TY - JOUR
T1 - Observed UV Continuum Slopes (β) of Galaxies at z = 0.40-0.75 in the GOODS-North Field
AU - Mondal, Chayan
AU - Saha, Kanak
AU - Windhorst, Rogier A.
AU - Jansen, Rolf A.
N1 - Funding Information:
This work is primarily based on observations taken by AstroSat/UVIT. The UVIT project is a result of collaboration between IIA, Bengaluru, IUCAA, Pune, TIFR, Mumbai, several centers of ISRO, and CSA. Indian Institutions and the Canadian Space Agency have contributed to the work presented in this paper. Several groups from ISAC (ISRO), Bengaluru, and IISU (ISRO), Trivandrum have contributed to the design, fabrication, and testing of the payload. The Mission Group (ISAC) and ISTRAC (ISAC) continue to provide support in making observations with and reception and initial processing of the data. We gratefully acknowledge all of the individuals involved in the various teams for providing their support to the project from the early stages of the design to launch and observations with it in orbit. This work also uses observations taken by the 3D-HST Treasury Program (HST-GO-12177 and HST-GO-12328) with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This research made use of Matplotlib (Hunter 2007), Astropy (Astropy Collaboration et al. 2013, 2018), and community-developed core Python packages for Astronomy and SAOImageDS9 (Joye & Mandel 2003). Finally, we thank the referee for providing valuable suggestions.
Funding Information:
This work is primarily based on observations taken by AstroSat/UVIT. The UVIT project is a result of collaboration between IIA, Bengaluru, IUCAA, Pune, TIFR, Mumbai, several centers of ISRO, and CSA. Indian Institutions and the Canadian Space Agency have contributed to the work presented in this paper. Several groups from ISAC (ISRO), Bengaluru, and IISU (ISRO), Trivandrum have contributed to the design, fabrication, and testing of the payload. The Mission Group (ISAC) and ISTRAC (ISAC) continue to provide support in making observations with and reception and initial processing of the data. We gratefully acknowledge all of the individuals involved in the various teams for providing their support to the project from the early stages of the design to launch and observations with it in orbit. This work also uses observations taken by the 3D-HST Treasury Program (HST-GO-12177 and HST-GO-12328) with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This research made use of Matplotlib (Hunter ), Astropy (Astropy Collaboration et al. , ), and community-developed core Python packages for Astronomy and SAOImageDS9 (Joye & Mandel ). Finally, we thank the referee for providing valuable suggestions.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/4/1
Y1 - 2023/4/1
N2 - We estimate the UV continuum slope (β) of 465 galaxies (with luminosities of 0.028-3.3 L z = 0.5 * ) in the Great Observatories Origins Survey Northern field in the redshift range z = 0.40-0.75. We use two AstroSat/UVIT (N242W, N245M) bands, two Hubble Space Telescope (F275W, F336W) bands, and a KPNO (U) band to sample the UV continuum slope of selected galaxies between 1215 and 2600 Å. The mean (median) and 1σ scatter in the observed β are found to be −1.33 ± 0.07 ( − 1.32) and 0.60 within the considered redshift range. We do not find any significant evolution in the mean β within our redshift window. Our measurements add new data points to the global β-z relation in the least-explored redshift regime, further reinforcing the gradual reddening of galaxy UV continuum with cosmic time. We notice no strong consistent trend between β and M 1500 for the entire luminosity range −21 <M 1500 < − 15 mag. However, the majority of the most-luminous galaxies (M 1500 < − 19 mag) are found to have relatively redder slopes. Using UVIT, we detect galaxies as faint as M 1500 = − 15.6 mag (i.e., 0.028 L z = 0.5 * ). The faintest galaxies (M 1500 > − 16 mag) tend to be redder, which indicates they were less actively forming stars during this cosmic time interval. Our study highlights the unique capability of UVIT near-UV imaging to characterize the rest-frame far-UV properties of galaxies at redshift z ∼ 0.5.
AB - We estimate the UV continuum slope (β) of 465 galaxies (with luminosities of 0.028-3.3 L z = 0.5 * ) in the Great Observatories Origins Survey Northern field in the redshift range z = 0.40-0.75. We use two AstroSat/UVIT (N242W, N245M) bands, two Hubble Space Telescope (F275W, F336W) bands, and a KPNO (U) band to sample the UV continuum slope of selected galaxies between 1215 and 2600 Å. The mean (median) and 1σ scatter in the observed β are found to be −1.33 ± 0.07 ( − 1.32) and 0.60 within the considered redshift range. We do not find any significant evolution in the mean β within our redshift window. Our measurements add new data points to the global β-z relation in the least-explored redshift regime, further reinforcing the gradual reddening of galaxy UV continuum with cosmic time. We notice no strong consistent trend between β and M 1500 for the entire luminosity range −21 <M 1500 < − 15 mag. However, the majority of the most-luminous galaxies (M 1500 < − 19 mag) are found to have relatively redder slopes. Using UVIT, we detect galaxies as faint as M 1500 = − 15.6 mag (i.e., 0.028 L z = 0.5 * ). The faintest galaxies (M 1500 > − 16 mag) tend to be redder, which indicates they were less actively forming stars during this cosmic time interval. Our study highlights the unique capability of UVIT near-UV imaging to characterize the rest-frame far-UV properties of galaxies at redshift z ∼ 0.5.
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U2 - 10.3847/1538-4357/acc110
DO - 10.3847/1538-4357/acc110
M3 - Article
AN - SCOPUS:85152245974
SN - 0004-637X
VL - 946
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 90
ER -