scholarly journals Powerful Molecular Outflows in Nearby Active Galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 291-297
Author(s):  
Sylvain Veilleux ◽  
Marcio Meléndez ◽  
Keyword(s):  
Star Formation Rate ◽  
Dominant Role ◽  
Formation Rate ◽  
Wide Angle ◽  
Galaxy Mergers ◽  
Infrared Galaxies ◽  
Molecular Outflows ◽  
Ultraluminous Infrared Galaxies ◽  
Silicate Feature ◽  
Line Widths

AbstractWe report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel-PACS† in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7-μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than −50 km s−1, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (~ 145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s−1, is seen in only 4 objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ~ −1000 km s−1 are measured in several objects, but median outflow velocities are typically ~ −200 km s−1. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large AGN fractions and luminosities [log (LAGN/L⊙) ≥ 11.8 ± 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. In contrast, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

scholarly journals AGN Absorption Linked to Host Galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 319-322
Author(s):  
Stéphanie Juneau
Keyword(s):  
Star Formation Rate ◽  
Formation Rate ◽  
Far Infrared ◽  
Host Galaxies ◽  
Infrared Galaxies ◽  
Nuclear Activity ◽  
X Ray ◽  
Star Forming ◽  
Diagnostic Diagram ◽  
X Ray Absorption

AbstractMultiwavelength identification of AGN is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity (obscuration, efficiency, etc.). A panchromatic strategy plays an especially important role when the host galaxies are star-forming. Selecting far-Infrared galaxies at 0.3<z<1, and using AGN tracers in the X-ray, optical spectra, mid-infrared, and radio regimes, we found a twice higher AGN fraction than previous studies, thanks to the combined AGN identification methods and in particular the recent Mass-Excitation (MEx) diagnostic diagram. We furthermore find an intriguing relation between AGN X-ray absorption and the specific star formation rate (sSFR) of the host galaxies, indicating a physical link between X-ray absorption and either the gas fraction or the gas geometry in the hosts. These findings have implications for our current understanding of both the AGN unification model and the nature of the black hole-galaxy connection.

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 A HERSCHEL SURVEY OF THE [N II] 205 μm LINE IN LOCAL LUMINOUS INFRARED GALAXIES: THE [N II] 205 μm EMISSION AS A STAR FORMATION RATE INDICATOR

2013 ◽  
Vol 765 (1) ◽  
pp. L13 ◽  
Author(s):  
Yinghe Zhao ◽  
Nanyao Lu ◽  
C. Kevin Xu ◽  
Yu Gao ◽  
S. Lord ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies

scholarly journals ISOCAM Deep Surveys and the Cosmic Infrared Background

2002 ◽  
Vol 12 ◽  
pp. 485-488
Author(s):  
David Elbaz
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Steep Slope ◽  
Infrared Galaxies ◽  
Redshift Distribution ◽  
Infrared Background ◽  
Number Counts ◽  
Hubble Deep Field

AbstractThe steep slope of the ISOCAM 15 μmnumber counts indicates that infrared galaxies have strongly evolved sincez∼ 1 − 1.5. A nearly complete spectroscopic sample of ISOCAM galaxies in the Hubble Deep Field North (HDFN) shows that their redshift distribution is peaked aroundz∼ 0.8. We show that the 7 μmluminosity of local galaxies is correlated with their 8-1000 μmluminosity, and therefore star formation rate (SFR). We use this correlation in the rest-frame of the ISOCAM galaxies to deduce their IR luminosities (∼ 4 × 1011L⊙), SFR (∼ 80M⊙yr−1) and contribution to the peak of the cosmic IR background (CIRB) at 140 μm. We find that they most probably produce the bulk of the CIRB.

scholarly journals Deep learning for galaxy mergers in the galaxy main sequence

2019 ◽  
Vol 15 (S341) ◽  
pp. 104-108
Author(s):  
William J. Pearson ◽  
Lingyu Wang ◽  
James Trayford ◽  
Carlo E. Petrillo ◽  
Floris F. S. van der Tak
Keyword(s):  
Deep Learning ◽  
Star Formation ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Galaxy Mergers ◽  
The Galaxy ◽  
Galaxy Population ◽  
Stellar Masses

AbstractStarburst galaxies are often found to be the result of galaxy mergers. As a result, galaxy mergers are often believed to lie above the galaxy main sequence: the tight correlation between stellar mass and star formation rate. Here, we aim to test this claim.Deep learning techniques are applied to images from the Sloan Digital Sky Survey to provide visual-like classifications for over 340 000 objects between redshifts of 0.005 and 0.1. The aim of this classification is to split the galaxy population into merger and non-merger systems and we are currently achieving an accuracy of 92.5%. Stellar masses and star formation rates are also estimated using panchromatic data for the entire galaxy population. With these preliminary data, the mergers are placed onto the full galaxy main sequence, where we find that merging systems lie across the entire star formation rate - stellar mass plane.

scholarly journals Three regimes of CO emission in galaxy mergers

2019 ◽  
Vol 621 ◽  
pp. A104 ◽  
Author(s):  
Florent Renaud ◽  
Frédéric Bournaud ◽  
Emanuele Daddi ◽  
Axel Weiß
Keyword(s):  
Star Formation ◽  
Conversion Factor ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Galaxy Mergers ◽  
Isolated Galaxies ◽  
Molecular Masses ◽  
Hydrodynamical Simulations ◽  
Classical Means ◽  
Large Velocity Gradient

The conversion factor αCO from the observable CO(1-0) luminosity to the mass of molecular gas is known to vary between isolated galaxies and some mergers, but the underlying reasons are not clearly understood. Thus, the value(s) of αCO that are to be adopted remain highly uncertain. To provide better constraints, we applied the large velocity gradient method to a series of hydrodynamical simulations of galaxies and derived the evolution of αCO. We report significant variations of αCO, and identify three distinct regimes: disk galaxies, starbursts, and post-burst phases. We show that estimating the star formation rate over 20Myr smoothes out some of these differences, but still maintains a distinction between disks and starbursts. We find a tighter correlation of αCO with the gas depletion time than with star formation rate, but deviations are induced by the transitions to and from the starburst episodes. We conclude that αCO fluctuates because of both feedback energy and velocity dispersion. Identifying the phase of an interaction by classical means (e.g., morphology or luminosity) could then help to select the relevant conversion factor that is to be used and to obtain more accurate estimates of the molecular masses of galaxies.

scholarly journals High angular resolution radio and infrared view of optically dark supernovae in luminous infrared galaxies

2016 ◽  
Vol 12 (S329) ◽  
pp. 332-336
Author(s):  
Seppo Mattila ◽  
Erkki Kankare ◽  
Erik Kool ◽  
Cristina Romero-Cañizales ◽  
Stuart Ryder ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Angular Resolution ◽  
Formation Rate ◽  
High Angular Resolution ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies ◽  
Ultraluminous Infrared Galaxies ◽  
Central Regions ◽  
Nuclear Regions ◽  
The Universe

AbstractIn luminous and ultraluminous infrared galaxies (U/LIRGs), the infall of gas into the central regions strongly enhances the star formation rate (SFR), especially within the nuclear regions which have also large amounts of interstellar dust. Within these regions SFRs of several tens to hundreds of solar masses per year ought to give rise to core-collapse supernova (SN) rates up to 1-2 SNe every year per galaxy. However, the current SN surveys, almost exclusively being ground-based seeing-limited and working at optical wavelengths, have been blinded by the interstellar dust and contrast issues therein. Thus the properties and rates of SNe in the nuclear environments of the most prolific SN factories in the Universe have remained largely unexplored. Here, we present results from high angular resolution observations of nearby LIRGs at infrared and radio wavelengths much less affected by the effects of extinction and lack of resolution hampering the optical searches.

scholarly journals ACHANDRAPERSPECTIVE ON GALAXY-WIDE X-RAY BINARY EMISSION AND ITS CORRELATION WITH STAR FORMATION RATE AND STELLAR MASS: NEW RESULTS FROM LUMINOUS INFRARED GALAXIES

2010 ◽  
Vol 724 (1) ◽  
pp. 559-571 ◽  
Author(s):  
B. D. Lehmer ◽  
D. M. Alexander ◽  
F. E. Bauer ◽  
W. N. Brandt ◽  
A. D. Goulding ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Infrared Galaxies ◽  
X Ray ◽  
Luminous Infrared Galaxies

scholarly journals A Galaxy Merging Sequence Traced by X-rays

2004 ◽  
Vol 217 ◽  
pp. 430-431
Author(s):  
Yu Gao ◽  
Q. Daniel Wang ◽  
Ted A. Markowsky
Keyword(s):  
Numerical Simulations ◽  
X Rays ◽  
Galaxy Mergers ◽  
Infrared Galaxies ◽  
Merging Galaxies ◽  
X Ray ◽  
Luminous Infrared Galaxies ◽  
Optical Images ◽  
Ultraluminous Infrared Galaxies

We are studying a sample of nearly 20 nearby (cz≲13,000 km s−1) IR-luminous interacting/merging galaxies observed with the ACIS in the Chandra archive (e.g., Gao et al. 2003; Ptak et al. 2003). Most galaxies in the sample are luminous infrared galaxies (LIGs) and nearly half of them are ultraluminous infrared galaxies (ULIGs) with bolometric luminosities comparable to QSOs. Based on multiwavelength data and numerical simulations of gas-rich galaxy mergers, we have attempted to arrange them in a merger sequence perspective and compared their broadband X-ray emission here with the optical images (mostly DSS).

scholarly journals Correlations between mass, stellar kinematics, and gas metallicity in eagle galaxies

2020 ◽  
Vol 496 (1) ◽  
pp. L33-L37
Author(s):  
L J Zenocratti ◽  
M E De Rossi ◽  
M A Lara-López ◽  
T Theuns
Keyword(s):  
Star Formation ◽  
Dominant Role ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
Galaxy Mergers ◽  
Stellar Kinematics ◽  
Star Forming ◽  
Stellar Feedback ◽  
Star Formation Histories

ABSTRACT The metallicity of star-forming gas in galaxies from the eagle (Evolution and Assembly of GaLaxies and their Environments) simulations increases with stellar mass. Here, we investigate whether the scatter around this relation correlates with morphology and/or stellar kinematics. At redshift z = 0, galaxies with more rotational support have lower metallicities on average when the stellar mass is below M⋆ ≈ 1010 M⊙. This trend inverts at higher values of M⋆, when prolate galaxies show typically lower metallicity. At increasing redshifts, the trend between rotational support and metallicity becomes weaker at low stellar mass but more pronounced at high stellar mass. We argue that the secondary dependence of metallicity on stellar kinematics is another manifestation of the observed anticorrelation between metallicity and star formation rate at a given stellar mass. At low masses, such trends seem to be driven by the different star formation histories of galaxies and stellar feedback. At high masses, feedback from active galactic nuclei and galaxy mergers plays a dominant role.

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