Active Galactic Nuclei and the Truncation of Star Formation in K+a Galaxies

Brown, M. J. I.; Moustakas, John; Caldwell, Nelson; Palamara, David P.; Cool, R. J.; Dey, Arjun; Hickox, Ryan C.; Jannuzi, Buell T.; Murray, Stephen S.; Zaritsky, Dennis

doi:10.1088/0004-637x/703/1/150

Cited by 28 publications

(53 citation statements)

References 60 publications

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“…However, their location in the upper right corner of the UVgz diagram is consistent with little or no dust extinction(cf. Balogh et al 2005;Kaviraj et al 2007;Brown et al 2009;Chilingarian & Zolotukhin 2012;Whitaker et al 2012). We also showed in Figure 5 that about 80% of QPSBs do not show significantly dust-obscured star formation (have f 12 μm /f 0.2 μm < 200).…”

Section: A2 the Color-color Diagram: The Intrinsic Colors Of Obscursupporting

confidence: 61%

“…These sources are mostly low-luminosity AGNs at best and have a hard mean stacked X-ray spectrum suggesting moderate levels of obscured AGN activity in the bulk of this population. Similarly, Brown et al (2009) have found that one-third (8/24) of their K+A galaxies at z ∼ 0.2 are X-ray sources with luminosities of ∼10 42 erg s −1 . To improve on these previously incomplete estimates of the AGN fraction in post-starbursts, we assemble a large and less biased sample of post-starbursts, which includes emissionline galaxies, to robustly identify AGNs.…”

Section: Finding All Agns Including a Population Of Highly Obscured mentioning

confidence: 78%

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From Starburst to Quiescence: Testing Active Galactic Nucleus Feedback in Rapidly Quenching Post-Starburst Galaxies

Yesuf

Faber

Trump

et al. 2014

ApJ

121

151

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Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses Sloan Digital Sky Survey, the Galaxy Evolution Explorer, and Wide-field Infrared Survey Explorer observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts (QPSBs) in the narrow mass range log M(M ) = 10.3-10.7, and identifies "transiting" post-starbursts (TPSBs) which are intermediate between these two populations. In this mass range, ∼0.3% of galaxies are starbursts, ∼0.1% are QPSBs, and ∼0.5% are the transiting types in between. The TPSBs have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The active galactic nucleus (AGN) fraction, as estimated from optical line ratios, of these post-starbursts is about three times higher ( 36% ± 8%) than that of normal star forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of 200 ± 100 Myr), in agreement with previous studies. The time delay is inferred by comparing the broadband near-NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust obscured than normal star forming galaxies in the same mass range. About 20% of the starbursts and 15% of the TPSBs can be classified as "dust-obscured galaxies" (DOGs), with a near-UV-to-mid-IR flux ratio of 900, while only 0.8% of normal galaxies are DOGs. The time delay between the starburst phase and AGN activity suggests that AGNs do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation by removing gas and dust during the post-starburst phase.

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Section: A2 the Color-color Diagram: The Intrinsic Colors Of Obscursupporting

confidence: 61%

Section: Finding All Agns Including a Population Of Highly Obscured mentioning

confidence: 78%

From Starburst to Quiescence: Testing Active Galactic Nucleus Feedback in Rapidly Quenching Post-Starburst Galaxies

Yesuf

Faber

Trump

et al. 2014

ApJ

121

151

View full text Add to dashboard Cite

show abstract

“…Many studies into post-starbursts have aimed to confirm the presence of AGNs in these systems. Brown et al (2009) observed a slight enhancement in X-rays in a sample of K+A galaxies in the NOAO Deep Wide-field Survey, though not to a significance to be definitively from AGN emission. Shin et al (2011) cross-identify 1.4 GHz FIRST (Becker et al 1995) sources with the Goto (2007) E+A sample, but detections are ambiguous (most sources unresolved and lacking clear radio jets).…”

Section: Agns In Post-starburstsmentioning

confidence: 81%

Welcome to the Twilight Zone: The Mid-infrared Properties of Post-starburst Galaxies

Alatalo

Bitsakis

Lanz

et al. 2017

ApJ

Self Cite

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We investigate the optical and Wide-field Survey Explorer (WISE) colors of "E+A" identified post-starburst galaxies, including a deep analysis of 190 post-starbursts detected in the 2 μm All Sky Survey Extended Source Catalog. The post-starburst galaxies appear in both the optical green valley and the WISE Infrared Transition Zone. Furthermore, we find that post-starbursts occupy a distinct region of WISE colors, enabling the identification of this class of transitioning galaxies through the use of broadband photometric criteria alone. We have investigated possible causes for the WISE colors of post-starbursts by constructing a composite spectral energy distribution (SED), finding that the mid-infrared (4-12 μm) properties of post-starbursts are consistent with either 11.3 μm polycyclic aromatic hydrocarbon emission, or thermally pulsating asymptotic giant branch (TP-AGB) and post-AGB stars. The composite SED of extended post-starburst galaxies with 22 μm emission detected with signal-to-noise ratio 3  requires a hot dust component to produce their observed rising midinfrared SED between 12 and 22 μm. The composite SED of WISE22 μm non-detections (S/N<3), created by stacking 22 μm images, is also flat, requiring a hot dust component. The most likely source of the mid-infrared emission of these E+A galaxies is a buried active galactic nucleus (AGN). The inferred upper limits to the Eddington ratios of post-starbursts are 10 −2 -10 −4 , with an average of 10. This suggests that AGNs are not radiatively dominant in these systems. This could mean that including selections capable of identifying AGNs as part of a search for transitioning and post-starburst galaxies would create a more complete census of the transition pathways taken as a galaxy quenches its star formation.

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“…Although the SDSS spectroscopy aims to be 100% complete at r=17.77 (Strauss et al 2002), we find that our sample is ∼80% complete at this level, as shown in Fig.1. Most studies of post-starbursts use a typical S/N of 3-5 in the continuum, as evidenced by Pracy et al (2005) (S/N>5); Couch & Sharples (1987) (S/N>3) and Brown et al (2009) (S/N>4), hence we adopt a minimum S/N of 5.…”

Section: Sample Selectionmentioning

confidence: 99%

The evolutionary sequence of post-starburst galaxies

Wilkinson

Pimbblet

Stott

2017

Monthly Notices of the Royal Astronomical Society

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There are multiple ways in which to select post-starburst galaxies in the literature. In this work, we present a study into how two well-used selection techniques have consequences on observable post-starburst galaxy parameters, such as colour, morphology and environment and how this affects interpretations of their role in the galaxy duty cycle. We identify a master sample of Hδ strong (EW Hδ > 3Å) post-starburst galaxies from the value-added catalogue in the 7th data release of the Sloan Digital Sky Survey (SDSS DR7) over a redshift range 0.01 < z < 0.1. From this sample we select two E+A subsets, both having a very little [OII] emission (EW OII > −2.5Å) but one having an additional cut on EW Hα (> −3Å). We examine the differences in observables and AGN fractions to see what effect the Hα cut has on the properties of post-starburst galaxies and what these differing samples can tell us about the duty cycle of post-starburst galaxies. We find that Hδ strong galaxies peak in the 'blue cloud', E+As in the 'green valley' and pure E+As in the 'red sequence'. We also find that pure E+As have a more early-type morphology and a higher fraction in denser environments compared with the Hδ strong and E+A galaxies. These results suggest that there is an evolutionary sequence in the post-starburst phase from blue disky galaxies with residual star formation to passive red early-types.

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Active Galactic Nuclei and the Truncation of Star Formation in K+a Galaxies

Cited by 28 publications

References 60 publications

From Starburst to Quiescence: Testing Active Galactic Nucleus Feedback in Rapidly Quenching Post-Starburst Galaxies

From Starburst to Quiescence: Testing Active Galactic Nucleus Feedback in Rapidly Quenching Post-Starburst Galaxies

Welcome to the Twilight Zone: The Mid-infrared Properties of Post-starburst Galaxies

The evolutionary sequence of post-starburst galaxies

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