central black hole and the whole galaxy or their co-evolution history along with cosmic time, a complete census of active galactic nucleus ...(AGN) is crucial. However, AGNs are often missed in optical, UV, and soft X-ray observations since they could be obscured by gas and dust. A mid-infrared (MIR) survey supported by multiwavelength data is one of the best ways to find obscured AGN activities because it suffers less from extinction. Previous large IR photometric surveys, e.g. Wide field Infrared Survey Explorer and Spitzer, have gaps between the MIR filters. Therefore, star-forming galaxy-AGN diagnostics in the MIR were limited. The AKARI satellite has a unique continuous nine-band filter coverage in the near to MIR wavelengths. In this work, we take advantage of the state-of-the-art spectral energy distribution modelling software, cigale, to find AGNs in MIR. We found 126 AGNs in the North Ecliptic Pole-Wide field with this method. We also investigate the energy released from the AGN as a fraction of the total IR luminosity of a galaxy. We found that the AGN contribution is larger at higher redshifts for a given IR luminosity. With the upcoming deep IR surveys, e.g. JWST, we expect to find more AGNs with our method.
ABSTRACT
We study the galaxy merger fraction and its dependence on star formation mode in the 5.4 deg2 of the North Ecliptic Pole-Wide Field. We select 6352 galaxies with AKARI 9 $\mu$m detections, ...and identify mergers among them using the Gini coefficient and M20 derived from the Subaru/Hyper Suprime-Cam (HSC) optical images. We obtain the total infrared luminosity and star formation rate of galaxies using the spectral energy distribution templates based on one band, AKARI$9\, \mu$m. We classify galaxies into three different star formation modes (i.e. starbursts, main-sequence, and quiescent galaxies) and calculate the merger fractions for each. We find that the merger fractions of galaxies increase with redshift at z < 0.6. The merger fractions of starbursts are higher than those of main-sequence and quiescent galaxies in all redshift bins. We also examine the merger fractions of far-infrared-detected galaxies that have at least one detection from Herschel/Spectral and Photometric Imaging Receiver (SPIRE). We find that Herschel-detected galaxies have higher merger fraction compared to non-Herschel-detected galaxies, and both Herschel-detected and non-Herschel-detected galaxies show clearly different merger fractions depending on the star formation modes.
ABSTRACT
Galaxy clusters provide an excellent probe in various research fields in astrophysics and cosmology. However, the number of galaxy clusters detected so far in the AKARI North Ecliptic Pole ...(NEP) field is limited. In this work, we provide galaxy cluster candidates in the AKARI NEP field with the minimum requisites based only on the coordinates and photometric redshift (photo-z) of galaxies. We used galaxies detected in five optical bands (g, r, i, z, and Y) by the Subaru Hyper Suprime-Cam (HSC), with additional data from the u band obtained from the Canada-France-Hawaii Telescope (CFHT) MegaPrime/MegaCam, and from the IRAC1 and IRAC2 bands from the Spitzer space telescope for photo-z estimation. We calculated the local density around every galaxy using the 10th-nearest neighbourhood. Cluster candidates were determined by applying the friends-of-friends algorithm to over-densities. A total of 88 cluster candidates containing 4390 member galaxies below redshift 1.1 in 5.4 deg2 were identified. The reliability of our method was examined through false-detection tests, redshift-uncertainty tests, and applications on the Cosmic Evolution Survey (COSMOS) data, giving false-detection rates of 0.01 to 0.05 and a recovery rate of 0.9 at high richness. Three X-ray clusters previously observed by ROSAT and Chandra were recovered. The cluster galaxies show a higher stellar mass and lower star formation rate compared with the field galaxies in two-sample Z-tests. These cluster candidates are useful for environmental studies of galaxy evolution and future astronomical surveys in the NEP, where AKARI has performed unique nine-band mid-infrared photometry for tens of thousands of galaxies.
Extended ionized Fe objects in the UWIFE survey Kim, Yesol; Koo, Bon-Chul; Pyo, Tae-Soo ...
Monthly notices of the Royal Astronomical Society,
02/2024, Letnik:
528, Številka:
3
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We explore systematically the shocked gas in the first Galactic quadrant of the Milky Way using the United Kingdom Infrared Telescope (UKIRT) Wide-field Infrared Survey for Fe+ (UWIFE). The ...UWIFE survey is the first imaging survey of the Milky Way in the Fe ii 1.644 μm emission line and covers the Galactic plane in the first Galactic quadrant (7° < $\mathit {l}$ < 62°; $|b| $ ≲ 1$_{.}^{\circ }$5). We identify 204 extended ionized Fe objects (IFOs) using a combination of a manual and automatic search. Most of the IFOs are detected for the first time in the Fe ii 1.644 μm line. We present a catalogue of the measured sizes and fluxes of the IFOs and searched for their counterparts by performing positional cross-matching with known sources. We found that IFOs are associated with supernova remnants (25), young stellar objects (100), H ii regions (33), planetary nebulae (17), and luminous blue variables (4). The statistical and morphological properties are discussed for each of these.
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