FAINT CO LINE WINGS IN FOUR STAR-FORMING (ULTRA)LUMINOUS INFRARED GALAXIES

AbstractThe stellar populations of 849 local infrared-selected galaxies from SDSS and IRAS (including 419 star-forming galaxies, 326 composite galaxies, 35 Seyfert 2s, and 69 LINERs in 4 spectral classes) are studied by using STARLIGHT. Among the 4 spectral classes, the importance of young populations decreases from star-forming, composite, Seyfert 2 to LINER; and Seyfert 2 and LINER are more metal-rich; ULIGs (ultra luminous infrared galaxies) & LIGs present the youngest populations among 3 infrared luminosity bins; and normal galaxies are more metal-rich. The dominant contributors to masses are all old populations.

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A Study of the Distribution of Star-forming Regions in Luminous Infrared Galaxies by Means of H Imaging Observations

The Astronomical Journal ◽

10.1086/381060 ◽

2004 ◽

Vol 127 (2) ◽

pp. 736-757 ◽

Cited By ~ 36

Author(s):

T. Hattori ◽

M. Yoshida ◽

H. Ohtani ◽

H. Sugai ◽

T. Ishigaki ◽

...

Keyword(s):

Infrared Galaxies ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Star Forming Regions

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Luminous IR Galaxies: Evolution and Molecular Gas

International Astronomical Union Colloquium ◽

10.1017/s0252921100040690 ◽

1997 ◽

Vol 159 ◽

pp. 439-440 ◽

Cited By ~ 1

Author(s):

Yu Gao

Keyword(s):

Molecular Gas ◽

Infrared Galaxies ◽

Galaxy Interactions ◽

Merging Galaxies ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Star Forming Regions ◽

Ir Sources ◽

Order Of Magnitude ◽

The Universe

Luminous infrared galaxies (LIRGs), denned by the criterion LIR ≳ 2 × 1011L⊙ (for H0=75 kms−1 Mpc−1), are the most powerful IR sources in the Universe, with most of their emission (~ 90%) in the far-IR. Most LIRGs are interacting/merging galaxies with large amounts of molecular gas as revealed by CO surveys (Sanders et al. 1991; Solomon et al. 1996). However, whether starbursts or dust-enshrouded AGNs/QSOs dominate the IR luminosity is not resolved.CO may not trace the active star-forming regions where gas density is more than one order of magnitude higher than the average. Dense molecular gas is better traced by high dipole-moment molecules like HCN and CS (e.g., Nguyen-Q-Rieu et al. 1992; Gao & Solomon 1996). Therefore, it is essential to survey HCN emission in a large sample of LIRGs to better reveal the nature of LIRGs. We here study IR and molecular gas properties vs. galaxy-galaxy interactions in LIRGs over various merging phases to trace their evolution and explore some links among interactions, starbursts, and AGN phenomena.

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A Very Large Array Survey of Luminous Extranuclear Star-forming Regions in Luminous Infrared Galaxies in GOALS

The Astrophysical Journal ◽

10.3847/1538-4357/ab2872 ◽

2019 ◽

Vol 881 (1) ◽

pp. 70 ◽

Cited By ~ 3

Author(s):

S. T. Linden ◽

Y. Song ◽

A. S. Evans ◽

E. J. Murphy ◽

L. Armus ◽

...

Keyword(s):

Large Array ◽

Infrared Galaxies ◽

Very Large Array ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Star Forming Regions

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The molecular gas in Luminous Infrared Galaxies: a new emergent picture

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313001117 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 209-214

Author(s):

Padelis P. Papadopoulos ◽

Zhi-Yu Zhang ◽

Axel Weiss ◽

Paul van der Werf ◽

Kate Isaak ◽

...

Keyword(s):

Cosmic Ray ◽

Molecular Gas ◽

Infrared Galaxies ◽

Space Observatory ◽

Local Universe ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Physical Conditions ◽

J 13 ◽

Line Survey

AbstractResults from a large, multi-J CO, 13CO, and HCN line survey of Luminous Infrared Galaxies (LIRGs: LIR≥ 1010 L⊙) in the local Universe (z≤0.1), complemented by CO J=4–3 up to J=13–12 observations from the Herschel Space Observatory (HSO), paints a new picture for the average conditions of the molecular gas of the most luminous of these galaxies with turbulence and/or large cosmic ray (CR) energy densities UCR rather than far-UV/optical photons from star-forming sites as the dominant heating sources. Especially in ULIRGs (LIR>1012 L⊙) the Photon Dominated Regions (PDRs) can encompass at most a few % of their molecular gas mass while the large UCR∼ 103 UCR, Galaxy, and the strong turbulence in these merger/starbursts, can volumetrically heat much of their molecular gas to Tkin∼ (100-200) K, unhindered by the high dust extinctions. Moreover the strong supersonic turbulence in ULIRGs relocates much of their molecular gas at much higher average densities (≥104 cm−3) than in isolated spirals (∼ 102–103 cm−3). This renders low-J CO lines incapable of constraining the properties of the bulk of the molecular gas in ULIRGs, with substantial and systematic underestimates of its mass possible when only such lines are used. Finally a comparative study of multi-J HCN lines and CO SLEDs from J=1–0 up to J=13–12 of NGC 6240 and Arp 193 offers a clear example of two merger/starbursts whose similar low-J CO SLEDs, and LIR/LCO,1−0 and LHCN, 1−0/LCO,1-0 ratios (proxies of the so-called SF efficiency and dense gas mass fraction), yield no indications about their strongly diverging CO SLEDs beyond J=4–3, and ultimately the different physical conditions in their molecular ISM. The much larger sensitivity of ALMA and its excellent site in the Atacama desert now allows the observations necessary to assess the dominant energy sources of the molecular gas and its mass in LIRGs without depending on the low-J CO lines.

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A Herschel Survey of the [N ii] 205 μm Emission in Local Infrared Luminous Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313001312 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 256-256

Author(s):

Yinghe Zhao ◽

Nanyao Lu ◽

C. Kevin Xu ◽

Yu Gao ◽

Keyword(s):

Statistical Study ◽

Star Formation Rate ◽

Formation Rate ◽

Line Emission ◽

Infrared Galaxies ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

High Ionization ◽

Luminous Galaxies ◽

Ionization Parameter

AbstractThe [N ii] line is a major coolant in ionized interstellar medium, and is expected to be a good star formation rate indicator. Here we present a statistical study of [N ii] line emission for a large sample of local luminous infrared galaxies (LIRGs) using Herschel SPIRE FTS data (Lu et al. 2012; Zhao et al. 2012, in preparation). For our sample of galaxies, the [N ii] to the total infrared luminosity ratio (L[Nii]/LIR) varies from ∼ 10−5 to ∼ 10−4. We investigate the correlation between L[Nii] and LIR, as well as the dependence of L[Nii]/LIR on LIR, infrared colors (f60/f100) and the OIII 88 μm to [N ii] luminosity ratio. We find that L[Nii] strongly, and almost linearly correlates with LIR for star-forming galaxies, namely log LIR = (4.23 ± 0.33) + (0.99 ± 0.05) log L[NII] (see Fig. 1). The scatter in this relation is mainly due to the variation of hardness, and/or high ionization parameter, of the background UV field.

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The Nature of the Energy Source in LINERs

International Astronomical Union Colloquium ◽

10.1017/s025292110004077x ◽

1997 ◽

Vol 159 ◽

pp. 477-484

Author(s):

L. Colina ◽

A. Koratkar

Keyword(s):

Minor Role ◽

Host Galaxies ◽

Infrared Galaxies ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Star Forming Regions ◽

Resolution Imaging ◽

Imaging And Spectroscopy ◽

A Minor ◽

High Spatial Resolution Imaging

AbstractLINERs are found in ~30% of all bright galaxies, including luminous infrared galaxies. They form a heterogeneous class powered by a variety of ionizing mechanisms such as low-luminosity AGNs, starbursts, shocks, or any combination of these.In early-type spirals, LINERs are powered by a low-luminosity AGN, or by an AGN surrounded by circumnuclear star-forming regions. In luminous infrared galaxies, LINERs are powered by starbursts with associated wind-related extended shocks, and an AGN may play a minor role, if any. LINERs in some FR I radio galaxies show a strong evidence for the presence of a massive central black hole, and there are indications for the existence of shocks in the nuclear disks of these galaxies. Yet, the dominant ionizing mechanism for LINERs in radio-quiet ellipticals and FR I host galaxies is still unclear.Multifrequency high spatial resolution imaging and spectroscopy are essential to discriminate among the different ionizing mechanisms present in LINERs.

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Mid-IR Spectroscopy of Submm Galaxies: Extended Star Formation in High-z Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310010082 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 423-424

Author(s):

K. Menéndez-Delmestre ◽

A. W. Blain ◽

I. Smail ◽

D. M. Alexander ◽

S. C. Chapman ◽

...

Keyword(s):

Star Formation ◽

High Redshift ◽

Dust Emission ◽

Infrared Galaxies ◽

Local Universe ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Star Formation Activity ◽

Polycyclic Aromatic ◽

Intense Star Formation

AbstractUltra-luminous infrared galaxies (ULIRGs; L > 1012 L⊙) are quite rare in the local universe, but seem to dominate the co-moving energy density at z > 2. Many are optically-faint, dust-obscured galaxies that have been identified only relatively recently by the detection of their thermal dust emission redshifted into the sub-mm wavelengths. These submm galaxies (SMGs) have been shown to be a massive objects (M* ~ 1011 M⊙) undergoing intense star-formation(SFRs ~ 102 − 103 M⊙ yr−1) and the likely progenitors of massive ellipticals today. However, the AGN contribution to the far-IR luminosity had for years remained a caveat to these results. We used the Spitzer Infrared Spectrograph (IRS) to investigate the energetics of 24 radio-identified and spectroscopically-confirmed SMGs in the redshift range of 0.6 < z < 3.2. We find emission from Polycyclic Aromatic Hydrocarbons (PAHs) – which are associated with intense star-formation activity – in >80% of our sample and find that the median mid-IR spectrum is well described by a starburst component with an additional power-law continuum representing < 32% AGN contribution to the far-IR luminosity. We also find evidence for a more extended distribution of warm dust in SMGs compared to the more compact nuclear bursts in local ULIRGs and starbursts, suggesting that SMGs are not simple high-redshift analogs of local ULIRGs or nuclear starbursts, but have star formation which resembles that seen in less-extreme star-forming environments at z ~ 0.

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The OTELO survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833296 ◽

2019 ◽

Vol 631 ◽

pp. A11 ◽

Cited By ~ 2

Author(s):

Marina Ramón-Pérez ◽

Ángel Bongiovanni ◽

Ana María Pérez García ◽

Jordi Cepa ◽

Jakub Nadolny ◽

...

Keyword(s):

Equivalent Width ◽

Emission Lines ◽

X Rays ◽

Late Type ◽

Infrared Galaxies ◽

Mid Infrared ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Different Types ◽

Tunable Emission

Aims. We take advantage of the capabilities of the OSIRIS Tunable Emission Line Object (OTELO) survey to select and study the AGN population in the field. In particular, we aim to perform an analysis of the properties of these objects, including their demography, morphology, and IR luminosity. Focusing on the population of Hα emitters at z ∼ 0.4, we also aim to study the environments of AGN and non-AGN galaxies at that redshift. methods. We make use of the multiwavelength catalogue of objects in the field compiled by the OTELO survey, unique in terms of minimum flux and equivalent width. We also take advantage of the pseudo-spectra built for each source, which allow the identification of emission lines and the discrimination of different types of objects. Results. We obtained a sample of 72 AGNs in the field of OTELO, selected with four different methods in the optical, X-rays, and mid-infrared bands. We find that using X-rays is the most efficient way to select AGNs. An analysis was performed on the AGN population of OTELO in order to characterise its members. At z ∼ 0.4, we find that up to 26% of our Hα emitters are AGNs. At that redshift, AGNs are found in identical environments to non-AGNs, although they represent the most clustered group when compared to passive and star-forming galaxies. The majority of our AGNs at any redshift were classified as late-type galaxies, including a 16% proportion of irregulars. Another 16% of AGNs show signs of interactions or mergers. Regarding the infrared luminosity, we are able to recover all the luminous infrared galaxies (LIRGs) in the field of OTELO up to z ∼ 1.6. We find that the proportion of LIRGs and ultra-luminous infraed galaxies (ULIRGs) is higher among the AGN population, and that ULIRGs show a higher fraction of AGNs than LIRGs.

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Spatially-Resolved View of High-Redshift Starbursts: the case of Sub-mm Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313004407 ◽

2012 ◽

Vol 8 (S295) ◽

pp. 92-92

Author(s):

Karín Menéndez-Delmestre ◽

Andrew W. Blain ◽

Mark Swinbank ◽

Ian Smail ◽

Rob J. Ivison ◽

...

Keyword(s):

Star Formation ◽

Adaptive Optics ◽

Spatial Scales ◽

Large Fraction ◽

Spectroscopic Techniques ◽

Infrared Galaxies ◽

Star Forming ◽

Luminous Infrared Galaxies ◽

Disk Structure ◽

Hα Emission

AbstractUltra-luminous infrared galaxies (LIR > 1012 L⊙) are locally rare, but appear to dominate the co-moving energy density at higher redshifts (z>2). Many of these are optically-faint, dust-obscured galaxies that have been identified by the detection of their thermal dust emission at sub-mm wavelengths. Multi-wavelength spectroscopic follow-up observations of these sub-mm galaxies (SMGs) have shown that they are massive (Mstellar ~ 1011 M⊙) objects undergoing intense star-formation (SFRs ~ 102−103 M⊙ yr−1) with a mean redshift of z ~ 2, coinciding with the epoch of peak quasar activity. The large fraction of AGNs in SMGs and the derived SMBH masses (M• < 108 M⊙) in these galaxies suggest that the submm phase may play an important role in the rapid growth of SMBHs. When both AGN and star-formation activity are present, long-slit spectroscopic techniques face difficulties in disentangling their contributions and may result in SFR and mass overestimates. We present an integral field view of the Hα emission in a sample of 3 SMGs at z~1.4–2.4 with the IFU instrument OSIRIS on Keck. Designed to be used with Laser Guide Star Adaptive Optics, OSIRIS allows a spatial resolution of up to 10× higher than what has been possible in previous seeing-limited studies of the ionized gas in these galaxies. Our main results are the following: (1) We detect multiple galactic-scale sub-components: the compact, broad Hα emission (FWHM >1000 km s−1) likely associated with an AGN, the more extended narrow-line Hα emission (FWHM ≲500 km s−1) of star-forming regions; the latter are dominated by multiple 1–2 kpc sized Hα-bright clumps, each contributing 1-25% of the total clump-integrated Hα emission. (2) We derive clump dynamical masses ~1–10×109M⊙, 1–2 orders of magnitude larger than the kpc-scaled stellar clumps uncovered in optically-selected z ~ 2 star-forming galaxies. (3) We determine high star-formation rate surface densities (ΣSFR~1–50 M⊙yr−1 kpc−2, after extinction correction), similar to local starbursts and luminous infrared galaxies. In contrast to these local environments, SMGs undergo such intense activity on significantly larger spatial scales as revealed by extended Hα emission over 4–16 kpc. (4) We find no evidence of ordered global motion as it would be found in a disk, but rather large velocity offsets (~ few × 100 km s−1) between the distinct stellar clumps. The merger interpretation is likely the most accurate scenario for the SMGs in our sample. However, the final test of whether an underlying disk structure is present will come from studies of the cold gas at the high spatial resolutions possible with ALMA.We refer the reader to Menéndez-Delmestre et al. (2012) for more details.

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