astropy/photutils: v0.6

Bradley, Larry; Sipőcz, Brigitta; Robitaille, Thomas; Tollerud, Erik; Vinícius, Zé; Deil, C.; Barbary, Kyle; Günther, Hans Moritz; Cara, Mihai; Busko, I.; Conseil, Simon; Droettboom, Michael; Bostroem, Azalee; Bray, E. M.; Bratholm, Lars Andersen; Wilson, Tom J.; Craig, Matt; Barentsen, Geert; Pascual, S.; Donath, Axel; Greco, Johnny P.; Perren, G. I.; Lim, Pey Lian; Kerzendorf, Wolfgang

doi:10.5281/zenodo.2533376

Cited by 127 publications

(107 citation statements)

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“…Aperture photometry of the SDSS-g and SDSS-r images was carried out using photutils (Bradley et al 2019) and calibrated against field stars in the PanSTARRS catalogue (Chambers et al 2016). The optical counterpart of 4U 1812−12 is detected in both exposures, even though it is significantly fainter in the blue filter (g = 25.3 ± 0.3) than in the red band (r = 22.76 ± 0.07).…”

Section: Analysis and Resultsmentioning

confidence: 99%

Optical spectroscopy of 4U 1812–12

Padilla

Muñoz-Darias

Jiménez-Ibarra

et al. 2020

A&A

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The persistent low-luminosity neutron star X-ray binary 4U 1812−12 is a potential member of the scarce family of ultra-compact systems. We performed deep photometric and spectroscopic optical observations with the 10.4 m Gran Telescopio Canarias in order to investigate the chemical composition of the accreted plasma, which is a proxy for the donor star class. We detect a faint optical counterpart (g ∼ 25, r ∼ 23) that is located in the background of the outskirts of the Sharpless 54 H II region, whose characteristic nebular lines superimpose on the X-ray binary spectrum. Once this is corrected for, the actual source spectrum lacks hydrogen spectral features. In particular, the Hα emission line is not detected, with an upper limit (3σ) on the equivalent width of < 1.3 Å. Helium (He I) lines are also not observed, even though our constraints are not restrictive enough to properly test the presence of this element. We also provide stringent upper limits on the presence of emission lines from other elements, such as C and O, which are typically found in ultra-compact systems with C−O white dwarfs donors. The absence of hydrogen features, the persistent nature of the source at low luminosity, and the low optical–to–X-ray flux ratio confirm 4U 1812−12 as a compelling ultra-compact X-ray binary candidate, for which we tentatively propose a He-rich donor based on the optical spectrum and the detection of short thermonuclear X-ray bursts. In this framework, we discuss the possible orbital period of the system according to disc instability and evolutionary models.

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Section: Analysis and Resultsmentioning

confidence: 99%

Optical spectroscopy of 4U 1812–12

Padilla

Muñoz-Darias

Jiménez-Ibarra

et al. 2020

A&A

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“…The dust absorption on the "blue" filter data was estimated by subtracting a model of the stellar emission. We attempted to calculate the stellar emission model either with a functional form obtained with GAL-FIT 3 (Peng et al 2010) or with the python library photutils 4 (Bradley et al 2019), or with a linear function of the "red" filter assuming that the galaxy SED does not change much across the galaxy. For GALFIT, we first fitted a single component and increased the complexity up to three components (not including a sky background component).…”

Section: Dust Absorption From Hstmentioning

confidence: 99%

“…Software: CASA (v4.7.2, McMullin et al 2007), ZAP (Soto et al 2016), CIGALEMC (Serra et al 2011) MAG-PHYS14 (Da Cunha et al 2008, XSPEC (Arnaud 1996), SPEX (Kaastra et al 1996), scikit-learn (Pedregosa et al 2011, GALFIT (Peng et al 2010), photutils (Bradley et al 2019)…”

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confidence: 99%

Probing multiphase gas in local massive elliptical galaxies via multiwavelength observations

Temi,

Gaspari,

Brighenti

et al. 2022

Preprint

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We investigate the cold and warm gas content, kinematics, and spatial distribution of six local massive elliptical galaxies to probe the origin of the multiphase gas in their atmospheres. We report new observations, including SOFIA [CII], ALMA CO, MUSE Hα+[NII] and VLA radio observations. These are complemented by a large suite of multiwavelength archival datasets, including thermodynamical properties of the hot gas and radio jets, which are leveraged to investigate the role of AGN feeding/feedback in regulating the multiphase gas content. Our galaxy sample shows a significant diversity in cool gas content, spanning filamentary and rotating structures. In our non-central galaxies, the distribution of such gas is often concentrated, at variance with the more extended features observed in central galaxies. Misalignment between the multiphase gas and stars suggest that stellar mass loss is not the primary driver. A fraction of the cool gas might be acquired via galaxy interactions, but we do not find quantitative evidence of mergers in most of our systems. Instead, key evidence supports the origin via condensation out of the diffuse halo. Comparing with Chaotic Cold Accretion (CCA) simulations, we find that our cool gas-free galaxies are likely in the overheated phase of the self-regulated AGN cycle, while for our galaxies with cool gas the k-plot and AGN power correlation corroborate the phase of CCA feeding in which the condensation rain is triggering more vigorous AGN heating. The related C-ratio further shows that central/non-central galaxies are expected to generate an extended/inner rain, consistent with our sample.

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“…We run forced photometry at these SN locations using a pipeline, hereafter known as the ZUDS pipeline 1 (Dhawan et al, in prep), which performs aperture photometry using the Astropy affiliated package PhotUtils (Bradley et al 2019), using a six pixel diameter aperture on the difference images. The reference images for the difference images are constructed by co-adding exposures from epochs at least 30 days or more before the initial estimate of the time of maximum from the alert photometry, using the software SWARP (Bertin 2010).…”

Section: Data Processing Of the Transient Light Curvesmentioning

confidence: 99%

“…software: Numpy (van der Walt et al 2011), Astropy (Astropy Collaboration et al 2013, sncosmo (Barbary et al 2016), PhotUtils (Bradley et al 2019), ZTFQuery (Rigault 2018), SWARP (Bertin 2010), HOTPANTS (Becker 2015), ZUDS, fringez (Medford et al 2021), LAMBDAR Wright et al (2016), Prospector (Leja et al 2017), emcee (Foreman-Mackey et al 2013, pygtc (Bocquet & Carter 2016), matplotlib (Hunter 2007), IPAC forced Photometry Service.…”

Section: Data Availabilitymentioning

confidence: 99%

Two c’s in a pod: cosmology-independent measurement of the Type Ia supernova colour–luminosity relation with a sibling pair

Biswas

Goobar

Dhawan

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Using Zwicky Transient Facility (ZTF) observations, we identify a pair of ”sibling” Type Ia supernovae (SNe Ia), i.e., hosted by the same galaxy at z = 0.0541. They exploded within 200 days from each other at a separation of $0.6^{\prime \prime}$corresponding to a projected distance of only 0.6 kpc. Performing SALT2 light curve fits to the gri ZTF photometry, we show that for these equally distant ‘standardizable candles”, there is a difference of 2 magnitudes in their rest frame B-band peaks, and the fainter SN has a significantly red SALT2 colour c = 0.57 ± 0.04, while the stretch values x1 of the two SNe are similar, suggesting that the fainter SN is attenuated by dust in the interstellar medium of the host galaxy. We use these measurements to infer the SALT2 colour standardization parameter, β = 3.5 ± 0.3, independent of the underlying cosmology and Malmquist bias. Assuming the colour excess is entirely due to dust, the result differs by 2σ from the average Milky-Way total-to-selective extinction ratio, but is in good agreement with the colour-brightness corrections empirically derived from the most recent SN Ia Hubble-Lemaitre diagram fits. Thus we suggest that SN ”siblings”, which will increasingly be discovered in the coming years, can be used to probe the validity of the colour and lightcurve shape corrections using in SN Ia cosmology while avoiding important systematic effects in their inference from global multi-parameter fits to inhomogeneous data-sets, and also help constrain the role of interstellar dust in SN Ia cosmology.

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astropy/photutils: v0.6

Cited by 127 publications

References 0 publications

Optical spectroscopy of 4U 1812–12

Optical spectroscopy of 4U 1812–12

Probing multiphase gas in local massive elliptical galaxies via multiwavelength observations

Two c’s in a pod: cosmology-independent measurement of the Type Ia supernova colour–luminosity relation with a sibling pair

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