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Measuring the Heating and Cooling of the Interstellar Medium at High Redshift: PAH and [C II] Observations of the Same Star-forming Galaxies at z ∼ 2

McKinney, Jed and Pope, Alexandra and Armus, Lee and Chary, Ranga-Ram and Díaz-Santos, Tanio and Dickinson, Mark E. and Kirkpatrick, Allison (2020) Measuring the Heating and Cooling of the Interstellar Medium at High Redshift: PAH and [C II] Observations of the Same Star-forming Galaxies at z ∼ 2. Astrophysical Journal, 892 (2). Art. No. 119. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20200403-115232187

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Abstract

Star formation depends critically on cooling mechanisms in the interstellar medium (ISM); however, thermal properties of gas in galaxies at the peak epoch of star formation (z ~ 2) remain poorly understood. A limiting factor in understanding the multiphase ISM is the lack of multiple tracers detected in the same galaxies, such as Polycyclic Aromatic Hydrocarbon (PAH) emission, a tracer of a critical photoelectric heating mechanism in interstellar gas, and [C ii] 158 μm fine-structure emission, a principal coolant. We present ALMA Band 9 observations targeting [C ii] in six z ~ 2 star-forming galaxies with strong Spitzer IRS detections of PAH emission. All six galaxies are detected in dust continuum and marginally resolved. We compare the properties of PAH and [C ii] emission, and constrain their relationship as a function of total infrared luminosity (L_(IR)) and IR surface density. [C ii] emission is detected in one galaxy at high signal-to-noise (34σ), and we place a secure upper limit on a second source. The rest of our sample are not detected in [C ii] likely due to redshift uncertainties and narrow ALMA bandpass windows. Our results are consistent with the deficit in [C ii]/L_(IR) and PAH/L_(IR) observed in the literature. However, the ratio of [C ii] to PAH emission at z ~ 2 is possibly much lower than what is observed in nearby dusty star-forming galaxies. This could be the result of enhanced cooling via [O i] at high-z, hotter gas and dust temperatures, and/or a reduction in the photoelectric efficiency, in which the coupling between interstellar radiation and gas heating is diminished.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ab77b9DOIArticle
ORCID:
AuthorORCID
McKinney, Jed0000-0002-6149-8178
Pope, Alexandra0000-0001-8592-2706
Armus, Lee0000-0003-3498-2973
Chary, Ranga-Ram0000-0001-7583-0621
Díaz-Santos, Tanio0000-0003-0699-6083
Dickinson, Mark E.0000-0001-5414-5131
Kirkpatrick, Allison0000-0002-1306-1545
Additional Information:© 2020. The American Astronomical Society. Received 2019 November 26; revised 2020 February 12; accepted 2020 February 17; published 2020 April 3. We are very grateful to the referee for the detailed comments and suggestions that significantly improved this work. J.M. and A.P. acknowledge D. Brisbin and C. Ferkinhoff for assistance in interpreting ZEUS [C ii] results. J.M. acknowledges I. Yoon, J. Braatz, and J. Thorley for their insights into ALMA data reduction. We thank J. D. Smith for his helpful discussion. T.D-S. acknowledges support from the CASSACA and CONICYT fund CAS-CONICYT Call 2018. Support for this work was provided by the NSF through award SOSPA5-008 from the NRAO and through the Massachusetts Space Grant Consortium (MASGS). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2017.1.01347.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
CAS South America Center for AstronomyUNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
National Radio Astronomy ObservatorySOSPA5-008
Massachusetts Space Grant ConsortiumUNSPECIFIED
NSFUNSPECIFIED
Subject Keywords:Starburst galaxies ; Galaxies ; Galaxy evolution ; Interstellar medium ; High-redshift galaxies ; Ultraluminous infrared galaxies
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Starburst galaxies (1570); Galaxies (573); Galaxy evolution (594); Interstellar medium (847); High-redshift galaxies (734); Ultraluminous infrared galaxies (1735)
Record Number:CaltechAUTHORS:20200403-115232187
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200403-115232187
Official Citation:Jed McKinney et al 2020 ApJ 892 119
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102327
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Apr 2020 20:30
Last Modified:03 Apr 2020 20:30

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