scholarly journals Stellar populations of local infrared-selected galaxies

2009 ◽  
Vol 5 (S262) ◽  
pp. 313-314
Author(s):  
X. Y. Chen ◽  
Y. C. Liang ◽  
F. Hammer ◽  
Y. H. Zhao ◽  
G. H. Zhong
Keyword(s):  
Stellar Populations ◽  
Infrared Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
Normal 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.

Characterizing circumnuclear starbursts in the local universe with the VLA

2020 ◽  
Vol 15 (S359) ◽  
pp. 462-463
Author(s):  
Yiqing Song ◽  
Sean T. Linden ◽  
Aaron S. Evans ◽  
Loreto Barcos-Muñoz ◽  
Eric J. Murphy
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Radio Continuum ◽  
Infrared Galaxies ◽  
Very Large Array ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
Normal Galaxies ◽  
Star Forming Regions ◽  
Nuclear Ring

AbstractNuclear rings are excellent laboratories to study star formation (SF) under extreme conditions. We compiled a sample of 9 galaxies that exhibit bright nuclear rings at 3-33 GHz radio continuum observed with the Jansky Very Large Array, of which 5 are normal star-forming galaxies and 4 are Luminous Infrared Galaxies (LIRGs). Using high frequency radio continuum as an extinction-free tracer of SF, we estimated the size and star formation rate of each nuclear ring and a total of 37 individual circumnuclear star-forming regions. Our results show that majority of the SF in the sample LIRGs take place in their nuclear rings, and circumnuclear SF in local LIRGs are much more spatially concentrated compared to those in the local normal galaxies and previously studied nuclear and extra-nuclear SF in normal galaxies at both low and high redshifts.

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

2015 ◽  
Vol 811 (1) ◽  
pp. 15 ◽  
Author(s):  
Adam K. Leroy ◽  
Fabian Walter ◽  
Roberto Decarli ◽  
Alberto Bolatto ◽  
Laura Zschaechner ◽  
...  
Keyword(s):  
Infrared Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies

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

2004 ◽  
Vol 127 (2) ◽  
pp. 736-757 ◽  
Author(s):  
T. Hattori ◽  
M. Yoshida ◽  
H. Ohtani ◽  
H. Sugai ◽  
T. Ishigaki ◽  
...  
Keyword(s):  
Infrared Galaxies ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
Star Forming Regions

scholarly journals Luminous IR Galaxies: Evolution and Molecular Gas

1997 ◽  
Vol 159 ◽  
pp. 439-440 ◽  
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.

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

2019 ◽  
Vol 881 (1) ◽  
pp. 70 ◽  
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

scholarly journals VLBI Imaging of Luminous Infrared Galaxies: Starbursts & AGN

1999 ◽  
Vol 194 ◽  
pp. 60-65
Author(s):  
Harding E. Smith ◽  
Carol J. Lonsdale ◽  
Colin J. Lonsdale ◽  
Philip J. Diamond
Keyword(s):  
Infrared Galaxies ◽  
Complete Sample ◽  
Maser Emission ◽  
Luminous Infrared Galaxies ◽  
Normal Galaxies ◽  
Vlbi Observations

Luminous Infrared Galaxies (LIGs) are locally more numerous than normal galaxies, AGN, and QSOs above L ˜ 1011L⊙ and may be the evolutionary precursors of classical radio-quiet quasars. VLBI observations of a complete sample show that high-Tb radio cores are common, perhaps universal among LIGs. VLBI imaging shows that these radio cores may be produced by intense starbursts which generate luminous radio supernovae, as in the case of Arp 220 (Smith et al. 1998), or by a classical AGN core, as in the case of Mrk 231, which we interpret as a newly formed QSO emerging from a starburst. Compact OH 1667MHz maser emission appears to be common in LIGs and may be related to AGN activity. These results lend further support to the scenario suggested by Sanders et al (1988) in which mergers of gas-rich galaxies lead first to luminous starbursts which evolve into radio-quiet quasars.

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

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.

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

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.

scholarly journals The Nature of the Energy Source in LINERs

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.

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

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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