The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Chris Pearson - One of the best experts on this subject based on the ideXlab platform.

  • a high redshift population of galaxies at the north ecliptic pole unveiling the main sequence of dusty galaxies
    arXiv: Astrophysics of Galaxies, 2020
    Co-Authors: L Barrufet, Chris Pearson, S Serjeant, K Malek, I Baronchelli, M C Camposvarillas, G J White, I Valtchanov, H Matsuhara, L Conversi
    Abstract:

    Dusty high-z galaxies are extreme objects with high star formation rates (SFRs) and luminosities. Characterising the properties of this population and analysing their evolution over cosmic time is key to understanding galaxy evolution in the early Universe. We select a sample of high-z dusty star-forming galaxies (DSFGs) and evaluate their position on the main sequence (MS) of star-forming galaxies, the well-known correlation between stellar mass and SFR. We aim to understand the causes of their high star formation and quantify the percentage of DSFGs that lie above the MS. We adopted a multi-wavelength approach with data from optical to submillimetre wavelengths from surveys at the North Ecliptic Pole (NEP) to study a submillimetre sample of high-redshift galaxies. Two submillimetre selection methods were used, including: sources selected at 850$\mathrm{\, \mu m}$ with the Sub-millimetre Common-User Bolometer Array 2) SCUBA-2 instrument and {\it Herschel}-Spectral and Photometric Imaging Receiver (SPIRE) selected sources (colour-colour diagrams and 500$\mathrm{\, \mu m}$ risers), finding that 185 have good multi-wavelength coverage. The resulting sample of 185 high-z candidates was further studied by spectral energy distribution (SED) fitting with the CIGALE fitting code. We derived photometric redshifts, stellar masses, SFRs, and additional physical parameters, such as the infrared luminosity and active galactic nuclei (AGN) contribution. We find that the different results in the literature are, only in part, due to selection effects. The difference in measured SFRs affects the position of DSFGs on the MS of galaxies; most of the DSFGs lie on the MS (60\%). Finally, we find that the star formation efficiency (SFE) depends on the epoch and intensity of the star formation burst in the galaxy; the later the burst, the more intense the star formation.

  • polycyclic aromatic hydrocarbon feature deficit of starburst galaxies in the akari north ecliptic pole deep field
    Astronomy and Astrophysics, 2014
    Co-Authors: Kazumi Murata, Hideo Matsuhara, Hanae Inami, Takehiko Wada, Tomotsugu Goto, L Armus, Chris Pearson
    Abstract:

    We study the behaviour of polycyclic aromatic hydrocarbon (PAH) emission in galaxies at z = 0.3–1.4 using 1868 samples from the revised catalogue of AKARI North Ecliptic Pole Deep survey. The continuous filter coverage at 2–24 μm makes it possible to measure 8 μm luminosity, which is dominated by PAH emission, for galaxies at up to z = 2. We compare the IR8 (≡L_(IR)/L(8)) and 8 μm to 4.5 μm luminosity ratio (νL(8) /νL(4.5)) with the starburstiness, R_(SB), defined as excess of specific star-formation rate over that of main-sequence galaxy. All AGN candidates were excluded from our sample using a spectral energy distribution fitting. We find νL(8) /νL(4.5) increases with starburstiness at log R_(SB) 0. This behaviour is seen in all redshift range of our study. These results indicate that starburst galaxies have deficient PAH emission compared with main-sequence galaxies. We also find that galaxies with extremely high νL(8) /νL(4.5) ratio have only moderate starburstiness. These results suggest that starburst galaxies have compact star-forming regions with intense radiation, which destroys PAHs, and/or have dusty HII regions resulting in a lack of ionising photons.

  • polycyclic aromatic hydrocarbon feature deficit of starburst galaxies in the akari north ecliptic pole deep field
    arXiv: Astrophysics of Galaxies, 2014
    Co-Authors: Kazumi Murata, Hideo Matsuhara, Hanae Inami, Takehiko Wada, Tomotsugu Goto, L Armus, Chris Pearson
    Abstract:

    We study the behaviour of polycyclic aromatic hydrocarbon emission in galaxies at z=0.3-1.4 using 1868 samples from the revised catalogue of AKARI North Ecliptic Pole Deep survey. The continuous filter coverage at 2-24um makes it possible to measure 8um luminosity, which is dominated by polycyclic aromatic hydrocarbon emission for galaxies at up to z=2. We compare the IR8 (= LIR/L(8)) and 8um to 4.5um luminosity ratio (L(8)/L(4.5)) with the starburstiness, Rsb, defined as excess of specific star -formation rate over that of main-sequence galaxy. All AGN candidates were excluded from our sample using an SED fitting. We found L(8)/L(4.5) increases with starburstiness at log Rsb 0. This behaviour is seen in all redshift range of our study. These results indicate that starburst galaxies have deficient polycyclic aromatic hydrocarbon emission compared with main-sequence galaxies. We also find that galaxies with extremely high L(8)/L(4.5) ratio have only moderate starburstiness. These results suggest that starburst galaxies have compact star-forming regions with intense radiation, which destroys PAHs and/or have dusty HII regions resulting in a lack of ionising photons.

K M Menten - One of the best experts on this subject based on the ideXlab platform.

  • trigonometric parallaxes of massive star forming regions ix the outer arm in the first quadrant
    The Astrophysical Journal, 2012
    Co-Authors: A Sanna, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler, T M Dame, Ye Xu
    Abstract:

    We report a trigonometric parallax measurement with the Very Long Baseline Array for the water maser in the distant high-mass star-forming region G75.30+1.32. This source has a heliocentric distance of 9.25(-0.40)(+0.45) kpc, which places it in the Outer arm in the first Galactic quadrant. It lies 200 pc above the Galactic plane and is associated with a substantial H i enhancement at the border of a large molecular cloud. At a Galactocentric radius of 10.7 kpc, G75.30+1.32 is in a region of the Galaxy where the disk is significantly warped toward the North Galactic Pole. While the star-forming region has an instantaneous Galactic orbit that is nearly circular, it displays a significant motion of 18 km s(-1) toward the Galactic plane. The present results, when combined with two previous maser studies in the Outer arm, yield a pitch angle of about 12 degrees for a large section of the arm extending from the first quadrant to the third.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    The Astrophysical Journal, 2009
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star-forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19+(0.24)(-0.20) kpc and 3.27+(0.56)(-0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star-forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of approximate to 13 km s(-1) and approximate to 16 km s(-1) counter to Galactic rotation and approximate to 9 km s(-1) toward the North Galactic Pole.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    arXiv: Astrophysics, 2008
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19 (+0.24 -0.20) kpc and 3.27 (+0.56 -0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of ~13 km/s and ~16 km/s counter to Galactic rotation and ~9 km/s toward the North Galactic Pole.

  • interstellar hydroxyl masers in the galaxy ii zeeman pairs and the galactic magnetic field
    The Astrophysical Journal, 2003
    Co-Authors: Vincent L Fish, M J Reid, A L Argon, K M Menten
    Abstract:

    We have identified and classified Zeeman pairs in the survey by Argon, Reid, & Menten of massive star-forming regions with 18 cm (2Π3/2,J = 3/2) OH maser emission. We have found a total of more than 100 Zeeman pairs in more than 50 massive star-forming regions. The magnetic field deduced from the Zeeman splitting has allowed us to assign an overall line-of-sight magnetic field direction to many of the massive star-forming regions. Combining these data with other data sets obtained from OH Zeeman splitting, we have looked for correlations of magnetic field directions between star-forming regions scattered throughout the Galaxy. Our data do not support a uniform, Galactic-scale field direction, nor do we find any strong evidence of magnetic field correlations within spiral arms. However, our data suggest that in the solar neighborhood the magnetic field outside the solar circle is oriented clockwise as viewed from the north Galactic pole, while inside the solar circle it is oriented counterclockwise. This pattern, including the magnetic field reversal near the Sun, is in agreement with results obtained from pulsar rotation measures.

A Brunthaler - One of the best experts on this subject based on the ideXlab platform.

  • trigonometric parallaxes of massive star forming regions ix the outer arm in the first quadrant
    The Astrophysical Journal, 2012
    Co-Authors: A Sanna, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler, T M Dame, Ye Xu
    Abstract:

    We report a trigonometric parallax measurement with the Very Long Baseline Array for the water maser in the distant high-mass star-forming region G75.30+1.32. This source has a heliocentric distance of 9.25(-0.40)(+0.45) kpc, which places it in the Outer arm in the first Galactic quadrant. It lies 200 pc above the Galactic plane and is associated with a substantial H i enhancement at the border of a large molecular cloud. At a Galactocentric radius of 10.7 kpc, G75.30+1.32 is in a region of the Galaxy where the disk is significantly warped toward the North Galactic Pole. While the star-forming region has an instantaneous Galactic orbit that is nearly circular, it displays a significant motion of 18 km s(-1) toward the Galactic plane. The present results, when combined with two previous maser studies in the Outer arm, yield a pitch angle of about 12 degrees for a large section of the arm extending from the first quadrant to the third.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    The Astrophysical Journal, 2009
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star-forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19+(0.24)(-0.20) kpc and 3.27+(0.56)(-0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star-forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of approximate to 13 km s(-1) and approximate to 16 km s(-1) counter to Galactic rotation and approximate to 9 km s(-1) toward the North Galactic Pole.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    arXiv: Astrophysics, 2008
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19 (+0.24 -0.20) kpc and 3.27 (+0.56 -0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of ~13 km/s and ~16 km/s counter to Galactic rotation and ~9 km/s toward the North Galactic Pole.

Bo Zhang - One of the best experts on this subject based on the ideXlab platform.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    The Astrophysical Journal, 2009
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star-forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19+(0.24)(-0.20) kpc and 3.27+(0.56)(-0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star-forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of approximate to 13 km s(-1) and approximate to 16 km s(-1) counter to Galactic rotation and approximate to 9 km s(-1) toward the North Galactic Pole.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    arXiv: Astrophysics, 2008
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19 (+0.24 -0.20) kpc and 3.27 (+0.56 -0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of ~13 km/s and ~16 km/s counter to Galactic rotation and ~9 km/s toward the North Galactic Pole.

M J Reid - One of the best experts on this subject based on the ideXlab platform.

  • trigonometric parallaxes of massive star forming regions ix the outer arm in the first quadrant
    The Astrophysical Journal, 2012
    Co-Authors: A Sanna, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler, T M Dame, Ye Xu
    Abstract:

    We report a trigonometric parallax measurement with the Very Long Baseline Array for the water maser in the distant high-mass star-forming region G75.30+1.32. This source has a heliocentric distance of 9.25(-0.40)(+0.45) kpc, which places it in the Outer arm in the first Galactic quadrant. It lies 200 pc above the Galactic plane and is associated with a substantial H i enhancement at the border of a large molecular cloud. At a Galactocentric radius of 10.7 kpc, G75.30+1.32 is in a region of the Galaxy where the disk is significantly warped toward the North Galactic Pole. While the star-forming region has an instantaneous Galactic orbit that is nearly circular, it displays a significant motion of 18 km s(-1) toward the Galactic plane. The present results, when combined with two previous maser studies in the Outer arm, yield a pitch angle of about 12 degrees for a large section of the arm extending from the first quadrant to the third.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    The Astrophysical Journal, 2009
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star-forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19+(0.24)(-0.20) kpc and 3.27+(0.56)(-0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star-forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of approximate to 13 km s(-1) and approximate to 16 km s(-1) counter to Galactic rotation and approximate to 9 km s(-1) toward the North Galactic Pole.

  • trigonometric parallaxes of massive star forming regions iv g35 20 0 74 and g35 20 1 74
    arXiv: Astrophysics, 2008
    Co-Authors: Bo Zhang, X W Zheng, M J Reid, K M Menten, L Moscadelli, A Brunthaler
    Abstract:

    We report trigonometric parallaxes for the high-mass star forming regions G35.20-0.74 and G35.20-1.74, corresponding to distances of 2.19 (+0.24 -0.20) kpc and 3.27 (+0.56 -0.42) kpc, respectively. The distances to both sources are close to their near kinematic distances and place them in the Carina-Sagittarius spiral arm. Combining the distances and proper motions with observed radial velocities gives the locations and full space motions of the star forming regions. Assuming a standard model of the Galaxy, G35.20-0.74 and G35.20-1.74 have peculiar motions of ~13 km/s and ~16 km/s counter to Galactic rotation and ~9 km/s toward the North Galactic Pole.

  • interstellar hydroxyl masers in the galaxy ii zeeman pairs and the galactic magnetic field
    The Astrophysical Journal, 2003
    Co-Authors: Vincent L Fish, M J Reid, A L Argon, K M Menten
    Abstract:

    We have identified and classified Zeeman pairs in the survey by Argon, Reid, & Menten of massive star-forming regions with 18 cm (2Π3/2,J = 3/2) OH maser emission. We have found a total of more than 100 Zeeman pairs in more than 50 massive star-forming regions. The magnetic field deduced from the Zeeman splitting has allowed us to assign an overall line-of-sight magnetic field direction to many of the massive star-forming regions. Combining these data with other data sets obtained from OH Zeeman splitting, we have looked for correlations of magnetic field directions between star-forming regions scattered throughout the Galaxy. Our data do not support a uniform, Galactic-scale field direction, nor do we find any strong evidence of magnetic field correlations within spiral arms. However, our data suggest that in the solar neighborhood the magnetic field outside the solar circle is oriented clockwise as viewed from the north Galactic pole, while inside the solar circle it is oriented counterclockwise. This pattern, including the magnetic field reversal near the Sun, is in agreement with results obtained from pulsar rotation measures.