Characteristics of mid-infrared PAH emission from star-forming galaxies selected at 250 μm in the North Ecliptic Pole field

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.

Download Full-text

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2988 ◽

2020 ◽

Vol 499 (3) ◽

pp. 4068-4081 ◽

Cited By ~ 1

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.

Download Full-text

Near- and mid-infrared colours of star-forming galaxies in European Large Area ISO Survey fields

Monthly Notices of the Royal Astronomical Society ◽

10.1046/j.1365-8711.2002.06006.x ◽

2002 ◽

Vol 337 (3) ◽

pp. 1043-1058 ◽

Cited By ~ 18

Author(s):

P. Vaisanen ◽

T. Morel ◽

M. Rowan-Robinson ◽

S. Serjeant ◽

S. Oliver ◽

...

Keyword(s):

Large Area ◽

Mid Infrared ◽

Star Forming

Download Full-text

A MULTIWAVELENGTH STUDY OF YOUNG MASSIVE STAR-FORMING REGIONS. III. MID-INFRARED EMISSION

The Astrophysical Journal ◽

10.1088/0004-637x/698/1/488 ◽

2009 ◽

Vol 698 (1) ◽

pp. 488-501 ◽

Cited By ~ 6

Author(s):

Esteban F. E. Morales ◽

Diego Mardones ◽

Guido Garay ◽

Kate J. Brooks ◽

Jaime E. Pineda

Keyword(s):

Massive Star ◽

Infrared Emission ◽

Mid Infrared ◽

Star Forming ◽

Star Forming Regions

Download Full-text

Different evolutionary stages in S235A-B

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307002001 ◽

2006 ◽

Vol 2 (S237) ◽

pp. 412-412

Author(s):

Marcello Felli ◽

Fabrizio Massi ◽

Riccardo Cesaroni

Keyword(s):

High Resolution ◽

Far Infrared ◽

Mid Infrared ◽

Star Forming ◽

Maser Line ◽

Water Maser

AbstractThe star forming region S235A-B has been studied at high resolution with radio (IRAM Interferometer and VLA) and infrared (JCMT and Spitzer) observations. The region was mapped in HCO+, C34S, H2CS, SO2 and CH3CN as well as in the 1.2 and 3.3 continuum, in the cm continuum at 6, 3.6, 1.3 and 0.7 cm and in the 22 GHz water maser line, in the far infrared at 450 and 850 μm and in the mid infrared from 3.6 to 8 μm. Finally, use was made of the Medicina water maser patrol, from 1987 to 2005, to study the maser variability.

Download Full-text

B. Radio Studies

Transactions of the International Astronomical Union ◽

10.1017/s0251107x00006465 ◽

1985 ◽

Vol 19 (1) ◽

pp. 409-416

Keyword(s):

Measure Data ◽

Star Forming ◽

Star Forming Regions ◽

The North ◽

Rotation Measure ◽

Turbulent Characteristics ◽

Radio Studies ◽

Local Medium ◽

North Polar ◽

Perseus Arm

Several regional surveys of southern HI made with the Argentine 100-m telescope were published (30.155.031). HI and other data were used by Dolidze (30.155. 044) to study the local distribution of gas and star forming regions. The Perseus arm region was the subject of an analogous study by Gerasimenko (34.155.139). Vallée (34.155.005) used rotation measure data from extragalactic sources in the direction of the Perseus arm to determine the magnetic field structure there and to constrain gravitational collapse theories of magnetic compression. HI in the direction of the Puppis window was surveyed by Stacy and Jackson (32.131.277) and used to study the turbulent characteristics of the interstellar medium. HI related to Gould“s Belt was studied by Pöppel and Olano (32.155.024, 33.155.030). Salter (34. 131.014) reviewed radio and other observations pertaining tc Loop I, the North Polar Spur, and considered the influence which this structure might have on the local medium.

Download Full-text

The Youngest Star-Forming Regions in Galaxies: Giant Compact HII Regions and Protoglobular Clusters?

Symposium - International Astronomical Union ◽

10.1017/s0074180900221049 ◽

2001 ◽

Vol 205 ◽

pp. 224-227

Author(s):

Jean L. Turner

Keyword(s):

Dwarf Galaxy ◽

Hii Regions ◽

Starburst Galaxies ◽

Mid Infrared ◽

Infrared Observations ◽

Star Forming ◽

Bolometric Luminosity ◽

Star Forming Regions ◽

Young Clusters ◽

Compact Hii Regions

Subarcsecond radio and infrared observations reveal a class of luminous, obscured, optically thick HII regions associated with extremely large young clusters in nearby starburst galaxies. VLA images show bright radio nebulae with ne ∼ 104 cm−3, densities characteristic of young Galactic compact HII regions. Excitation of the nebulae requires the presence of several thousand O stars within regions of 1-10 pc extent, corresponding to clusters containing 105–106 stars. The compact nebulae are also bright in the mid-infrared, and can for significant fractions of not only the total IR luminosity, but also the total bolometric luminosity, of the parent galaxies. The prototype for these “supernebulae” is the large, obscured cluster in the dwarf galaxy NGC 5253.

Download Full-text