Variability of Accreting White Dwarf Binaries and Other Compact Objects

Manuel Pichardo Marcano (Texas Tech University)

Liliana Rivera Sandoval & Thomas J. Maccarone

Compact Binaries Surveys

1- SCOVaS: Survey for Compact Objects and Variables

Pichardo Marcano et al. (2021a)

Pichardo Marcano et al. (in prep.)

 

 

 

2- TACOS: TESS AM CVn Outbursts Survey

Pichardo Marcano et al. (2021b)

Compact Binaries Surveys

X-ray unbiased search

SCOVaS: Survey for Compact Objects and Variables Stars

  • HST Archive
  • 7 Globular Clusters
  • Many Exposures
  • Different properties
    • Metallicity
    • Core-collapsed
    • Non core-collapse

SCOVaS: Survey for Studying Compact Objects and Variables

  

  • Focus: Cataclysmic Variables (CVs) with HST
  • First Unbiased Survey for CVs in Globular Clusters
    • X-ray faint CVs
    • Orbital Periods
  • Spatial Distribution:
    • Looking at the dense Core of Clusters
    • Next: Search in the Outskirts
  • Optical Counterpart X-ray/Radio Sources in GCs

Preliminary Results

NGC 6397

  • WFPC-2
  • March-April 2005:
    • 126 orbits
    • F814W, F606W and F336W
    • Exp time: 500-700 s

Preliminary Results

NGC 6397

  • WFPC-2
  • March-April 2005:
    • 126 orbits
    • F814W, F606W and F336W
    • Exp time: 500-700 s

A new candidate Redback Pulsar

HUGS catalogue. (Piotto et al. 2015, Nardiello et al. 2018)

Pichardo Marcano et al. (2021a)

X-ray

HST F336W

Radio

Zhao et  al.(2020)

Zhao, [...], Pichardo Marcano,  et al. (2020)

A new candidate Redback MSP

Pichardo Marcano et. al (2021a)

  • Porb 1.96 days
  • Longest Porb for Redback in GCs
  • Missed MSP in Pulsar Searchers

Blue Variables

  • Periodicity Search:
    • Lomb-Scargle
    • Phase Dispersion Minimization
  • False Alarm Probability < 10-8

Light Curves of Known CV Candidates

High and Low state?

Nova-like Candidate

Pichardo Marcano et. al (in prep)

U19

U21

Nova-like Candidate

First Magnetic He WD Candidate

Pichardo Marcano et. al (in prep)

Magnetic He WD

  • Vrad > 100 km/s (MUSE)
  • Not Detected in X-rays
  • Rotation Period 
    • 18.4 hours

Pichardo Marcano et. al (in prep)

Pre-Cataclysmic Variable

Pichardo Marcano et. al (in prep)

Detached White Dwarf-Red Dwarf

  • Not Detected in X-rays
  • Potential Porb 
    • 5.21 hours

Pichardo Marcano et. al (in prep)

Detached White Dwarf-Red Dwarf

NGC 6397

  • Pipeline to find interesting objects:
    • CMD Position and Periodicity/Variability Searches
  • We were able to recover all known CV Candidates
  • Found Orbital Period Redback Pulsar
  • Detached White Dwarf-Red Dwarf
  • First Magnetic He Core WD in GCs
  • Many more variables to analyze...

Compact Binaries Surveys

1- SCOVaS: Survey for Compact Objects and Variables

Pichardo Marcano et al. (2021a)

Pichardo Marcano et al. (in prep.)

 

 

 

2- TACOS: TESS AM CVn Outbursts Survey

Pichardo Marcano et al. (2021b)

Compact Binaries Surveys

Outbursts

Pichardo Marcano et al. (2021)

  • Precursor
    • TESS (Duffy et al. 2021)
  • Echo Outbursts
  • DIM with Enhanced Mass Transfer  (e.g. Hameury & Lasota 2021)

TESS AM CVn Outbursts Survey

Pichardo Marcano et al. (2021)

ZTF

TESS

Long-term monitoring

Pichardo Marcano et al. (2021)

  • Orbital Periods:
    • 2-minute cadence
  • Limits on Recurrence Time
  • "Normal Outburts"

Superoutburst duration vs Porb

Pichardo Marcano et al. (2021)

TACOS Summary

  • Precursors and "Normal" Outbursts:
    • Relatively Common
    • Short Duration (missed by ground-based)
  • Echo Outbursts:
    • Different morphology
    • Enhanced Mass Transfer
  • Superoutburst durations overestimated
  • Two new candidate orbital periods
  • Color Evolution

Other work with Accreting WDs

  • Follow-up eROSITA transient:

  • TESS time series analysis

    • Atel: Pichardo Marcano (2020)

    • Paper: Schwope, [...], Pichardo Marcano, et al. (2021)

Caltech

Preliminary Results

M 92

  • WFPC-2
  • 2008-01-25 to 2008-01-30:
    • 76 Exposures
    • F555W
    • Exp time: 10 s

New Variables in the Core

SX Phe

 

  • Good Distance indicator:
    • Strong P-L relation
  • Less common than RR Lyrae
  • Blue Straggler
    • Product of Binary evolution

P = 1.38 hr

Pichardo Marcano et. al (in prep)

Summary

  • BlackGEM:
    • Time-domain astronomy
      • ZTF, ATLAS, TESS, HST
    • Experience Transients
      • Expand my expertise
      • Study 'contaminants'
  • Experience Spectroscopy:
    • IFU: MUSE, VIMOS
    • GEMINI

Future Work

NGC 6397

M 92

Spectroscopy (MUSE)

AO Gemini IR

Extra Slides

PTF1 J0719+4858:

  • Similar to Dwarf Novae:
    • Hameury et al. (2020)
    • Rivera Sandoval et al. (2021)

Color Evolution

Pichardo Marcano et al. (2021)

TACOS Summary

  • Precursors and "Normal" Outbursts:
    • Relatively Common
    • Short Duration (missed ground-based)
  • Echo Outbursts:
    • Different morphology
    • Enhanced Mass Transfer
  • SO durations overestimated
  • Two new candidate periods
  • Color Evolution

Long-term monitoring

Pichardo Marcano et al. (2021)

  • Orbital Periods:
    • 2-minute cadence
  • Limits on Recurrence Time
  • "Normal Outburts"

Outbursts

Pichardo Marcano et al. (2021)

Transiting Exoplanet Survey Satellite (TESS)

Caltech

  • Porb 20 to ~ 60 minutes (?)

  • Superoutburts (SO) and "Normal" outbursts (NO)

    • SO: Superhumps (periodic brightness variation )

  • Disk instability model (DIM)

    •  Constant Mass transfer rate

    • Tidal-thermal disk instability model

Outbursting Systems

Empirical Relationships

  1. Trec prop Porb^7.35
  2. Tdur prop Porb^4.54
  3. Delta mag prop Porb
  4. Long-term
  5. Ground-Based:
    1. PTF
    2. CRTS

Levitan et al. 2015

See also Duffy et al. 2021