scholarly journals AKARI mid-infrared slitless spectroscopic survey of star-forming galaxies at z ≲ 0.5

2018 ◽  
Vol 618 ◽  
pp. A101 ◽  
Author(s):  
Y. Ohyama ◽  
T. Wada ◽  
H. Matsuhara ◽  
T. Takagi ◽  
M. Malkan ◽  
...  
Keyword(s):  
Rest Frame ◽  
Formation Rate ◽  
Infrared Camera ◽  
Spectral Energy ◽  
Mid Infrared ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
The North ◽  
Stellar Component ◽  
Polycyclic Aromatic

Context. Deep mid-infrared (MIR) surveys have revealed numerous strongly star-forming galaxies at redshift z ≲ 2. Their MIR fluxes are produced by a combination of continuum and polycyclic aromatic hydrocarbon (PAH) emission features. The PAH features can dominate the total MIR flux, but are difficult to measure without spectroscopy. Aims. We aim to study star-forming galaxies by using a blind spectroscopic survey at MIR wavelengths to understand evolution of their star formation rate (SFR) and specific SFR (SFR per stellar mass) up to z ≃ 0.5, by paying particular attention to their PAH properties. Methods. We conducted a low-resolution (R ≃ 50) slitless spectroscopic survey at 5–13 μm of 9 μm flux-selected sources (>0.3 mJy) around the north ecliptic pole with the infrared camera (IRC) onboard AKARI. After removing 11 AGN candidates by using the IRC photometry, we identify 48 PAH galaxies with PAH 6.2, 7.7, and 8.6 μm features at z < 0.5. The rest-frame optical–MIR spectral energy distributions (SEDs) based on CFHT and IRC imaging covering 0.37–18 μm were produced, and analysed in conjunction with the PAH spectroscopy. We defined the PAH enhancement by using the luminosity ratio of the 7.7 μm PAH feature over the 3.5 μm stellar component of the SEDs. Results. The rest-frame SEDs of all PAH galaxies have a universal shape with stellar and 7.7 μm bumps, except that the PAH enhancement significantly varies as a function of the PAH luminosities. We identify a PAH-enhanced population at z ≳ 0.35, whose SEDs and luminosities are typical of luminous infrared galaxies. They show particularly larger PAH enhancement at high luminosity, implying that they are vigorous star-forming galaxies with elevated specific SFR. Our composite starburst model that combines a very young and optically very thick starburst with a very old population can successfully reproduce most of their SED characteristics, although we cannot confirm this optically think component from our spectral analysis.

Reconstruction of Star Formation and AGNs Activities in Galaxies Classified with the Balmer Break, 1.6 μm Bump and PAH Features up to z ≃2

2010 ◽  
Vol 6 (S277) ◽  
pp. 182-185
Author(s):  
Hitoshi Hanami ◽  
Tsuyoshi Ishigaki ◽  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Formation Rate ◽  
Massive Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
The North ◽  
Deep Survey ◽  
Multi Wavelength ◽  
Dusty Torus

AbstractWe have studied the star-forming and AGN activity of massive galaxies in the redshift range z = 0.4−2, which are detected in a deep survey field using the AKARI and Subaru telescopes toward the North Ecliptic Pole (NEP). The multi-wavelength survey allows us to select Mid-InfraRed (MIR) bright populations as Luminous InfraRed Galaxies (LIRGs) with L(IR) ≃ 1010–11 L⊙, which can be also sub-classified into Balmer Break Galaxies (BBGs) and Infra-Red (IR) Bump Galaxies (IRBGs). AKARI/IRC multiband photometry can distinguish their star-forming/AGN activity for LIRGs with/without the Polycyclic-Aromatic Hydrocarbon (PAH) emission bands at 6.2, 7.7 and 11.3 μm, and estimate the Star Formation Rate (SFR) from their total emitting InfraRed (IR) luminosities for star-formings and the emissions from dusty torus for AGNs. The results are summarised as below: 1) The rest-frame 7.7 μm luminosity is still a good tracer of the total IR (tIR) luminosity, as the PAH emission dominates for star-forming galaxies even up to z ≃ 2, 2) Rest-frame 5μm Luminosities may trace emissions from dusty torus of AGN in the LIRGs, 3) SFR of Starburst-AGN LIRGs (s/a-LIRGs) tends to quench at z < 0.8 more rapidly than that of Starburst dominated LIRGs (sb-LIRGs), 4) Intrinsic Stellar populations in the s/a-LIRGs show redder colours than those in the sb-LIRGs. These results suggest that Super Massive Black Holes (SMBH) could already have grown to ≃ 3 × 108M⊙ in the agn-LIRGs, with ≃ 1011L⊙ at z > 1.2, and the growth of SMBH tends to follow the star-forming activities around z = 1–2.

scholarly journals Spitzer view of Lyman break galaxies

2007 ◽  
Vol 3 (S245) ◽  
pp. 451-454
Author(s):  
Georgios E. Magdis ◽  
Dimitra Rigopoulou
Keyword(s):  
Rest Frame ◽  
Near Infrared ◽  
Optical Observations ◽  
Spectral Energy ◽  
Stellar Content ◽  
Mid Infrared ◽  
Lyman Break Galaxies ◽  
Polycyclic Aromatic ◽  
Stellar Masses ◽  
First Time

AbstractUsing a combination of deep MID-IR observations obtained by IRAC, MIPS and IRS on board Spitzer we investigate the MID-IR properties of Lyman Break Galaxies (LBGs) at z~3, establish a better understanding of their nature and attempt a complete characterisation of the population. With deep mid-infrared and optical observations of ~1000 LBGs covered by IRAC/MIPS and from the ground respectively, we extend the spectral energy distributions (SEDs) of the LBGs to mid-infrared. Spitzer data reveal for the first time that the mid-infrared properties of the population are inhomogeneous ranging from those with marginal IRAC detections to those with bright rest-frame near-infrared colors and those detected at 24μm MIPS band revealing the newly discovered population of the Infrared Luminous Lyman Break Galaxies (ILLBGs). To investigate this diversity, we examine the photometric properties of the population and we use stellar population synthesis models to probe the stellar content of these galaxies. We find that a fraction of LBGs have very red colors and large estimated stellar masses M∗>5×1010M⊙. We discuss the link between these LBGs and submm-luminous galaxies and we report the detection of rest frame 6.2 and 7.7 μm emission features arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum of an infrared-luminous Lyman break galaxy at z=3.01.

scholarly journals Stellar populations of galaxies in the ALHAMBRA survey up to z ∼ 1

2019 ◽  
Vol 631 ◽  
pp. A156 ◽  
Author(s):  
L. A. Díaz-García ◽  
A. J. Cenarro ◽  
C. López-Sanjuan ◽  
I. Ferreras ◽  
M. Cerviño ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Stellar Population ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Stellar Mass ◽  
Spectral Energy ◽  
Population Parameters ◽  
Star Forming ◽  
Set Constraints

Aims. Our aim is to determine the distribution of stellar population parameters (extinction, age, metallicity, and star formation rates) of quiescent galaxies within the rest-frame stellar mass–colour diagrams and UVJ colour–colour diagrams corrected for extinction up to z ∼ 1. These novel diagrams reduce the contamination in samples of quiescent galaxies owing to dust-reddened galaxies, and they provide useful constraints on stellar population parameters only using rest-frame colours and/or stellar mass. Methods. We set constraints on the stellar population parameters of quiescent galaxies combining the ALHAMBRA multi-filter photo-spectra with our fitting code for spectral energy distribution, MUlti-Filter FITting (MUFFIT), making use of composite stellar population models based on two independent sets of simple stellar population (SSP) models. The extinction obtained by MUFFIT allowed us to remove dusty star-forming (DSF) galaxies from the sample of red UVJ galaxies. The distributions of stellar population parameters across these rest-frame diagrams are revealed after the dust correction and are fitted by LOESS, a bi-dimensional and locally weighted regression method, to reduce uncertainty effects. Results. Quiescent galaxy samples defined via classical UVJ diagrams are typically contaminated by a ∼20% fraction of DSF galaxies. A significant part of the galaxies in the green valley are actually obscured star-forming galaxies (∼30–65%). Consequently, the transition of galaxies from the blue cloud to the red sequence, and hence the related mechanisms for quenching, seems to be much more efficient and faster than previously reported. The rest-frame stellar mass–colour and UVJ colour–colour diagrams are useful for constraining the age, metallicity, extinction, and star formation rate of quiescent galaxies by only their redshift, rest-frame colours, and/or stellar mass. Dust correction plays an important role in understanding how quiescent galaxies are distributed in these diagrams and is key to performing a pure selection of quiescent galaxies via intrinsic colours.

scholarly journals Local starbursts seen when the Universe was 2–4 Gyr old

2009 ◽  
Vol 5 (S266) ◽  
pp. 499-499
Author(s):  
S. M. Petty ◽  
D. F. de Mello ◽  
J. P. Gardner ◽  
J. S. Gallagher
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Rest Frame ◽  
Formation Rate ◽  
Starburst Galaxies ◽  
Spectral Energy ◽  
Multiple Star ◽  
Star Forming ◽  
The Galaxy ◽  
The Universe

AbstractWe explore the multiwavelength properties of three nearby starburst galaxies: NGC 3079, NGC 7673, and Mrk 08. We established that each of these galaxies has similar rest-frame far-ultraviolet (FUV) morphologies as Lyman-break galaxies (LBGs) at z ~ 1.5 and 4, when the age of the Universe was ~ 4.3 and ~ 1.6 Gyr, respectively. LBGs are at an important stage in galaxy evolution when the Universe had a peak in the star-formation-rate density. Many LBGs are primarily composed of star-forming clumps, i.e., stellar clusters, with a significant lack of older stellar populations. Here, we present the comparison of the spectral-energy distributions (SEDs) of three nearby starburst galaxies with those of typical LBGs. From our nearby sample, each object has been artificially redshifted to observe what the galaxies would look like at z ~ 1 to 4 in the rest-frame FUV. NGC 3079 is an edge-on Seyfert 2 galaxy. It has a bright bulge and is interacting with two other galaxies, with extended Hi only along NGC 3079. The redshifting process changes its appearance, so that at high z it looks like a chain galaxy with multiple knots of star formation and no bulge. NGC 7673 has extended Hi and the star formation is mostly within the inner optical region in the multiple star-forming clumps defining the galaxy morphology. In the FUV, the galaxy looks highly compact with little detail resolved. As it is artificially redshifted, the galaxy continues to look more spherical. Mrk 8 is a merging pair, with the two galaxies observable in the visible spectrum. It is classified as a Wolf–Rayet galaxy, which suggests a very young burst, and is composed of several large star-forming regions. The FUV image does not resolve the separate galaxies, and the appearance remains similar for each redshift. We use the Gini coefficient, M20, and the Sérsic index to quantify the morphologies. The SEDs of the objects have similarities with LBG stellar population models. Because these local galaxies can be studied in more detail, they act as a bridge between nearby observations of starburst galaxies and high-z starburst galaxies such as LBGs.

scholarly journals Linear radio size evolution of μJy populations

2018 ◽  
Vol 618 ◽  
pp. L8 ◽  
Author(s):  
M. Bondi ◽  
G. Zamorani ◽  
P. Ciliegi ◽  
V. Smolčić ◽  
E. Schinnerer ◽  
...  
Keyword(s):  
Rest Frame ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Angular Size ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Size Evolution ◽  
Multi Wavelength

We investigate the linear radio size properties of the μJy populations of radio-selected active galactic nuclei (AGN) and star-forming galaxies (SFGs) using a multi-resolution catalog based on the original VLA-COSMOS 3 GHz 0.″75 resolution mosaic and its convolved images (up to a resolution of 2.″2). The final catalog contains 6399 radio sources above a 3 GHz total flux density of ST >  20 μJy (median ⟨ST⟩=37 μJy), with redshift information (median ⟨z⟩=1.0), and multi-wavelength classification as SFGs, radio-excess AGN (RX-AGN), or non-radio-excess AGN (NRX-AGN). RX-AGN are those whose radio emission exceeds the star formation rate derived by fitting the global spectral energy distribution. We derive the evolution with redshift and luminosity of the median linear sizes of each class of objects. We find that RX-AGN are compact, with median sizes of ∼1–2 kpc and increasing with redshift, corresponding to an almost constant angular size of 0.″25. NRX-AGN typically have radio sizes a factor of 2 larger than the RX-AGN. The median radio size of SFGs is about 5 kpc up to z ∼ 0.7, and it decreases beyond this redshift. Using luminosity-complete subsamples of objects, we separately investigate the effect of redshift and luminosity dependance. We compare the radio sizes of SFGs with those derived in the rest-frame far-infrared (FIR) and UV bands. We find that SFGs have comparable sizes (within 15%) in the radio and rest-frame FIR, while the sizes measured in the UV-band are systematically larger than the radio sizes.

Star formation and polycyclic aromatic hydrocarbons in ELAIS N1 galaxies as seen by AKARI

2019 ◽  
Vol 71 (2) ◽  
Author(s):  
Tímea O Kovács ◽  
Denis Burgarella ◽  
Hidehiro Kaneda ◽  
Dániel Cs Molnár ◽  
Shinki Oyabu ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Star Formation ◽  
Aromatic Hydrocarbons ◽  
Main Sequence ◽  
Compact Star ◽  
Formation Rate ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Polycyclic Aromatic

Abstract We have examined the relationship between star formation and polycyclic aromatic hydrocarbons (PAHs) in a variety of galaxies. PAHs are excited by the ultraviolet photons of young stars, but they are disassociated by strong UV radiation in starbursts. Therefore their emission (which is in the wavelength range covered by AKARI) can be used as a star formation tracer in main sequence galaxies. We selected our targets in the ELAIS N1 field with AKARI detections, matched them with the Herschel Point Source Catalog, and collected other publicly available photometric data. Their spectral energy distributions (SEDs) were fitted, and several parameters of the galaxies were estimated, e.g., star formation rate (SFR), stellar mass, and the fraction of PAHs compared to dust mass (qPAH), and we examined the relationships between these parameters. The final sample consisted of 48 galaxies, with redshifts from 0.04 to 2.36. The estimated qPAH values were lower on average than typical values in the literature. This could be due to various reasons, such as low metallicity, or ongoing active galactic nucleus or starburst activity. Of our sample, 83% of the objects fell in the star-forming main sequence of galaxies, while only 8% could be considered as starbursts. We found a decreasing qPAH trend with increasing AV and consequently LIR, suggesting the possible presence of compact star-forming regions. We compared the qPAH values with the known relations of the PAH luminosities, but they did not always follow the same trends (SFR, LIR), and showed only slight correlation with the PAH luminosities.

scholarly journals The effects of star formation history in the SFR–M* relation of H ii galaxies

2020 ◽  
Vol 500 (3) ◽  
pp. 3240-3253
Author(s):  
Amanda R Lopes ◽  
Eduardo Telles ◽  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Star Formation History ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Good Tool ◽  
Star Forming ◽  
Additional Information ◽  
Star Formation Histories

ABSTRACT We discuss the implications of assuming different star formation histories (SFH) in the relation between star formation rate (SFR) and mass derived by the spectral energy distribution fitting (SED). Our analysis focuses on a sample of H ii galaxies, dwarf starburst galaxies spectroscopically selected through their strong narrow emission lines in SDSS DR13 at z &lt; 0.4, cross-matched with photometric catalogues from GALEX, SDSS, UKIDSS, and WISE. We modelled and fitted the SEDs with the code CIGALE adopting different descriptions of SFH. By adding information from different independent studies, we find that H ii galaxies are best described by episodic SFHs including an old (10 Gyr), an intermediate age (100−1000 Myr) and a recent population with ages &lt; 10 Myr. H ii galaxies agree with the SFR−M* relation from local star-forming galaxies, and only lie above such relation when the current SFR is adopted as opposed to the average over the entire SFH. The SFR−M* demonstrated not to be a good tool to provide additional information about the SFH of H ii galaxies, as different SFH present a similar behaviour with a spread of &lt;0.1 dex.

scholarly journals Extinction-free Census of AGNs in the AKARI/IRC North Ecliptic Pole Field from 23-band infrared photometry from Space Telescopes

2020 ◽  
Vol 499 (3) ◽  
pp. 4068-4081 ◽  
Author(s):  
Ting-Wen Wang ◽  
Tomotsugu Goto ◽  
Seong Jin Kim ◽  
Tetsuya Hashimoto ◽  
Denis Burgarella ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Cosmic Time ◽  
Spectral Energy ◽  
Wide Field ◽  
Space Telescopes ◽  
Distribution Modelling ◽  
Star Forming ◽  
The North ◽  
Band Filter ◽  
Infrared Survey

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.

scholarly journals Towards a census of high-redshift dusty galaxies with Herschel

2018 ◽  
Vol 614 ◽  
pp. A33 ◽  
Author(s):  
D. Donevski ◽  
V. Buat ◽  
F. Boone ◽  
C. Pappalardo ◽  
M. Bethermin ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Far Infrared ◽  
Virgo Cluster ◽  
Spectral Energy ◽  
Distribution Fitting ◽  
Redshift Distribution ◽  
Star Forming

Context. Over the last decade a large number of dusty star-forming galaxies has been discovered up to redshift z = 2 − 3 and recent studies have attempted to push the highly confused Herschel SPIRE surveys beyond that distance. To search for z ≥ 4 galaxies they often consider the sources with fluxes rising from 250 μm to 500 μm (so-called “500 μm-risers”). Herschel surveys offer a unique opportunity to efficiently select a large number of these rare objects, and thus gain insight into the prodigious star-forming activity that takes place in the very distant Universe. Aims. We aim to implement a novel method to obtain a statistical sample of 500 μm-risers and fully evaluate our selection inspecting different models of galaxy evolution. Methods. We consider one of the largest and deepest Herschel surveys, the Herschel Virgo Cluster Survey. We develop a novel selection algorithm which links the source extraction and spectral energy distribution fitting. To fully quantify selection biases we make end-to-end simulations including clustering and lensing. Results. We select 133 500 μm-risers over 55 deg2, imposing the criteria: S500 > S350 > S250, S250 > 13.2 mJy and S500 > 30 mJy. Differential number counts are in fairly good agreement with models, displaying a better match than other existing samples. The estimated fraction of strongly lensed sources is 24+6-5% based on models. Conclusions. We present the faintest sample of 500 μm-risers down to S250 = 13.2 mJy. We show that noise and strong lensing have an important impact on measured counts and redshift distribution of selected sources. We estimate the flux-corrected star formation rate density at 4 < z < 5 with the 500 μm-risers and find it to be close to the total value measured in far-infrared. This indicates that colour selection is not a limiting effect to search for the most massive, dusty z > 4 sources.

scholarly journals A complete census of circumgalactic Mg ii at redshift z ≲ 0.5

2021 ◽  
Vol 502 (4) ◽  
pp. 4743-4761 ◽  
Author(s):  
Yun-Hsin Huang ◽  
Hsiao-Wen Chen ◽  
Stephen A Shectman ◽  
Sean D Johnson ◽  
Fakhri S Zahedy ◽  
...  
Keyword(s):  
Rest Frame ◽  
Formation Rate ◽  
Host Galaxies ◽  
Clear Trend ◽  
Stellar Objects ◽  
Star Forming ◽  
Multiple Parameters ◽  
Isolated Galaxies ◽  
Cool Gas ◽  
Gas Accretion

ABSTRACT This paper presents a survey of Mg ii absorbing gas in the vicinity of 380 random galaxies, using 156 background quasi-stellar objects (QSOs) as absorption-line probes. The sample comprises 211 isolated (73 quiescent and 138 star-forming galaxies) and 43 non-isolated galaxies with sensitive constraints for both Mg ii absorption and H α emission. The projected distances span a range from d = 9 to 497 kpc, redshifts of the galaxies range from z = 0.10 to 0.48, and rest-frame absolute B-band magnitudes range from MB = −16.7 to −22.8. Our analysis shows that the rest-frame equivalent width of Mg ii, Wr(2796), depends on halo radius (Rh), B-band luminosity(LB), and stellar mass (Mstar) of the host galaxies, and declines steeply with increasing d for isolated, star-forming galaxies. At the same time, Wr(2796) exhibits no clear trend for either isolated, quiescent galaxies or non-isolated galaxies. In addition, the covering fraction of Mg ii absorbing gas 〈κ〉 is high with 〈κ〉 ≳ 60 per cent at &lt;40 kpc for isolated galaxies and declines rapidly to 〈κ〉 ≈ 0 at d ≳ 100 kpc. Within the gaseous radius, the incidence of Mg ii gas depends sensitively on both Mstar and the specific star formation rate inferred from H α. Different from what is known for massive quiescent haloes, the observed velocity dispersion of Mg ii absorbing gas around star-forming galaxies is consistent with expectations from virial motion, which constrains individual clump mass to $m_{\rm cl} \gtrsim 10^5 \, \rm M_\odot$ and cool gas accretion rate of $\sim 0.7\!-\!2 \, \mathrm{ M}_\odot \, \rm yr^{-1}$. Finally, we find no strong azimuthal dependence of Mg ii absorption for either star-forming or quiescent galaxies. Our results demonstrate that multiple parameters affect the properties of gaseous haloes around galaxies and highlight the need of a homogeneous, absorption-blind sample for establishing a holistic description of chemically enriched gas in the circumgalactic space.

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